Análises da mediação e moderação do mindfulness sobre medidas de afeto, ansiedade e estresse em adultos jovens saudáveis

1 UNIVERSIDADE FEDERAL DO RIO GRANDE DO NORTE

PROGRAMA DE PÓS-GRADUAÇÃO EM NEUROCIÊNCIAS

Análises da mediação e moderação do mindfulness sobre medidas de afeto, ansiedade e estresse em adultos jovens saudáveis

AUTOR: Geovan Menezes de Sousa Júnior ORIENTADORA: Maria Bernardete Cordeiro de Sousa

2 GEOVAN MENEZES DE SOUSA JÚNIOR

Análises da mediação e moderação do mindfulness sobre medidas de afeto, ansiedade e estresse em adultos jovens saudáveis

Dissertação apresentada ao Programa de Pós- Graduação em Neurociências da Universidade Federal do Rio Grande do Norte como pré-requisito parcial para obtenção do título de Mestre em Neurociências.

Área de Concentração: Ciências Biológicas II- Neurobiologia de Sistemas e Cognição

ORIENTADORA: Maria Bernardete Cordeiro de Sousa

Natal 2020

3

Universidade Federal do Rio Grande do Norte - UFRN Sistema de Bibliotecas - SISBI

Catalogação de Publicação na Fonte. UFRN - Biblioteca Setorial Árvore do Conhecimento - Instituto do Cérebro - ICE

Sousa Júnior, Geovan Menezes de.

Análises da mediação e moderação do mindfulness sobre medidas de afeto, ansiedade e estresse em adultos jovens saudáveis / Geovan Menezes de Sousa Júnior. - Natal, 2020.

52f.: il.

Dissertação (mestrado) - Instituto do Cérebro, Programa de Pós-Graduação em Neurociências, Universidade Federal do Rio Grande do Norte, 2020.

Orientadora: Maria Bernardete Cordeiro de Sousa.

1. Treinamento de mindfulness. 2. Atenção plena. 3. Bem-estar psicológico. 4. Psicofisiologia. 5. Relações metafísicas mente-corpo. I. Sousa, Maria Bernardete Cordeiro de. II. Título. RN/UF/Biblioteca Setorial Árvore do Conhecimento CDU 159.95

4 Nome: Geovan Menezes de Sousa Júnior

Título: Análises da mediação e moderação do mindfulness sobre medidas de afeto, ansiedade e estresse em adultos jovens saudáveis

Dissertação apresentada ao Programa de Pós-Graduação em Neurociências da Universidade Federal do Rio Grande do Norte como pré-requisito para obtenção do título de Mestre em Neurociências.

Aprovação em: ____/____/____

Banca examinadora

__________________________________________________ Dra. Maria Bernardete Cordeiro de Sousa (Orientadora)

Instituto do Cérebro

Universidade Federal do Rio Grande do Norte (UFRN)

__________________________________________________ Dr. Dráulio Barros de Araújo

Instituto do Cérebro

Universidade Federal do Rio Grande do Norte (UFRN)

__________________________________________________ Dr. Luiz Carlos Serramo Lopez

Departamento de Sistemática e Ecologia Universidade Federal da Paraíba (UFPB)

5 AGRADECIMENTOS

Estudar é um ato de resistência. Este fato torna-se ainda mais claro quando se é de origem rural, pobre e etnia diferente da branca. A cada novo título recebido, me vem mais forte a lembrança de que minhas conquistas dependem, principalmente, de algumas mulheres: minha mãe, Severina, e minhas irmãs, Gabriela e Camila. Tudo surge da insistência de uma mãe solo e agricultora do agreste que confiou seu filho aos estudos. A partir daí, acreditei que era capaz viver uma vida diferente. Foi por causa do suporte e abrigo que afirmo a importância das minhas irmãs em tudo que faço. A essas mulheres fortes, meu amor e meu imenso agradecimento.

E como “ninguém educa ninguém, ninguém educa a si mesmo, os homens se educam entre si, mediatizados pelo mundo”, conforme dizia Paulo Freire, devo agradecer também às mulheres que estiveram presentes na minha vida acadêmica e que me proporcionaram o prazer pelo conhecimento e pela Ciência. Nicole Coelho, que, mais que me orientar durante a iniciação científica, me introduziu ao pensamento científico; Geissy Araújo, que aceitou a colaboração para explorar seus dados do doutorado, com quem tanto tenho aprendido no último ano, cujo suporte fez imensa diferença e tornou esse processo menos estressante e mais prazeroso — sua parceria tem enorme relevância; Professora Bernardete Sousa, a quem sempre tive imensa admiração e cujo apoio têm sido crucial para esse momento, incluindo Skype nas férias e qualificação nas vésperas de Ano Novo — hoje, além de admiração, sinto honra pela oportunidade de fazer parte da sua carreira acadêmica como aprendiz. A essas mulheres, minha inspiração e meus agradecimentos.

Agradeço também aos professores Nicole Coelho e Dráulio Barros por aceitarem a participação como membros do Comitê de Acompanhamento, inclusive durante as vésperas de Ano Novo. Esse trabalho não seria o mesmo sem suas importantes contribuições. Da mesma forma, adianto os agradecimentos ao Professor Luiz Lopez por aceitar compor a banca de avaliação junto ao Professor Dráulio.

Finalmente, preciso agradecer a Vinícius, meu namorado, sempre disposto a me ouvir e me apoiar, e a quem devo o suporte diário; aos amigos do BELab (Rafaela, Luana, Thati...), do LMH (Lara, Raíssa, as Cecílias, Erick, Martina, Mari, Lílian...), da graduação (Lara de novo, Alana, Matheus, Ray e Holda...) e do ICe, pelos aprendizados, saídas e risadas juntos; vocês são parte essencial. E obrigado a Alexandra Elbakyan, sem a qual seria impossível fazer Ciência em um país em desenvolvimento.

6 SUMÁRIO CONSIDERAÇÕES INICIAIS ... 7 RESUMO ... 9 ABSTRACT ... 11 INTRODUÇÃO GERAL ... 13

Estresse e estilo de vida ... 13

Mindfulness ... 14

OBJETIVOS ... 18

Geral ... 18

Específicos ... 18

ARTIGO – Brief Mindfulness-based Training and Mindfulness Trait Attenuate Psychological Stress in University Students ... 19

Abstract ... 21

1. Introduction ... 22

2. Materials and Methods ... 25

3. Results ... 29

4. Discussion ... 36

References ... 40

Appendix: Supplementary material ... 46

Supplementary figure 1 ... 46

Supplementary table 1 ... 47

Supplementary figure 2 ... 48

CONSIDERAÇÕES FINAIS ... 49

7 CONSIDERAÇÕES INICIAIS

O presente projeto consiste em um conjunto de análise de dados gerados a partir do projeto de doutorado de Geissy Lainny de Lima Araújo (ARAÚJO, 2018). Tal projeto consistiu em uma intervenção randomizada e controlada (por controle ativo) para avaliar os efeitos psicofisiológicos agudos de uma prática breve de mindfulness sobre habilidades atencionais e interoceptivas, reatividade ao estresse, e medidas de afeto e ansiedade. A intervenção do grupo mindfulness (n=20, 10 mulheres) consistia em uma prática breve de mindfulness guiada por áudio, enquanto o grupo controle (n=20, 10 mulheres) ouvia um áudio com temas relacionados à saúde seguido de uma atividade de pintura de um livro para colorir; ambas as intervenções tiveram os mesmos 30 minutos de duração e ocorreram em 3 dias consecutivos.

Para avaliar o efeito dessa intervenção breve, foram coletados dados autorrelatados (questionários e escalas para mensurar traço e estado de mindfulness e de ansiedade, afeto positivo e negativo, estresse percebido, sensibilidade interoceptiva e devaneio) e dados fisiológicos (bioquímicos e eletrofisiológicos: cortisol salivar e plasmático, variabilidade da frequência cardíaca, resposta galvânica da pele e eletroencefalografia), durante o contexto basal (no primeiro dia experimental, antes da intervenção) e no terceiro dia experimental, após a intervenção. No primeiro e terceiro dias, o participante também era submetido a um teste de atenção sustentada (Go/No-Go), uma tarefa de estresse (Mannheim multicomponent stress test) e um teste de interocepção (contagem de batimentos cardíacos em blocos de 25, 35 e 45 segundos), sendo a eletroencefalografia e os dados autonômicos coletados nesse contexto (delineamento experimental na figura abaixo; extraído de ARAÚJO, 2018).

8 Diante do conjunto de dados gerados, outras possíveis perguntas passíveis de investigação emergiram, como a implicação do traço de mindfulness nesse contexto. Mais especificamente, na presente dissertação, buscamos responder à pergunta: Indivíduos com alto traço de mindfulness diferem daqueles com baixo traço em nível basal e em resposta a uma intervenção breve baseada em mindfulness? Dessa forma, buscamos contribuir para a compreensão das diferenças individuais na habilidade frente à prática de mindfulness, investigando seus correlatos psicológicos a fim de gerar novos conhecimentos sobre seus mecanismos psicofisiológicos e neurobiológicos.

9 RESUMO

O estilo de vida contemporâneo tem promovido forte impacto na saúde e bem-estar mental das pessoas, conforme sugerem indicadores atuais da Organização Mundial de Saúde. Tal comprometimento, geralmente, está vinculado à desregulação dos mecanismos psicofisiológicos da resposta ao estresse, dada à variedade e à frequência de eventos estressores aos quais a população está exposta diariamente. Neste contexto, intervenções não-medicamentosas para reduzir o impacto destes agentes têm sido utilizadas, entre as quais, aquelas que integram as dimensões mente x corpo, como o mindfulness (ou atenção plena). Esta prática meditativa, que tem sido implicada na redução de sintomas de ansiedade, depressão e estresse, é normalmente definida em termos da habilidade para voltar a atenção ao momento presente com abertura, aceitação e gentileza, sendo avaliada como um estado ou um traço. Deste modo, o presente estudo se propôs a demonstrar, por meio de uma abordagem exploratória, se uma prática breve de mindfulness é influenciada pelo traço ou estado de mindfulness, ou ambos, e interfere sobre variáveis que expressam bem-estar psicológico. As nossas hipóteses predizem que (1) o alto traço de mindfulness está associado a melhor bem-estar psicológico; (2) a prática breve de mindfulness reduz os indicadores negativos e aumenta os indicadores positivos de bem-estar psicológico e, (3) essas mudanças são mediadas pelo aumento no estado de mindfulness induzido pela prática. A amostra foi formada por jovens universitários saudáveis (n=40; 20 homens) e foram coletadas medidas associadas à ansiedade (IDATE), afeto (PANAS), estresse (PSS, cortisol plasmático) e mindfulness (estado, SMS; traço, FFMQ). Inicialmente, por meio de uma análise de cluster (k-means), tais indivíduos foram classificados como alto/baixo traço de

mindfulness, na qual aqueles com traço alto apresentaram menores níveis de estado e traço

de ansiedade e de estresse percebido. Adicionalmente, a amostra foi testada a partir de sua divisão em um grupo controle (GC, n=20) e um grupo mindfulness (GM, n=20) utilizando uma análise de variância mista (between: grupo, within: sessão [antes/após intervenção]) para investigar o efeito da intervenção entre e dentre os grupos. Apenas dentro do GM houve redução do estado de ansiedade e do estresse percebido, e aumento do estado de

mindfulness, após a prática. Dentro de ambos os grupos houve redução do afeto negativo e

dos níveis plasmáticos de cortisol, e nenhuma diferença foi encontrada em relação ao afeto positivo. Uma análise de mediação moderada evidenciou que o aumento do estado de

mindfulness medeia aumento no afeto positivo e redução no estresse percebido e no

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só ocorreu em indivíduos com alto traço de mindfulness. A despeito das limitações do tamanho amostral e da natureza exploratória do estudo, que utilizou múltiplas testagens para o mesmo conjunto de dados, esses resultados sugerem que o traço de mindfulness está associado a baixos níveis de estresse, e que uma intervenção breve baseada em mindfulness promove uma atenuação na resposta psicofisiológica negativa e media aumento no afeto positivo. Estes resultados apontam para um efeito positivo de uma prática breve de

mindfulness, em um grupo específico de indivíduos, e abre perspectivas para novas

investigações e sua aplicação em diferentes populações.

Palavras-chave: traço de mindfulness, treinamento de mindfulness, bem-estar psicológico,

11 ABSTRACT

Contemporary lifestyle has a strong impact on people's health and mental well-being, as suggested by current World Health Organization indicators. Such impairment is generally linked to the deregulation of the psychophysiological mechanisms of stress response, given the variety and the frequency of stressful events to which the population is exposed daily. In this context, non-pharmacological interventions to reduce the impact of these agents have been used, including those that integrate the mind and body dimensions, such as mindfulness. This meditative practice, which has been implicated in reducing symptoms of anxiety, depression, and stress, is usually defined in terms of the ability to pay attention to the present moment with openness, acceptance, and kindness, being evaluated as a state or a trait. Thus, the present study aimed to demonstrate, through an exploratory approach, whether a brief practice of mindfulness depends on the trait or state of mindfulness, or both, and interferes with variables that express psychological well-being. Our hypotheses predict that (1) the high level of mindfulness is associated with better psychological well-being; (2) a brief practice of mindfulness reduces the indicators and increases the positive indicators of psychological well-being, and (3) these changes are mediated by practice-induced increase in state mindfulness. A sample consisted of healthy young university students (n = 40; 20 men) and measures associated with anxiety (STAI), affect (PANAS), stress (PSS, plasma cortisol), and mindfulness (state, SMS and trait, FFMQ) were collected. Initially, by means of a cluster analysis (k-means), these individuals were classified as high / low mindfulness trait, in which those with high trait presented lower levels of anxiety state and perceived stress. Additionally, the sample was tested by dividing it into an active control group (AC, n = 20) and a mindfulness training group (MT, n = 20) using a mixed variance analysis (between: group, within: session [before / after intervention]) to investigate the effect of the intervention between and within groups. Only within MT there was a reduction in the anxiety state and perceived stress in addition to an increase in state mindfulness after the practice. Within both groups there was a reduction in negative affect and plasma cortisol levels and no difference was found for positive affect. Moderated mediation analysis showed that the increase in state mindfulness mediated an increase in positive affect and a decrease in perceived stress and cortisol. The mediating effect of state mindfulness in decreasing anxiety state occurs only in individuals with high mindfulness trait. Despite the limitations of the sample size and the exploratory nature of the study, which uses multiple tests for the same dataset, these results suggest that the

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mindfulness trait is associated with lower stress levels, and that a brief mindfulness-based intervention promotes attenuation of the negative psychophysiological response, and mediate increase in positive affect. These results point to a positive effect of a brief mindfulness practice in a specific group of individuals, and open perspectives for further investigation and its application in different populations.

Keywords: mindfulness trait, mindfulness training, psychological well-being, mind-body

13 INTRODUÇÃO GERAL

Estresse e estilo de vida

A mudança no estilo de vida das sociedades pós-modernas tem levado a significativo adoecimento mental e físico (EGGER, 2017; EHLERS; KAUFMANN, 2010). Uma das consequências deste novo contexto social implica, frequentemente, na ativação do sistema de resposta ao estresse, cuja desregulação pode levar ao desenvolvimento de transtornos neuropsiquiátricos (KENDLER; KARKOWSKI; PRESCOTT, 1999; MCEWEN, 2017), cuja prevalência tem crescido em todo o mundo, sendo os mais representativos a depressão (4,4% global, 5,8% no Brasil), e a ansiedade (3,6% global; 9,3% no Brasil) (WORLD HEALTH ORGANIZATION, 2017).

A resposta ao estresse evoluiu como um fenômeno biológico de enorme valor adaptativo, diretamente relacionado à sobrevivência do indivíduo e composto por mecanismos de ativação difusos, envolvendo, principalmente, sistema nervoso autônomo (SNA), eixo hipotálamo-pituitária-adrenal (HPA) e sistema imune. Assim, frente a um agente estressor (real ou imaginário) que traga risco à integridade física/saúde ou à homeostase, uma resposta generalizada e inespecífica é desencadeada pela mobilização de sistemas que preparam o indivíduo somática e cognitivamente para enfrentá-lo (SOUSA; SILVA; GALVÃO-COELHO, 2015).

O evento estressor desencadeia a ativação da divisão simpática do sistema nervoso autônomo, promovendo um estado de alerta geral, incrementando funções cardiorrespiratórias, imunes e metabólicas, além de mobilizar e direcionar compostos energéticos para músculos e encéfalo, e ativar o núcleo paraventricular do hipotálamo (PVN) (HERMAN et al., 2016). As células parvocelulares do PVN liberam o fator de liberação da corticotrofina (CRF, corticotropin releasing factor) na circulação porta-hipofisária, de forma que este alcança a hipófise e estimula a produção e liberação de hormônio adrenocorticotrófico (ACTH, adrenocorticotropic hormone). O ACTH, por sua vez, é liberado na circulação sistêmica e, ao alcançar a glândula adrenal, induz a síntese e secreção de corticosteroides, principalmente do glicocorticoide cortisol, por meio da estimulação de enzimas esteroidogênicas (FEHER, 2016). O cortisol liberado é transportado por globulinas e/ou albuminas para que exerça seus efeitos, que consistem na mobilização (glicogenólise, lipólise, e gliconeogênese) e no direcionamento energético para encéfalo e músculos (inibição do crescimento, reprodução e digestão), e atuando em áreas

14 cerebrais chave da resposta ao estresse, tais como hipotálamo, córtex pré-frontal, hipocampo e complexo amigdaloide (SAPOLSKY, 2015).

Embora o arcabouço neurobiológico para o enfrentamento ao estresse seja filogeneticamente conservado nos vertebrados, a resposta é multifatorial e pode ser fortemente modulada por fatores individuais (como estilo de enfrentamento, sexo, idade e (epi)genótipo). Adicionalmente, esta resposta é influenciada pelas características do evento estressor como a controlabilidade, previsibilidade, duração e intensidade (GALVÃO-COELHO; SILVA; SOUSA, 2015). Sendo assim, a recuperação de uma resposta ao estresse tem sido abordada em termos de resiliência e vulnerabilidade, processos dinâmicos e individuais, com componentes inatos (e.g. background genético) e aprendidos (e.g. regulação emocional). A resiliência é definida pela American Psychological Association como “o processo de boa adaptação diante de adversidades, traumas, tragédias, ameaças ou fontes significativas de estresse”, consistindo de adaptações durante o evento estressor que perpassam os domínios psicológicos e são refletidos no encéfalo principalmente como mudanças na neuroplasticidade e no perfil epigenômico (GALVÃO-COELHO; SILVA; SOUSA, 2015; MCEWEN, 2016). A resiliência têm sido avaliada por meio de escalas e desfechos de boa saúde mental após evento adverso (JOYCE et al., 2018; KALISCH et al., 2017), e pode ser treinada ou facilitada por meio do exercício físico (HUNTER; GRAY; MCEWEN, 2018; REUL et al., 2015), do suporte social (HUNTER; GRAY; MCEWEN, 2018), e do treinamento mental (JOYCE et al., 2018), por exemplo.

A partir destas evidências, a promoção de estratégias para redução do estresse, medicamentosas e/ou complementares, tem se popularizado e sido pensada com base em intervenções alternativas para a prevenção ou a remediação de transtornos de natureza física e mental (GOLDBERG et al., 2018; MARCHAND, 2013; SOUTHWICK; CHARNEY, 2012). Nesse contexto, práticas terapêuticas complementares não-invasivas, como as práticas contemplativas— dentre elas, o mindfulness —, vêm desempenhando importante papel para aliar a saúde mental a um estilo de vida que promova o bem-estar do indivíduo.

Mindfulness

O termo mindfulness tem origem do Pali sati, que se refere a lembrança, relembrar e ciência (awareness) (SHARF, 2017). Embora tenha raízes budistas, a prática de mindfulness “ocidentalizada” se distancia de seus diversos aspectos intelectuais no Budismo – no qual compõe um complexo conceito metafísico. A adaptação em uma prática

15 leiga e uma compreensão de sati como “atenção pura” (bare awareness) exemplificam tal distanciamento (SHARF, 2017). A conceituação do mindfulness (ou atenção plena), então, pode ser baseada em concepções budistas, psicológicas e populares (isto é, do senso comum), sendo que cada categoria de concepção abarca uma variedade de definições, podendo se sobrepor em algum grau uma em relação a outra concepção (BAER, 2019). Nas concepções psicológicas, o mindfulness é geralmente conceituado em termos de uma ação (estar atento, ciente, ou focado às experiências do momento presente) realizada de uma forma específica (com propósito, aceitação, abertura, curiosidade e gentileza) (BAER, 2019). O mindfulness como uma intervenção laica foi sistematizado a partir da fundação do programa de Redução de Estresse Baseada em Mindfulness (MBSR, Mindfulness-Based Stress Reduction) por Jon Kabat-Zinn, nos anos 1970, esquematizado em 8 semanas e tendo como objetivo a redução do sofrimento e do estresse de pacientes com enfermidades relacionadas à desregulação na resposta ao estresse (KABAT-ZINN, 1992). Desde então, diversas intervenções baseadas em mindfulness foram desenvolvidas, adaptando as práticas de acordo com o objetivo (SHAPERO et al., 2018), como, por exemplo, a Terapia Cognitiva Baseada em Mindfulness (MBCT, Mindfulness-Based Cognitive Therapy), desenvolvida por Zindel Segal, Mark Williams e John Teasdale, e utilizada com pacientes com depressão e ansiedade (SEGAL; WILLIAMS; TEASDALE, 2002).

A atenção plena também pode ser caracterizada como um conjunto de habilidades atencionais que podem se apresentar como um estado de consciência, favorecido a partir de exercícios meditativos dentro de uma intervenção, por exemplo os programas baseados em mindfulness, ou como um componente inerente ao indivíduo, como um traço (KABAT-ZINN, 1992; KABAT-ZINN; LIPWORTH; BURNEY, 1985) que também pode ser treinado por meio de práticas regulares (QUAGLIA et al., 2016). A mensuração desses componentes é realizada por meio de instrumentos psicométricos para o estado de mindfulness, tais como a Escala de Estado de Mindfulness (SMS), que mensura o mindfulness no instante presente, e o Questionário das Cinco Facetas do Mindfulness (FFMQ) para avaliar o traço de mindfulness, que corresponde a uma medida mais estável (ao longo do tempo) das habilidades de mindfulness do indivíduo. O traço de mindfulness é considerado um constructo multidimensional, expresso no FFMQ pelas suas 5 facetas, Observar, Descrever, Agir com Ciência, Não julgamento da experiência interna e Não reatividade da experiência interna.

Recentemente, uma revisão sistemática abordou a relação entre o traço de mindfulness e a saúde mental em populações saudáveis com base em três categorias:

16 sintomas psicopatológicos, processos cognitivos e fatores emocionais (TOMLINSON et al., 2018). Quanto à primeira categoria, foi observada correlação negativa entre o traço de mindfulness e sintomas depressivos e de ansiedade, bem como de outras psicopatologias como os transtornos alimentar, borderline e estresse pós-traumático. Em relação aos processos cognitivos, o traço de mindfulness parece ser inversamente relacionado com estratégias de enfrentamento evitativas (procrastinação e ruminação) e neuroticismo (traço de personalidade relacionado à instabilidade emocional), e positivamente relacionado com funções executivas. Quanto aos fatores emocionais, de maneira geral, o traço de mindfulness se correlaciona negativamente ao estresse percebido e ao bem-estar psicológico (TOMLINSON et al., 2018). Recentemente, tais achados foram corroborados por uma meta-análise que investigou as correlações do FFMQ e suas facetas com medidas de bem-estar (CARPENTER et al., 2019).

As implicações das habilidades e da prática de mindfulness têm sido avaliadas em algumas revisões sistemáticas e meta-análises (GOLDBERG et al., 2018; GU et al., 2015). Gu e colaboradores (2015) investigaram os mecanismos psicológicos pelos quais o mindfulness melhoraria a saúde mental e o bem-estar psicológico, encontrando que o estado de mindfulness e a mudança em pensamentos repetitivos negativos, conforme mensurados por instrumentos psicométricos, mediam parcialmente esse desfecho (GOLDBERG et al., 2018; GU et al., 2015). Com tamanho de efeito moderado, intervenções baseadas em mindfulness superam a ausência de tratamento e se equiparam a outras intervenções baseadas em evidência (como tratamentos farmacológicos de escolha) quanto à melhora de depressão e ansiedade (GOLDBERG et al., 2018).

Os efeitos de práticas meditativas, sobretudo de mindfulness, em biomarcadores fisiológicos da resposta ao estresse foram avaliados em uma meta-análise realizada por Pascoe et al. (2017), incluindo marcadores do eixo HPA (cortisol plasmático), autonômicos (pressão arterial, frequência cardíaca, variabilidade da frequência cardíaca, noradrenalina), imunes (TNF-α, proteína C-reativa, IL-6) e metabólicos (LDL, HDL, triglicerídeos, glicemia de jejum) (PASCOE et al., 2017), contemplando os 4 sistemas alostáticos da resposta ao estresse. Os autores analisaram 45 estudos, encontrando alto nível de evidência da implicação de práticas meditativas na redução de cortisol e variabilidade da frequência cardíaca em repouso, e nível moderado para redução da proteína C-reativa, TNF- α, pressão arterial e triglicerídeos (PASCOE et al., 2017), indicando que tais práticas atuam de forma sistêmica e difusa.

17 De modo semelhante à hipótese do tamponamento do estresse pelo suporte social (HENNESSY; KAISER; SACHSER, 2009), a teoria de tamponamento do estresse pelo mindfulness postula que o incremento na saúde fornecido pela prática de mindfulness se dá pela redução da reatividade ao estresse e pela mitigação da avaliação do evento estressor (CRESWELL; LINDSAY, 2014). De acordo com essa teoria, o mindfulness regularia sistemas alostáticos de resposta ao estresse como os eixos simpatoadrenomedular (redução da liberação de noradrenalina e adrenalina, e ativação da divisão parassimpática do SNA) e HPA (redução ou normalização do cortisol diurno), por meio da modulação de estruturas cerebrais relacionadas ao processamento da resposta ao estresse, como amígdala, córtex pré-frontal e córtex cingulado (CRESWELL; LINDSAY, 2014). Interessantemente, alto traço de mindfulness prediz tamponamento do estresse percebido em condição basal, e baixa reatividade ao estresse após uma tarefa de estresse social (BERGIN; PAKENHAM, 2016; BROWN; WEINSTEIN; CRESWELL, 2012).

Estes estudos demonstram que os efeitos positivos da prática de mindfulness em relação à diminuição de sinais e sintomas relacionados à resposta ao estresse ou aos transtornos de humor dela decorrentes (GOLDBERG et al., 2018; GU et al., 2015; PASCOE et al., 2017) abrem perspectivas para o seu emprego mais amplo em diferentes cenários de intervenção para a atenção à saúde mental. Nesse contexto, no presente trabalho, buscamos avaliar os efeitos de uma prática breve de atenção focada nas sensações da respiração e do corpo em medidas psicológicas autorrelatadas e nos níveis do cortisol plasmático, por meio da investigação da influência do traço de mindfulness em medidas basais e nos possíveis efeitos da prática, considerando o estado de mindfulness como mediador das respostas observadas.

18 OBJETIVOS

Geral

Investigar os efeitos de uma prática breve de mindfulness sobre as características individuais e sobre o perfil de cortisol, e analisar as possíveis interações entre diferentes domínios das escalas psicológicas indicativas de bem-estar em indivíduos jovens saudáveis.

Específicos

• Avaliar a relação do traço de mindfulness com medidas de bem-estar em indivíduos sem experiência prévia com práticas meditativas;

• Investigar se o estado de mindfulness medeia as mudanças no estresse percebido, na ansiedade, no afeto e no cortisol, e se o traço de mindfulness modera tal mediação.

19 ARTIGO – Brief Mindfulness-based Training and Mindfulness Trait Attenuate Psychological Stress in University Students

Artigo a ser submetido ao Research Topic “Psychological Distress among University Students”, do periódico Frontiers in Psychology.

20

Brief Mindfulness-based Training and Mindfulness Trait

Attenuate Psychological Stress in University Students

Geovan Menezes de Sousa Junior1, Geissy Lainny de Lima-Araujo1, Dráulio Barros de Araújo1, Maria Bernardete Cordeiro de Sousa1*

1_{Brain Institute, Federal University of Rio Grande do Norte, Natal, RN, Brazil}

Running title: Mindfulness attenuates psychological stress in students

Correspondence

Maria Bernardete Cordeiro de Sousa

Brain Institute – Federal University of Rio Grande do Norte Av. Nascimento de Castro 2155, Lagoa Nova

59056-450, Natal, Brazil Telephone/Fax: +55 84 3215-2709 E-mail: mbcsousa@neuro.ufrn.br Pages: 29 Words: 5350 Tables: 3 Figures: 6 Appendix: 1 References: 63

21 Abstract

Psychological distress in University settings has grown and became a public health issue, due the high prevalence of anxiety and depression disorders reported by students. In this context, contemplative practices, such as mindfulness, have been proposed as a strategy that could help students to manage the stress from these sources. Mindfulness is usually described as the ability to attend to the present moment on purpose and acceptance, being evaluated as a state or a trait. To analyze the effects of mindfulness trait and a brief mindfulness intervention (30 minutes/session performed for 3 consecutive days) in healthy young subjects (n=40) we analyzed measures of anxiety, affect, stress (here called together as well-being measures) and mindfulness state and trait. Initially, subjects were classified as Low/High Mindfulness Trait by k-means clustering and then well-being measures compared between them. Wilcoxon sum rank test showed that High Trait individuals have lower levels of anxiety trait, anxiety state and perceived stress. Further, sample was allocated to an active control (AC, n=20, females = 10) or mindfulness training (MT, n=20, females = 10) group and mixed analysis of variance performed, using group as between factor and session (post and pre) as within factor. After intervention, only Mindfulness Training group reduced anxiety state and perceived stress, while increased state mindfulness. Both groups reduced negative affect and cortisol, and no change was found in positive affect. Additionally, moderated mediation analysis showed that the meditation-induced change in state mindfulness mediated the increase in positive affect and the decrease in perceived stress and cortisol. The partial mediation effect of state mindfulness decreasing anxiety state only occurs in individuals with High Mindfulness Trait. Together, these results suggest that higher mindfulness trait is associated with low levels of distress and that a brief mindfulness-based intervention seems to be useful to reduce distress measures and mediates changes in positive affect.

Keywords: mindfulness training, distress, dispositional mindfulness, psychological well-being, cortisol

22 1. Introduction

Mental health has been a present topic in university scenario and around students. A survey published in 2017 pointed that 12% of PhD students sought for help with anxiety and depression (Woolston 2017), a number that increased to alarming 36% in 2019 (Woolston 2019). Evidence aiming to uncover the sources of the psychological distress among students point to academy-related ones, such as relationship with supervisor, academic performance and financial concerns (Sverdlik et al. 2018; Beiter et al. 2015). The reported prevalence of major depressive disorder (21.2%) and generalized anxiety disorder (18.6-16.7%) in students is higher than that for general population (depression, 4,4%; anxiety, 3,6%) (Auerbach et al. 2018; World Health Organization 2017). A recent systematic review and meta-analysis of 195 studies accounting for 47 countries found a prevalence of depressive symptoms around 27.2% and 11.1% of suicidal ideation in medical students (Rotenstein et al. 2016). The high prevalence of psychiatric disorders in this population claims for public policies and strategies that could enhance psychological well-being and help them coping adversities, one of which that is under investigation is contemplative practices.

Contemplative practices are becoming even more popular in Western societies maybe because of its potential in improving well-being by several mechanisms (Dahl, Lutz, and Davidson 2015). These practices involve a plethora of movement and meditation techniques, of which mindfulness meditation is a popular one. Commonly known as a meditation style rooted in Buddhism, mindfulness can assume a number of definitions based not only on Buddhist, but on psychological and popular conceptions as well (R. Baer 2019). Here we make use of its psychological conception of a measurable construct, aligned with its Kabat-Zinn's definition as the act of being present on purpose, acceptance and openness (Kabat-Zinn 1992). Mindfulness can also be interpreted as a set of skills composed of state and trait domains (Tang, Hölzel, and Posner 2015). State mindfulness is often increased at the moment of and immediately after mindfulness training while the trait domain is more stable over time but can be enhanced with regular mindfulness training (Kiken et al. 2015). Both dimensions are measured by self-report instruments such as State Mindfulness Scale (SMS) for state mindfulness, and Five Facets of Mindfulness Questionnaire (FFMQ) for trait mindfulness.

Some evidences have been pointing to a beneficial effect of high mindfulness trait on mental health and psychological well-being. Tomlinson and colleagues found negative relationship of mindfulness trait with depressive and anxiety symptoms, perceived stress and rumination, and a positive relationship with executive functioning and psychological well-being (Tomlinson et al. 2018). A recent correlational meta-analysis showed an inverse correlation of mindfulness trait with negative affect symptoms (Carpenter et al. 2019). Importantly, the authors also highlighted the multidimensional nature of mindfulness trait by showing differentially patterns of relationship between FFMQ facets and affective symptoms, where Observe positively correlated with social anxiety disorder symptoms, Describe was negatively correlated with generalized anxiety symptoms, and Non-react inversely correlated with depressive and anxiety symptoms (Carpenter et al. 2019). Furthermore, cross-sectional studies often show a different pattern of brain functioning and structure favoring eudaimonic well-being and receptivity to unpleasant stimuli in individuals with high mindfulness trait (Kong et al. 2016; Brown, Goodman, and Inzlicht 2013).

23 In addition to psychological effects, mindfulness is also reported to modulate physiological measures of stress. Despite evolved as a highly adaptive reaction to homeostasis disruptions, modern lifestyles marked by bad nutrition, poor sleep quality, inactivity and social inequity, generally lead to intermittent and dysregulated stress response (Egger 2017). This chronic profile often overcome beneficial effects of acute stress response and become a high-risk factor for development of chronic and mental illnesses (Ehlers and Kaufmann 2010; Egger 2017). The physiological response to a stressful event is mainly guided by sympathoadrenomedullary system and hypothalamic-pituitary-adrenal axis, through epinephrine and cortisol release, respectively, but also is modulated by immune and metabolic systems. Signals of stressful events are integrated in the hypothalamus where it triggers the release of corticotropin releasing factor by paraventricular nuclei’s cells, which stimulates the release of adrenocorticotropic hormone by anterior pituitary (Godoy et al. 2018). In relation to the interaction between mindfulness skills and stress mediators, it is hypothesized that higher mindfulness buffer stress reactivity, decreasing epinephrine and cortisol responses, in addition to changing the way that stressful events are perceived, that is, the stress appraisal (Creswell and Lindsay 2014).

The implication of mindfulness skills and training for improvement of mental health and psychological well-being was evaluated by some meta-analysis. Mindfulness-based intervention for psychiatric disorders was found to be better than no treatment and non-active controls conditions, in addition to have a similar effect of evidence-based treatment such as cognitive behavioral therapy and antidepressant medications for depression and anxiety (Goldberg et al. 2018), in line with other meta-analytic report (Hedman-Lagerlöf, Hedman-Lagerlöf, and Öst 2018). Training can mediate mental health changes and well-being not only by increasing mindfulness skills but also by reducing repetitive negative thinking, such as rumination (Gu et al. 2015). In addition to psychological effects, meditation also affect biological measures of stress response as reported in a meta-analysis performed by Pascoe and colleagues (Pascoe et al. 2017). The authors evaluated markers of neuroendocrine, immune and autonomic systems of 45 randomized controlled trials and found a high level of evidence of reductions in plasma cortisol and resting heart rate, and a moderate level for C-reactive protein, TNF-α, blood pressure and triglycerides favouring meditation practice over active interventions, such as exercise and relaxation (Pascoe et al. 2017), suggesting a diffuse systemic effect of meditation that could provide some protection against dysregulation of stress response systems.

In university settings, a growing body of evidence is showing that mindfulness training leads to improvement in several measures of well-being. A recent large prospective study showed that 8 weeks of mindfulness course reduced psychological distress and improved well-being during and after an examination period, a significant source of stress for students (Galante et al. 2018). The same time of intervention reduced mental distress and study stress while increased subjective well-being but only in women (de Vibe et al. 2013). In addition to long-term interventions, there are also some reports that brief mindfulness-based intervention improves mood and decreases stress in academic and scholar settings (Tang et al. 2014; Chiodelli et al. 2018). Not only mindfulness training but mindfulness trait also seems to play a role, as it has been reported to mediate the development of empathy in university students (de la Fuente-Anuncibay et al. 2019).

In light of all this, we make use of an exploratory approach in order to investigate whether mindfulness trait influences baseline well-being measures in non-meditators, and to analyze the psychological variables of overall changes induced by a brief mindfulness training as well as the possible role of mindfulness trait in their expression. Our hypotheses are

24 threefold: first, higher mindfulness trait is related to psychological well-being, in an inverse relationship with measures of anxiety, stress and negative affect, and direct related with positive affect; second, a brief mindfulness training reduces negative indicators of psychological well-being while increasing the positive ones, and finally, that these changes are mediated by meditation-induced increase in state mindfulness and moderated by mindfulness trait.

25 2. Materials and Methods

2.1. Experimental design and interventions

Sample consisted of graduate and undergraduate students (mean age: 24.15 + 3.61) of the Federal University of Rio Grande do Norte (UFRN) enrolled by online recruitment and were eligible if declared the absence of: psychiatric disorders, psychotropic or anti-inflammatory prescriptions and experience with meditation or yoga. Age- and sex-matched participants were randomly allocated either in a mindfulness training (MT group, n=20, females = 10, mean age: 24.05 + 3.76), consisting in an audio-guided meditation focused on the body sensations of breathing, or in an active control group (AC, n=20, females = 10, mean age: 24.25 + 3.55), characterized by coloring figures and listening to an audio related to health themes. Interventions had the same total duration (30 minutes) and occurred along three consecutive days. In the first and third days, self-reported psychometric instruments (see Section 2.2) and blood sample were collected before (in the first day) or after (in the third day) intervention (Figure 1A). Eligibility was reached by 162 students, but only 40 were analyzed (MT = 20, females = 20; AC = 20, females = 20) (Figure 1B). All procedures were approved by ethical committee from the Federal University of Rio Grande do Norte, Brazil (CAEE.55193416.4.0000.5537, 1.761.383).

26 Figure 1. Experimental design (A) and CONSORT (Consolidated Standards of Reporting Trials) study flow (B). Forty-three participants were allocated (Control: n=23, Mindfulness: n=20) but 3 excluded from Control, remaining 20 individuals per group. MBI = Mindfulness-Based Intervention.

2.2. Questionnaires and hormonal assessment

State and trait mindfulness were assessed by State Mindfulness Scale (SMS) and Five Facets of Mindfulness Questionnaire (FFMQ), respectively. SMS is a 5-point Likert scale that assesses state of mindfulness in the moment of response (Tanay and Bernstein 2013). FFMQ is a 5-point Likert questionnaire composed by five facets of mindfulness skills, namely Observing (noticing to internal and external experiences), Describing (labeling internal experiences), Act with Awareness (focusing in activities of the moment, as opposed to automatic pilot), Non-judgment of inner experience (non-evaluative stance about thoughts and feelings) and Non-reactivity to inner experience (allow thoughts and feelings to come and go) (de Barros et al. 2014). Internal consistency (Cronbach’s alpha, α) for these instruments were good for our sample (SMS: α = .91, FFMQ: α = .85). State and trait anxiety were measured by the 4-point Likert State and Trait Anxiety Inventory (STAI), composed of two parts, the State Anxiety Inventory (SAI, α = .90) and Trait Anxiety Inventory (TAI, α = .81) (Biaggio and Natalício 1979). Positive and Negative Affect Schedule (PANAS) was used to evaluate positive (PAS, α = .87) and negative affect (NAS, α = .84) (de Carvalho et al. 2013). Perceived stress was assessed by the 14-questions version of Perceived Stress Scale (PSS, α = .83) (Dias et al. 2015). Except for SMS, which is still under validation, all other instruments were validated for Brazilian population. Blood samples (10 mL) were collected by venipuncture at 1st _{and 3}rd _{days of training,}

between 8:00 AM and 9:00 AM, after 45 minutes of resting and before completing questionnaires. Participants were requested to avoid caffeine consumption before blood collection. Plasma cortisol was measured by chemiluminescence (Access Cortisol, Beckman Coulter, Cat. Number 33600). Intra-assay variation was 4.39 + 5.92%.

2.3. Data mining and analysis

2.3.2. Classification of mindfulness trait

Clustering analysis was implemented in order to classify the sample based on levels of trait mindfulness, using as grouping variables the prior to intervention z-scores of FFMQ facets (Describe, Act with Awareness, Non-judging to internal experiences and Non-reacting to internal experiences). Despite the good internal consistency of FFMQ, this instrument has some nuances mainly when using it with a mixed sample of meditators and non-meditators (R. A. Baer et al. 2008). Specifically, the facet Observe showed to be sensible to meditation experience, where it fits well in confirmatory analysis when the sample have some experience with meditation but not in an overall sample (R. A. Baer et al. 2008; 2006), suggesting that a four-factor structure of this questionnaire may be more reliable when dealing with non-meditators, yielding to suggestion of remove Observe score when using total FFMQ (R. Baer 2019). Since our sample comprised non-meditators, this facet was not included as grouping variable.

27 Number of clusters was calculated based on the several indexes provided by NbClust package available in R software (Charrad et al. 2014) and then this value was used to compute k-means. The k-means method is an unsupervised learning algorithm used to classify non-previously labelled data. It works by randomly and repeatedly positioning k centers to the n-dimensional scatter plot and calculating the distance between each point of the data from these centers until the assignment of centers do not change (the so-called iteration process). We used Euclidian distance to calculate similarity between centers and 25 as the minimal number of iterations. Wilcoxon sum rank was used to compare facets between clusters, since Describe was not normally distributed (Shapiro-Wilk, W = 0.93, p = 0.03).

2.3.3. Baseline and post-intervention comparisons

Baseline measures of perceived stress, positive and negative affect, anxiety trait and state, state mindfulness and cortisol were compared across clusters using Wilcoxon sum rank test, since negative affect did not show a normal distribution (Shapiro-Wilk, W = 0.93, p = 0.02). To assess the effect of intervention on these measures, we performed mixed analysis of variance (ANOVA) using group as between and session (pre and post intervention) as within factor. Investigation of potential influences of mindfulness trait on intervention outcomes is described in the next section. In order to avoid inflation of type I error due multiple testing, we adjusted p-values for repeated variable testing based on Benjamini and Hochberg method, which provide an interesting approach once its adjustment reduces not only false positive but also false negatives (Jafari and Ansari-Pour 2019). Effect sizes are given by Cohen’d for mixed ANOVA and |𝑟| for Wilcoxon sum rank tests. All analyzes were performed using R software.

2.3.4. Moderated mediation: an approach to evaluate mechanisms of brief mindfulness intervention and the role mindfulness trait

In order to have some exploratory insight into mechanisms of brief mindfulness intervention, we used second-stage moderated mediation, since it is a potentially powerful analysis and commonly used in psychological research (Lee, Herbert, and McAuley 2019; Windgassen et al. 2016). Mediation analysis tests if the effect of an independent variable X on a dependent variable Y (X → Y, c-path or total effect) is mediated by a variable M (X → M, a-path; M → Y, b-path). Mediation effect occurs when there is a significant indirect effect (X → M → Y, both a- and b-path is significant), and the effect on c-path is lost or decreased (so-called c’-path or direct effect). When significance of c’-path is lost it is called full mediation, while when it remains significant (but with a significant indirect effect) it is called partial mediation. Second-stage moderated mediation tests if a mediation effect is moderated by a variable W, specifically on b pathway, that is, if the effect of the mediator variable on an outcome occurs at precise levels of moderator (W). Presence of moderated mediation can be accessed by the index of moderated mediation (ω), defined as

𝜔= 𝑎(𝑏₁+ 𝑏₃𝑊),

where a stands for estimated a-path, b1 stands for the estimated effect of mediator on

dependent variable in absence of the moderator and b3W stands for the estimated interaction

effect between mediator and moderator on dependent variable (Hayes 2015). The index of moderated mediation is considered significant when its bootstrapped confidence interval (95%) does not cross zero and can be interpreted in terms of modulation of indirect effect, that is, when ω > 0, the indirect effect increases (i.e, mediation effect gets stronger), as

28 opposed to when ω < 0. Here, we used group of intervention as independent variable (X, control = 0, mindfulness = 1), state mindfulness as mediator (M), variables that changed within mindfulness group after intervention as outcomes (Y), and level of mindfulness trait as moderator (W). We used the difference between scores of 3rd and 1st day (Δ = Post – Pre) of mediator and dependent variables. Indirect effects were estimated with 10,000 bootstrap samples. Analysis was performed using processr package available in R software

All analyzes were done using RStudio Integrated Development Environment (version 1.2.5033) for R software (version 3.6.1). Statistical significance was set to p < .05. When .05 < p < .10 we refer it as marginal significance or trend. Confidence interval (95%) is reported inside brackets as [lower, upper].

29 3. Results

3.1. Definition of mindfulness trait

Majority of indexes provided by NbClust suggested 2 as an optimal number of clusters and so that was the number provided to k-means. The overall variability in the two dimensions of cluster accounted for 63.5% (Figure 2A). Based on centers (weight of each variable in the two cluster dimensions) of grouped variables the clusters were labelled as Low Trait (Cluster 1, n = 27), since its centers were below the mean, and High Trait (Cluster 2, n = 13) due to its high centers (Figure 2B). All facets showed to be different between clusters (Wilcoxon sum rank test: Describe: W= 88.5, p = .01, p-adjusted = .03, r= .40; Act with Awareness: W = 38.5 p = 7.53e-05, p-adjusted = .0003, r = .63; Non-judge: W= 72.5, p = .003, p-adjusted = .09, r = .47; Non-reactivity: W= 36, p = 5.65e-05, p-adjusted = .0001, r = .64), indicating a good segregation (Figure 2C). Cluster validation metrics can be accessed in Figure S1 and Table T1. Variables means and standard deviations across groups and levels of mindfulness trait can be seen in Table 1. There was an equity in sex distribution between cluster (Figure S2).

Figure 2. Cluster plot (A) and centers of grouping variables for each cluster (B), showing a clear separation between individuals with low (Cluster 1) from those with high mindfulness trait (Cluster 2). (C) Boxplots of FFMQ facets. Wilcoxon sum rank test showed that all facets are significantly different between clusters. *p< .05, **p< .01, ***p< .001.

3.2. Baseline measures of well-being between levels of mindfulness trait

Wilcoxon sum rank test found that Anxiety State (W = 261, p = .01, p-adjusted = .02, r = .39), Anxiety Trait (W = 287, p = .001, r = .51) and Perceived Stress (W = 264, p = .01, p-adjusted = .02, r = .40) are significantly lower in High Trait when compared with Low Trait individuals. A trend in High Trait individuals show lower levels of Negative Affect (W = 237, p = .08, adjusted = .08, r = .28) and higher levels of Cortisol (W = 113, p = .07, p-adjusted = .07, r = .28) was also found. No difference was found for State Mindfulness (W = 141, p = .32, adjusted = .32, r = .16) and Positive Affect (W = 156.5, p = .59, p-adjusted = .74, r = .09) (Figure 3).

30 Table 1. Mean and standard deviation (SD) of variables between mindfulness trait levels.

Low Trait High Trait

p-value Effect size (r)

Mean SD Mean SD Age 23.93 3.51 24.62 3.93 .52 .10 FFMQ 109.07 11.59 139.31 11.35 < .0001 .80 Describe 25.30 7.15 31.23 5.26 .01 .40 Act w/ Awareness 23.48 6.31 32.23 3.24 < .0001 .63 Non-judge 21.22 6.41 29.46 7.11 .003 .47 Non-react 14.96 3.52 21.31 3.57 < .0001 .64 State Mindfulness 71.93 11.55 75.23 10.87 .32 .16 Positive Affect 28.93 6.62 30.85 8.35 .59 .09 Negative Affect 24.96 7.05 20.31 6.02 .08 .28 Anxiety State 41.15 8.69 35.08 5.41 .01 .39 Anxiety Trait 49.30 6.78 40.92 7.04 .001 .51 Perceived Stress 32.52 6.61 26.46 6.28 .01 .40 Cortisol 10.38 3.96 13.09 4.98 .07 .28

Figure 3. Well-being measures before intervention between low and high mindfulness trait. Black points denote variable mean. For means and standard deviations, see Table 1. P-values after Wilcoxon sum rank test.

31 3.3. Well-being measures post-intervention within and between AC and MT groups

For facets of FFMQ, mixed ANOVA showed an interaction between groups and session for facet Act with Awareness (Group*Session: F(1,38) = 15.00, p = .0004) with a decrease for

control group (Post – Pre + Standard Error = - 3.00 + 1.03, p = .006, p-adjusted = .009, d = .72) and an increase for mindfulness group (Post – Pre = 2.65 + 1.03, p = .01, p-adjusted = .01), as well as a significant effect of session increasing Non-react (F(1,38) = 4.62, p = .03;

Post – Pre = 1.3 + .60), but only a trend for increase in mindfulness group was found (MT: Post – Pre = 1.45 + .85, p = .098, adjusted = .14; AC: Post – Pre = 1.15 + .85, p = .19, p-adjusted = .19) (Figure 4, Table 2).

Table 2. Mean and standard deviation (SD) of variables between groups. d = Cohen’s d effect size.

Control Mindfulness Mean SD d Mean SD d Age 24.25 3.55 - 24.05 3.76 - FFMQ Baseline _{121.75 20.03} .07 116.05 16.40 .75 Post _{121.15 20.03 124.95 14.17} Describe Baseline _{27.90 7.33} .11 26.55 6.99 .14 Post _{28.25 9.08 27.10 7.88} Act w/ Awareness Baseline _{27.95 6.02} .72 24.70 7.39 .53 Post _{24.95 7.87 27.35 6.96} Non-judge Baseline _{23.65 7.90} .09 24.15 7.55 .32 Post _{24.20 9.12 25.50 7.31} Non-react Baseline _{17.40 4.47} .34 16.65 4.84 .34 Post _{18.55 5.15 18.10 4.39} State Mindfulness Baseline _{74.50 13.02} .35 71.50 9.38 .73 Post _{69.95 17.54 76.70 12.09} Positive Affect Baseline _{30.90 7.43} .07 28.20 6.83 .40 Post _{30.55 5.92 30.20 7.40} Negative Affect Baseline _{24.75 8.23} .97 22.15 5.43 .87 Post _{19.90 7.26 17.70 5.97} Anxiety State Baseline _{38.65 9.43} .00 39.70 7.03 .57 Post _{38.65 9.82 35.20 7.28} Perceived Stress Baseline _{30.50 7.39} .45 30.60 6.85 .93 Post _{28.35 6.65 24.25 8.18} Cortisol Baseline _{11.53 5.18} .57 10.99 3.68 .56 Post _{9.71 5.35 9.81 3.78}

32 Figure 4. Facets of FFMQ before and after interventions for each group. For means and standard deviations, see Table 2. Mixed ANOVA test, #p< .10, *p< .05, **p< .01, ***p< .001.

For well-being measures, Mixed ANOVA showed effects of session for all variables (Negative Affect: F(1,38) = 33.76, p = .000001, Post – Pre = -4.65; Anxiety State: F(1,38) =

4.34, p = .04, Post – Pre = -2.25; Perceived Stress: F(1,38) = 33.76, p = .00005, Post – Pre =

-4.25; Cortisol: F(1,38) = 12.32, p = .001, Post – Pre = -1.5), except for Positive Affect

(Session: F(1,38) =1.16, p = .28) and State Mindfulness (Session: F(1,38) = .03, p = .84).

Interactions between group and session were found for Anxiety State (Group*Session: F(1,38) = 4.34, p = .04), Perceived Stress (Group*Session: F(1,38) = 5.14, p = .03) and State

Mindfulness (Group*Session: F(1,38) = 8.63, p = .005), where only mindfulness training

reduced both Anxiety State (MT: Post – Pre = -4.5, p = .005, p-adjusted = .01; AC: Post – Pre = 0.0, p = 1.00, p-adjusted = 1.00) and Perceived Stress (MT: Post – Pre = -6.35, p = .00001, p-adjusted = .00003; AC: Post – Pre = -2.15, p = .11, p-adjusted = .11), while increased State Mindfulness (MT: Post – Pre = 5.20, p = .03, p-adjusted = .09). AC group showed a trend in decrease State Mindfulness (AC: Post – Pre = -4.55, p = .06, p-adjusted = .09). Both groups reduced Negative Affect (MT: Post – Pre = -4.45, p = .0003, p-adjusted =

33 .0004, AC: Post – Pre = -4.85, p = .0001, p-adjusted = .0003) and Cortisol (MT: Post – Pre = -1.18, p = .058, p-adjusted = .07, AC: Post – Pre = -1.83, p = .005, p-adjusted = .01) (Figure 5, Table 2).

Figure 5. Well-being measures before and after interventions for each group. Mindfulness training induced an overall change in psychological and physiological variables. Black points denote variable mean. For means and standard deviations, see Table 2. Mixed ANOVA test, #p< .10, *p< .05, **p< .01, ***p< .001.

3.2. Assessment of state mindfulness-induced mechanisms and role of mindfulness trait

In order to evaluate whether mindfulness trait has some role in brief mindfulness training-induced changes on measures of well-being, we performed a second-stage moderated mediation, using as outcome variables that significantly or marginally changed after mindfulness training, state mindfulness as mediator and level of mindfulness trait as moderator.

A significant a-path showed that mindfulness training increased state mindfulness (a = 9.75, p = .003). A full (but not moderated) mediation effect was found for state mindfulness

34 increasing positive affect (b1 = .15 [.03, .27], p = .01) and decreasing perceived stress (b1 =

- .23 [- .37, - .09], p = .001) and cortisol (b1 = - .11 [- .20, - .03], p = .007) (Figure 6, Table

3). No overall mediation effect was found for negative affect (b1 = .07, p = .36).

Mindfulness trait fully moderated the decrease in state anxiety (b3 = 10.23, p = .005, ω =

99.70 [26.33, 234.58]), showing that mediation effect gets stronger when mindfulness trait is high (ωHigh = 98.14 [25.41, 231.62], ωLow = -1.56 [-4.72, 0.43]) (Figure 6, Table 3). In

other words, State Mindfulness only mediates the decrease in anxiety under the condition of High Mindfulness Trait.

Figure 6. Conceptual diagram of second-stage moderated mediation showing overall mediation effect of mindfulness training and the role of high mindfulness trait as moderator of mediation effect of State Mindfulness on Anxiety State. Values on State Mindfulness → Outcomes pathways indicate b1 estimate, while that on Mindfulness Trait → Anxiety State

indicate b3 estimate and Index of Moderated Mediation for High Mindfulness Trait

condition (ωHigh). Black arrow stands for significant path, dashed black line stands for

marginal significance of path and gray line stands for no significant path. For ease of presentation c’-path is omitted, see Table 3 for indexes of moderated mediation, bootstrapped confidence interval and c’-path. *p< .05, **p< .01.

35 Table 3. Pathways and Index of Moderated Mediated of second-stage moderated mediation

(mediator = ΔState Mindfulness, moderator = Mindfulness Trait)

a b1 b3 c’ ω ωLow ωHigh PAS 9.75 .15 -5.55 3.19 -54.15 1.50 -52.65 Boot CI 3.61, 16.45 .03, .28 -11.33, 4.46 - .42, 6.25 -145.76, 23.79 .24, 3.79 -143.12, 25.24 NAS 9.75 .07 -2.22 .25 -21.63 .71 -20.92 Boot CI 3.60, 16.45 - .11, .21 -15.77, 5.54 -3.00, 3.59 -179.23, 51.76 - .86, 2.50 -176.45, 53.02 SAI 9.75 - .16 10.23 -5.50 99.70 -1.56 98.14 Boot CI 3.58, 16.56 - .34, .08 2.95, 117.25 -10.51, - .58 26.33, 234.58 -4.72, .44 25.41, 231.62 PSS 9.75 - .23 2.00 -1.92 19.50 -2.24 17.27 Boot CI 3.64, 16.57 - .37, - .09 -4.28, 7.87 -6.44, 2.57 -39.98, 93.24 -4.57, - .67 -42.80, 88.93 Cortisol 9.75 - .11 2.99 1.12 29.20 -1.12 28.08 Boot CI 3.67, 16.59 - .20, - .03 -1.01, 6.42 - .77, 2.84 -3.76, 83.57 -2.20, - .41 -4.38, 82.00

a = Mindfulness Training → State Mindfulness pathway, b1 = State Mindfulness → Outcome pathway, b3 =

interaction term between b1 and Mindfulness Trait, c’ = Mindfulness Training → Outcomes pathway after removing

contribution of mediator, ω = Index of Moderated Mediation, ωLow = Index of Moderated Mediation in Low

Mindfulness Trait condition, ωHigh = Index of Moderated Mediation in High Mindfulness Trait condition, PAS =

Positive Affect Schedule, NAS = Negative Affect Schedule, SAI = State Anxiety Inventory, TAI = Trait Anxiety Inventory, PSS = Perceived Stress, Boot CI = bootstrapped 95% confidence interval. Significant estimates are shown in black.

4. Discussion

Mindfulness-based practices have been used as a complementary approach to address stress-related issues like anxiety and depression (Marchand 2013), with an increasingly use in University settings (Galante et al. 2018; Gallego et al. 2014; de Vibe et al. 2013). Besides that, little is known about the impact of mindfulness trait on well-being measures before mindfulness training. Our aims in this exploratory study were mainly twofold: to assess the influence of mindfulness trait level on baseline well-being measures and to evaluate the effects of a brief mindfulness-based training accounting to mindfulness trait on these outcomes, using a sample of graduate and undergraduate students.

According to our results, there is an important relation between mindfulness trait and measures of well-being such as affect, perceived stress and anxiety. Our data shows that higher mindfulness trait is inversely related to levels of stress, anxiety state and anxiety trait, supporting our first hypothesis. After a brief mindfulness-based training we observed a decrease in negative affect, anxiety state, perceived stress and a marginal decrease in cortisol and increase in positive affect, corroborating our second hypothesis. We also found a mediation effect of meditation on positive affect, perceived stress and cortisol through state mindfulness; for anxiety state, the mediation effect only occurred in high trait individuals, partially confirming our third hypothesis.

There are plenty of ways to categorize different groups based on mindfulness trait such as by median split (Brown, Weinstein, and Creswell 2012) and by latent profile analysis, a finite gaussian mixture model (Bravo, Pearson, and Kelley 2018; Pearson et al. 2015). Classification by latent profile analysis often show a 4-profiles solution applied for college students (Bravo, Pearson, and Kelley 2018; Pearson et al. 2015). Specifically, in addition to the two “extremes” profiles (all high and all low mindfulness trait facets scores) the authors found intermediate profiles named as “judgmentally observing”, showing high score in Observe and low in Non-judge and Act with awareness, and non-judgmentally aware, due to its high score in Non-judge and Act with awareness and low Observe score. Importantly, good psychological health outcomes were found for “non-judgmentally aware” and high mindfulness profiles and poor psychological health for judgmentally observing and low mindfulness (Bravo, Pearson, and Kelley 2018; Pearson et al. 2015). Interestingly, the adaptive profiles do not differ between them, while the maladaptive ones do not differ in almost all outcomes.

In the present study, we used an unsupervised learning algorithm, k-means, to label the data collected from FFMQ instrument without the Observe facet, due its unreliability in non-meditators population (R. A. Baer et al. 2006). According to indexes that address the better number of clusters, our sample was better categorized on two subsamples that comprised individuals who score high in all mindfulness facets and those who score low in all facets. In this sense, we found that High Trait individuals score lower in measures of psychological distress such as anxiety and perceived stress, and marginally in negative affect. So, it seems that removing Observe from grouping techniques collapse the intermediate profiles found by latent profile analysis for college students (Bravo, Pearson, and Kelley 2018; Pearson et al. 2015);specifically, the non-judgmentally aware profile would collapse with High Trait group while judgmentally observing would profile collapse with Low Trait group, what would explain the similar pattern of psychological health shared by these profiles and our clusters. The relationship between mindfulness trait and psychological health has been quite reported (Tomlinson et al. 2018). Executive functioning seems to be positively correlated with