Exploring the links between mindfulness skills, physical activity, signs of anxiety, and signs of depression among non-clinical participants

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ORIGINAL ARTICLE

Exploring the links between mindfulness skills, physical activity, signs of anxiety, and signs of depression among non-clinical participants Exploration des liens entre les capacités de pleine conscience, l’activité physique, les signes d’anxiété et les signes de dépression auprès d’individus sains Alexis Ruffault a,b,∗, Marjorie Bernier c, Emilie Thiénot d, Jean F. Fournier b,1, Cécile Flahault a a

Laboratoire de Psychopathologie et Processus de Santé (EA4057), Institut de Psychologie, Université Paris Descartes Sorbonnes Paris Cité, 71, avenue Edouard-Vaillant, 92100 Boulogne-Billancourt, France b Département de la Recherche, Institut National du Sport (INSEP), 11, avenue du Tremblay, 75012 Paris, France c Laboratoire Interdisciplinaire de Recherche sur les Transformations des Pratiques Éducatives et des Pratiques Sociales (EA 7313), Université Paris-Est Créteil Val De Marne, 94000 Créteil, France d English Institute of Sport (EIS), Sportcity, Gate 13, Rowsley Street, Manchester, M11 3FF England, United Kingdom Received 23 June 2015 ; received in revised form 21 September 2016; accepted 22 September 2016

KEYWORDS Dispositional mindfulness; Acceptance; Physical activity; Anxiety; Depression

Summary Introduction. — Physical activity has been shown to reduce anxiety and/or depression levels in patients with chronic physical diseases as well as healthy individuals. Similarly, mindfulnessand acceptance-based interventions have also been shown to reduce levels of anxiety and depression. Furthermore, recent research suggests that mindfulness is also associated with the level of physical activity. The aim of this correlational study was to predict signs of anxiety and depression with acceptance, dispositional mindfulness, and levels of physical activity in non-clinical individuals. Methods. — One hundred randomly chosen participants were interviewed with regard to their general anxiety (BAI), depression (BDI-II), physical activity (IPAQ), acceptance (AAQ-II), and dispositional mindfulness (MAAS).

∗ Corresponding author at: Laboratoire de Psychopathologie et Processus de Santé (EA 4057), Institut de Psychologie, Université Paris Descartes Sorbonne Paris Cité, 71, avenue Edouard-Vaillant, 92100 Boulogne-Billancourt, France. E-mail address: [email protected] (A. Ruffault). 1 Actual address: UFR STAPS, Université Paris Ouest Nanterre la Défense, Nanterre, France ([email protected]).

http://dx.doi.org/10.1016/j.jtcc.2016.09.003 1155-1704/© 2016 Association Franc ¸aise de Therapie Comportementale et Cognitive. Published by Elsevier Masson SAS. All rights reserved.

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ARTICLE IN PRESS A. Ruffault et al. Results. — On average, participants scored underneath the pathological threshold for anxiety and depression inventories. As expected, dispositional mindfulness and acceptance variables were negatively correlated to the psychopathological variables. Hierarchical model analyses showed that acceptance, dispositional mindfulness, and physical activity level explain 21% of the data for depression level among non-clinical participants. Conclusion. — This exploratory study may lead other researchers to develop and test the validity of mindfulness- and acceptance-based interventions associated to physical activity programs in order to reduce depression level among healthy individuals. © 2016 Association Franc ¸aise de Therapie Comportementale et Cognitive. Published by Elsevier Masson SAS. All rights reserved.

MOTS CLÉS Pleine conscience ; Acceptation ; Activité physique ; Anxiété ; Dépression

Résumé Introduction. — Il est avéré que l’activité physique réduit les niveaux d’anxiété et de dépression de patients atteints de maladies chroniques et/ou présentant des troubles psychiatriques, mais aussi d’individus sains. De même, depuis une trentaine d’années, la pleine conscience (c.-à-d., la capacité à orienter son attention sur le moment présent, de manière volontaire, et sans jugement) a montré des effets sur la réduction des symptômes psychopathologiques (p. ex., symptômes de l’anxiété, ou de la dépression). D’autre part, certaines études récentes ont montré que les individus les plus mindful sont également ceux qui suivent le mieux les recommandations des autorités de santé, et plus particulièrement en termes d’activité physique. Le but de cette étude corrélationnelle est de prédire l’existence de signes d’anxiété et de dépression d’individus sains à partir de leurs niveaux d’acceptation, de pleine conscience et d’activité physique. Notre hypothèse est que la prédiction des scores des variables psychopathologiques (c.-à-d., anxiété et dépression) est plus forte lorsque les scores d’activité physique sont ajoutés aux scores de pleine conscience et d’acceptation que lorsque ces variables sont étudiées séparément. Méthode. — Cent individus sains (48 femmes), choisis aléatoirement, ont été recrutés pour participer à cette étude. L’âge moyen des participants est de 33,49 ans (SD = 11,64 ; 18—54 ans) ; leur consentement libre et éclairé a été recueilli (signé) avant qu’ils ne répondent aux questionnaires. Les individus sains ont rempli l’inventaire d’anxiété de Beck (BAI ; ␣ de Cronbach = 0,81), l’inventaire de dépression de Beck (BDI-II ; ␣ de Cronbach = 0,70), le questionnaire d’acceptation et d’action (AAQ-II ; ␣ de Cronbach = 0,78), l’échelle de prédisposition à la pleine conscience (MAAS ; ␣ de Cronbach = 0,82), et le questionnaire international d’activité physique (IPAQ) dans leur version franc ¸aise. Des analyses de corrélation non-paramétriques ( de Kendall) ainsi que des analyses de régression hiérarchique ont été menées. Ainsi, pour prédire chaque variable psychopathologique, les capacités de pleine conscience, les scores d’acceptation et les scores d’activité physique étaient respectivement prédicteur en étape 1, 2 et 3. Résultats. — Les résultats montrent que l’anxiété et la dépression sont corrélées positivement, tout comme l’acceptation et les capacités de pleine conscience. De même, les capacités de pleine conscience et l’acceptation sont corrélées négativement aux niveaux d’anxiété et de dépression des individus de notre échantillon. De plus, les scores d’acceptation ont montré une corrélation positive avec les niveaux d’activité physique. Les analyses de régression hiérarchique ne montrent pas de résultat significatif dans la prédiction des niveaux d’anxiété. En revanche, les capacités de pleine conscience prédisent significativement les scores de dépression (R2 = 10 % ; ␤ = —0,31 ; p < 0,01) ; de même lorsque les scores d’acceptation sont ajoutés au modèle à l’étape 2 (R2 = 18 % ; ␤ = —0,33 ; p < 0,01) ; ainsi que lorsque les scores d’activité physique sont ajoutés à l’étape 3 (R2 = 21 % ; ␤ = 0,18 ; ns). Ainsi, ajouter les scores d’activité physique dans le modèle en étape 3 (R2 = 21 % ; ␤ = 0,18 ; ns) a augmenté la valeur du R2 pour atteindre 21 % de variance des scores de dépression (R2 = 0,21 ; F(3,96) = 8,68 ; p < 0,001). Conclusion. — L’hypothèse est partiellement confirmée. En effet, alors que le modèle prédisant les scores de dépression avec les scores de pleine conscience, d’acceptation et d’activité physique explique plus de variance des scores de dépression que le modèle ne comprenant que les scores de pleine conscience et d’acceptation ; cette différence n’est pas observée dans la prédiction des scores d’anxiété de 100 individus sains. Les résultats de cette étude corrélationnelle permettent de s’interroger sur la combinaison des capacités de pleine conscience et d’acceptation avec les niveaux d’activité physique en prévention de l’apparition de symptômes dépression d’individus sains. Les recherches à venir pourraient évaluer les effets d’interventions combinant des entraînements à la pleine conscience et à l’acceptation avec des programmes de reprise d’activité physique. © 2016 Association Franc ¸aise de Therapie Comportementale et Cognitive. Publi´ e par Elsevier Masson SAS. Tous droits r´ eserv´ es.

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Mindfulness, exercise, and psychopathology

Introduction Physical exercise to reduce physical and psychological symptoms Various studies have shown the benefits of an active lifestyle on physical health [1], and demonstrated the impact of physical activity (PA) on the prevention of several chronic diseases like obesity, type-II diabetes, osteoporosis, arterial pressure, and coronary disease [2—4]. Similarly, there is a growing interest in investigating the relationship between PA and visible signs of patients’ psychological distress in individuals with somatic diseases [5,6]. In a large sample cross-sectional study, de Wit et al. [7] used the DSM-IV Composite International Diagnostic Interview [8] and the International Physical Activity Questionnaire (IPAQ) [9] to show that higher levels of anxiety and depression were associated with lower PA levels in the general population. Further, Oeland et al. [10], showed that a 20-week PA program delivered in a group setting with 48 anxious and depressed patients led to higher PA levels as well as lower anxiety and depression scores among the participants. In the last 20 years, the literature in clinical psychology, PA, and health care showed a growing interest in the third wave of the cognitive-behavioral therapies, and particularly in mindfulness- and acceptance-based interventions.

Enhancing mindfulness skills to reduce psychological distress Mindfulness is commonly defined as a non-judgmental and moment-to-moment awareness of the present experience [11]. Brown and Ryan [12] placed a strong emphasis on the self-regulatory function of mindfulness, which is characterized by ‘‘being attentive to and aware of what is taking place in the present moment’’ (p.882). Hayes et al. [13] highlighted the importance of acceptance: the non-judgmental component of mindfulness, which can be seen as an active process of ‘‘allowing’’ current thoughts, emotions or sensations to occur without attempting to react, minimize or suppress them. Mindfulness training is a core component of acceptance-based interventions, and awareness of external and internal stimuli from the present moment leads to acceptance of those stimuli [12]. Originating from the Oriental Buddhist tradition, various mindfulness-based interventions have also been reported aiming at decreasing levels of anxiety [11], and more Occidental mindfulness-based interventions (such as Mindfulness-Based Cognitive Therapy [MBCT]) aimed at preventing a relapse of depression [14]. In Baer’s empirical review [15], mindfulness-based interventions have also been seen to be beneficial in the prevention of somatic diseases and associated psychological symptoms. Acceptance and Commitment Therapy (ACT) specialists have shown a growing interest in psychological and physical conditions [13].

Enhancing mindfulness skills to increase physical activity Moreover, there is a growing interest in health psychology to conduct mindfulness- and acceptance-based interventions

3 in order to promote PA. These interventions have shown conclusive results for engagement in PA practice [16] and maintenance of PA levels [17]. Roberts and Danoff-Burg [18] demonstrated that a higher tendency to be mindful was positively correlated to overall perceived good health, as well as several healthy behaviors (e.g., eating well, good quality of sleep, and PA), and negatively correlated to restriction in health-related activity. By being conscious of their thoughts, emotions and sensations and by accepting them, individuals displayed healthier behavior patterns [19]. Butryn et al. [16] showed, in a study of healthy young female students, that by using Acceptance and Commitment Therapy (ACT) [13], individuals develop mindfulness skills (such as acceptance) and increase PA class attendance after an 8-week follow-up. In a correlational study, Ulmer et al. [17] have shown that healthy young adults with a high tendency to be mindful, with high acceptance levels and a low thought suppression tendency, displayed high IPAQ scores and presented a better maintenance in exercise programs over a year. The authors suggested ‘‘that mindfulness and acceptance intervene between activity-related cognitions/emotions and overt behavior in a way that facilitates one’s ability to respond to rather than react to cognitive, behavioral or emotional threats to physical activity’’ [17]. Recently, a study from Ruffault et al. [20] showed that mindfulness plays a moderating role between intrinsic motivation to exercise and PA level in healthy individuals. This means that mindful individuals are more likely to experience PA when intrinsically motivated than their less mindful counterparts.

Combining physical exercise and mindfulness training to reduce psychological distress Several reviews have investigated the effects of mind-body exercises (e.g., Yoga, Tai chi, Qigong, Feldenkrais) on anxiety and/or depression [21—26]. Yoga, for instance, is part of the Mindfulness-Based Stress Reduction (MBSR) protocol, adding a contemplative aspect to PA, unifying the mind and body’s activity [25]. Being fully aware of slow and controlled movements of the body increases mindfulness skills and improves flexibility, balance, range of motion, and strength [24]. According to these reviews, the effects of mind-body interventions have been studied in patients with chronic physical conditions (e.g., chronic pain, cancer, cardiovascular diseases), as well as in patients with depressive or anxiety disorders. The main results of two meta-analyses showed (a) positive effects of Yoga on depression as compared to usual care, and to aerobic exercise [22], (b) no effect of Yoga on anxiety as compared to usual care [22], and (c) positive effects of Tai chi on depression as compared to control [27]. In a review, Saeed et al. [23] reported that less data exist on the effects of these exercises on anxiety than on depression, partly due to the lack of anxious individuals’ compliance in exercise programs. The authors reported methodological weaknesses, such as ‘‘short duration of treatment, small numbers of participants, and variability in interventions’’ (p. 982) and variability in the targeted populations (e.g., with or without any depressive or anxiety disorder, with or without any chronic physical condition) in studies investigating mind-body exercises’ effects on psychopathological

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A. Ruffault et al.

variables. More generally, two recent systematic reviews and meta-analyses of this mind-body approach reported a large majority of short-term assessments of the effects on psychopathological outcomes in studies, leading to the fact that the long-term effects of these programs remain unknown [22,27]. Moreover, according to these authors, the underlying mechanisms of action in mind-body exercises from stressors, inducing positive thinking, enhancing the activity of the autonomic nervous system, acting on the decrease of cortisol levels, are still unclear. Indeed, the effects of mindfulness and PA levels on psychopathology were not investigated separately. Thus, it remains unknown whether it is the mindfulness components, the PA components, or a combination of both which have the most positive effects on depression and anxiety symptoms after mind-body exercises practice.

Objectives and hypotheses In summary, (a) anxiety and/or depression levels can be reduced by PA or mindfulness- and acceptance-based interventions in clinical and non-clinical individuals; and (b) mindfulness practice has been associated with PA in healthy young adults. Thus, it could be expected that a combined PAmindfulness-acceptance-based intervention would lead to a better prevention of anxiety and/or depression symptoms in comparison with PA or mindfulness- and acceptance-based interventions alone. The studies investigating the impact of mind-body exercises on anxiety and depression support this hypothesis. However, studies have not investigated the underlying mechanisms and effects on anxiety and depression of mindfulness and PA in mind-body exercises, and yet, there is no evidence to prove that the association of PA and mindfulness is positively associated with anxiety and depression prevention among non-clinical individuals. Therefore, the aim of this study is to predict signs of anxiety and depression using mindfulness skills (i.e., dispositional mindfulness and acceptance) and levels of PA as predictors in non-clinical individuals. Our first hypothesis is that higher scores in mindfulness skills and PA are correlated with lower anxiety levels and/or depression levels. Our second hypothesis is that the prediction of signs of anxiety and depression with mindfulness skills and PA together is stronger than the prediction of signs of anxiety and depression with mindfulness skills alone or PA alone. Cross-sectional design was preferred to interventional design to investigate whether mindfulness skills and PA level would significantly predict signs of psychopathology in healthy individuals. This correlational design would then — if the hypotheses are confirmed — provide information enabling the design of an intervention based on the improvement of mindfulness skills as well as improvement in PA level.

Methods Participants and procedure The principal investigator asked individuals at their workplaces to participate in the study by filling out questionnaires, and then provided names or contact information

of co-workers who might be interested in participating in this study. The inclusion criterion was to be between 18 and 55 years of age. The exclusion criterion was any diagnosed psychopathological disorder. Participants may have had experience in mindfulness or acceptance programs, or not. One hundred healthy individuals (52 men and 48 women), between 18 and 54 years old (mean age: 33.49 ± 11.64) were questioned about their general anxiety and depression levels, their PA habits, and their mindfulness skills (i.e., dispositional mindfulness and acceptance). Participants’ characteristics are displayed in Table 1. The participants gave their informed consent for their participation and filled out five questionnaires. They answered the Beck Anxiety Inventory (BAI) [28], the Beck Depression Inventory (BDI-II) [29], the International Physical Activity Questionnaire (IPAQ) [9], the Acceptance and Action Questionnaire (AAQ-II) [30], and the Mindful Attention Awareness Scale (MAAS) [12]. The present research has been approved by the by the local ethic committee.

Materials Anxiety The French version of BAI [31] contains 21-items rated on a 4-point Likert scale ranging from 0 (‘‘not at all’’) to 3 (‘‘severely, I could barely stand it’’). It is a self-report measure of the severity of anxiety symptoms with a summed score of all items ranging from 0 (no symptom) to 63 (great severity of the symptoms). Measuring the severity of anxiety symptoms aims to reflect a continuum and therefore includes non-pathological levels of anxiety. The Beck Anxiety Inventory is a valid and reliable measure of anxiety. In our sample, BAI showed good internal consistency (Cronbach’s ␣ = 0.81). Depression The BDI-II is a widely used 21-items self-report instrument measuring the severity of affective, cognitive, behavioral, and somatic symptoms of depression [29]. Each item is rated on a 4-point scale ranging from 0 to 3, and the summed score of all items is ranging from 0 (no depression) to 63 (intense severity of depression). Measuring the severity of depression symptoms aims to reflect a continuum and therefore includes non-pathological levels of depression. The Beck Depression Inventory is a valid and reliable measure of depression. In our sample, the French version of BDI-II showed good internal consistency (Cronbach’s ␣ = 0.70). PA level The French version of the IPAQ is a widely used selfreport 7-items measure of PA level [9]. It provides information on the participants’ time spent on walking and on vigorous and moderate physical activities during 7 days. The unit of this measure is an overall energy expenditure expressed in Metabolic Equivalent Total (MET). In brief, the IPAQ calculations are: walking METmin/week = 3.3 × walking minutes × walking days; moderate MET-min/week = 4.0 × moderate-intensity activity minutes × moderate days; vigorous MET-min/week = 8.0 × vigorous-intensity activity minutes × vigorous-intensity

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Table 1 Description of the population. Description de la population. Variables Gender (% female) Age (years) Educational degree Secondary Undergraduate Graduate Post-graduate Familial situation Single In a relationship (no child) In a relationship (children) Married (no child) Married (children) Divorced Widowed

M

SD

33.49

11.64

%

Range

48.00 [18; 54] 30.00 42.00 17.00 11.00 51.00 3.00 4.00 7.00 31.00 4.00 0.00

M: mean scores; SD: standard deviation of mean scores. M : moyenne ; SD : écart-type.

days. Total physical activity MET-min/week = sum of walking + moderate + vigorous MET minutes. The total MET-min per week was used as a continuous indicator for physical activity. The International Physical Activity Questionnaire is a valid and reliable tool for measuring PA levels. Acceptance The French version of the AAQ-II [32] is a single factor 10items self-report measure of acceptance on a 7-point Likert scale, ranging from 1 (‘‘never true’’) to 7 (‘‘always true’’). The summed score is ranging from 10 (i.e., low level of acceptance) to 70 (i.e., high level of acceptance), and the score of items 2, 3, 4, 5, 7, 8, and 9 are reversed. The Acceptance and Action Questionnaire is a valid and reliable measure of acceptance. In our sample, AAQ-II showed good internal consistency (Cronbach’s ␣ = 0.78). Dispositional mindfulness Csillik et al. [33] translated and validated the French version of the MAAS, which is a single factor 15-items self-report instrument measuring the frequency to be mindful in day-today life. Each item is rated on a 6-point Likert scale ranging from 1 (‘‘almost always’’) to 6 (‘‘almost never’’), and the score is the mean of all items, ranging from 1 (i.e., low frequency of mindful states) to 6 (i.e., high frequency of mindful states). The Mindful Attention and Awareness Scale is a valid and reliable measure of dispositional mindfulness. In our sample, MAAS showed good internal consistency (Cronbach’s ␣ = 0.82).

assumption of the population distribution; (b) the scores obtained at the BDI, BAI, and IPAQ tests were not normally distributed. Correlation coefficients were judged as weak, moderate or strong according to the generic guidelines of Kendall’s test. Hierarchical regression analyses were conducted to elaborate our hypothesis, using (a) depression levels as a dependent variable, and dispositional mindfulness, acceptance, and PA levels as predictors respectively at step 1, step 2, and step 3; and (b) anxiety levels as a dependant variable and dispositional mindfulness, acceptance, and PA levels as predictors respectively at step 1, step 2, and step 3. For example, a test for predicting depression can be modeled as depression = ␤1 × acceptance + ␤2 × dispositional mindfulness + ␤3 × PA level + ␣, where ␤i represents the standardized regression coefficients for each response, and ␣ represents the intercept term. Plotting the Pearson residuals enabled us to check the normality of their distribution. The basic assumptions for a multiple regression analysis are satisfied. In the hierarchical regression analyses, we defined the PA level variable as the log2 of the IPAQ score. This choice was motivated by the nature of the IPAQ scoring, as METs roughly double when the perceived physical activity intensity increases by 1 (from low, to moderate, to vigorous). Moreover, the distribution of the PA levels has the neat property of being normally distributed, in contrast to the raw IPAQ scores. Descriptive statistics, correlations, and regressions were tested for each subgroup of the demographical variables. No differences were observed across subgroups.

Data analyses

Results

Data analyses were conducted in R [34]. Descriptive (i.e., mean scores and standard deviations) and correlation (i.e., non-parametric Kendall test) statistics were run on the five variables. The non-parametric Kendall correlation test was used for two reasons: (a) this test does not rely on a specific

Descriptive statistics No missing data was detected, thus statistical analysis was conducted on all the observations. The mean scores and standard deviations of the five variables are displayed in

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A. Ruffault et al. Table 2 General statistics. Statistiques générales. Variables

Anxiety level Depression level Acceptance Mindfulness PA level

␣

0.81 0.70 0.78 0.82

Descriptive statistic

Correlations

M

SD

1

2

3

4

5

6.28 5.01 50.61 4.15 3181.70

5.63 3.78 8.99 0.76 2910.07

1.00

0.37*** 1.00

—0.18* —0.33*** 1.00

—0.14* —0.26*** 0.30*** 1.00

0.01 —0.03 0.19** 0.06 1.00

␣: the coefficient of internal consistency of the questionnaires; M: mean scores; SD: standard deviation of mean scores. ˛ : coefficient de consistance interne des questionnaires ; M : moyenne ; SD : écart-type. * P < 0.05. ** P < 0.01. *** P < 0.001.

Table 3 Hierarchical regression analyses, reporting the variance in psychopathological variables explained by mindfulness skills, acceptance and PA level. Analyses de régression hiérarchique rapportant la part de variance des variables psychopathologiques expliquée par les capacités de pleine conscience, l’acceptation et le niveau d’activité physique. Dependant variable

Step

Independent variable

R2

Anxiety

1 2 3 1 2 3

Mindfulness Acceptance PA level Mindfulness Acceptance PA level

0.02 0.03 0.05 0.10** 0.18*** 0.21***

Depression

R2 change

0.01 0.02 0.08 0.03

B

B SE

␤

␤ SE

t

F

—1.11 —0.07 0.73 —1.55 —0.14 0.60

0.74 0.07 0.51 0.48 0.04 0.31

—0.15 —0.12 0.14 —0.31** —0.33** 0.18

0.10 0.11 0.10 0.10 0.10 0.09

—1.51 —1.06 1.42 —3.25 —3.20 1.90

2.27 1.69 1.81 10.59 10.92 8.68

R2 : the proportion of the criterion variance explained by predictors over and above response; R2 change: the difference between R2 in step-by-step regression; B: unstandardized regression coefficients; SE: standard error; ␤: standardized regression coefficients. * P < 0.05. R2 : proportion de variance expliquée par les prédicteurs ; R2 change : différence de valeur de R2 entre les étapes de régression ; B : coefficients de régression non-standardisés ; SE : erreur standardisée ; ˇ : coefficients de régression standardisés. ** P < 0.01. *** P < 0.001.

Table 2. We note that participants’ anxiety and depression mean scores were under the pathological thresholds of the two Beck’s inventories (anxiety: 6.28 ± 5.63; depression: 5.01 ± 3.78); and for acceptance and dispositional mindfulness, scores were higher than the norms established for these instruments (acceptance: 50.61 ± 8.99; dispositional mindfulness: 4.15 ± 0.76). For PA level, participants scored with a mean of 3181.70 MET-min per week (SD = 2910.07).

Correlations The correlation matrix is displayed in Table 2. As expected, anxiety scores and depression scores were strongly significantly positively correlated ( = 0.37; P < 0.001); and dispositional mindfulness and acceptance ( = 0.30; P < 0.001) too. We noted that acceptance was weakly significantly negatively correlated to anxiety level ( = —0.18; P < 0.05) and strongly to depression level ( = —0.33; P < 0.001). Also, dispositional mindfulness was weakly significantly negatively correlated to anxiety level ( = —0.14; P < 0.05) and

moderately to depression level ( = —0.26; P < 0.001). PA level was weakly significantly positively correlated to acceptance ( = 0.19; P < 0.01). Otherwise, PA level was neither significantly correlated with the psychopathological variables, nor with dispositional mindfulness.

Predicting psychopathological variables Hierarchical regression analyses are displayed in Table 3. For each dependant variable (i.e., anxiety scores and depression scores), three steps were tested. First, we tested a model in which dispositional mindfulness is the predictor (step 1). Second, we tested the prediction weights of dispositional mindfulness and acceptance (step 2). And third, we tested the prediction weights of dispositional mindfulness, acceptance, and PA levels (step 3). Anxiety elements Results of the hierarchical regression analysis using anxiety level as a dependant variable in step 1 showed no significant

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Mindfulness, exercise, and psychopathology predictor of the dependant variable among dispositional mindfulness, acceptance, and PA level at each of the three steps (all Ps > 0.05). Moreover, no model explained a significant proportion of variance of the dependant variable. On the other hand, comparing the models between step 1 and step 3 showed no significant difference between the models predicting anxiety. Depression elements Results of the hierarchical regression analysis using depression level as a dependant variable in step 1 indicated that mindfulness level significantly negatively predicts depression (␤ = —0.31; t = —3.25; P < 0.01), and that the model significantly explains 10% of the variance of depression scores (R2 = 0.10; F(1.98) = 10.59; P < 0.01). At step 2, adding acceptance (␤ = —0.33; t = —3.20; P < 0.001) in the model increased the value of R2 to reach 18% of the variance of depression scores (R2 = 0.18; F(2.97) = 10.92; P < 0.001). Comparing step 1 and step 2 suggested that the model at step 2 predicted a significantly larger proportion of variance than the model at step 1 (R2 change = 0.08; F(1.97) = 10.25; P < 0.01). At step 3, adding PA level (␤ = 0.18; t = 1.90; ns) in the model increased the value of R2 to reach 21% of the variance of depression scores, which remained strongly significant (R2 = 0.21; F(3.96) = 8.68; P < 0.001). Comparing the models from step 2 and step 3 showed no significant difference in the proportion of variance between the models (R2 change = 0.03; F(1.96) = 3.62; ns). Anova between models at step 1 and step 3 indicated that the increase in R2 between the two steps is significant (R2 change = 0.11; F(2.96) = 7.07; P < 0.01), which means that adding acceptance and PA level as predictors of depression scores with mindfulness increased the proportion of variance of the dependant variable (i.e., depression) by 11 percentage points.

Discussion The aim of this study was to predict signs of anxiety and depression using mindfulness skills (i.e., dispositional mindfulness and acceptance) and levels of PA as predictors in non-clinical individuals. The participants can be considered as a non-clinical population, as their anxiety and depression levels were under the pathological thresholds. The mean scores also reflected high levels of acceptance and dispositional mindfulness. Previous studies showed that mindful individuals are more likely to adopt healthy lifestyles [18], meaning that non-mindful individuals would be more likely to experience clinical symptoms, and thus, they would not be eligible for this study. As hypothesized, these tendencies (i.e., being mindful and not depressed nor anxious) showed that dispositional mindfulness was negatively correlated with anxiety level and depression level, which is concordant with Brown and Ryan’s findings [12]. In the MAAS-validation’s study, Brown and Ryan [12] measured anxiety and depression using multiple tools, including Beck’s inventories. Similar results were found for acceptance levels, which were negatively correlated with anxiety level and depression level, in accordance with Hayes et al.’s findings [30]. The AAQ validation’s studies [30,32] showed negative associations between acceptance and depression, and between acceptance and anxiety in

7 healthy individuals and in psychiatric patients. Moreover, acceptance was positively correlated with higher PA level, which is similar to the results obtained by Ulmer et al. [17]. In their previous study investigating the effects of an acceptance-based program on PA level, Butryn et al. [16] argued that if the increase of PA level could be sustained with the program, participants could show significant physical and/or mental health benefits. In fact, accepting negative thoughts and feelings — not only about PA but also in day-to-day life — should improve self-regulation, and increase PA levels. Brown and Ryan [12] argued that mindful states of mind lead to fostering self-endorsed behavioral regulation, which can be associated with a better mental health. These authors hypothesized that mindfulness helps to prevent automatic reactions by bringing awareness of or attention to the emotional and behavioral responses in the present moment. Our hypothesis was that the prediction of signs of anxiety and depression with mindfulness constructs and PA together is stronger than the prediction of signs of anxiety and depression with mindfulness skills alone or PA alone. This hypothesis is partly confirmed (it is not confirmed for anxiety) in this one time survey by the comparison of the models, revealing that the models at step 3 explained a larger share of variance than the models from previous steps did (i.e., 10% at step 1 and 21% at step 3). The distribution of the data did not make it possible to run a parametric analysis, which represents a limitation in our correlational analyses. This could be due to our sample of 100 non-clinical randomly chosen adults, since firstly, the number is low considering the number of healthy individuals; and secondly, even if it had represented the general population for such investigations, the participants are very different from each other (e.g., age, gender, family, education). Thus, larger samples would make it possible to study the general population better. The lack of participants was a major bias for IPAQ scores, which did not show a normal distribution — the standard deviation was too close to the mean. Thus, in this study, the low prediction of PA level in the models could not be entirely explained by a low impact of PA level on psychopathological variables, but rather by a lack of statistical power. With a larger sample we might have observed a higher regression coefficient of PA in the model. Individuals’ contributions to the explained variance in anxiety levels were lower than 10 per cent, which is relatively low. These results, as well as the lack of significance in all the models predicting anxiety level, could be explained by the fact that our sample is not a clinical sample of individuals experiencing high anxiety. In a clinical sample of anxious patients, the links between mindfulness skills and PA with anxiety could have been highlighted. Moreover, plotting the frequency diagram, we found a large number of the participants on the left of the scale (i.e., low anxiety scores). This result could be explained by the items of the BAI (i.e., a list of symptoms), which are difficult to discriminate if one does not focus on them over a few days. Another limitation to our study was the correlational design itself. No causal relationship between mindfulness skills and PA with regard to psychopathological variables could be analyzed. Despite the higher regression coefficient of dispositional

Please cite this article in press as: Ruffault A, et al. Exploring the links between mindfulness skills, physical activity, signs of anxiety, and signs of depression among non-clinical participants. Journal de thérapie comportementale et cognitive (2016), http://dx.doi.org/10.1016/j.jtcc.2016.09.003

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mindfulness and acceptance, the role of PA levels remains unknown in this relationship. With depressed patients, Oeland et al. [10] showed that a PA program can reduce anxiety and depression, but patients’ compliance in the program was only due to the presence of an instructor. However, Ruffault et al. [20] showed that mindful individuals engage in PA for intrinsic motives (i.e., not for extrinsic motives such as ‘‘to please others’’). In our study, the absence of association between PA level and psychopathological variables could be explained by the lack of information about how our participants practiced physical activities in their daily lives. Indeed, it was not known whether the participants usually exercised within group settings or individually, and how this affected their engagement in PA. Moreover, we could have investigated what kinds of exercises the participants regularly practiced. In fact, this information would have been useful to check whether the participants were engaged in the practice of mind-body exercises or not. We could have expected that our model would be better fitted to the psychopathological data (i.e., anxiety level and depression level) for individuals practicing mind-body exercises.

Conclusion Better knowledge about the effects of mindfulness- and acceptance-based interventions on psychopathological comorbidities and health behaviors is needed in the field of health psychology. For instance, there is still neither a specific nor an effective mindfulness- or acceptancebased training program combined with physical exercise that would be useful in prevention or for the rehabilitation of chronic patients among the European population. This exploratory study may lead other researchers to develop and test the validity of mindfulness- and acceptance-based interventions associated with PA programs in order to reduce depression levels among healthy individuals. Future investigations should also measure the long-term effects of mindfulness and PA in these interventions. It also seems necessary in future research to use structural equation modeling on a larger sample, which will test the fit of a model, including the variables of anxiety levels, depression levels, dispositional mindfulness, acceptance, PA levels, and the type of PA practice in the general population. This model analysis will also make it possible to run invariance testing using demographic groups such as gender, age, professional status, number of children, and family status, in order to enhance the understanding of the role of mindfulness skills and PA level in the field of psychopathology. Additionally, the causal links between mindfulness and PA could be studied to determine whether an increase in dispositional mindfulness impacts PA levels more than an increase in PA levels impacts mindfulness skills.

Disclosure of interest The authors declare that they have no competing interest.

Acknowledgements Catherine O’Malley and Laura Killian for translation corrections.

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Please cite this article in press as: Ruffault A, et al. Exploring the links between mindfulness skills, physical activity, signs of anxiety, and signs of depression among non-clinical participants. Journal de thérapie comportementale et cognitive (2016), http://dx.doi.org/10.1016/j.jtcc.2016.09.003