Background : Only a handful of population-based studies have investigated the relationship between major depressive disorder (MDD) and physical activity (PA) while taking into account the different subtypes of MDD, which refer to melancholic, atypical or others. Our knowledge about the neurobiology of those subtypes remains pretty scarce. Only a few studies have included psychometry instruments covering a longer period of time like the Global assessment of functioning (GAF) score. Despite major progress in the neurobiology of MDD, our knowledge about its impact on daily life remains scarce and poses a major challenge for basic and clinical neuroscience.
Evidence suggests that physical activity reduces the impact of cardiovascular risk factors (CVRF) and MDD, however the direction of causal relationships remains obscure. The time spent in moderate to vigorous physical activity (MVPA) and estimated cardiorespiratory fitness (eCRF) may help us to better assess the link between PA and mood disorders.
Given the strong relationship between MVPA, eCRF, and mental health, we sought to investigate the association between physical activity and depression dis- order subtypes in the PsyColaus cohort. Our first hypothesis is that a low level of MVPA and eCRF would be related to a higher incidence of lifetime and atypical MDD paralleled by a lower GAF score. Our second hypothesis is that low level of MVPA and eCRF would be associated with a low CVRF.
Methods : We analyzed cross-sectional data from the second follow-up (2014- 2017) of the CoLaus/Psycholaus cohort recruited from the general population of Lausanne, Switzerland. We selected 1750 participants (53.6% female, age mean = 62.8, SD = 10.0 years) who performed both psychiatric and physical activity assess- ment. All participants had a somatic examination including cardiovascular risk factors such as age, body mass index (BMI), hypertension, diabetes, dyslipidemia and smoking status. They also had a psychiatric evaluation, including a semi-structured interview covering mental disorders, drawn from the Diagnostic Interview for Ge- netic Studies (DIGS), with a clinical assessment. According to this, the patients with MDD were stratified into atypical, melancholic, mixed, and unspecified. In addition, the GAF score was assessed for each individual. Concerning PA, we col- lected actigraphic data over 2 weeks (24h/24h continuous measurements) and we calculated MVPA as the sum of time spent in moderate and vigorous physical activ- ity. Estimated CRF (eCRF) was determined using algorithms based on somatic and actimetry evaluation. Pearsons and Spearmans correlation coefficient were used to test for correlations between MDD subtypes, GAF score, CVRF, MVPA, and eCRF after applying Bonferroni correction. No covariates adjustment was performed.
Results : In the second follow-up of the PsyCoLaus cohort, eCRF was nega- tively linked to MDD atypical (r = -0.07, 95CI [-0.12,-0.02], p-value < 0.0028) and MDD lifetime (r = -0.05, 95%CI [-0.1, -0.0], p-value <0.04). MVPA was not sig- nificantly associated with any types of MDD. GAF score was also not significantly associated either with MVPA or eCRF. However, MVPA was negatively associated with CVRF, which included BMI (r = -0.18, 95%CI [-0.22, -0.13], p-value < 6.80e- 14), hypertension (r = -0.22, 95%CI [-0.26, -0.17], p-value < 6.19e-21), diabetes (r = -0.15, 95%CI [-0.2, - 0.11], p-value < 1.71e-11) and dyslipidemia (r = -0.13, 95%CI [-0.18, - 0.08], p-value < 4.49e-8). A high eCRF was also associated with lower CVRF, which mean less hypertension (r = -0.23, 95%CI [-0.28, -0.19], p-value < 3.90e-23), dyslipidemia (r = -0.09, 95%CI [-0.14, -0.05], p-value < 1.13e-5) and diabetes (r = -0.16, 95%CI [-0.2, -0.11], p-value < 2.21e-11).
Conclusion : This study suggests that high MVPA and eCRF were associ- ated with a lower incidence of CVRF. In contrast to our hypothesis, no association between physical activity and major depressive disorder was observed. Future stud- ies exploring pathophysiological mechanisms shared between CVRF, depression and physical activity are warranted.