Depression, anxiety and physical function: exploring the strength of causality.

BACKGROUND: Depression, anxiety and physical function may be bi-directionally related. We aim to estimate the strength of the longitudinal associations between depression, anxiety and physical function. METHODS: Prospective cohort study of general practice attendees across Europe (N=4757) assessed at baseline, 6, 12 and 24 months. Main outcome measures were Diagnostic and Statistical Manual of Mental Disorders-IV major depression, Patient Health Questionnaire anxiety and Short Form 12 physical function. Complete-case analyses using random coefficient models and logistic regression models were performed. RESULTS: Those with depression (β=-1.90, 95% CI -3.42 to -0.39), anxiety (β=-4.12, 95% CI -5.39 to -2.86) or depression and anxiety (β=-5.74, 95% CI -7.38 to -4.10) had lower levels of physical function at baseline and over time compared with no diagnosis after adjustment for potential confounders. Physical function increased over time, but the rate of increase was not different between the groups. When compared with depression, those with anxiety (β=-2.22, 95% CI -4.08 to -0.36) or depression and anxiety (β=-3.83, 95% CI -5.95 to -1.71) had significantly lower levels of physical function at baseline. Lower levels of physical function at baseline were associated with onset of depression (OR 1.83, 95% CI 1.08 to 3.10) but even stronger with anxiety (OR 2.79, 95% CI 1.52 to 5.12) or depression and anxiety (OR 5.05, 95% CI 2.55 to 9.99) during 24 months compared with no dysfunction, after adjustment for potential confounders. CONCLUSION: It is essential to prevent lower levels of physical function as this is likely to lead to onset of depression and anxiety over time

Differential impact of risk factors for women and men on the risk of major depressive disorder.

PURPOSE: Our aim is to examine which risk factors have a greater impact in women than in men on the risk of major depressive disorder (MDD) and whether factors differ between a possible recurrent MDD and a first onset of MDD. METHODS: Prospective cohort study of general practice attendees in seven countries, who were followed up at 6 and 12 months (predictD). Absolute risk differences (interaction contrast) across sex for onset of DSM-IV MDD after 6 or 12 months of follow-up were estimated for 35 risk factors from 7101 participants without MDD at baseline. RESULTS: A total of 599 participants (80% female) had an onset of MDD at 6 or 12 months. Most risk factors had a greater impact in women than in men on the risk of MDD and were not restricted to a specific class of risk factors. After we stratified for a history of depressive symptoms, we found that the impact of risk factors across sex was generally stronger on possible recurrent MDD than on a first onset of MDD. CONCLUSIONS: Our findings may partly account for the observed difference in incidence of MDD between men and women