Prospective relationship of depressive symptoms, drinking, and tobacco smoking among middle-aged and elderly community-dwelling adults: Results from the China Health and Retirement Longitudinal Study (CHARLS)

Background
Previous studies in Western countries have consistently documented positive associations of smoking and heavy drinking with depressive symptoms but a prospective analysis of these relationships among middle-aged and elderly community members in China have not previously been reported.

Methods
Using data from the China Health and Retirement Longitudinal Study, a two-wave nationally representative survey conducted in 15,628 adults 45 years of age and older, we estimated the prospective association between depressive symptoms and an array of smoking and drinking behaviors. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale (CES-D) short form.

Results
Inverse associations were the dominant pattern of association. For the population as a whole, individuals with baseline depressive symptoms were less likely to start drinking (OR=0.7, 95% CI=0.5, 0.9) or smoking (OR=0.6, 95% CI=0.4, 0.8). Similarly, baseline drinkers and smokers were less likely to develop depressive symptoms (ORdrinkers=0.6, 95% CI=0.5, 0.7; ORsmokers=0.7, 95% CJ=0.6, 0.9). No evidence was found for an increased incidence or persistence of depressive symptoms among high-frequency drinkers or heavy smokers or vice versa. Males who had never smoked prior to the onset of depressive symptoms tended to have more rapid onset of tobacco dependence compared to those without such symptoms. Males and females had different association patterns.

Limitations
The study is observational in nature and provides limited evidence for causality.

Discussion
The results are inconsistent with previous findings in Western countries, throwing into question the presumed universality of the association between alcohol drinking or tobacco use and depression among middle-aged and elderly adults.