Cigarette smoking and the onset and persistence of depression among adults in the United States: 1994-2005.

BACKGROUND The present study investigated the relationship between daily cigarette smoking and risk of onset and persistence of major depressive disorder (MDD) over a 10-year period among adults in the United States and whether successful smoking cessation reduced the risk for MDD. METHOD Data were drawn from the Midlife Development in the United States Survey (MIDUS; n=2101) Waves I and II. Logistic regressions were used to investigate the relations between smoking and the onset and persistence of MDD, adjusting for demographic characteristics and substance use problems. RESULTS Daily smoking in 1994 [OR=1.9 (1.2-3.2)] and persistent daily smoking (in 1994 and 2005) [OR=2.2 (1.3-3.7)] were both associated with a significantly increased likelihood of MDD in 2005. Additionally, abstinence, compared to daily smoking, for more than 10years significantly reduced the risk of MDD in 2005 [OR=0.5 (0.3-0.87)] and persistent MDD in 1994 and 2005; [OR=0.5 (0.3-0.87)]. CONCLUSIONS Findings from this study provide new insights into the role of smoking in the onset and persistence of MDD. Namely, among those in mid-adulthood, smoking is associated with greater MDD risk and quitting may help to reduce such risk. These results suggest that there may be merit in targeting smoking to reduce the risk of MDD and the mental health benefits of quitting smoking in the form of reduced risk of MDD could usefully be added to common information listed as reasons to quit.