Does the association between depression and smoking vary by body mass index (BMI) category?

The purpose of this study was to explore how weight might influence the relationship between depression and smoking.

Data were obtained from a cross-sectional survey representative of women age 40-65 enrolled in Group Health Cooperative, a health plan serving members in Washington and northern Idaho (n=4640). We examined the relationships between depression and smoking in normal weight, overweight, and obese women using weighted multiple logistic regression with both minimal and full adjustment.

Current depression was significantly associated with current smoking in obese women (adjusted odds ratio=2.48, 95% confidence interval=1.26-4.88) but not in underweight/normal or overweight women. Among ever smokers, obese women, but not other groups, were significantly less likely to have quit smoking in the past.

In our preliminary study, the association between smoking and depression in middle-aged women appears to be limited to the obese subset and may stem from a lesser likelihood of obese ever smokers to have quit. This population represents an important target for preventive medicine efforts.