Coffee, caffeine and risk of depression among women

A total of 50,739 US women (mean age 63 years) free of depressive symptoms at baseline (in 1996) were prospectively followed up through 1 June 2006. Consumption of caffeine was measured from validated questionnaires completed from 1 May 1980, through 1 April 2004, and computed as cumulative mean consumption with a 2-year latency period applied.

Clinical depression was defined as self-reported physician-diagnosed depression and antidepressant use. Relative risks of clinical depression were estimated using Cox proportional hazards regression models.

During 10 years of follow-up (between 1996 and 2006), 2607 incident cases of depression were identified. Compared with women consuming one or less cups of caffeinated coffee per week, the multivariate relative risk of depression was 0.85 (95% confidence interval, 0.75-0.95) for those consuming two to three cups per day and 0.80 (0.64-0.99; P for trend <.001) for those consuming four cups per day or more. Multivariate relative risk of depression was 0.80 (95% confidence interval, 0.68-0.95; P for trend = .02) for women in the highest ( 550 mg/d) vs lowest (<100 mg/d) of the five caffeine consumption categories. Decaffeinated coffee was not associated with depression risk.

In this large longitudinal study, scientists found that depression risk decreases with increasing caffeinated coffee consumption. Further investigations are needed to confirm this finding and to determine whether usual caffeinated coffee consumption can contribute to depression prevention.