Coffee, caffeine, and risk of completed suicide: Results from three prospective cohorts of American adults

Abstract

Objective.To evaluate the association between coffee and caffeine consumption and suicide risk in three large-scale cohorts of US men and women. Methods. We accessed data of 43,599 men enrolled in the Health Professionals Follow-up Study (HPFS, 1988–2008), 73,820 women in the Nurses’ Health Study (NHS, 1992–2008), and 91,005 women in the NHS II (1993–2007). Consumption of caffeine, coffee, and decaffeinated coffee, was assessed every 4 years by validated food-frequency questionnaires. Deaths from suicide were determined by physician review of death certificates. Multivariate adjusted relative risks (RRs) were estimated with Cox proportional hazard models. Cohort specific RRs were pooled using random-effect models. Results. We documented 277 deaths from suicide. Compared to those consuming ≤ 1 cup/week of caffeinated coffee (< 8 oz/237 ml), the pooled multivariate RR (95% confidence interval [CI]) of suicide was 0.55 (0.38–0.78) for those consuming 2–3 cups/day and 0.47 (0.27–0.81) for those consuming ≥ 4 cups/day (P trend < 0.001). The pooled multivariate RR (95% CI) for suicide was 0.75 (0.63–0.90) for each increment of 2 cups/day of caffeinated coffee and 0.77 (0.63–0.93) for each increment of 300 mg/day of caffeine. Conclusions. These results from three large cohorts support an association between caffeine consumption and lower risk of suicide.

Key words::

• Coffee
• caffeine
• suicide
• cohorts
• food-frequency questionnaires

Acknowledgements

None.

Statement of interest

The authors have no conflict of interest to declare.

Supported by research grants P01 CA087969, U19 CA055075, and R01 CA050385 from the National Institutes of Health (NIH) for the maintenance and follow-up of the cohorts that provided data for the study. Dr Ascherio is supported by NIH Grant R01 NS061858. Dr Lucas received a postdoctoral fellowship from Fonds de recherche en santé du Québec (FRSQ). The funding source had no role in the design and conduct of the study, analysis or interpretation of the data, preparation or final approval of the manuscript, or the decision to submit the manuscript for publication.

The contributions of each author were as follows: all authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: ML, WCW and AA. Acquisition of data: WCW and AA. Analysis and interpretation of data: ML, EJO’R, AP, FM, OIO, WCW and AA. Writing the first draft of the manuscript: ML. Critical revision of the manuscript for important intellectual content: ML, EJO’R, AP, FM, OIO, WCW and AA. Statistical analysis: ML, EJO’R and AA. Obtained funding: WCW and AA. Administrative, technical, and material support: WCW and AA. Study supervision: WCW, OIO and AA.