Coffee and caffeine consumption and depression: A meta-analysis of observational studies.
OBJECTIVE
The results from observation studies on the relationship between coffee intake and risk of depression and the relationship between caffeine consumption and depression remain controversial. We conducted a meta-analysis with a dose-response analysis to quantitatively summarize the evidence about the association between coffee and caffeine intakes and risk of depression.


METHODS
Relevant articles were identified by researching PubMed, Web of Science, China National Knowledge Infrastructure and WANFANG DATA in English or Chinese from 1 January 1980 to 1 May 2015. Case-control, cohort or cross-sectional studies evaluating coffee or caffeine consumption and depression were included. A random-effects model was used to combine study-specific relative risk and 95% confidence interval. Dose-response relationship was assessed by restricted cubic spline functions.


RESULTS
Data were obtained from 11 observation articles; 330,677 participants from seven studies in seven articles were included in the coffee-depression analysis, while 38,223 participants from eight studies in seven articles were involved in the caffeine-depression analysis. Compared with the lowest level consumption, the pooled relative risk (95% confidence interval) for coffee-depression and caffeine-depression was 0.757 [0.624, 0.917] and 0.721 [0.522, 0.997], respectively. For dose-response analysis, evidence of a linear association was found between coffee consumption and depression, and the risk of depression decreased by 8% (relative risk = 0.92, 95% confidence interval = [0.87, 0.97], p = 0.002) for each cup/day increment in coffee intake; a nonlinear association was found between caffeine consumption and depression, the risk of depression decreased faster and the association became significant when the caffeine consumption was above 68 mg/day and below 509 mg/day.


CONCLUSIONS
Coffee and caffeine consumption were significantly associated with decreased risk of depression.
Department of Epidemiology and Health Statistics, Qingdao University Medical College, Qingdao, China.
Longfei
L
Wang
Department of Epidemiology and Health Statistics, Qingdao University Medical College, Qingdao, China.
Xiaoli
X
Shen
Department of Epidemiology and Health Statistics, Qingdao University Medical College, Qingdao, China.
Yili
Y
Wu
Department of Epidemiology and Health Statistics, Qingdao University Medical College, Qingdao, China zhangdf1961@126.com zhangdf1962@aliyun.com.
Dongfeng
D
Zhang
D002110:Caffeine / Q000008:administration & dosage*; D003069:Coffee; D003863:Depression / Q000453:epidemiology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D064887:Observational Studies as Topic
D003069:Coffee; D002110:Caffeine
Coffee; caffeine; depression; dose–response analysis and meta-analysis