Green Tea Drinking in Elderly Linked to Lower Risk for Depression
Laurie Barclay, MD
December 29, 2009 — More frequent consumption of green tea is associated with a lower prevalence of depressive symptoms in the community-dwelling older population, according to the results of a cross-sectional study reported in the December issue of the American Journal of Clinical Nutrition.
"Green tea is reported to have various beneficial effects (e.g., anti–stress response and anti-inflammatory effects) on human health," write Hideko Takahashi, from Tohoku University Graduate School of Biomedical Engineering in Sendai, Japan, and colleagues. "Although these functions might be associated with the development and progression of depressive symptoms, no studies have investigated the relation between green tea consumption and depressive symptoms in a community-dwelling population."
The objective of the study was to evaluate the association between green tea drinking and depressive symptoms in 1058, community-dwelling, elderly Japanese subjects 70 years or older who widely consumed green tea. A self-administered questionnaire was used to determine green tea intake. The 30-item Geriatric Depression Scale was used to evaluate depressive symptoms, with a cutoff point of 11 indicating mild and severe depressive symptoms and a cutoff value of 14 indicating severe depressive symptoms. Antidepressant use was also considered to indicate depressive symptoms.
In this cohort, 34.1% had mild and severe depressive symptoms, and 20.2% had severe depressive symptoms. Compared with green tea consumption of 1 or less cup per day, odds ratios for mild and severe depressive symptoms were 0.96 for 2 to 3 cups (95% confidence interval [CI], 0.66 - 1.42) and 0.56 for 4 or more cups of green tea per day (95% CI, 0.39 - 0.81; P for trend = .001), after adjustment for confounding factors. Similar associations were seen for severe depressive symptoms.
"A more frequent consumption of green tea was associated with a lower prevalence of depressive symptoms in the community-dwelling older population," the study authors write.
Limitations of this study include cross-sectional design, preventing causal inferences; possible confounding factors; and lack of data on other psychiatric conditions, symptoms, or treatments. In addition, participants were more active and healthy than those who did not undergo the assessment, and the Geriatric Depression Scale is not designed for making a clinical diagnosis of depressive episodes.
"In the present study, higher green tea consumption (as measured by self-administered questionnaires) was significantly associated with a lower prevalence of depressive symptoms in community-dwelling elderly individuals," the study authors conclude. "This finding suggested that the consumption of green tea may have a potentially beneficial effect on the prevention of depressive symptoms. A prospective study or randomized trials are required to clarify the causality."
The Ministry of Education, Culture, Sports, Science and Technology of Japan; the Japan Atherosclerosis Prevention Fund; and the Ministry of Health, Labor, and Welfare of Japan supported this study. The study authors have disclosed no relevant financial relationships.
Am J Clin Nutr. 2009;90:1615-1622.