The risk of depression appears to decrease for women with increasing consumption of caffeinated coffee, according to a report based on a survey of nurses.
Caffeine is the most frequently used central nervous system stimulant in the world, and approximately 80% of consumption is in the form of coffee, according to background information in the article, which appears in the Archives of Internal Medicine. Previous research, including one prospective study among men, has suggested an association between coffee consumption and depression risk.
Because depression is a chronic and recurrent condition that affects twice as many women as men, including approximately one of every five U.S. women during their lifetime, “identification of risk factors for depression among women and the development of new preventive strategies are, therefore, a public health priority,” wrote the authors, who sought to examine whether in women, consumption of caffeine or certain caffeinated beverages is associated with the risk of depression.
Michel Lucas, PhD, RD, from the Harvard School of Public Health, and colleagues studied 50,739 U.S. women who participated in the Nurses’ Health Study. Participants, who had an average age of 63, had no depression at the start of the study in 1996 and were prospectively followed up through June 2006. Researchers measured caffeine consumption through questionnaires completed from May 1980 through April 2004, including the frequency that caffeinated and noncaffeinated coffee, nonherbal tea, caffeinated soft drinks (sugared or low-calorie colas), caffeine-free soft drinks (sugared or low-calorie caffeine-free colas or other carbonated beverages) and chocolate were usually consumed in the previous 12 months. The authors defined depression as reporting a new diagnosis of clinical depression and beginning regular use of antidepressants in the previous two years.
During a 10-year follow-up period from 1996 to 2006, researchers identified 2,607 new-onset cases of depression. When compared with women who consumed one cup of caffeinated coffee or less per week, those who consumed two to three cups per day had a 15% decrease in relative risk for depression, and those consuming four cups or more per day had a 20% decrease in relative risk. Compared with women in the lowest (less than 100 milligrams per day) categories of caffeine consumption, those in the highest category (550 mg per day or more) had a 20% decrease in relative risk of depression. No association was found between intake of decaffeinated coffee and depression risk.
The authors noted that this observational study “cannot prove that caffeine or caffeinated coffee reduces the risk of depression but only suggests the possibility of such a protective effect.” They called for further investigation to confirm their results and to determine whether regular caffeinated coffee consumption could contribute to prevention or treatment of depression.
To view a study summary, visit http://archinte.ama-assn.org/cgi/content/short/171/17/1571.