From dementia to stroke, suicide to lethal forms of cancer, coffee has been touted as reducing risk of all such medical conditions. Now, coffee drinkers, here's another reason to refill that cup of joe: A new prospective study found that risk of depression decreases as java consumption increases.
The catch? The findings apply only to post-menopausal women who smoke.
The research, published in the Archives of Internal Medicine, studied more than 50,000 women who participated in the Nurses' Health Study, a long-term Harvard study of some of the biggest issues affecting women's health. None of the women, who had an average age of 63, suffered from depression at the start of the study in 1996. By June 2006, researchers followed up and found that, for women who smoked, the more coffee they drank, the less they were at risk of depression.
Compared with women who drank 100 milligrams of coffee or less per day, women who drank four or more cups per day had 20 percent less risk of depression.
The association was not seen in nonsmoking women, and researchers could not analyze women who drank very high amounts of coffee -- more than six cups per day -- due to an insignificant number of people who consumed such quantities.
"Regular coffee drinkers have a lower risk of developing depression than nondrinkers," said Alberto Ascherio, professor of epidemiology and nutrition at Harvard School of Public Health and co-author of the study. But he warned, he said: "These are preliminary results that need to be confirmed."
In the study, the caffeinated coffee was associated with a decline in depression risk among older female smokers, but decaf coffee saw no such association. Oddly, when looking at other caffeinated resources (tea, soda, chocolate), researchers did not see an associated decrease of depression either. Study authors wrote that this could be because an insignificant portion of people made up the group after excluding those who drank one or more cups of coffee per day.
This type of depression is also not the typical kind that may develop in the younger years, researchers noted. Post-menopausal women are at higher risk of depression due to hormone and chemical changes in the brain. Because of this, the association of decreased depression risk cannot be directly linked to younger women.
"The association found in this study should be taken with caution," said Dr.Sudeepta Varma, assistant professor of psychiatry at NYU Langone Medical Center. "Caffeine, like other stimulants, can be addictive [and] has potential for producing withdrawal symptoms such as low mood. Also, the use of caffeine can cause anxiety, and at times too close to bedtime, insomnia, both of which are symptoms linked to depression."
More than half of American adults drink some form of coffee each day, according to the National Coffee Association, and caffeine is the most frequently consumed stimulant in the world.
"One has to be careful not to generalize, but it looks like in a large population, there were a significant amount of people who were less likely to be depressed," said Dr. Ken Robbins, clinical professor of psychiatry at the University of Wisconsin. "For someone who hasn't responded to antidepressants or talk therapy, this is something to consider in a trial, assuming there aren't going to be any adverse medical problems."