Coffee and caffeine can help prevent depression
Women who drink a couple of cups of coffee every day are less likely to develop depression than women who drink no coffee. American nutritionists at the University of Harvard announced this in 2011 in JAMA Internal Medicine.
The researchers used data that had been gathered during the Nurses Health Study, an epidemiological project that started in 1976, in which researchers closely follow tens of thousands women working in healthcare. The researchers monitored the women's health and assessed the women's lifestyle every two years.
For this study the researchers followed 50,739 participants between 1996 and 2006. At the start of the study the average age of the women was 63. The researchers looked at their coffee intake (80 percent of the caffeine consumed by Americans comes from coffee [J Am Diet Assoc. 2005 Jan;105(1):110-3.])), and asked whether the women were being treated by a doctor for depression.
Compared with women who drank little or no coffee, women who drank 2-3 cups of coffee per day were 15 percent less likely to develop depression. Women who drank 4 or more cups of coffee per day had a 20-percent less chance of developing depression.
The table below shows the relationship between depression and daily caffeine intake.
The researchers assumed that a cup of coffee contains 137 mg caffeine and that a cup of tea or soft drink with caffeine in it contains 46-47 mg caffeine.
"Long-term caffeine consumption has several biological effects that should be taken into account when considering the plausibility of its potential to reduce depression risk," the researchers wrote. "At low to moderate doses, caffeine has well-known psychostimulant effects, such as improved psychomotor performance, increased vigilance, elevated arousal (ie, lesser somnolence and greater activation), and increased sensations of well-being and energy." [J Neurochem. 2008 May;105(4):1067-79.]
"The known effects of caffeine are dose dependent but typically biphasic (ie, low doses are perceived as pleasant and stimulating, but the reverse effect is observed with higher doses)." [Pharmacol Rev. 1999 Mar;51(1):83-133.]
"Most individuals seem to adapt their caffeine consumption to their own level of tolerance so that their habitual consumption level is within the range between reinforcing and aversive effects."
"Caffeine affects brain function mainly by its antagonist action on the adenosine A2A receptor and, therefore, plays a role in the modulation of dopaminergic transmission. The antagonist effect of caffeine on adenosine also might imply nondopaminergic mechanisms, such as modulation of the release of acetylcholine and serotonin." [Front Biosci. 2008 Jan 1;13:2391-9.]
"In conclusion, our results support a possible protective effect of caffeine, mainly from coffee consumption, on risk of depression. These findings are consistent with earlier observations that suicide risk is lower among persons with higher consumption of coffee. [Ann Epidemiol. 1993 Jul;3(4):375-81.] [Arch Intern Med. 1996 Mar 11;156(5):521-5.] Further investigations are needed to confirm this finding and to determine whether usual caffeinated coffee consumption may contribute to prevention or treatment of depression."
Arch Intern Med. 2011 Sep 26;171(17):1571-8.
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