Coffee and tea may do more than just jolt you awake—they could also help keep your brain healthy, according to a slew of recent studies. Researchers have linked these beverages with protection from depression, Alzheimer's disease and Parkinson's disease.
One large study investigated the link between depression and the intake of coffee, tea and sweet drinks [see box below]by following more than a quarter of a million older adults for 10 years. Researchers at the National Institutes of Health recorded consumption of each type of beverage in 1995 and 1996 and then compared those figures with participants' self-reported diagnoses of depression after 2000. Results showed that coffee intake was associated with a slightly lower risk for depression, according to a paper published last April in PLOS ONE. The paper found little effect from tea, but other work has shown tea to be protective.
A study reported in November 2013 found older Chinese adults who regularly drank any kind of tea had a significantly smaller risk for depression: 21 percent for those who drank tea between one and five days a week and 41 percent for daily drinkers. The researchers also asked about the participants' leisure activities to ensure that the tea, and not teatime socializing, provided the protective effect.
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Some studies suggest that coffee and tea drinkers have lower rates of cognitive decline, too, but the evidence is mixed. Research in rodents that has focused on specific compounds in coffee and tea supports the idea that some of these chemicals reduce the risk for Alzheimer's and Parkinson's. In one such study, published online last June in Neurobiology of Aging, supplementing rats' diets with a component of coffee called eicosanoyl-5-hydroxytryptamide shielded the animals' brains against the pathological changes typical of Alzheimer's. In 2013 another experiment found the same compound to have protective effects against a mouse model of Parkinson's. Caffeine may not just defend the brain but help it, too—a paper in September in the same publication reports that spiking the mice's drinking water with caffeine reduced the protein tangles seen in Alzheimer's, and it also prevented spatial memory deficits.
It is still too soon to say whether coffee and tea truly protect the brain, but most researchers agree a daily habit couldn't hurt.