August 6, 2007
Enjoy that morning super-sized latte? It may be good for your brain. Researchers report that older women who drank three or more cups of coffee a day, or an equivalent amount of caffeine-rich tea, had sharper memories than women who held off on the java. The findings appeared in Neurology, the medical journal of the American Academy of Neurology.
The researchers, studying more than 7,000 older men and women living in three cities in France, found that women age 65 and older who drank more than three cups of coffee scored better on tests that measure thinking and memory skills than women who drank a cup or less of coffee or tea a day. The results held up even after researchers adjusted for other factors that could affect memory, such as age, education, disability, medications, depression, high blood pressure, heart disease, and other chronic illnesses. The men in the study, however, did not show the same benefits from drinking coffee as the women.
"Caffeine is a psycho-stimulant which appears to reduce cognitive decline in women," said study author Dr. Karen Ritchie of INSERM, the French National Institute for Health and Medical Research, in Montpellier, France. "While we have some ideas as to how this works biologically, we need to have a better understanding of how caffeine affects the brain before we can start promoting caffeine intake as a way to reduce cognitive decline."
"But the results are interesting," Ritchie continues. "Caffeine use is already widespread, it has fewer side effects than other treatments for cognitive decline, and it requires a relatively small amount for a beneficial effect."
At the start of the study, all the seniors were evaluated for thinking and memory function. None had Alzheimer's disease or other signs of serious memory loss, such as mild cognitive impairment. They were then evaluated over the following four years. Compared to women who drank one cup or less of coffee per day, those who drank over three cups were less likely to show as much decline in memory. Moreover, the benefits increased with age. Coffee drinkers were 30 percent less likely to score poorly on memory tests at age 65 than those who drank little or no coffee. That figure increased to 70 percent in those older than 80. Women who drank two or three cups of coffee a day did not show any notable boosts in memory.
The heavy coffee drinkers scored particularly well in tests that measured verbal recall, such as the ability to remember particulars of a story. They did slightly better in tests that measure visual and spatial memory.
Caffeine drinkers, however, did not seem to have lower rates of Alzheimer's disease. "We really need a longer study to look at whether caffeine prevents dementia; it might be that caffeine could slow the dementia process rather than preventing it," said Dr. Ritchie.
The researchers aren't sure why caffeine didn't show the same result in men. "Women may be more sensitive to the effects of caffeine," Dr. Ritchie said. "Their bodies may react differently to the stimulant, or they may metabolize caffeine differently."
Previous studies have suggested that caffeine may have benefits for the brain. Caffeine is known to boost vigilance, attention, mood, and arousal. It may also stimulate brain activity and protect the nerves, some research suggests. In mice, for example, caffeine has been shown to limit the accumulation of beta-amyloid, a toxic protein that builds up in the brains of Alzheimer's sufferers. Other studies suggest that caffeine may provide some protection against Alzheimer's, though they were small and require much more rigorous follow-up.
One found that Alzheimer's was more likely in people who drank little coffee in the previous 20 years. Another recent 10-year study in Finnish men found that drinking three cups or more of coffee a day may protect against Alzheimer's. And a third reported that drinking coffee, but not tea, helped protect against Alzheimer's five years later. These studies, however, did not adjust for factors like smoking, depression, medications, heart disease, and others that may impair memory.
The current study did adjust for these factors, and was much larger. Still, this study does not prove that coffee drinking prevents cognitive decline or helps to preserve cognition. Another possibility is that those women who drink at least three cups of coffee a day possess a trait that helps them resist cognitive decline. In that case, the tendency to drink a lot of coffee might be a consequence of having a protective trait, but the coffee itself might not provide protection. This type of uncertainty in inherent in most studies that try to draw conclusions based on peoples' habits.
That's why when testing new drugs, doctors randomly assign who gets the drug and who gets the placebo (dummy pill). In addition, it might not be the caffeine in the coffee that is having an effect on cognition. Besides caffeine, a cup of coffee contains over 1,000 other chemical compounds. Many of these could have biological effects on the brain and memory.
More research is needed before doctors can recommend a java jolt to keep memory sharp in seniors. Caffeine can cause jitteriness, keep people up at night, and cause palpitations or stomach upset in some people. Caffeine-rich drinks, including sodas, may also raise blood pressure, some research suggests.
In addition, there's no evidence that coffee wards off Alzheimer's disease. The study is ongoing, however, and researchers will continue to follow the elderly subjects to see if it reduces the risk of dementia.
K. Ritchie, PhD; I. Carriere, PhD, A. de Mendonca, MD, PhD, et al: "The Neuroprotective Effects of Caffeine: A Prospective Study (the Three City Study)." Neurology, Volume 69, August 7, 2007, pages 536-545. The American Academy of Neurology.