January 27, 2009
Middle-aged men and women who drank three to five cups of coffee a day were less likely to get Alzheimer's disease in old age, a new study found. The report, from researchers in Finland and Sweden, was published in the Journal of Alzheimer's Disease.
The results were part of the Finnish Cardiovascular Risk Factors, Aging and Dementia (CAIDE) Study, which followed 1,409 people in Finland over two decades. It began when most people were in their 40s or 50s, and concluded more than twenty years later, when they were in their late 60s or 70s. During that time, 61 of those in the study developed Alzheimer's or another form of dementia.
The researchers looked at both coffee and tea consumption. Both beverages have been linked to a decreased risk of Alzheimer's in some earlier studies.
"We aimed to study the association between coffee and tea consumption at midlife and dementia and Alzheimer's disease risk in late-life, because the pathologic processes leading to Alzheimer's disease may start decades before the clinical manifestation of the disease," said lead researcher Dr. Miia Kivipelto, from the University of Kuopio in Finland and The Karolinska Institute in Stockholm. "The long-term impact of caffeine on the central nervous system was still unknown."
Study participants were asked about how much coffee or tea they drank. Coffee drinking was categorized into three groups: 0 to 2 cups (low), 3 to 5 cups (moderate) and more than 5 cups (high) per day. Most of the participants didn't drink tea, so its effects on later Alzheimer's development were not assessed.
The study found that coffee drinkers at midlife had lower risk for Alzheimer's disease later in life compared to those who didn't drink coffee or who drank very little. Moderate coffee drinkers were found to have the lowest risk, a 65 percent reduction in Alzheimer's.
"The finding needs to be confirmed by other studies, but it opens the possibility that dietary interventions could modify the risk of Alzheimer's disease," Dr. Kivipelto said. He also noted that understanding how coffee may aid the brain could lead to the development of new therapies for Alzheimer's .
Previous studies have suggested that caffeine may have benefits for the brain. A 2007 study from France, for example, found that women age 65 and older who drank more than three cups of coffee, or an equivalent amount of caffeine-rich tea, scored better on tests that measure thinking and memory skills than women who drank a cup or less of coffee or tea a day.
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 also suggest that caffeine may provide some protection against Alzheimer's . One found that Alzheimer's was more likely in people who drank little coffee in the previous 20 years. Another 10-year study in Finnish men found that drinking three cups or more of coffee a day was associated with reduced risk for Alzheimer's. And a third reported that drinking coffee, but not tea, helped protect against Alzheimer's five years later.
Age remains the most important risk factor for Alzheimer's: The older you are, the more likely you are to develop the disease. Smoking, high blood pressure, years of schooling, and genetic factors may also contribute to risk, other research has shown.
Marjo H. Eskelinen, Tiia Ngandu, Jaakko Tuomilehto, Hilkka Soininen, Miia Kivipelto. "Midlife Coffee and Tea Drinking and the Risk of Late-Life Dementia: A Population-based CAIDE Study." Journal of Alzheimer's Disease, 16(1)