Further evidence has come to light that drinking coffee may have a protective effect against dementia. Dementia and Alzheimer’s disease are common problems in the elderly population. Although research is improving our knowledge of the underlying biology of these disorders, we still have little understanding of the “modifiable” risk factors.
Caffeine has been suggested to have a protective effect against dementia. This new study comes from the University of Kuopio, Finland and the Karolinska Institutet in Stockholm, Sweden. Dr. Miia Kivipelto and colleagues are involved in the ongoing Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study. The team looked at figures from 1,409 adults aged 65 to 79 who had been followed for an average of 21 years. Of these, 61 had been diagnosed with dementia. Daily coffee consumption was categorized into low (0-2 cups), moderate (3-5 cups) and high (more than five cups).
Results showed that moderate coffee drinkers had a 65 percent lower risk for dementia and Alzheimer’s disease later in life than the other groups. Tea consumption was categorized into not drinking tea versus drinking tea. But tea drinking was relatively uncommon, and showed no links with dementia or Alzheimer’s disease.
Dr. Kivipelto said, “We aimed to study the association between coffee and tea consumption at midlife and dementia/Alzheimer’s disease risk in late-life, because the long-term impact of caffeine on the central nervous system was still unknown, and as the pathologic processes leading to Alzheimer’s disease may start decades before the clinical manifestation of the disease.
“Given the large amount of coffee consumption globally, the results might have important implications for the prevention of or delaying the onset of dementia/Alzheimer’s disease.”
Dr. Kivipelto cautioned that the finding must be confirmed by future studies, however it “opens the possibility that dietary interventions could modify the risk of dementia/Alzheimer’s disease.” She added that identification of mechanisms of how coffee exerts its protection against dementia/Alzheimer’s disease might help in the development of new treatments. Findings are published in the January 2009 issue of the Journal of Alzheimer’s Disease.
The authors explain that caffeine causes short-term stimulation of the central nervous system, but its long-term impact on cognition is unclear. Although many earlier studies suggest that drinking coffee may reduce the risk of neurodegenerative diseases such as Alzheimer’s disease, the biological basis of any effect is still unexplained.
A recent study indicated that caffeine may protect the brain and cut the risk of dementia by blocking the damage that can be done by cholesterol. A team led by Dr. Jonathan Geiger of the University of North Dakota says that rabbits fed a fat-rich diet were protected by a caffeine supplement.
In the Journal of Neuroinflammation, they explain that they investigated the “blood-brain barrier,” a vital barrier between the brain and the body’s main blood supply. It acts as a filter to protect the brain from potentially harmful chemicals carried in the bloodstream. As previous studies have shown that high levels of cholesterol in the blood can make this barrier “leaky,” Dr. Geiger’s team predicted that this could cause damage which may trigger or contribute to Alzheimer’s disease.
They put rabbits on a high-cholesterol diet for 12 weeks, giving half of the animals the equivalent amount of caffeine found in one cup of coffee each day. At the end of the experiment, the blood-brain barrier in those given caffeine was “far more intact” than in those given no caffeine.
This is the “best evidence yet” of coffee’s benefits, they believe. Dr. Geiger said, “Caffeine appears to block several of the disruptive effects of cholesterol that make the blood-brain barrier leaky. High levels of cholesterol are a risk factor for Alzheimer’s disease, perhaps by compromising the protective nature of the blood-brain barrier.
“Caffeine is a safe and readily available drug, and its ability to stabilize the blood-brain barrier means it could have an important part to play in therapies against neurological disorders.”
Further studies are needed to establish whether the same effect could be seen in humans, and whether coffee, tea or other forms of caffeine consumption (cocoa, cola or chocolate) can have a significant effect on an individual’s risk of Alzheimer’s disease or dementia. If this proves to be the case, caffeine and similar drugs may become a common treatment for Alzheimer’s disease and dementia.
Eskelinen, M. H. et al. Midlife Coffee and Tea Drinking and the Risk of Late-Life Dementia: A Population-based CAIDE Study. Journal of Alzheimer’s Disease, Vol. 16, 2009, in press.
Chen, X. et al. Caffeine blocks disruption of blood brain barrier in a rabbit model of Alzheimer’s disease. The Journal of Neuroinflammation, Vol. 5, April 3, 2008.