From a New York Times article today:
A team of Swedish and Danish researchers tracked coffee consumption in a group of 1,409 middle-age men and women for an average of 21 years. During that time, 61 participants developed dementia, 48 with Alzheimer’s disease.
After controlling for numerous socioeconomic and health factors, including high cholesterol and high blood pressure, the scientists found that the subjects who had reported drinking three to five cups of coffee daily were 65 percent less likely to have developed dementia, compared with those who drank two cups or less. People who drank more than five cups a day also were at reduced risk of dementia, the researchers said, but there were not enough people in this group to draw statistically significant conclusions.
The article goes on to observe that there may also be a correlation between coffee consumption and decreased risk of type 2 diabetes and Parkinson’s disease. All I know is that if this is true then my consumption of a pound and a half of coffee a week is all worth it.