Smoking, Drinking, Cholesterol May Be Alzheimer's Ri...(ate drinking as three or four drinks a d...),Health

Despite those findings, "I suggest that more than two drinks a day is probably not a good idea," Duara said. "No one has shown that one or two a day is not as good as three or four a day in protecting" general health.

It's hard to tell why high blood cholesterol in the 40s should predict Alzheimer's disease in the 70s, but a study of 9,752 California men and women detected the link, said Rachel Whitmer, a research scientist with the Kaiser Permanente division of research in Oakland.

The study found people with total cholesterol levels between 249 and 500 milligrams were one-and-a-half times more likely to develop Alzheimer's disease than those with cholesterol levels less than 198 milligrams. People with total cholesterol levels of 221 to 248 milligrams were more than one-and-a-quarter times more likely to develop the disease.

"We definitely cannot say that this is cause and effect," Whitmer said. "But we know that total cholesterol levels in midlife are predictive of Alzheimer's disease later in life. We can only say that it is a risk factor."

It's not possible to conclude from the study that LDL cholesterol, the "bad" kind that clogs arteries, is responsible for the relationship, she said. In the 1960s and 1970s, when data on the participants were gathered, no distinction had been made between LDL cholesterol and HDL cholesterol, the "good" kind that helps keep arteries open.

"Future studies need to look at that question," Whitmer said.

Meanwhile, "people need to be thinking about their risk factors for Alzheimer's disease even in their 40s," she said. "What is good for your heart is also good for your brain."

More information

You can learn what is known about risk factors for Alzheimer's disease from the