June 3, 2008
Heavy drinkers and heavy smokers develop Alzheimer's disease years earlier than people with Alzheimer's who do not drink or smoke heavily, according to new research.
"These results are significant because it's possible that if we can reduce or eliminate heavy smoking and drinking, we could substantially delay the onset of Alzheimer's disease for people and reduce the number of people who have Alzheimer's at any point in time," said study author Ranjan Duara, M.D., of the Wien Center for Alzheimer's Disease at Mount Sinai Medical Center in Miami Beach, Fla. The findings were presented April 16 at the American Academy of Neurology 60th Anniversary Annual Meeting in Chicago.
In the study, researchers found that the combination of heavy drinking and heavy smoking sped up the age of onset of Alzheimer's by six to seven years. That is a considerable number, making them among the most important preventable risk factors for Alzheimer's disease.
The number of cases of Alzheimer's is expected to balloon in coming years, as the aging baby boomers reach their 70s and 80s, when Alzheimer's is most likely to strike. Delaying its onset by six to seven years through a healthy, smoke-free lifestyle could cut considerably the number of expected cases of the disease.
The study looked at 938 people age 60 and older who were diagnosed with possible or probable Alzheimer's disease. The researchers gathered information from family members on drinking and smoking history and determined whether the participants had the APO-E4 gene, which increases the risk of Alzheimer's disease. People who carry this gene variant also tend to develop Alzheimer's at an earlier age than those who do not have it, though it is by no means a guarantee that someone will develop Alzheimer's.
About 7 percent of the study participants had a history of heavy drinking, which was defined as more than two drinks per day. One in five, or 20 percent, had a history of heavy smoking, which was defined as smoking one pack of cigarettes or more per day. And 27 percent had the APO-E4 gene variant.
Researchers found that people who were heavy drinkers developed Alzheimer's 4.8 years earlier than those who were not heavy drinkers. Heavy smokers developed the disease 2.3 years sooner than people who were not heavy smokers. People with APO-E4 developed the disease three years sooner than those without the gene variant.
Adding the risk factors together led to earlier onset of the disease. People who had all three risk factors developed the disease 8.5 years earlier than those with none of the risk factors. The 17 people in the study with all three risk factors developed Alzheimer's at an average age of 68.5 years; the 374 people with none of the three risk factors developed the disease at an average age of 77 years.
Earlier studies have shown that smoking and heavy drinking may be bad for the brain. In 2004, researchers in Europe reported that a cigarette habit appears to speed up mental decline as you age. Older men and women who smoked showed greater decline in memory than those who had never smoked. [See the article, "Smoking Is Bad for Your Brain, Too"]
Some earlier scientific reports suggested that nicotine and other substances in cigarette smoke may actually help protect against the mind-robbing ravages of Alzheimer's disease. However, other studies have linked smoking to an increased risk of dementia.
Heavy drinking, like cigarettes, may be bad for the entire body, including the brain. Excess alcohol is known to damage the liver and other organs, including the brain. In some cases, heavy drinking can lead to permanent memory problems that resemble those of Alzheimer's.
Any damage to the brain -- whether it's due to alcohol, poor blood flow, a stroke, or other reasons -- is not a good thing. Alcohol damage may be particularly important for those concerned about ailments like Alzheimer's, since a diminished brain capacity may contribute to memory problems and speed the onset of mental decline, research suggests.
A drink or two a day, on the other hand, is recognized by many as an effective way to ease stress and may reduce the risk of developing Alzheimer's. Some studies suggest that antioxidants and other substances in wine and other beverages may boost longevity and heart health and possibly even help to ward off serious ailments like Alzheimer's disease. A glass of red wine with dinner is part of the traditional Mediterranean diet, which has also been shown to reduce the risk for Alzheimer's.
The bottom line: If you drink, do so in moderation. That means two drinks a day tops for younger men, and just a drink a day for women and older people. And if you smoke, quit.
For more about the causes and risk factors for Alzheimer's, visit www.ALZinfo.org, The Alzheimer's Information Site.
Presented at the American Academy of Neurology 60th Anniversary Annual Meeting in Chicago, April 12 to 19, 2008.