January 2, 2007
A gene that helps people live into their 90s and beyond also appears to help keep the brain young and the memory sharp, researchers report. Elderly men and women who inherit the gene were better able to think and learn new things than those who did not carry the gene. The findings appeared in Neurology, the scientific journal of the American Academy of Neurology.
The gene variant alters cholesterol particles in the blood, making them bigger than normal. Researchers believe that smaller particles can more easily lodge themselves in blood vessel linings, leading to the fatty buildup that can cause heart attacks and strokes. Fatty buildup in the blood vessels in the brain has also been linked to dementia and problems with memory in seniors.
The study examined 158 people of Ashkenazi, or Eastern European, Jewish descent, who were 95 years old or older. Those who had the gene were twice as likely to have good brain function compared to those who did not have the gene. The researchers also validated these findings in a group of 124 Ashkenazi Jews who were between the ages of 75 and 85.
"It's possible that this gene variant also protects against the development of Alzheimer's disease," said study leader Nir Barzilai, M.D., the director of the Institute for Aging Research at Albert Einstein College of Medicine in Bronx, NY.
Other genes have been linked to Alzheimer's, and researchers are looking at the role of various inherited factors in the onset of the disease. Few studies, however, have looked at people who live to a very old age and remain generally healthy.
Only about one in 10,000 people in the general population lives to the age of 100. And many of these elders develop Alzheimer's disease and other problems.
In the current study, researchers looked at people who were close to 100 in age. "In studying these centenarians," says Dr. Barzilai, "we hope to learn what factors lessen their risk for diseases that affect the general population at a much younger age. Our results bring us a step closer to understanding the role that genes play in longevity."
The investigators found that a special form of the gene that determines the size of cholesterol particles in the blood was three times more common in those who were close to 100 in age and mentally alert, compared to a sample of average 70-year-olds. In another resent study, a similar abundance of this particular gene was noted in elderly Italians living near Florence.
Work is also being done to develop new medicines that can mimic the effect of this gene variation, the researchers note. However, more research on the genetic basis of Alzheimer's disease as well as on healthy old age is needed. It will likely be many years before a beneficial drug is developed.
Multiple Risk Factors
This study points out an interesting link between a robust memory in old age and the presence of a particular gene. However, many other risk factors have been linked to Alzheimer's disease. These include:
- Advancing age. Doctors have known for many years that the older you are, the more likely you are to get Alzheimer's disease.
- Fewer years of schooling. Those who have the fewest years of formal schooling are most likely to develop Alzheimer's and other forms of dementia in old age.
- High blood pressure. Years of high blood pressure can take a serious toll not just on the heart but on many parts of the body, including the brain.
- High cholesterol. Increasingly, doctor's realize what's good for the heart is also good for the brain. High cholesterol may also increase Alzheimer's risk through other mechanisms.
- Obesity. The fatter you are, the more likely you are to develop Alzheimer's disease.
- A Mediterranean-style diet. If you eat a heart-healthy diet rich in fruits, vegetables, whole grain, and fish, you may be less likely to develop Alzheimer's.
- Exercise. Getting plenty of exercise as you age may be key to a healthy body, and a healthy mind.
Indeed, many risk factors appear to come into play in the onset of Alzheimer's disease. Unfortunately, many of these risk factors are not well understood. Some people who seem to be at high risk may stay mentally alert to age 100. Others who have few risk factors may succumb to Alzheimer's.
For more on the risk factors for Alzheimer's and ways you might help prevent the disease, visit www.ALZinfo.org.
By alzinfo.org, The Alzheimer's Information Site. Reviewed by William J. Netzer, Ph.D., Fisher Center for Alzheimer's Research Foundation at The Rockefeller University.
N. Barzilai, M.D.; G. Atzmon, Ph.D.; C. A. Derby, Ph.D.; et al: "A Genotype of Exceptional Longevity Is Associated with Preservation of Cognitive Function." Neurology, Volume 67, December 26, 2006, pages 2170-2175.
American Academy of Neurology