New Genetic Information about Alzheimer's Disease

Alzheimer's Association
Wednesday, 20 August 1997

Newly published research suggesting a possible gene that may impact the age of onset of Alzheimer's disease is encouraging, and provides another promising avenue for research, according to the Alzheimer's Association.

"This is an interesting preliminary finding, and we're eagerly awaiting confirmation by other scientists, " said Zaven Khachaturian, Ph.D., director of the Association's Ronald & Nancy Reagan Research Institute. "As the authors point out, we don't know for certain the precise role HLA-A2, the gene examined in the study, might play in determining the age of onset of Alzheimer's disease; whether it acts alone or in combination with other genetic or environmental factors. "

"This is a provocative finding because it strengthens the argument for the important role the immune system may play in the expression of Alzheimer's disease, " Khachaturian said. The study, "Evidence for Association of HLA-A2 allele with onset age of Alzheimer's disease, " by Haydeh Payami, Ph.D., of Oregon Health Sciences University, and colleagues, appears in the August 1997 issue of Neurology.

The researchers found that, in a population of 207 people with Alzheimer's disease, those who had the HLA-A2 gene got the disease an average of about three years earlier than those who did not have the gene. The researchers, however, point out that the connection may not be with HLA-A2 but with a gene closely linked to it.

The research was funded by grants from the Alzheimer's Association, National Institute on Aging and National Institutes of Health. The Association is a strong supporter of increasing knowledge about what causes Alzheimer's, including the genetics of the disease, as a gateway to developing treatments.

"The primary goal of the Reagan Institute is to delay the onset of Alzheimer's disease, " explained Khachaturian. "If we can push back the onset of Alzheimer's for five years, we can cut in half the number of people who get the disease, and save this country billions of dollars in healthcare costs. Through research such as Dr. Payami's, and that of her colleagues at UCLA and other facilities, we begin to gain a clearer understanding of what modifies the age of onset. With more information we will be able to design drugs to delay the onset of the disease. "

"It is evident there are many contributing factors to the cause and progression of Alzheimer's disease, and that almost certainly there are multiple genes involved. We need to track down all the genetic leads and then find out how they interact with each other and with other risk factors in the environment. In other words, determine how each fits into the big picture, " said Khachaturian.

An example of this interaction involves APOE-e4, a known genetic risk factor for Alzheimer's disease, and head injury. Some previous studies found that head injury was related to increased risk of getting Alzheimer's, while other studies did not find a connection. Through further research, it was discovered that increased risk of Alzheimer's results from a combination of having two copies of the APOE-e4 gene and head injury.

"Our knowledge of genetics helped us understand and interpret the otherwise confusing information uncovered in the earlier head injury studies, " said Khachaturian. "That's one more reason this very important work not only needs to continue, but expand."

For more information, or to contact Alzheimer's Association, see their website at: www.alz.org