St. Paul, Minn. – In people age 90 and older, the presence of the gene variation apolipoprotein ?4 (APOE?4) is linked to an increased probability of Alzheimer’s disease (AD), according to a study published in the June 26, 2001 issue of Neurology, the scientific journal of the American Academy of Neurology.
The study of elderly people over the age of 85 showed approximately 63 percent with APOE?4, a variation on chromosome 19, suffered from AD, compared with only 20 percent who did not carry APOE?4 but suffered from AD. When the patients were over age 90, the prevalence increased to 71 percent and 22 percent, respectively.
“This significant difference shows that the connection between APOE?4 and Alzheimer’s disease lasts a lifetime,” said study author Matti J. Haltia, MD, PhD, of the Department of Pathology, University of Helsinki, Helsinki, Finland. “While everyone is at an increased risk for AD as they grow older, some people with this genetic factor appear to be on a different probability slope, starting earlier.”
However, Haltia added, the study also found people with APOE?4 who have lived to a very old age without any signs of dementia.
“These relatively rare individuals may be important for further research concerning how we can protect the brain or how we can slow the changes caused by AD,” Haltia said. “We need to learn more about resolving the biological mechanism underlying this effect as it appears that APOE?4 is the most important genetic factor influencing the risk of AD in the population as a whole."
The results are based on a study of 532 Finnish people, age 85 years or older. Each was tested for dementia in 1991 and genotyped for APOE. In addition to the clinical diagnosis, an autopsy involving neuropathological diagnosis of AD was performed on 118 out of 198 deceased demented subjects and 62 out of 201 deceased non-demented individuals. This was the first autopsy-controlled, prospective and population-based study conducted on the prevalence of AD in very elderly people.
Alzheimer''s disease is a progressive, degenerative disease that attacks the brain. It is the most common form of dementia, which is a loss of intellectual functioning so severe that it interferes with daily activities.
The American Academy of Neurology recently released clinical practice guidelines regarding the detection, diagnosis and management of dementia. The practice guidelines can be found at www.aan.com.
The American Academy of Neurology, an association of more than 19,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer's disease, epilepsy, Parkinson's disease, autism and multiple sclerosis.
For more information about the American Academy of Neurology, visit www.aan.com.
- end -