Are Signs Of Alzheimer's Disease Earlier Than Thought
Research provides scientists with new insights into the origin of a Alzheimer's disease. The latest study suggest that people have a genetic propensity to develop this disease. The early symptoms and signs of Alzheimer's disease show earlier and people begin to experience memory loss as early as in their fifties.
People with "Alzheimer's gene" began to have memory problems related to the age of 60 years before, even when they had no symptoms of dementia, a group of U.S. researchers report. In another study, a second team found that those who knew that they carry the gene had not been emotionally disturbed by this.
Both findings, published in New England Journal of Medicine, provide new support for genetic tests to detect Alzheimer's disease, a neurodegenerative condition for which there are very few treatments and no cure.
Alzheimer's disease affects 26 million people around the world.
Using local advertisements, the researchers recruited cognitively normal subjects between the ages of 21 and 97 years, who were grouped according to their APOE 4 status. They then followed the subjects with longitudinal neuropsychological testing. Anyone in whom mild cognitive impairment or dementia developed during follow-up was excluded. Researchers compared the rates of decline in predetermined cognitive measures between carriers and noncarriers of the APOE 4 allele, using a mixed model for longitudinal change with age.
The study team, lead by Mayo Clinic of Arizona's Richard J. Caselli, M.D., found that people who had the genetic variation ApoE4 had signs of memory problems at an earlier age than those without the mutation.
Caselli studied 815 healthy people 21 to 97 years were grouped according to their genetic status. The authors found that those with the ApoE4 gene were more likely to develop memory problems associated with age before age 60 and the speed of the deterioration was greater in people who had inherited the variation from both parents.
Having the ApoE4 mutation does not imply that the person will inevitably develop Alzheimer's disease. One of the team doctors, Dr. Allen Roses of Duke University in North Carolina, reported at a conference on the disease this week that a second gene closely associated with the ApoE4, called TOMM40, also increases the risk.
Roses noted that, overall, the two genes account for between 85 and 90 per cent of the hereditary forms of Alzheimer's. However, doctors do not recommend that people undergo genetic evaluations of Alzheimer's disease on a routine basis, partly because of fears that the test may increase anxiety or stress. But a group of experts from the School of Medicine, Boston University challenged that view and said that this is not true. The researchers studied 162 adult children of patients with the disease and sought to examine the presence of the ApoE4 gene.
The team measured the anxiety-related test for six weeks, six months and a year and found that people who had inherited the gene "did not show more anxiety, depression or anxiety associated with the test compared to those who do not" carry it, Dr. Robert Green said in a statement.
Those, who knew that they had not inherited the gene, "experienced considerable relief," added the expert.
Two of the researchers who participated in this study had received funding from a genetics company now defunct. Dr. Gary Kennedy, director of geriatric psychiatry at Montefiore Medical Center New York, said he did not recommend testing unless patients have many close relatives (parents or siblings) with Alzheimer's disease.
By Armen Hareyan
- NEJM: Longitudinal Modeling of Age-Related Memory Decline and the APOE 4 Effect - Abstract
- NEJM: Disclosure of APOE Genotype for Risk of Alzheimer's Disease - Abstract