Alzheimer’s Gene Impacts Brain Years Before Symptoms Begin

Rebecca Lewis July 15, 2015

The well-known genetic variant linked to Alzheimer’s may promote deposits of plaque in the brain long before any symptoms of the disease can be measured on tests, according to new research.

The study, carried out by investigators from Indiana University School, provide additional evidence for focusing research, and eventually treatment, on people at risk of Alzheimer’s long before the disease is diagnosed. Their study focuses on "significant memory concerns," defined as older adults who complained that they had mentally slipped in recent months or years, but when given standard cognition and memory tests they fell within normal ranges. People in this category have also been called the "subjective cognitive decline" group by Alzheimer’s researchers.

Since it is becoming clear that effective treatments for Alzheimer’s may need to be applied many years before serious symptoms appear, researchers are focusing more intently on at-risk patients with significant memory concerns.

"These are the individuals who are the logical target for the next wave of clinical trials," says lead researcher Andrew J. Saykin, Psy.D., director of the Indiana Alzheimer Disease Centre and IU Centre for Neuroimaging.

"There are many potential interventions, and not only on the pharmaceutical side," he said. "There are intensive studies now of exercise, diet modification, cognitive stimulation, sleep and other lifestyle factors that could lead to an improvement."

The gene in question, APOE, has several variants, or "alleles." One of those variants, APOE ε4, has been linked to an increased risk of developing Alzheimer’s disease in older adults. It is found in about 25 per cent of the population. Patients with Alzheimer’s disease who also have APOE ε4 tend to have an earlier age of onset of symptoms.

The researchers found evidence of Alzheimer’s-like pathologies from several biomarkers among the APOE ε4 carriers including: increased levels of amyloid plaque, decreased levels of the protein precursor to the plaques, and increased levels of tau, another protein associated with Alzheimer’s disease.

Their findings, published in the journal Alzheimer’s and Dementia, found that patients at risk of Alzheimer’s earlier than in much other research.

Source of this article: Indiana University