SOURCE: Indiana University, news release, July 13, 2015
WEDNESDAY, July 15, 2015 (HealthDay News) -- Neurologists have long known that a variant of a gene called APOEe4 can raise the odds for Alzheimer's disease in people who carry it.
Now, new research suggests that the gene is already affecting the brain years before the onset of the illness.
Researchers at Indiana University in Indianapolis looked at 600 older adults, including some who said that they had significant memory problems even though they showed normal results on standard thinking and memory tests.
The researchers compared people with the APOEe4 gene variant against those with other, less harmful variants of the APOE gene.
Based on tests, people who carried the APOEe4 variant had higher brain levels of amyloid plaque -- those clumps of protein fragments that are commonly found in the brains of Alzheimer's patients.
Their cerebrospinal fluid also had lower levels of a protein "precursor" to the plaques, suggesting that this protein is being diverted to the brain as part of the plaque formation process that's so strongly tied to Alzheimer's disease.
The cerebrospinal fluid of the patients with the APOEe4 variant also had higher levels of tau, another protein strongly associated with Alzheimer's disease, the findings showed.
One thing the study did not find: People who carried the APOEe4 variant did not show signs of wasting in brain structures, something that occurs with full-blown Alzheimer's disease.
The study was published July 13 in the journal Alzheimer's and Dementia.
The findings show the value of focusing research -- and perhaps, someday, treatment -- on people at risk of Alzheimer's long before they are diagnosed with the disease, the researchers said.
"There are many potential interventions, and not only on the pharmaceutical side," study co-leader Andrew Saykin, director of the Indiana Alzheimer Disease Center and Indiana University's Center for Neuroimaging, said in a university news release.
"There are intensive studies now of exercise, diet modification, cognitive [mental] stimulation, sleep and other lifestyle factors that could lead to an improvement," he said.
The U.S. National Institute on Aging has more about Alzheimer's disease.