Sept. 11 (HealthDay News) -- A gene variant linked to a higher risk of Alzheimer's disease seems to affect the brain when people are young, much earlier than previously thought, new research suggests.

The brains of people in their mid-20s who had the gene variant known as APOE4 -- which boosts the risk of Alzheimer's but doesn't guarantee it -- seem to work differently than those of other people who don't have the gene, the researchers said.

"While young people with and without the APOE4 gene had similar scores on a battery of memory tests, the brains of young people with the gene appear to be working harder or less efficiently to achieve the same results as people without the gene," study co-author Jeffrey Browndyke, director of the Functional Imaging Neurogenomics of Disease Lab at Duke University, said in a university news release.

The researchers looked at 24 healthy adults, 12 of whom had the gene variation. The volunteers took memory tests while their brains were being scanned with functional MRI.

"While all of the young adults performed similarly and their brains appeared the same, there are clear differences in brain activity and interconnection in people with the APOE4 gene that appear earlier in life than previously observed," Browndyke said. "We need to further explore the gene's effect on brain development and early cognitive function to determine who ultimately is at risk for Alzheimer's disease."

The findings were published online in the journal Alzheimer's & Dementia.

SOURCE: Duke University news release