Oregon Health and Science University researchers said their finding suggests changes predisposing a person to Alzheimer's and other forms of dementia might occur much sooner in the brain than previously thought.

The study involved 55 healthy boys and girls ages 7 to 10. Among them were eight girls and six boys who carried the apoE4 gene, which is known to increase a person's risk of age-related cognitive decline. The study also included 17 girls and 24 boys who did not carry the gene.

The children were administered paper- and computer-based tests, including a computer-based test of spatial learning and memory in which the children use visual cues to navigate to four marked locations.

Only 43 percent of children with the apoE4 gene navigated close to the visible target location, compared with more than 75 percent of children who did not have the gene.

The study was presented this week in San Diego during the 37th annual meeting of the Society for Neuroscience.