New research suggests that, in people who don't currently have memory problems, those with smaller regions of the brain's cortex may be more likely to develop symptoms consistent with very early Alzheimer's disease.

The study was published Wednesday in the online issue of Neurology, the medical journal of the American Academy of Neurology.

For the study, researchers used brain scans to measure the thickness of regions of the brain's cortex in 159 people free of dementia with an average age of 76. The brain regions were chosen based on prior studies showing that they shrink in patients with Alzheimer's dementia.

Of the 159 people, 19 were classified as at high risk for having early Alzheimer's disease due to smaller size of particular regions known to be vulnerable to Alzheimer's in the brain's cortex, 116 were classified as average risk and 24 as low risk. At the beginning of the study, participants were also given tests that measured memory, problem solving and ability to plan and pay attention. The tests will go on over the next three years

The study found that 21 percent of those at high risk experienced cognitive decline during three years of follow-up after the MRI scan, compared to seven percent of those at average risk and none of those at low risk.

"Further research is needed on how using MRI scans to measure the size of different brain regions in combination with other tests may help identify people at the greatest risk of developing early Alzheimer's as early as possible," said study author Bradford Dickerson, of Massachusetts General Hospital in Boston and a member of the American Academy of Neurology.