People with no Alzheimer's disease signs whose brain cortex regions are smaller than normal probably have a higher risk of developing early symptoms of the disease, researchers from the University of Pennsylvania and Massachusetts General Hospital reported in the peer-reviewed journal Neurology this week.

Susan Resnick, PhD, who works at the National Institute of Aging, in an Accompanying Editorial in the same journal wrote:

"The ability to identify people who are not showing memory problems and other symptoms but may be at a higher risk for cognitive decline is a very important step toward developing new ways for doctors to detect Alzheimer's disease."

Bradford Dickerson, MD, and team used MRI (magnetic resonance imaging) scans to measure regions of the brain's cortex in 159 participants aged 76 years (average). None of them had any symptoms of dementia when the scans were done.

The researchers scanned regions of the cortex because other studies had demonstrated that this area of the brain becomes smaller in patients with diagnosed Alzheimer's disease.

Nineteen of the participants were found to have smaller brain cortex regions, and thus deemed to be of high risk of having early Alzheimer's. Twenty-four of them were classified as at low risk, while 116 were of average risk.

All participants were given tests that measured their memory, ability to pay attention, plan, and solve problems. These tests were performed at the beginning of the study, and then regularly over the following three years.

The authors reported that 21% of their high risk participants were found to have cognitive decline during the 36-month follow-up period, versus just 7% among those classified at average risk. None of the low-risk ones developed signs and symptoms of cognitive decline.

Dr. Dickerson said:

"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."

Sixty per cent of the high risk participants had abnormally high levels of proteins (beta amyloid) linked to Alzheimer's disease in their cerebrospinal fluid, compared to just 36% among the average risk individuals, and just 19% in the low risk people.

In an Abstract in the journal, the authors concluded:

"This approach to the detection of individuals at high risk for preclinical AD - identified in single CN individuals using this quantitative ADsig MRI biomarker - may provide investigators with a population enriched for AD pathobiology and with a relatively high likelihood of imminent cognitive decline consistent with prodromal AD."

Written by Christian Nordqvist