ICAD: Brain Atrophy Patterns May Aid Early Identification of Alzheimer's

By Todd Neale
CHICAGO, 30 july 2008 -- A pattern of Alzheimer's disease-type brain atrophy in asymptomatic patients may help diagnose incipient disease at its very earliest stages, a researcher suggested here. In 109 patients ages 60 and older with no cognitive impairment, the presence of Alzheimer's-like patterns of structural abnormality, as seen by serial MRIs, increased slowly with age, Christos Davatzikos, Ph.D., of the University of Pennsylvania, reported at the International Conference on Alzheimer's Disease here. The rate at which the Alzheimer's-like pattern was found accelerated at about age 75, he said.
"Although the clinical significance of these Alzheimer's-like patterns of brain atrophy must be further evaluated," he said, "we are very hopeful that these pattern analysis tools will provide early indicators of brain changes that resemble those seen in people with Alzheimer's, years before memory problems are recognized clinically."
Dr. Davatzikos and colleagues used MRI scans from the Alzheimer's Disease Neuroimaging Initiative for high-dimensional pattern analysis and classification to find the Alzheimer's-like patterns of structural changes.
Each patient was given a score -- called the SPARE-AD index -- on the basis of how closely their brain patterns matched negative Alzheimer's-like pattern scores, which indicated a more normal brain, and positive scores, which indicated an Alzheimer's-like pattern.
The pattern was then applied to a cohort of healthy participants in the Baltimore Longitudinal Study on Aging as well as 15 patients with mild cognitive impairment. All of the participants were followed for up to nine years.
Using the pattern, 98.7% of the cognitively normal participants were correctly classified as normal through the end of the study.
In the patients who had mild cognitive impairment, many showed progression to an Alzheimer's-like pattern of structural abnormality in the brain, and at a faster rate than the healthy participants.
Overall, participants who had a score indicating an Alzheimer's-like pattern had lower scores of cognitive function compared with those who did not have evidence of the pattern according to results of two measures on the California Verbal Learning Test (P=0.0075 and P=0.0067).
"Structural abnormality scores and their rates of change define subgroups of cognitively normal and mild cognitive impairment individuals whose cognitive scores differ significantly," Dr. Davatzikos said, "further indicating the clinical relevance of this structural biomarker."
He said that the SPARE-AD index could be used in conjunction with other imaging markers to recognize the early signs of Alzheimer's disease before they present clinically.
Dr. Davatzikos was supported in part by grants from the National Institute on Aging and by a grant from the Institute for the Study of Aging.
Primary source: International Conference on Alzheimer's DiseaseSource reference:Davatzikos C, et al "Longitudinal progression of AD-like patterns of brain atrophy in a normal elderly cohort and in MCI: a high-dimensional pattern classification study" ICAD 2008; Abstract IC-P2-090.