BOSTON—For patients with mild cognitive impairment (MCI), the rate of brain atrophy may predict the level of future cognitive decline.
Every 1% increase in the rate of whole brain atrophy during a single year translated into a 1.7-point decline on the Mini-Mental State Examination (MMSE) score at three years, Kelvin Leung, PhD, said at the 2013 Alzheimer’s Association International Conference.
“Many studies have shown associations between concurrent brain atrophy rates and cognitive decline, when compared and measured over the same time period,” said Dr. Leung, of the Centre for Medical Image Computing, University College London. “However, fewer have looked at the association between brain atrophy rates and future cognitive decline.”
To examine that question, Dr. Leung used cognitive and imaging data from the Alzheimer’s Disease Neuroimaging Initiative. His study cohort included 471 patients (295 with MCI and 176 normal controls). The primary outcome was 36-month change on the MMSE. Secondary measures included changes in auditory verbal learning, immediate recall, category fluency, trail making, and backward digit span.
He used an MRI measurement called boundary shift integral to calculate brain volume changes from baseline to 12 months. Boundary shift integral takes into account whole brain shrinkage, hippocampus shrinkage, and ventricle expansion to calculate a percentage difference from one time point to another.
When looking at the raw scores, Dr. Leung found that every 1% increase in the one-year brain atrophy rate was associated with a statistically significant 1.7-point decrease on the MMSE. That atrophy rate also was significantly associated with a two-point decline on an audio verbal learning test, a 2.8-point decline on the Category Fluency Test, and an 11-point decline on the Trail Making Test A. The control subjects showed no significant cognitive changes.
Similar changes were seen when looking only at hippocampal volume. For every 1% increase in the one-year rate of hippocampal atrophy, patients with MCI experienced significant declines in the MMSE, audio verbal learning test, immediate memory, Category Fluency Test, and Trail Making Test. Control patients showed no changes.
Finally, Dr. Leung reported that a nearly identical correlation was observed between ventricular volume expansion and the cognitive measures.
—Michele G. Sullivan
IMNG Medical News