MIDLINE CEREBRAL MORPHOMETRY DISTINGUISHES FRONTOTEMPORAL DEMENTIA AND ALZHEIMERS-DISEASE

We investigated and contrasted midline cerebral structures in frontote mporal dementia (FTD) and Alzheimer's disease (AD). FTD and AD may be difficult to distinguish clinically. FTD typically affects frontal and anterior temporal regions, whereas AD tends to involve more posterior temporal and parietal areas. We hypothesized that disease-specific ce rebral alterations would be differentially reflected in corresponding regions of the corpus callosum (CC), pericallosal CSF space (PCS), or their ratio (CC:PCS). Regions-of-interest (ROIs) from midsagittal MRIs in 17 AD, 16 FTD, and 12 elderly control (EC) subjects were analyzed. ROIs were divided into four regions using an anatomic landmark-based computer algorithm and were adjusted for head size variation. FTD subj ects had a much smaller anterior CC region and significantly larger PC S area, particularly in anterior regions. AD and EC subjects did not d iffer significantly in any total or regional ROI measure. Total and an terior CC:PCS ratios were markedly lower in FTD patients. Across group s, total CC:PCS correlated significantly with midsagittal cerebral are a and was similarly associated with Mini-Mental State Examination scor e. Anterior CC (AD) and PCS (FTD) regions exhibited disease-specific r elationships to these variables. A discriminant model using two ROI va riables correctly classified 91% of AD and FTD patients, comparing fav orably with blind clinical MRI diagnostic ratings. Midline cerebral st ructural alterations reflect differential patterns of cerebral degener ation in AD and FTD, yielding morphometric indices that may facilitate the study of brain-behavior relationships and differential diagnosis of dementia.