Rates of global and regional cerebral atrophy in AD and frontotemporal dementia

Objective: Serial registered MRI provides a reproducible technique for dete cting progressive cerebral atrophy in vivo and was used to determine if the re were differences between the rates of cerebral atrophy in AD and frontot emporal dementia (FTD). Methods: Eighty-four patients with dementia (54 AD and 30 FTD) and 27 age-matched control subjects each had at least two volum etric MR scans. Serial scans were positionally matched (registered), and br ain volume loss was determined by calculation of the brain boundary shift i ntegral. Results: There was a difference between the rates of whole-brain a trophy in patients (mean annual volume loss 2.7% of total brain volume) and in control subjects (mean annual volume loss 0.5%). AD and FTD were associ ated with different rates of atrophy (mean annual losses 2.4 and 3.2%). The range of atrophy rates in the FTD group (0.3 to 8.0%) greatly exceeded tha t in the AD group (0.5 to 4.7%). Frontal-variant FTD was associated with a wider range of atrophy rates than temporal-variant FTD. Analysis of regiona l brain atrophy rates revealed that, there was widespread symmetrically dis tributed cerebral volume loss in AD, whereas in frontal FTD there was great er atrophy anteriorly and in temporal FTD the atrophy rate was greatest in the left anterior cerebral cortex. Conclusions: Both AD and FTD patients ha d increased rates of brain atrophy. Whereas the patients with AD were assoc iated with a relatively restricted spread of atrophy rates, the greater spr ead of rates observed in the patients with FTD may reflect the heterogeneit y of disease in FTD, with differences observed between frontal and temporal FTD. Increased rates of whole-brain atrophy did not discriminate AD from F TD, but analysis of regional atrophy rates revealed marked differences betw een patient groups.