Neuropsychological and functional measures of severity in Alzheimer disease, frontotemporal dementia, and semantic dementia.

Many studies attempting to compare the clinical features in different dementia syndromes have attempted to control for overall disease severity using neuropsychological or functional measures. However, these measures may not give equivalent estimates of disease severity. We examined a functional measure of severity (Clinical Dementia Rating scale [CDR] scores) in patients with Alzheimer disease (AD, n = 23), frontotemporal dementia (FTD, n = 24), and semantic dementia (SD, n = 25) who were matched for age and Mini-Mental State Examination (a neuropsychological measure of severity). Total CDR scores were significantly worse in the FTD group compared with both AD and SD patients, whose total CDR scores were similar to each other. FTD showed no difference in memory or orientation compared with AD but did show more impairment in judgment and problem solving, community affairs, home and hobbies, and personal care compared with AD and SD. Thus, in FTD the CDR reveals functional impairments in a wide variety of domains that are more severe than those seen in AD or SD patients with an equivalent Mini-Mental State Examination.