Utility of clinical criteria in differentiating frontotemporal lobar degeneration (FTLD) from AD

Objective: To assess the ability of the current diagnostic criteria for frontotemporal lobar degeneration (FTLD) to differentiate FTLD from AD. Methods: Thirty cases with autopsy-proven FTLD and 30 cases of AD, matched for Mini-Mental State Examination score, were identified from the clinical databases of three dementia subspecialty centers, and their charts were reviewed for the presence of clinical features described in the current criteria for FTLD. The proportion of patients with each clinical feature at the first clinical presentation was compared across groups. Results: A significantly larger proportion of patients with FTLD showed behavioral abnormalities, particularly social and personal conduct disorders and emotional blunting, than patients with AD. Few differences in language features were seen between the groups, and many of the language features detailed in the criteria were found in only a small proportion of patients. In both groups, many patients showed neuropsychological abnormalities, except for perceptual difficulties, which were present in many patients with AD but only in a few patients with FTLD. Extrapyramidal motor symptoms were more likely to be present in FTLD. Logistic regression revealed that five features-social conduct disorders, hyperorality, akinesia, absence of amnesia, and the absence of a perceptual disorder-correctly classified 93% of patients with FTLD and 97% of patients with AD. Conclusion: A combination of behavioral, neuropsychological, and physical findings is most useful in distinguishing FTLD from AD. Future studies should be directed at establishing more objective methods of identifying these clinical features.