Perception of emotion in frontotemporal dementia and in Alzheimer's disease

Frontotemporal dementia (FTD) is the second cause of degenerative dementia. Behavioral changes occur before the cognitive decline and remain the major feature. A poor perception of emotion could account for some behavioral symptoms. The aim of this study was to assess the perception of emotion in patients with FTD and to compare it with that of patients with Alzheimer disease (AD). Fifty subjects performed the tests: 20 patients with probable AD, 18 patients with FTD, and 12 matched controls. The two patient groups did not differ in age, sex, severity of dementia, duration of the disease, and language tests. Subjects had to recognize and point out the name of one of seven basic emotions (anger, disgust, happiness, fear, sadness, surprise, and contempt) on a set of 28 faces presented on slides. The three groups were equally able to distinguish a face displaying affect from one not displaying affect. Naming of emotion was worse in patients with FTD than in patients with AD (correct answers 46% vs. 62%; p = 0.0006) who did not differ significantly from controls (72%). Anger, sadness, and disgust were less recognized in FTD than in AD patients who did not differ from controls, whereas fear and contempt were poorly recognized in both groups of patients compared with controls. These findings argue for different neural substrates underlying the recognition of various basic emotions. Behavioral disorders in FTD may be partly due to an impaired interpretation of the emotional environment.