Are you really angry? The effect of intensity on facial emotion recognition in frontotemporal dementia

Frontotemporal dementia (FTD) is a neurodegenerative brain disorder that affects the frontal and temporal lobes predominantly. Impaired emotion recognition has been reported in two FTD subtypes: behavioral-variant FTD (bvFTD) and semantic dementia (SD), but has not been investigated in the third subtype: progressive nonfluent aphasia (PNFA). Methods: Recognition of six basic facial emotions (anger, disgust, fear, sadness, surprise, and happiness) was investigated in 41 FTD patients (bvFTD = 16; SD = 12; PNFA = 13) and 37 age- and education-matched controls, using two tests. In one task, intensity of emotional expression was increased to identify cognitive components contributing to emotion recognition performance. Results: All patient groups demonstrated impaired overall facial emotion recognition compared to controls. Performance, however, improved with increased emotion intensity in bvFTD and PNFA groups, the effect of intensity on emotion recognition being particularly pronounced for negative emotions. In contrast, increased intensity of facial emotion did not change performance in SD. Conclusions: Patients with SD demonstrate a primary emotion processing impairment, whereas PNFA and bvFTD patients' emotional disturbance is in part mediated by attentional deficits. These findings indicate that a subset of FTD patients may benefit from enhanced emotional intensity that will facilitate facial emotion recognition.