Facial Emotion Recognition Performance Differentiates Between Behavioral Variant Frontotemporal Dementia and Major Depressive Disorder.

OBJECTIVE Misdiagnosis of early behavioral variant frontotemporal dementia (bvFTD) with major depressive disorder (MDD) is not uncommon due to overlapping symptoms. The aim of this study was to improve the discrimination between these disorders using a novel facial emotion perception task. METHOD In this prospective cohort study (July 2013-March 2016), we compared 25 patients meeting Rascovsky diagnostic criteria for bvFTD, 20 patients meeting DSM-IV criteria for MDD, 21 patients meeting McKhann diagnostic criteria for Alzheimer's disease dementia, and 31 healthy participants on a novel emotion intensity rating task comprising morphed low-intensity facial stimuli. Participants were asked to rate the intensity of morphed faces on the congruent basic emotion (eg, rating on sadness when sad face is shown) and on the 5 incongruent basic emotions (eg, rating on each of the other basic emotions when sad face is shown). RESULTS While bvFTD patients underrated congruent emotions (P < .01), they also overrated incongruent emotions (P < .001), resulting in confusion of facial emotions. In contrast, MDD patients overrated congruent negative facial emotions (P < .001), but not incongruent facial emotions. Accordingly, ratings of congruent and incongruent emotions highly discriminated between bvFTD and MDD patients, ranging from area under the curve (AUC) = 93% to AUC = 98%. Further, an almost complete discrimination (AUC = 99%) was achieved by contrasting the 2 rating types. In contrast, Alzheimer's disease dementia patients perceived emotions similarly to healthy participants, indicating no impact of cognitive impairment on rating scores. CONCLUSIONS Our congruent and incongruent facial emotion intensity rating task allows a detailed assessment of facial emotion perception in patient populations. By using this simple task, we achieved an almost complete discrimination between bvFTD and MDD, potentially helping improve the diagnostic certainty in early bvFTD.