How Preserved is Emotion Recognition in Alzheimer Disease Compared With Behavioral Variant Frontotemporal Dementia?

Abstract

Background: Emotion deficits are a recognised biomarker for behavioural variant frontotemporal dementia (bvFTD), but recent studies have reported emotion deficits also in Alzheimer’s disease (AD). Methods: A hundred and twenty-three participants (33 AD, 60 bvFTD, 30 controls) were administered a facial emotion recognition test, to investigate the clinical factors influencing the diagnostic distinction on this measure. Binomial regression analysis revealed that facial emotion recognition in AD was influenced by disease duration and MMSE, whereas the same was not true for bvFTD. Based on this information, we median-split the AD group on disease duration (3 years) or MMSE (24) and compared the facial emotion recognition performance of mild-AD, moderate-AD, bvFTD patients and controls. Results: Results showed that very mild-AD performed consistently at control levels for all emotions. By contrast, mild/moderate-AD and bvFTD were impaired compared to controls on most emotions. Interestingly, mild/moderate-AD were significantly impaired compared to very mild-AD on total score, anger and sadness subscores. Logistic regression analyses corroborated these findings with ~94% of very mild-AD being successfully distinguished from bvFTD at presentation, while this distinction was reduced to ~78% for mild/moderate-AD. Conclusions: Facial emotion recognition in AD is influenced by disease progression, with very mild-AD being virtually intact for emotion performance. Mild/moderate-AD and bvFTD show consistent impairment in emotion recognition, with bvFTD being worse. A disease progression of over 3 years or a MMSE lower than 24 should warrant caution to put too much emphasis on emotion recognition performance in the diagnostic distinction of AD and bvFTD.