Can Social Cognition Measurements Differentiate Behavioral Variant Frontotemporal Dementia from Alzheimer's Disease Regardless of Apathy?

Background: Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) share cognitive and behavioral symptoms, such as apathy. Social cognition measurements are useful in distinguishing bvFTD from AD, but their accuracies may be affected by apathy. Objective: To investigate whether social cognition measurements can distinguish bvFTD from either apathetic or non-apathetic AD patients. Methods: Three groups of participants were enrolled in the present study: bvFTD (n = 22), AD (n = 20), and healthy controls (HC, n = 23). The AD group was divided into apathetic (n = 10) and non-apathetic (n = 10). All subjects underwent comprehensive neuropsychological examination, including the short version of the Social and Emotional Assessment (Mini-SEA), which comprises the facial emotion recognition test and the faux-pas recognition test (Faux-Pas Test). Apathy was assessed according to the Starkstein's Apathy (SA) Scale. Results: The bvFTD and AD groups did not differ on global cognitive efficiency and on executive functions. In comparison to the whole AD group, bvFTD displayed lower Faux-Pas Test and Mini-SEA scores. Both AD subgroups, apathetic or non-apathetic, exhibited similar performance on all social cognition measurements. In comparison to either apathetic AD or non-apathetic AD, bvFTD patients underperformed on the Faux-Pas Test and on the Mini-SEA. The area under the curve values for the Mini-SEA total score were 0.87 (bvFTD versus AD), 0.90 (bvFTD versus apathetic AD), and 0.83 (bvFTD versus non-apathetic AD). Conclusion: Social cognition tests provide accurate distinction between bvFTD against either apathetic AD or non-apathetic AD. Social cognition measurements did not correlate with apathy severity.