Multidimensional assessment of social cognition using non-immersive virtual reality in dementia with Lewy bodies and Alzheimer's disease: an exploratory study.

Introduction: Few studies have focused on social cognition in dementia with Lewy bodies (DLB), even though some brain structures being well known as underlying social cognitive processes are directly impacted in this disease. Furthermore, social cognition processes have been mostly studied independently using evaluations with poor ecological validity. We aimed at studying the ability of a new naturalistic and multidimensional social cognition task to reveal impairments in DLB patients. We chose to compare the profile of these patients with that of Alzheimer's disease (AD) patients, for which social cognition is better preserved.

Method: Fifteen patients (DLB: n = 7; AD: n = 8) and 28 healthy controls underwent the REALSoCog task. They encountered several social situations (e.g. control versus transgressions) in a non-immersive virtual city environment allowing the assessment of moral cognition, cognitive and affective theory of mind (ToM), emotional empathy and behavioral intentions.

Results: The main results showed (i) a lower ability to detect transgressions in DLB patients, particularly conventional ones, whereas moral cognition seemed better preserved in AD patients; (ii) a cognitive ToM impairment in both DLB and AD patients, while affective ToM is impaired only in DLB patients; (iii) a decreased emotional empathy specifically observed in DLB patients; (iv) more inappropriate behavioral intentions, mainly in DLB patients, but also in some AD patients.

Conclusions: This study suggests the feasibility and potential interest of the REALSoCog task in revealing social cognition deficits, particularly for DLB patients by showing different social patterns as compared to AD patients. These results offer interesting clinical perspectives to develop more naturalistic tasks in such populations and for clinical differential diagnosis. Limitations and future perspectives are discussed.