BACKGROUND: Preliminary studies reported Theory of Mind (ToM) deficits in patients with Korsakoff's syndrome (KS). However, they presented several limits as they did not (1) control for key biasing factors (e.g., understanding of the task, amnesia); (2) compare KS with severe alcohol use disorder (sAUD) regarding ToM deficits; (3) explore the links between ToM abilities and other cognitive abilities. We thus directly compared cognitive ToM in patients with KS and sAUD, while considering task understanding and other cognitive deficits.

METHODS: Sixteen patients with KS, 70 patients with sAUD, and 69 healthy controls (HC) underwent a neuropsychological examination including a global cognitive screening, working memory and executive tests, as well as a cognitive ToM task designed to reduce cognitive load through the use of nonverbal materials (comic-stories). The ToM task measured the ability to attribute first- and second-order mental states to others and the level of understanding of the story with a control task.

RESULTS: We found no group effect on performance for the control condition. For both the first- and second-order items of the ToM condition, HC performed significantly better than patients with sAUD and KS, who did not differ from each other. Results remained unchanged when controlling for the performance on the control task. However, when controlling for global cognitive status, patients with KS did not differ from HC anymore, contrary to patients with sAUD who remained altered. When controlling for executive/working memory performance, the main group effect was no longer observed. Flexibility was the only predictor of ToM performance in patients with sAUD.

CONCLUSIONS: Cognitive ToM is similarly affected in patients with KS and sAUD, but global cognitive deterioration may underlie ToM deficits in patients with KS, whereas they may be more specifically related to flexibility impairments in patients with sAUD.