The other side of the social interaction: Theory of mind impairments in people with schizophrenia are linked to other people's difficulties in understanding them.

Abstract

People with schizophrenia (SZ) often present with theory of mind (ToM) deficits and with speech production deficits. While a link has been established between ToM abilities and symptoms of thought disorder, much less is known about other aspects of speech production in SZ. This is a case-control study in which 25 stable outpatients with recent-onset SZ (27.1years, 22 men) and 22 matched healthy controls (25.6years, 16 men) performed a collaborative, verbal production task with a real interaction partner. Blind raters scored how easy participants made it to understand them (Facility ratings), how interesting they were to listen to (Interest ratings) and how expressive they were (Expressivity ratings). ToM was assessed with the Combined Stories Test and Sarfati's cartoon task. Symptoms were assessed with the PANSS five-factor version. Compared to healthy controls, SZ received significantly lower ratings for all three aspects of their verbal productions (Facility, Interest and Expressivity), despite the raters being blind to group membership. Interestingly, the Facility ratings were linked to ToM performance in the SZ group, which suggest that SZ participants who have difficulties understanding others (ToM deficits) also make it harder for others to understand them. Other notable findings include a strong link between the Expressivity ratings and the Interest ratings for both groups, and significant correlations between the Facility ratings and Cognitive/Disorganisation symptoms, and between the Expressivity ratings and both Negative and Depression/Anxiety symptoms in SZ. Studying speech production during real, collaborative social interactions could help move beyond the individual approach to SZ deficits, making it possible to involve the interaction partners to promote more efficient communication for people with schizophrenia.