Theory of mind and schizophrenia in young and middle-aged patients: Influence of executive functions

Theory of Mind (ToM) is compromised in schizophrenia, and responsible for social disability. We aim to study the correlation between ToM deficits and Executive Functions (EF), using the Faux Pas Test (FPT) for ToM evaluation, Behavioral Assessment of the Dysexecutive Syndrome (BADS) and Wisconsin Card Sorting Test (WCST) for EF assessment. Two groups of patients with schizophrenia were included: 22 young (18-35 years-old) and 18 middle-aged (>50 years-old) Patients, compared to age-matched Controls. We found worst FPT performances in both groups of patients, but with a more generalized pattern of dysfunction in the middle-aged patient group. This group had worse EF scores than both controls and younger patients. The association of EF with FPT items was uneven. In young patients only empathy (Q6) remained significant after controlling for EF and level of education, while in middle-aged patients faux pas explanation (Q4), false belief (Q5) and total scores remained significant. In young patients only affective TOM was impaired. No correlation was found with clinical symptoms, nor age at onset of the disease. We conclude that ToM deficit arises early during the course of the illness (already present in young patients), increases in middle-aged patients, and relates only partially with EF.