Theory of mind difficulties in people with social anhedonia : evidence from behavioural and task-based functional magnetic resonance imaging findings

Abstract

Background: Social Anhedonia (SA) is recognised as a negative symptom of the schizophrenia spectrum. Despite the emerging evidence of general impairment in Theory of Mind (ToM), the behavioural manifestation and underlying neural mechanisms of ToM deficits in SA remain unclear. The current study therefore adopted a multidimensional assessment approach to examine the effect of SA on ToM ability behaviourally and using fMRI. Methods: A total of 47 participants with high SA (Mage = 21.43 years, SD = 4.23) and 46 with low SA (Mage = 22.70, SD = 2.91) were recruited to complete an adapted version of the Virtual Assessment of Mentalising Ability to evaluate ToM. Group differences were analysed using 2 (Type: Cognitive vs Affective ToM) × 2 (Order: First- vs Second-Order ToM) × 2 (Group: high vs low SA) repeated measures ANOVA. fMRI data were examined with general linear models and group comparisons, including ROI analyses to assess correlations between brain activation and behavioural measures. Results: The participants with low SA showed better performance for first-order ToM than for second-order ToM. However, those with high SA did not show such a differential effect. Based on the fMRI results, the low SA group showed more activation than the high SA group in the medial frontal cortex and posterior cingulate cortex in second-order ToM than in first-order ToM. Conclusion: The results demonstrate the impairment of ToM performance among those with high SA and highlight that it is crucial to examine the pattern of results rather than solely focusing on general ToM.