White Matter Connectivity and Social Cognitive Impairment in a Transdiagnostic Sample

Abstract

Social cognitive deficits are impaired mental operations underlying social interactions and are present across psychotic disorders, including schizophrenia spectrum, bipolar, and depressive disorders. It is unclear what neurobiological factors underlie social cognitive impairment, though one possibility is that impaired white matter connections within social cognitive cerebral networks may give rise to social cognitive impairment in psychosis. This study extended current diffusion tensor imaging (DTI) research to a transdiagnostic sample of individuals with psychotic disorders and controls and employed a Research Domain Criteria (RDoC) multiple units of analysis approach. The current study aimed to (1) assess the relation between social cognition (theory of mind and emotion processing), social functioning, negative symptoms, and general cognitive ability, and (2) examine white matter integrity within the uncinate fasciculus (UF) and inferior longitudinal fasciculus (ILF) through fractional anisotropy (FA) values, and to investigate their relation to social cognition and social functioning.

Thirty-three participants, 25 with a history of clinically significant psychotic symptoms and 8 controls, completed the research project. Results indicated that social cognition was positively related to general cognitive ability, but not social functioning. However, better theory of mind was related to improved community functioning. Negative symptoms were differentially related to social cognition as there was only a negative association between theory of mind and expressive negative symptoms. More severe negative symptoms were associated with poorer social functioning and cognitive ability. White matter integrity within either identified tract did not contribute to social cognitive ability. Although FA within the left ILF was related to overall functioning and social functioning and FA within the left UF was related to community functioning, these relationships were in the opposite direction as originally predicted with better functioning contributing to lower FA.

This is the first study to investigate white matter microstructure in a transdiagnostic sample using an RDoC approach. Our results indicate that there may be unique challenges involved in implementing RDoC. We encourage future researchers to recruit larger sample sizes, administer several behavioral measures of interest to create latent variables, and consider novel imaging methods to better address the difficulties associated with crossing fiber tracts.