Quantifying the Overlap between Neurocognition, Social Cognition, and Symptoms in Schizophrenia

Purpose:

There has been a renewed focus on cognition as a treatment target in schizophrenia. However, there are ongoing debates about the overlap among dimensions of neuropsychological test performance. One issue concerns the strength of relationship between key features of schizophrenia such as neurocognitive and social-cognitive deficits. While an increasing body of factor analytic literature indicates that these dimensions are separable, there are also data revealing constraints on the amount of reliable performance variance across the domains. The purpose of this study is to replicate and extend research on the potential overlap by evaluating neurocognition, social cognition (SC), and symptomatology in a comparative analysis of deaf and hearing people with schizophrenia. The contribution each domain makes to explaining variance in functional outcome is addressed.

Method:

Sixty-five adults with schizophrenia (34 deaf, 31 hearing) were recruited from a community-based psychosocial rehabilitation agency. The population of potential deaf subjects was considerably smaller then the hearing population, however, no significant differences were found to exist with regards to social, ethnic, or demographic variables across the final sample. Symptomatology was evaluated with the Brief Psychiatric Rating Scale (BPRS) and the Structured Clinical Interview for DSM-IV Axis I Disorders-Patient Edition (SCID). Subjects were assessed using established measures of neurocognition including memory, attention, and visual processing. Subjects' social-cognitive skills were evaluated via the ability to decode facial affect (i.e., facial-affect processing) and the ability to infer another person's intentions (i.e., theory of mind). Functional outcomes were operationalized by a measure that assesses adaptive behaviors that influence community living. Neurocognition, SC, and symptomatology were factor analyzed to determine how much random or unique variance the observed variables contained and relationship patterns with functional outcome were analyzed. Tests of multicollinearity (e.g., correlational analyses) and multiple regressions were conducted.

Results:

SC mediated the relationship between neurocognition and functional outcome for deaf and hearing subjects. However, the independence of neurocognition and SC was only partially supported. Namely, there was a lack of unique variance between domains of neurocognition (e.g., visual processing) and facial-affect processing. Similarly, symptomatology, and in particular disorganized and anergic symptoms, were correlated, on average, at a medium level with domains of SC. This pattern of findings is consistent with the view that there may be constraints on the amount of reliable performance variance across symptomatology and neurocognitive and social-cognitive processing domains.

Implications:

SC has become a high priority area for the study of schizophrenia and it is clear that social competence is a core component of the disease process. This study contributes to the refinement of theories of social dysfunction by delineating the value of SC above and beyond neurocognition and symptomatology. The project also contributes to the debates surrounding whether cognitive deficits in schizophrenia are better characterized as generalized, or, as reflecting relatively independent deficits. For practitioners, the data from this research indicates that cognitive rehabilitation strategies should include not only interventions targeting specific cognitive abilities, such as attention and memory, but should include an emphasis on social-cognitive domains including theory of mind and facial-affect processing.