Neuro- and social-cognition in schizotypal personality disorder and schizophrenia: A spectrum of severity

Despite the significant number of impairments shared by diagnostic groups on the schizophrenia-phenotypic-spectrum, no work has directly compared neuro- and social-cognition of individuals with schizotypal personality disorder (SPD) with that of schizophrenia. This is the first study to compare social-cognition and neuro-cognition across schizophrenia-spectrum-diagnostic groups and explore associations (1) between neuro- and social-cognition in these groups and (2) between change-over-time (nine-month follow-up) in cognition and negative-symptom-severity. This study identified 127 age- and gender-matched healthy controls (HC; N = 49), antipsychotic-naïve individuals with SPD (N = 32), and patients with recent onset schizophrenia (within eight years of illness-onset; N = 46). Detailed profiles of clinical symptoms and cognition were obtained using gold-standard measures (e.g., NIH MATRICS Battery). Schizophrenia patients exhibited global cognitive impairment; SPD patients only exhibited impairment in social-emotional cognition compared with HC (Cohen d = 0.51) but still performed better than the schizophrenia group F[2, 124]=15.18, p < 0.001, Cohen d = 0.61. Multivariable linear regression revealed that social-cognition was associated with neuro-cognition, β=0.49, p < 0.001. In the combined patient group, a greater increase in social-cognition over time was associated with greater reduction in negative symptoms, (B = -0.12, SE=0.09, p = 0.038). Distinct profiles emerged: generalized cognitive impairment in schizophrenia and higher-order social-cognition impairment in SPD. Furthermore, change in social-cognition over time is associated with a change in negative symptoms. Results suggest that social-cognition is impaired across the schizophrenia-spectrum, and detailed examination of social-cognitive treatments should be considered, particularly for individuals with SPD, as they receive minimal attention in research studies.