Persistence, diagnostic specificity and genetic liability for context-processing deficits in schizophrenia

Context-processing deficits have been shown in schizophrenia during first-episode, medication-naïve status, that persist after short-term antipsychotic treatment and also in first-degree relatives of individuals with schizophrenia. To confirm longer term persistence of deficits, we examined schizophrenia patients (n = 63) during first-episode, medication-naïve status through to one-year follow-up, compared to healthy control (n = 83) and non-schizophrenia psychosis comparison (n = 47) groups, as well as unaffected first-degree relatives of individuals with schizophrenia (n = 31). Context-processing ability was assessed by performance on the AX-CPT (Continuous Performance Test) at baseline, 8. weeks, 6. months, and 1. year (relatives only at baseline). Reaction time, error rates and signal detection indices (d'-context) of context processing were analyzed. Linear discriminant analyses (LDA) on early timepoints (baseline, 8. weeks) were conducted to predict confirmatory diagnosis (schizophrenia vs. psychosis control) at 6. months. Schizophrenia patients showed evidence of impaired context-processing relative to both the healthy and psychosis comparator groups at baseline and continued through to 1. year. While context-processing impairments persisted in schizophrenia patients through one year, the impairments in psychosis controls, which were more modest at baseline, remitted at follow-up. First-degree relatives showed deficits that were intermediate between the schizophrenia and healthy control groups. LDA showed 67% classification rates for distinguishing schizophrenia from non-schizophrenia psychosis. The persistence, diagnostic specificity and association with genetic liability give support for context processing impairments serving as a cognitive endophenotype for schizophrenia and evaluation of context processing could contribute to diagnostic assessments.