Neurocognitive impairment is considered a core component of schizophrenia and is increasingly under investigation as a potential treatment target. On average, cognitive impairment is severe to moderately severe compared with healthy controls, and almost all patients with schizophrenia demonstrate cognitive decrements compared with their expected level if they had not developed the illness.

Keefe RSE, Fenton WS. How should DSM-V criteria for schizophrenia include cognitive impairment?  Schizophrenia Bulletin, 2007; 33(4): 912-920.  PMCID: PMC2632322.