Decline in several cognitive domains continues for a decade after disease onset and is not attributable to medication effects.

 Patients with first-episode schizophrenia demonstrate baseline cognitive deficits relative to peers, but little is known about long-term changes in patients with schizophrenia and other psychoses. Investigators in a U.K. population-based, study conducted neuropsychological assessments in 187 patients with first-episode psychosis and 177 healthy controls.  Assessments included full-scale IQ, memory, verbal knowledge, executive function/working memory, processing speed, and visuospatial abilities. At baseline  patients with schizophrenia and other psychoses had lower IQ and widespread cognitive impairment compared to controls. Patients with schizophrenia showed greater impairment than those with other psychoses.

Follow-up occurred approximately 10 years later in 106 patients at follow-up, patients with schizophrenia showed further declines in IQ whereas controls showed no decline; patients also showed greater declines on tests of memory and vocabulary only. Neither duration nor type of antipsychotics (typical vs. typical/atypical) influenced IQ decline. Schizophrenia patients with severe baseline psychotic symptoms showed greater cognitive decline than those with mild or moderate baseline symptoms. Over follow-up, patients with other psychoses also showed small declines in memory and vocabulary relative to controls but no declines in IQ or other domains.

This study did not examine other potential contributors to cognitive decline, including smoking, other substance use, or comorbid illnesses. Nevertheless, the findings suggest that the cognitive deficits seen in early psychosis are not static and that impairments and their changes over time occur across psychotic conditions. Cognitive remediation and retraining, especially focusing on memory and vocabulary, might particularly benefit patients with severe symptoms.