Cognitive deficits in schizophrenia are well established and are known to be present during the first episode of a psychotic disorder. In addition, consistent heterogeneity within these impairments remains unexplained. One potential source of variability may be the level of pre-morbid adjustment prior to the onset of first-episode psychosis (FEP).

Ninety-four FEP patients and 32 healthy controls were assessed at baseline on several neuropsychological tests comprising six cognitive domains (verbal memory, visual memory, working memory, processing speed, reasoning/problem-solving and attention) and an abbreviated version of the full IQ. A global neurocognitive domain was also computed. Pre-morbid adjustment patterns were divided into three distinct groups: stable-poor, stable-good and deteriorating course.

Based on a cut-off of 0.8 for effect size, the stable-poor pre-morbid adjustment group was significantly more impaired on most cognitive domains and full IQ compared to the deteriorating group, who were more severely impaired on all measures compared to the stable-good group. The type of cognitive deficit within each subgroup did not differ and the results indicate that a global neurocognition measure may reliably reflect the severity of cognitive impairment within each subgroup.

Pre-morbid adjustment patterns prior to onset of psychosis are associated with severity but not type of cognitive impairment. Patients in the stable-poor group are generally more impaired compared to the deteriorating group, who are, in turn, more impaired than the stable-good group.