IQ stabilization in childhood-onset schizophrenia

Abstract 

Objective

To examine the long term IQ trajectory for childhood-onset schizophrenia (COS) in an expanded, prospective longitudinal study.

Methods

Seventy children meeting DSM criteria for schizophrenia were tested at 2 year intervals with age appropriate Wechsler intelligence tests and repeated administration of information and comprehension WISC subtests even after age 18. For a subgroup with 31 patients, pre-NIH IQ test administrations were available including 18 pre-psychotic and 13 post-psychotic subjects. The pattern of IQ performance over time was determined using mixed model regression analysis.

Results

No progressive cognitive decline was seen up to 13+ years post psychosis onset. For the subgroup of subjects with pre-illness scores, there had been an initial steep decline in IQ, from about 2 years prior to 1.7 years after onset of psychotic symptoms, as reported for adult patients.

Conclusions

The level long-term trajectory of IQ measures in COS appears stable, similar to that reported for adult onset patients. For COS, level cognitive functioning extends up to 13+ years post psychosis onset, in spite of chronic illness and concomitant, progressive loss of cortical gray matter.

Keywords: Childhood-onset, Schizophrenia, Intelligence, IQ