Neurocognitive function in schizophrenia spectrum disorders: A 20-year prospective study of a community sample

Abstract

Longitudinal studies of neurocognition in schizophrenia spectrum disorders (SSD) usually follow relatively young first-episode patients across several years. Comparatively little is known about the neurocognitive trajectory of samples also consisting of older patients. This is a 20-year follow-up study of participants who performed the baseline assessment at different ages and utilizes data from the Swedish Clinical Long-Term Psychosis Study (CLIPS). At baseline, 61 SSD patients were included and available for clinical assessment after 20 years. Of these, 28 performed neurocognitive assessment at both baseline and 20 years later. The test results from this group were used for this study. After 20 years, the participants exhibited significantly worsening cognitive flexibility, verbal learning, verbal retention memory, and verbal intellectual function compared to baseline. All the statistically significant differences from baseline to follow-up had large effect sizes. The other cognitive domains showed no statistically significant changes from baseline for either group. We conclude that although the overall picture was one of neurocognitive stability across 20 years, our participants showed signs of accelerated ageing in the verbal domain specifically.