Stability and functional correlates of memory-based classification in older schizophrenia patients

Objective: There is an increasing interest in the usefulness of neurocognitive subtyping of schizophrenia. The classification of schizophrenia patients with cortical versus subcortical impairments has recently been validated with both neuropsychological and neurobiological measures. The authors examined the stability and correlations of these classifications with longitudinal assessments in older, chronically ill schizophrenia patients. Methods: Older, chronically ill patients (N = 589) were classified on the basis of their baseline profile, and a subset (N = 243) was followed for periods up to 8 years, with data analyses conducted to evaluate the stability of these profiles, to determine whether classification into cortical or subcortical impairment at baseline predicts changes in self-care and social functioning at endpoint, up to 8 years later. Results: Cortical profiles were most common and most stable over time, with the majority of patients with a subcortical profile at baseline found to have a cortical profile at follow-up. Those patients whose subcortical impairment profile was stable over time had less severe cognitive and functional impairments at baseline than those whose profile was found to be cortical at follow-up. Discussion: Cortical profiles of memory impairment were associated with substantial cognitive impairments at base-line and did not predict risk for subsequent cognitive decline, whereas subcortical profiles were associated with worsening of cognitive impairments in about half of the cases. Those patients with more severe negative symptoms and cognitive and functional impairments within the subcortical group were most likely to decline.