Cognitive Subtypes of Schizophrenia Characterized by Differential Brain Volumetric Reductions and Cognitive Decline

IMPORTANCE: Cognitively distinct subgroups of schizophrenia have been defined based on premorbid and current IQ, but little is known about the neuroanatomical differences among these cognitive subgroups. OBJECTIVES: To confirm previous findings related to IQ-based subgroups of patients with schizophrenia in an independent sample and extend those findings to determine the extent to which brain volumetric differences correspond to the IQ-based subgroups. DESIGN, SETTING, AND PARTICIPANTS: A total of 183 participants were assessed at the outpatient settings of Neuroscience Research Australia and Lyell McEwin Hospital from September 22, 2009, to August 1, 2012. Patients were classified using cluster analysis on the basis of current and premorbid IQ differences. Regional magnetic resonance imaging (MRI) brain volumes were compared among the IQ-based subgroups using analysis of covariance with intracranial volume and age as covariates. MAIN OUTCOMES AND MEASURES: Wechsler Adult Intelligence Scale, third edition, scores; Wechsler Test of Adult Reading scores; Positive and Negative Syndrome Scale scores; and MRI brain volumes. RESULTS: Ninety-six outpatients (mean [SD] age, 35.7 [8.4] years; age range, 18-51 years; 59 men) with schizophrenia or schizoaffective disorder and 87 healthy controls (mean [SD] age, 31.9 [8.4] years; age range, 20-50 years; 46 men) were studied. Sixty-two patients and 67 healthy controls underwent structural MRI of the brain. Cluster analyses revealed 25 putatively preserved patients (26%), 33 moderately deteriorated patients (34%), 27 severely deteriorated patients (28%), and 11 compromised patients (12%). Negative symptom scores were significantly worse in the severely deteriorated group relative to the putatively preserved group (F2,82 = 13.8, P