title: IQ trajectory, cognitive reserve, and clinical outcome following a first episode of psychosis: a 3-year longitudinal study.
abstract: Comparison of current and estimated premorbid IQ in schizophrenia suggests that there are subgroups with low IQ, deteriorated IQ (DIQ), or preserved IQ and that this is established by psychosis onset. There are no controlled studies examining the trajectory of these IQ subgroups longitudinally or their relationship with clinical and social outcomes. Of 129 individuals with first-episode schizophrenia or schizoaffective disorder, 25% showed stable low IQ, 31% showed stable IQ in the average/high range, and 44% demonstrated intellectual deterioration by 10 points or more. Patients in the low and deteriorated groups were equally impaired on tests of memory and executive function compared with the preserved average/high-IQ group and controls and showed more negative and disorganization symptoms than the preserved average/high-IQ group. Sixty patients and 27 controls were assessed again 1 and 3 years later. There was no evidence that those with IQ deterioration at baseline continued on a declining cognitive trajectory or that those with preserved average/high IQ experienced subsequent IQ decline. The low IQ group showed no change in IQ, whereas both the DIQ and the preserved IQ groups improved. However, the rate of improvement of these 2 subgroups was no greater than that of the healthy controls, suggesting that this reflected practice effects. Both the low and the deteriorated groups had longer index admissions, more core negative symptoms, and worse occupational outcomes at 3 years. These data suggest that following psychosis onset, IQ is stable and that it is IQ at psychosis onset rather than premorbid IQ predicts a more severe illness.
authors.affiliation: UCL Institute of Neurology, The National Hospital for Neurologyand Neurosurgery, University College London, Queen Square, London, UK. v.leeson@ion.ucl.ac.uk
authors.forename: Verity C
authors.initials: VC
authors.lastname: Leeson
authors.forename: Pranev
authors.initials: P
authors.lastname: Sharma
authors.forename: Masuma
authors.initials: M
authors.lastname: Harrison
authors.forename: Maria A
authors.initials: MA
authors.lastname: Ron
authors.forename: Thomas R E
authors.initials: TR
authors.lastname: Barnes
authors.forename: Eileen M
authors.initials: EM
authors.lastname: Joyce
mesh_terms: D000293:Adolescent; D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001364:Awareness; D003072:Cognition Disorders / Q000175:diagnosis* / Q000523:psychology / Q000534:rehabilitation; D058245:Cognitive Reserve; D005260:Female; D006801:Humans; D007360:Intelligence; D008137:Longitudinal Studies; D008297:Male; D055118:Medication Adherence / Q000523:psychology; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011214:Practice, Psychological; D011379:Prognosis; D011594:Psychometrics; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000523:psychology / Q000534:rehabilitation; D012016:Reference Values; D012050:Rehabilitation, Vocational; D012559:Schizophrenia / Q000175:diagnosis* / Q000534:rehabilitation; D012565:Schizophrenic Psychology; D012917:Social Adjustment; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents