title: Neuropsychological impairments in people with schizophrenia or bipolar disorder and their unaffected relatives.
abstract: BACKGROUND
  Neuropsychological abnormalities in schizophrenia are well replicated and are present in unaffected relatives. Cognitive findings in bipolar disorder are less clearly established.
  
  
  OBJECTIVE
  To examine the possibility that these abnormalities may provide a means by which the disorders might be separated and to clarify the associations of phenotypic expression and genetic liability.
  
  
  METHODS
  A neuropsychological test battery was administered to 50 control participants, 74 patients and 76 unaffected relatives recruited for the study. Patients included those with schizophrenia from families affected by schizophrenia alone, those with bipolar disorder from families affected by bipolar disorder alone and those with bipolar disorder from families affected by both disorders. Unaffected relatives were also recruited.
  
  
  RESULTS
  Current, verbal and premorbid IQ were impaired in people with schizophrenia and in their close relatives. Memory was impaired in all patient and relative groups. Psychomotor performance and performance IQ were impaired in patients, regardless of diagnosis.
  
  
  CONCLUSIONS
  This study finds evidence that intellectual abnormalities are related to a genetic liability to schizophrenia. Abnormalities of memory appear to be related to an increased liability to psychosis in general. No impairment was specific to bipolar disorder.
authors.affiliation: Division of Psychiatry, Royal Edinburgh Hospital, Edinburgh EH10 5HF, UK. andrew.mcintosh@ed.ac.uk
authors.forename: Andrew M
authors.initials: AM
authors.lastname: McIntosh
authors.forename: Lesley K
authors.initials: LK
authors.lastname: Harrison
authors.forename: Karen
authors.initials: K
authors.lastname: Forrester
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Lawrie
authors.forename: Eve C
authors.initials: EC
authors.lastname: Johnstone
mesh_terms: D000704:Analysis of Variance; D001714:Bipolar Disorder / Q000235:genetics / Q000523:psychology*; D003072:Cognition Disorders / Q000209:etiology* / Q000235:genetics; D006801:Humans; D007360:Intelligence; D008569:Memory Disorders / Q000209:etiology / Q000235:genetics; D009483:Neuropsychological Tests; D011597:Psychomotor Performance; D012565:Schizophrenic Psychology