title: Familial resemblance for executive functions in families of schizophrenic and bipolar patients.
abstract: Executive dysfunctions are considered to be putative markers of familial/genetic vulnerability to both schizophrenia and bipolar disorder. However, familial resemblance must be demonstrated before executive functions are used as a potential endophenotype. The aim of this study was to investigate familial resemblance for executive functions in families of schizophrenic and bipolar subjects. We assessed executive functions by means of two tests - the Wisconsin Card Sorting Test (WCST) and the Trail Making Test (TMT) - in 351 subjects from five populations: schizophrenic patients, bipolar patients, a group of relatives for each patient group and controls. For both tests, cognitive assessment results were consistent with previous studies: schizophrenic patients showed the greatest impairment, followed by bipolar patients and then the two groups of relatives. In families of bipolar patients we observed familial resemblance for the WCST and part A and part B of the TMT. However, by contrast with the classical point of view, considering executive measures to be markers of genetic vulnerability to schizophrenia, we did not demonstrate familial resemblance for either of the two executive tests in families of schizophrenic patients. Thus, executive measures, as assessed by the WCST or the TMT, should not be used as endophenotypes in genetic studies of schizophrenia unless confounders are identified and their effects eliminated.
authors.affiliation: Service de Psychiatrie Adulte, Hôpital Albert Chenevier et Henri Mondor (Assistance Publique - Hôpitaux de Paris), 94000 Créteil, France. andrei.szoke@ach.ap-hop-paris.fr
authors.forename: Andrei
authors.initials: A
authors.lastname: Szöke
authors.forename: Franck
authors.initials: F
authors.lastname: Schürhoff
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Golmard
authors.forename: Caroline
authors.initials: C
authors.lastname: Alter
authors.forename: Isabelle
authors.initials: I
authors.lastname: Roy
authors.forename: Alexandre
authors.initials: A
authors.lastname: Méary
authors.forename: Bruno
authors.initials: B
authors.lastname: Etain
authors.forename: Frank
authors.initials: F
authors.lastname: Bellivier
authors.forename: Marion
authors.initials: M
authors.lastname: Leboyer
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000453:epidemiology* / Q000235:genetics*; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D005190:Family; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010641:Phenotype; D015995:Prevalence; D012559:Schizophrenia / Q000453:epidemiology* / Q000235:genetics*; D012720:Severity of Illness Index