title: Subtle cognitive dysfunction in nonaffected siblings of individuals affected by nonpsychotic disorders.
abstract: BACKGROUND
  Previous studies have reported that as a group, individuals affected by psychotic and nonpsychotic disorders perform below norms on cognitive tests. Other studies have indicated that unaffected siblings of individuals affected by psychotic disorders also perform below norms on the same tests. We investigated cognitive performance on a large, population-based sample of individuals, affected at the time of testing by nonpsychotic disorders, and their unaffected siblings.
  
  
  METHODS
  Subjects were taken from a population-based cohort of 523,375, 16- to 17-year-old male adolescents who had been assessed by the Israeli Draft Board. Cognitive test scores were examined in sib-pairs discordant for nonpsychotic (n = 19,489) and psychotic (n = 888) disorders and compared with 224,082 individuals from sibships with no evidence of mental illness.
  
  
  RESULTS
  There appears to be a gradient in cognitive performance (worst to best) from individuals currently affected by psychotic illnesses (Cohen's d = -.82), followed by individuals currently affected by nonpsychotic illness (Cohen's d = -.58), unaffected siblings of individuals affected by psychotic illness (Cohen's d = -.37), unaffected siblings of individuals affected by nonpsychotic illness (Cohen's d = -.27), and members of sibships with no evidence of mental illness. Unaffected siblings of both psychotic and nonpsychotic individuals from multiple affected sibships (more then one affected sibling) had worse cognitive test scores compared with unaffected siblings from simplex sibships (only one affected sibling).
  
  
  CONCLUSIONS
  The results support, but do not prove, the notion that cognitive impairment in psychiatric disorders is familial and cuts across diagnostic entities.
authors.affiliation: Department of Psychiatry, Sheba Medical Center, Tel-Hashomer, Israel. mweiser@netvision.net.il <mweiser@netvision.net.il>
authors.forename: Mark
authors.initials: M
authors.lastname: Weiser
authors.forename: Abraham
authors.initials: A
authors.lastname: Reichenberg
authors.forename: Efrat
authors.initials: E
authors.lastname: Kravitz
authors.forename: Gad
authors.initials: G
authors.lastname: Lubin
authors.forename: Moti
authors.initials: M
authors.lastname: Shmushkevich
authors.forename: David C
authors.initials: DC
authors.lastname: Glahn
authors.forename: Raz
authors.initials: R
authors.lastname: Gross
authors.forename: Jonathan
authors.initials: J
authors.lastname: Rabinowitz
authors.forename: Shlomo
authors.initials: S
authors.lastname: Noy
authors.forename: Michael
authors.initials: M
authors.lastname: Davidson
mesh_terms: D000293:Adolescent; D003072:Cognition Disorders / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D015331:Cohort Studies; D020022:Genetic Predisposition to Disease / Q000235:genetics* / Q000523:psychology; D006801:Humans; D007557:Israel; D008297:Male; D008403:Mass Screening; D001523:Mental Disorders / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D008889:Military Personnel / Q000523:psychology; D009483:Neuropsychological Tests; D010552:Personality Assessment; D011618:Psychotic Disorders / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D035781:Siblings