title: Movement disorders are associated with schizotypy in unaffected siblings of patients with non-affective psychosis.
abstract: BACKGROUND
  Movement disorders and schizotypy are both prevalent in unaffected siblings of patients with schizophrenia and both are associated with the risk of developing psychosis or schizophrenia. However, to date there has been no research into the association between these two vulnerability factors in persons with an increased genetic risk profile. We hypothesized that unaffected siblings of patients with non-affective psychosis have more movement disorders and schizotypy than healthy controls and that these co-occur.
  
  
  METHODS
  In a cross-sectional design we assessed the prevalence and inter-relationship of movement disorders and schizotypy in 115 unaffected siblings (mean age 27 years, 44% males) and 100 healthy controls (mean age 26 years, 51% males). Movement disorders were measured with the Abnormal Involuntary Movement Scale (AIMS), the Unified Parkinson Disease Rating Scale (UPDRS), the Barnes Akathisia Rating Scale (BARS), and one separate item for dystonia. Schizotypy was assessed with the Structured Interview for Schizotypy--Revised (SIS-R).
  
  
  RESULTS
  There were significant differences in the prevalence of movement disorders in unaffected siblings versus healthy controls (10% v. 1%, p<0.01) but not in the prevalence of schizotypy. Unaffected siblings with a movement disorder displayed significantly more positive and total schizotypy (p=0.02 and 0.03 respectively) than those without. In addition, dyskinesia correlated with positive schizotypy (r=0.51, p=0.02).
  
  
  CONCLUSIONS
  The association between movement disorders (dyskinesia in particular) with positive and total schizotypy in unaffected siblings suggests that certain vulnerability factors for psychosis or schizophrenia cluster in a subgroup of subjects with an increased genetic risk of developing the disease.
authors.affiliation: Psychiatric Centre Symfora Group, Amersfoort, The Netherlands. jpf.koning@symfora.nl
authors.forename: J P
authors.initials: JP
authors.lastname: Koning
authors.forename: D E
authors.initials: DE
authors.lastname: Tenback
authors.forename: R S
authors.initials: RS
authors.lastname: Kahn
authors.forename: M G
authors.initials: MG
authors.lastname: Vollema
authors.forename: W
authors.initials: W
authors.lastname: Cahn
authors.forename: P N
authors.initials: PN
authors.lastname: van Harten
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000453:epidemiology* / Q000235:genetics; D009426:Netherlands / Q000453:epidemiology; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders; D012307:Risk Factors; D012569:Schizotypal Personality Disorder / Q000453:epidemiology* / Q000235:genetics; D035781:Siblings / Q000523:psychology*; D055815:Young Adult