title: Smooth pursuit and antisaccade eye movements in siblings discordant for schizophrenia.
abstract: Smooth pursuit eye movement (SPEM) and antisaccade deficits have been proposed as endophenotypes in the search for schizophrenia genes. We assessed these measures in 24 schizophrenia patients, 24 of their healthy siblings, and 24 healthy controls closely matched to the siblings. Between-group differences were assessed using a random effects regression model taking into account the relatedness between patients and siblings. Patients showed reduced SPEM gain, increased frequency of saccades during pursuit, increased antisaccade error rate, and reduced antisaccade gain compared to controls. Siblings performed intermediate, i.e. between patients and controls, on most measures, but were particularly characterised by reduced antisaccade gain. SPEM gain at one target velocity was significantly correlated between patients and siblings, highlighting the necessity of taking into account within-family correlations in the statistical analysis of between-group differences. It is concluded that subtle SPEM and antisaccade deficits are observed in clinically unaffected siblings of schizophrenia patients; these deficits may be useful markers of genetic liability to schizophrenia.
authors.affiliation: Division of Psychological Medicine, Institute of Psychiatry, UK.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ettinger
authors.forename: Veena
authors.initials: V
authors.lastname: Kumari
authors.forename: Trevor J
authors.initials: TJ
authors.lastname: Crawford
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Corr
authors.forename: Mrigendra
authors.initials: M
authors.lastname: Das
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Zachariah
authors.forename: Catherine
authors.initials: C
authors.lastname: Hughes
authors.forename: Alex L
authors.initials: AL
authors.lastname: Sumich
authors.forename: Sophia
authors.initials: S
authors.lastname: Rabe-Hesketh
authors.forename: Tonmoy
authors.initials: T
authors.lastname: Sharma
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D015835:Ocular Motility Disorders / Q000235:genetics* / Q000473:pathology*; D010641:Phenotype; D012044:Regression Analysis; D012559:Schizophrenia / Q000235:genetics* / Q000503:physiopathology*; D035781:Siblings