Childhood-onset schizophrenia: smooth pursuit eye-tracking dysfunction in family members.

Background: Childhood-onset schizophrenia (COS), a severe form of the disorder, is of interest for etiologic studies. Smooth pursuit eye-tracking dysfunction (ETD) is a biological marker for schizophrenia. Aims: To compare familial eye-tracking abnormalities for COS and adult-onset schizophrenia (AOS). Method. Eye-tracking performance for 70 COS parents, 64 ADS parents and 20 COS siblings was compared to their respective age-matched control groups. Results: COS and AOS parents had higher rate of dichotomously rated eye-tracking dysfunction than their respective controls (16% vs. 1% and 22% vs. 4%, respectively). COS parents and siblings also differed from controls on several continuous measures. However, scores for COS, AOS and control groups overlapped extensively. Conclusions: Genetic factors underlying eye-tracking dysfunction appear more salient for COS. However, eye-tracking measures have to be used with caution for endophenotypic definition due to low predictive power. Declaration of interest: The study was done at the National Institutes of Health. (C) 2004 Elsevier B.V. All rights reserved.