Catechol-O-Methyltransferase ValMet Polymorphism and Antisaccade Eye Movements in Schizophrenia

The catechol-O-methyltransferase (COMT) enzyme catabolizes dopamine. The valmet single nucleotide polymorphism (rs4680) in the COMT gene has received considerable attention as a candidate gene for schizophrenia as well as for frontally mediated cognitive functions. Antisaccade performance is a good measure of frontal lobe integrity. Deficits on the task are considered a trait marker for schizophrenia. The aim of this study was to investigate the association of COMT valmet polymorphism with antisaccade eye movements in schizophrenia patients and healthy controls. Schizophrenia patients (N 5 105) and healthy controls (N 5 95) underwent infrared oculographic assessment of antisaccades. Subjects were genotyped for COMT valmet and divided into 3 groups according to genotype (val/val, val/met, and met/met). Patients displayed significantly more reflexive errors, longer and more variable latency, and lower amplitude gain than controls (all P < 0.02). A greater number of val alleles was associated with shorter (P5 0.045) and less variable (P 5 0.028) antisaccade latency and, nonsignificantly, with lower reflexive error rate (P 5 0.056). None of these variables showed a group-by-genotype interaction (P > 0.1). There were no significant associations of genotype with measures of amplitude gain or spatial error (P > 0.2). The results suggest that COMT val carrier status is associated with better performance on the antisaccade task. Possible explanations of this finding are discussed.