Association study of a functional catechol-O-methyltransferase polymorphism and executive function in elderly males without dementia.

Cognitive function in older people is a major factor influencing quality of life. The catechol-O-methyltransferase (COMT) gene, which is essential in the metabolic degradation of prefrontal dopamine, has been considered as a leading candidate gene in the variation in cognitive performance. The aim of this study was to investigate the effect of a functional COMT (Val158Met) polymorphism on several cognition domains in a relatively homogeneous population consisting of elderly Chinese males without dementia. Six neuropsychological measurements, including Spatial Span Forward and Backward, Digit Span Forward and Backward, and Trail Making Test-A and -B, were assessed in 161 aged males. It was found that the Met/Met carriers showed a better performance than the Val/Met and Val/Val subjects on the Digit Span Forward (a measure of general attention; p=0.017, after correction for education level) test, but not on the other cognitive tests. These findings suggest that the COMT Val158Met genotype may contribute to differences in normal cognitive aging, particularly in the area of general attention.