A twin study of psychomotor and physiological response to an acute dose of alcohol. Behav. Genet

A battery of psychomotor tasks and physiological measures was admin-istered to 206 pairs of twins before alcohol and then three times at hourly intervals after they ingested a standard dose of ethanol (0.75 g/kg body weight). Repeat measurements were obtained for 4l of these pairs on a second occasion. Performance on motor coordination, standing steadi-ness, pursuit rotor, arithmetic omputation, and reaction-time tasks de-teriorated after alcohol, but decrements on the five tasks were generally independent of each other. Measurements of blood pressure, pulse rate, and skin temperature were all elevated following alcohol intake, but these responses were also uncorrelated. The variance in many of these meas-ures increased after alcohol. An analysis of covariance structure revealed that most of this additional variance exposed by alcohol was genetic in origin, particularly for standing steadiness, pursuit rotor, arithmetic om-putation, and pulse rate. Up to 50 % of the variance in body sway after alcohol was estimated to be due to genetic factors expressed only under the influence of alcohol. Although significant correlations were found with blood alcohol concentration, previous drinking experience, and the personality trait Extraversion, little of the genetic variance exposed by This work was supported by the Australian Associated Brewers