Long-term repeatability of human alcohol metabolism, sensitivity and acute tolerance.

Thirty-eight subjects in the Colorado Alcohol Research on Twins and Adoptees (CARTA) were brought back between 3 and 39 months after their initial testing to be retested on a shortened version of the standard CARTA procedures. As before, subjects were given a dose of ethanol (0.8 g/kg) calculated to bring their blood alcohol level (BAL) to near 100 mg/dl, but no topping doses were administered in the retests to maintain BALs near peak for 3 hours, as was done previously. Repeatability (test-retest correlation) for alcohol clearance rate was near zero, repeatability for time to peak BAL was 0.36 and that for peak BAL was 0.50. Repeatabilities of prealcohol baseline scores were generally high (median 0.55) for the shortened battery of physiological, motor coordination, perceptual speed and reaction time measures. Repeatabilities were near zero for sensitivity scores (median 0.02) and were low for acute tolerance scores (median 0.10) and perceived intoxication (median 0.27). These findings are highly consistent with an earlier report on repeatabilities of responses to alcohol over a 1-month time interval.