Effects of ethanol: II. Behavioral sensitivity and acute behavioral tolerance.

Two doses of ethyl alcohol were administered to 48 young male subjects (24 brother-pairs), and placebo doses were administered to five brother-pairs (controls). Dose 1 amount was calculated to result in a peak blood alcohol content (BAC) of 100 mg/100 ml; dose 2 was given when BAC had fallen to one-half the peak BAC resulting from dose 1, in an attempt to raise BAC back to 100 mg/100 ml. Prior to alcohol dosage, baseline measurements were made on a number of behavioral tests. Behavioral performances during metabolism of doses 1 and 2 were compared to baseline performance. Sensitivity to ethanol was indicated by performance decrements on nearly all tests after ethanol dosing. Acute behavioral tolerance to ethanol (ABTE) was indicated for some tests by improved performance after dose 2 compared to performance at a time after dose 1 when BACs were about equivalent. A preliminary search for possible genetic components of sensitivity and ABTE was undertaken by comparing the scores of the brothers.