Increased cerebral ventricular volume in monozygotic twins discordant for alcoholism

21 pairs of monozygotic twins discordant for alcoholism and heavy drinking were examined by computerised tomography. Brain and ventricular volumes were calculated by the use of a semiautomated method with the rater blind to twinship and drinking history. 11 severely dependent alcoholics had larger ventricular volumes and ventricle/brain ratios than did their normal cotwins. These changes correlated best with the length of time the alcoholic twin had been drinking eight centilitres pure alcohol, equivalent to a bottle of wine, a day.