• Significantly increased brain density was found in the frontal lobes and caudate and thalamic nuclei of monozygotic twins who were severely dependent on alcohol when compared with their normal-drinking co-twins. No significant differences in brain radiodensity were found in a group of identical twins who were discordant for less severe alcoholism. Hemispheric differences in brain density were also examined. Right-handed normal twins had greater density in the left caudate than in the right caudate region; this difference was reduced but still present in alcoholics.
Gurling HMD, Murray RM, Ron MA. Increased Brain Radiodensity in AlcoholismA Co-twin Control Study. Arch Gen Psychiatry. 1986;43(8):764-767. doi:10.1001/archpsyc.1986.01800080050007