The Difference of the 2nd to 4th Digit Length Ratio betweenType I and Type II Alcoholism

ABSTRACT

OBJECTIVES: The second to fourth digit ratio (2D 4D) is known to reflect testosterone level during intrauterine period. Testosterone is essential for masculinization of brain. Cloninger's type II alcoholism is characterized by early age at onset and largely limited to males. Compared with type I alcoholism, type II alcoholism is thought to be masculine. There is a possibility that the digit ratio of type II alcoholism is low compared with type I. We examined digit length ratio in Cloninger's type I and II alcoholism to understand the effects of intrauterine testosterone on the development of alcoholism. METHODS: The participants were 87 alcohol dependent patients. We divided two subtypes of patients by Irwin's symptom list, based on Cloninger's concept. We captured the images of both palms by the scanner and measured the lengths of digits by the graphic program. Then we analyzed the digit ratios by independent-sample t-test. RESULTS: The mean 2D 4D of type I was 0.942 (right), 0.952 (left). The mean 2D 4D of type II was 0.927 (right), 0.940 (left). In both hands, 2D 4D of type II was significantly lower than type I. CONCLUSIONS: Type II alcoholism showed masculine type of digit length ratio compared with type I. It suggests the exposure of testosterone during intrauterine period might play an important role in determining the course and feature of alcoholism.