The 2D:4D digit ratio as biomarker for alcohol consumption

Purpose: The 2D:4D digit ratio is a biological correlate for prenatal testosterone and estrogen exposure. Amniotic fluid analysis revealed a significant relationship between prenatal testosterone concentration and adult risk taking behavior. As the 2D:4D digit ratio does not change after the age of 2, it is worthwhile to further investigate the feasibility of the 2D:4D digit ratio as biomarker and potential screening tool for later life alcohol abuse. Methods: A survey was held among N = 557 Dutch students. In addition to demographics, alcohol consumption questions (Quick Drinking Screen) were completed. For both hands, digit length of the second (2D, index finger) an fourth (4D, ring finger) finger were measured using digital vernier calipers recording to 0.01 mm. Measurements were made from the mid-point of the finger crease proximal to the palm to the tip of the finger. The 2D:4D digit ratio was correlated with alcohol consumption variables. In addition, alcohol consumption of subjects with a hawk-type (2D:4D <1) and dove-type personality (2D:4D > 1) were compared. Results: Data from N = 448 alcohol consuming subjects was used for the statistical analyses; N = 125 (27.9%) of them were men. Overall, the left 2D:4D digit ratio correlated significantly with the number of alcoholic drinks per week (r = -0.119, p = 0.014) and the days drunk per month (r = -0.121, p = 0.011). For men, significant correlations were found between left 2D:4D digit ratio and first drinking age (r = 0.188, p = 0.035), and between the right 2D:4D digit ratio and the average number of drinks consumed per occasion (r = -0.229, p = 0.011), the number of alcoholic drinks per week (r = -0.185, p = 0.045), and the age of regular drinking (r = 0.190, p = 0.035). For women, the left 2D:4D digit ratio correlated significantly with the number of days being drunk (r = -0.137, =0.014). Those with a right 2D:4D <1 consumed significantly more alcohol on average occasion (p = 0.017) and reported a higher last month's maximum number of alcoholic drinks consumed (p = 0.075). Men with a left 2D:4D <1 had a significantly earlier age of onset of alcohol consumption (p = 0.009). Conclusion: Although the strength of the observed associations is only modest, subjects with a lower 2D:4D digit ratio tend to consume greater amounts of alcohol, and more frequently.