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, 6 (4), e19332

Low Digit Ratio 2D:4D in Alcohol Dependent Patients


Low Digit Ratio 2D:4D in Alcohol Dependent Patients

Johannes Kornhuber et al. PLoS One.


The ratio of the lengths of the second and fourth finger (2D∶4D) has been described as reflecting the degree of prenatal androgen exposure in humans. 2D∶4D is smaller for males than females and is associated with traits such as left-handedness, physical aggression, attention-deficit-hyperactivity disorder and a genetic polymorphism of the androgen receptor. All of these traits are known to be correlated to the vulnerability for alcohol dependency. We therefore hypothesized low 2D∶4D in patients with alcohol dependency. In the present study on 131 patients suffering from alcohol dependency and 185 healthy volunteers, we found that alcohol dependent patients had smaller 2D∶4D ratios compared to controls with preserved sexual dimorphism but with reduced right-left differences. The detection of alcohol dependency based on 2D∶4D ratios was most accurate using the right hand of males (ROC-analysis: AUC 0.725, sensitivity 0.667, specificity 0.723). These findings provide novel insights into the role of prenatal androgen exposure in the development of alcohol dependency and for the use of 2D∶4D as a possible trait marker in identifying patients with alcohol dependency.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.


Figure 1
Figure 1. Interaction line plots.
A 2 (diagnosis)×2 (sex)×2 (hand) factorial ANCOVA with repeated measurement on the factor hand with age as a covariate shows a reduced 2D∶4D ratio in alcohol dependent patients with preserved sexual dimorphism and reduced right-left difference.

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