2D:4D ratio and its association with examination scores and cognitive abilities in adolescent students - A cross-sectional study

Abstract

Background: 2D:4D ratio or the ratio of lengths of 2nd (index finger) and 4th (ring finger), a proxy marker for prenatal testosterone exposure, is known to be sexually dimorphic with males having lower values. Low digit ratio is associated with certain characteristics such as aggression in males and assertiveness in females. Similarly, high digit ratio in males is associated with increased sperm counts, increased risk for heart disease, obesity and metabolic syndrome, depression, and anxiety. Aims and Objectives: The objectives of the present study were to measure 2D:4D ratios of adolescent students and look for associations between 2D:4D ratios and their Higher Secondary School Board examination scores and their cognitive abilities such as attention, memory, spatial ability, and intelligence. Materials and Methods: The present study was conducted on 70 adolescents of 18-19 years age group pursuing their education in the campus of Saveetha University. The 2D:4D ratio was measured from the midpoint of bottom crease where the finger joins the hand to the tip of the finger using digital Vernier calipers. Selected few domains of cognition were evaluated using the tests for free and placement recall, category fluency tests, and visual N-back tests. Correlation between 2D:4D ratio and Higher Secondary Board examination scores and mean cognition test scores were tested using Pearson’s correlation test. Comparison of test scores between genders and low scorers versus normal scorers was performed using student t-test. Results: The mean 2D:4D ratio of the study population was 0.97 ± 0.034. The mean 2D:4D ratio of males (0.97 ± 0.32) was not significantly different from that of females (0.98 ± 0.035). There was no significant correlation between higher secondary scores and the 2D:4D ratio. Significant relationships with 2D:4D ratios and domains of cognition tested (free and placement recall, category fluency, and working memory) were not observed. Existing literature also revealed many inconsistencies within the pattern of associations between 2D:4D digit ratio and cognitive abilities. Conclusion: The future studies in a larger population with more and different tests for assessment of cognition would help us in ascertaining the role of 2D:4D ratio as a proxy marker for prenatal androgen exposure.