Prenatal testosterone (2D: 4D Ratio) and its association with learning and memory in medical undergraduates – A cross-sectional study

Abstract

The 2D:4D ratio is a sexually dimorphic trait, negatively related to prenatal testosterone which in turn influences the areas in brain, critical for learning and memory. The objective of the present study was to compare the 2D:4D ratios between sexes, right / left hands and correlate with mean scores of learning and memory. The cross-sectional study was conducted in 116 participants (80 males and 36 females) of 18 -19 years of age. Lengths of index and ring fingers were measured using vernier calipers to calculate 2D:4D ratios. Free & Placement recall and Working visual memory (Visual N Back test) were assessed. Verbal learning ability was assessed using Rey’s Auditory Verbal Learning Test (AVLT). Mean 2D:4D ratios of right hand (0.96±0.051) were significantly lower than left hand (0.98±0.1; p = 0.036). Females had higher ratios than males in both hands. In Free recall (FR) and Placement Recall (PR) tests, average hits and errors scores of females and males were comparable. In Visual N Back test, there were statistically significant correlations between 2D:4D ratios and mean hits & errors scores (M >F). The mean hits score in AVLT was lower in males (13.9±1.4) when compared to females (14.2±1.0). The findings of the present study can help us to associate a simple measure like 2D:4D ratio to learning abilities of an individual. Also, 2D:4D ratio, a non invasive measure can be used to evaluate one’s cognitive abilities with regard to memory and learning.