Differences in salivary testosterone, digit ratio and empathy between intellectually gifted and control boys

Testosterone was shown to organize brain structure and modulate cognitive functions. Higher prenatal testosterone exposure has been proposed to increase systemizing and to decrease empathizing. Whether intellectually gifted (IQ > 130) individuals differ in these aspects is largely unexplored. The aim of this paper is to compare the prenatal testosterone exposure (reflected by 2D:4D), the actual testosterone levels, and the ability of empathizing and systemizing in gifted boys (N = 66) and control boys of same age (N = 80). The comparison revealed significantly lower salivary testosterone levels (d = − 3.35, t = 2.46, p = 0.02) in gifted group compared to controls. Although the effect size was quite robust, this result did not remain significant after the correcting for multiple testing (new p value calculated after Bonferroni correction was 0.006). Lower left 2D:4D (standing for higher prenatal testosterone level; d = − 1.33, t = 4.96, p < 0.0001) was observed in intellectually gifted boys compared to control boys surviving the correction for multiple testing. No significant difference between groups was found in the number of CAG repeats in gene encoding the androgen receptor (d = − 0.06, t = 0.38, p = ns). Intellectually gifted boys achieved significantly lower score in reading mind in the eye test (d = − 0.75, t = 3.38, p = 0.003) that remained significant after correcting for multiple comparisons. It can be speculated that higher prenatal testosterone reflected by lower 2D:4D organizes the brain of gifted boys in a different way in comparison with controls. Consequences include differences in cognitive functions such as lower ability to mentalize-to understand the mental state of others. The physiological mechanisms of testosterone in intellectually gifted boys, especially at the molecular level remain to be elucidated.