Testosterone and Estradiol in Right-Handed men But Only Estradiol in Right-Handed Women is Inversely Correlated with the Degree of Right-Hand Preference

Abstract

Relations of sex hormones to the degree of right-hand preference was studied in right-handed male and female adult subjects. Hand preference was assessed by the Edinburgh and Waterloo Handedness Questionnaires. Males consisted of weakly, moderately, and strongly right-handed subjects. Females comprised only moderately and strongly right-handed subjects. In females, only serum estradiol was found to be negatively linearly and significantly correlated with the degree of right-hand preference. In males, testosterone, as well as estradiol. showed a significant negative linear correlation with the degree of right-hand preference. Sex hormone binding globulin also showed a similar relation to hand preference in males. Thus, nearly all sex hormones caused a decrease in the degree of right-hand preference in males, whereas only estradiol had the same effect on hand preference in females. This would be the cause of stronger right-hand preference in females than males and vice versa.

Key Words:

• Handedness
• hand preference
• testosterone
• estradiol
• cerebral lateralization