Hand preference in humans is associated with testosterone levels and androgen receptor gene polymorphism

• Published in: Neuropsychologia 2012-07, Vol.50 (8), p.2018-2025
• Main Authors: Hampson, Elizabeth, Sankar, Janani S.
• Format: Article
• Language: English
• Subjects: Adolescent; Anatomical correlates of behavior; Androgen receptor; Behavioral psychophysiology; Biological and medical sciences; Biomarkers; Functional Laterality - genetics; Functional Laterality - physiology; Fundamental and applied biological sciences. Psychology; Genes, X-Linked - genetics; Genotype; Handedness; Hormones and behavior; Humans; Male; Polyglutamine repeat; Polymorphism, Genetic; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Receptors, Androgen - genetics; Receptors, Androgen - physiology; Saliva - chemistry; Testosterone; Testosterone - analysis; Trinucleotide Repeat Expansion; X-linkage; Young Adult
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2012.04.027

Exposure of the central nervous system to androgens during the early developmental period has been proposed to play a role in the establishment of hand preference in males. Existing data, however, are inconclusive. In the present investigation, handedness was assessed in a large sample of left-, mixed-, and right-handed men (N=180) using a standardized handedness inventory. Saliva sampling was used to assay levels of bioavailable testosterone and DNA genotyping was carried out to quantify AR-CAG repeat length, a genetic marker of the capacity of the androgen receptor to respond to testosterone. Strongly left-handed males were found to have lower levels of bioavailable testosterone than right-handed males, while males with mixed handedness exhibited a weaker androgen receptor, but no significant difference from right-handers in circulating testosterone levels. These findings support the view that testosterone could play a role in the development of hand preference in males. Furthermore, because the AR gene lies on the X chromosome, it provides a potential theoretical bridge to genetic theories of handedness that postulate the existence of an X-linked locus important in the establishment of hand preference. ► Studied testosterone levels and androgen receptor genotype in left-, right-, and mixed handers. ► Strongly left-handed men were found to have lower testosterone than right-handed men. ► Weakly left-handed men (‘mixed’ handers) showed DNA evidence of a less active androgen receptor. ► Findings support theories suggesting handedness differences in testosterone exposure. ► Findings may offer a way to unite endocrine and genetic theories of handedness.