Associations between digit ratio (2D4D), mood, and autonomic stress response in healthy men

The ratio between the length of the second (index) and the fourth (ring) finger (2D4D) is a putative biomarker of prenatal testosterone (T) exposure, with higher exposure leading to a smaller ratio. 2D4D has further been linked to mental and somatic disorders. Healthy male Swiss recruits (N = 245; M_age = 20.30 years) underwent a psychosocial stress test. Mood and salivary alpha-amylase (sAA) were assessed before and after the stress test, while heart rate (HR) and heart rate variability (HRV) were measured continuously. Additionally, 2D4D (right: R2D4D; left: L2D4D) was determined and divided into quartile groups. Correlation analysis showed no associations between R/L2D4D and outcome measures. Comparing calculated quartiles for R2D4D, subjects in the lowest R2D4D quartile expressed trendwise (p < 0.10) lower positive and higher negative affect, significantly elevated sAA activity (p < 0.05), but no HR and HRV differences at baseline as compared to subjects in the upper three quartiles. With regard to acute stress, subjects in the lowest as compared to subjects in the upper three R2D4D quartiles showed a higher increase of negative affect and a stronger cardiac response (p < 0.05), but no alterations in positive affect and sAA activity. Young healthy men in the lowest R2D4D quartile revealed a more negative affect and increased physiological activity at baseline and in response to acute stress. An exposure to high levels of prenatal T might constitute a risk factor potentially increasing vulnerability to stress-related disorders in men.

No relationship between prenatal androgen exposure and autistic traits: convergent evidence from studies of children with congenital adrenal hyperplasia and of amniotic testosterone concentrations in typically developing children

BACKGROUND

There is a marked male preponderance in autism spectrum conditions. The extreme male brain theory and the fetal androgen theory of autism suggest that elevated prenatal testosterone exposure is a key contributor to autistic traits. The current paper reports findings from two separate studies that test this hypothesis.

METHODS

A parent-report questionnaire, the Childhood Autism Spectrum Test (CAST), was employed to measure autistic traits in both studies. The first study examined autistic traits in young children with congenital adrenal hyperplasia (CAH), a condition causing unusually high concentrations of testosterone prenatally in girls. Eighty one children with CAH (43 girls) and 72 unaffected relatives (41 girls), aged 4-11 years, were assessed. The second study examined autistic traits in relation to amniotic testosterone in 92 typically developing children (48 girls), aged 3-5 years.

RESULTS

Findings from neither study supported the association between prenatal androgen (testosterone) exposure and autistic traits. Specifically, young girls with and without CAH did not differ significantly in CAST scores and amniotic testosterone concentrations were not significantly associated with CAST scores in boys, girls, or the whole sample.

CONCLUSIONS

These studies do not support a relationship between prenatal testosterone exposure and autistic traits. These findings augment prior research suggesting no consistent relationship between early androgen exposure and autistic traits.