The high prevalence of tic disorders in males may be related to androgenic steroids during the intrauterine period. During the critical period of fetal development, the release of high levels of gonadal androgens and stress hormones may contribute to the etiology of tic disorders. To investigate the possible association between these hormones and tic disorder, the ratio of two to four digits (2D:4D) was used as a measure of fetal hormone exposure. Eighty children aged 7–17 years, including 40 children diagnosed with tic disorder and 40 healthy controls, were included in a cross‐sectional study. All participants had a psychopathology assessment, and their 2D:4D ratio was measured digitally. The 2D:4D ratio in the left hand was significantly higher in the controls than in the cases ( p = 0.003). Multivariate logistic regression analysis also supported that a low left 2D:4D ratio was independently associated with tic disorder ( p = 0.011). Girls showed a positive correlation between right 2D:4D ratio and vocal tic scores ( r = 0.715, p = 0.013). However, the 2D:4D ratio did not appear to be significantly associated with comorbidities, age at diagnosis, or age at onset of motor tic, vocal tic, or sensory phenomena. The results suggest that fetal sex hormone exposure may play a role in the development of tic disorders. This study showed that children and young people with tic disorders had a different 2D:4D ratio compared to healthy controls. A correlation between the ratio and the severity of the symptoms was also found. These novel findings may provide a solid basis for future longitudinal and mechanistic studies examining prenatal androgen exposure as a contributing factor in the etiology and clinical heterogeneity of tic disorders.
Şahin et al. (Thu,) studied this question.