Finger length patterns in children with PDD-NOS compared to other psychiatric groups
Objectives: Children with autism have a relatively short index finger (2D) compared to their ring finger (4D). It is often presumed that the 2D:4D ratio is associated with fetal testosterone levels and that high fetal testosterone levels could play a role in the etiology of autism. It is unknown however, whether this effect is specific to autism.
Methods: The 2D:4D ratios of boys, aged 6 - 14 years, with autism/Asperger syndrome (n = 24), PDD-NOS (n = 26), ADHD/ODD (n = 68), anxiety disorders (n = 26), and control boys (n = 96) were compared. Diagnoses were based on DSM-IV criteria and ratios were measured from handscans with vernier calipers.
Results: Boys with autism/Asperger syndrome (M = 0.934, SD = 0.033), PDD-NOS (M = 0.939, SD = 0.037), and ADHD/ODD (M = 0.943, SD = 0.031) had lower ratios than boys with an anxiety disorder (M = 0.964, SD = 0.037), and boys with autism/Asperger syndrome had lower ratios than control boys (M = 0.956, SD = 0.034).
Conclusions: Higher fetal testosterone levels may play a role not only in the origin of autism, but also in the etiology of PDD-NOS, and ADHD/ODD. Boys with anxiety disorders showed relatively high 2D:4D ratios, which suggests that they may have been exposed to lower prenatal testosterone levels.