Is there sexual dimorphism of hyperserotonemia in autism spectrum disorder?

The female groups were very small: 23 pre-pubertal girls and 14 post-pubertal girls, so comparisons between boys and girls had limited power. There was no typically developing comparison group, so high serotonin was defined from published norms rather than controls measured at the same time. Some participants were classified as pre- or post-pubertal by age rather than Tanner staging, which can misclassify puberty. Participants taking medications that affect serotonin were excluded, which may have removed people with high serotonin from the post-pubertal group. The male serotonin distribution was not normal, but it did not show two clear groups, so a separate high-serotonin subgroup could not be identified within the sample. The study did not test a treatment, so it cannot show a cause of autism or a treatment target.

Do not read the pre-pubertal sex difference as evidence that serotonin causes autism or that treatment should target serotonin. The study had no control group, few girls, and did not test a serotonin treatment.