A comparison study of autism spectrum disorder referrals 1997 and 1989.

Baker (2002) compared every autism referral in one Australian region in 1997 with those from 1989.

The team counted the kids, noted age, sex, and how severe the autism seemed.

Same clinic, same catchment area, just eight years apart.

Referrals doubled. Kids came in at older ages. More girls showed up.

Many of the new cases were mild—what we now call Asperger or PDD-NOS.

The boy-to-girl gap shrank from 6-to-1 to 4-to-1.

May et al. (2018) later tracked the same region with Medicare files. They show the gender gap kept closing through 2016, proving the trend did not stop.

Gal et al. (2012) saw a three-fold rise in Israeli registry data across similar years. The upward curve looks the same on two continents.

Fullana et al. (2007) in South Wales found classic autism rates flat while Asperger diagnoses rose. This matches C’s note that milder cases drove the boom.

Rutherford et al. (2016) add why girls were missed: they are referred later than boys even when symptoms are present. Later referral explains the slow narrowing of the ratio.

Rising numbers do not always mean more autism genes. They can mean better radar.

When you screen, remember girls and older kids were once invisible. Add sex-aware questions and widen your age net. Expect more “mild” profiles who still need help with social skills and anxiety.