While autism can be diagnosed reliably by 2 years of age, some people with autism don’t receive a formal diagnosis until much later.  Why not?  Racial and ethnic disparities as well as access to care issues are known factors.  This week, data from Denmark suggested that the diagnostic criteria has played a large role in prevalence in people with autism since 1980.  Many people who have autism may have been missed until they were older.  It suggests that older prevalence estimates were missing a proportion of autistic adolescents and adults.  Take away access and diagnostic barriers to a diagnosis, some kids followed from months of age in the baby siblings research consortium don’t receive a diagnosis at age 2, but do at age 5.  They always had autism, but their symptoms were sub-threshold for a formal diagnosis until age 5.

 

https://www.ncbi.nlm.nih.gov/pubmed/30398592 

https://www.ncbi.nlm.nih.gov/pubmed/30392626