My son’s is caused by a malformation of his brain. Cortical dysplacia.
The school systems of today aren’t set up to deal with kids born with disabilities. The Polio epdemic of the 1950’s brought about such schools. Liberals mainstreaming starting in the late 1980’s moving kids that needed help into regular schools where teachers were not really trained or gifted to deal with it. The special education schools really worked and made a huge difference.