Link to the study please.
As I said, it’s anecdotal evidence, not formal.
Gathered by observing the incidence of self-reported autism in conversations that take place on substance abuse recovery forums.
Also, I know a former Federal juvenile probation officer who indicated a belief among her peers that such a link exists.
Probably tough to get funding for such a study from a system that has a vested interest in creating a greater requirement for the services of that system - as opposed to enhancing the perception of individual, parental, responsibility.
FWIW, I think the special-needs parents here on this forum are exceptional in that they have taken personal responsibility for the welfare of their children. Many non-special-needs parents would do well to follow their example.