I was reading this web comic on the history of LSD and how in the 50’s and 60’s it was used to treat a variety mental health problems including this:
A quick Google found this page LSD Studies With Autistic Children (though most relate to schizophrenia) and also this study: Flashback to the 1960s: LSD in the treatment of autism.
Between 1959 and 1974, several groups of researchers issued reports on the use of d-Lysergic Acid Diethylamide (LSD) in the treatment of children with autism. This paper reviews that literature to consider how the authors justified these studies, as well as their methods, results, and conclusions. The justification for using LSD was often based on the default logic that other treatment efforts had failed. Several positive outcomes were reported with the use of LSD, but most of these studies lacked proper experimental controls and presented largely narrative/descriptive data. Today there is renewed interest in the use of psychedelic drugs for therapeutic purposes. While this resurgence of research has not yet included children with autism, this review of the LSD studies from the 1960s and 1970s offers important lessons for future efforts to evaluate new or controversial treatments for children with autism.