Some (but not all) cannabinoids may partially (but not fully) and reversibly (but not permanently) reduce some (but not all) symptoms of autism for some (but not all) people with some (but probably not all) autism spectrum conditions.
In response to Bou Khalil R, Would some cannabinoids ameliorate symptoms of autism,
Eur Child Adolesc Psychiatry. 2012 Apr;21(4):237-8. doi: 10.1007/s00787-012-0255-z. Epub 2012 Feb 17.