Don't know about this particular experiment. However, in the book How to Change your Mind, there are a lot of references to recent research of psychedelic therapy to treat addictions and after 1-3 sessions, 50-80% of subjects drop their addictions for good (at the time of the book's writing, they had only been able to follow the patients for up to 1 year). There's also the anecdote of one of the founders of AA, who quit alcohol through psychedelic therapy.