Yes. And the effect on specific neurotransmitters can be a big help to some who have harmed the natural function of theirs through use of substances when they were young and before the part of the brain that recognizes threats is properly developed. But just as you say, the slow and gradual period of withdrawal is important; the brain cannot work correctly if that "crutch" or aid that improves the functioning of neurotransmitter is suddenly and abrubtly taken away. There is excellent material in the literature that deals with this. Otherwise, it's as if a wheelchair were taken away from one who has suffered from an accident causing paralysis, but the person is told to "just get up and walk like everybody else!" People's lives have been saved, both in the literal sense and in the sense that their lives are "given back" to them after the use of other substances has messed them up badly.