Past recreational abuse of meds

I recently started to suspect that my 31-year-old husband of 2 years has undiagnosed ADHD. I've brought it up to him a couple of times and suggested that he get evaluated. He revealed that as a teenager, he abused Adderall that was not prescribed to him (I assume he got it from friends), using it for "partying". He said it did help him concentrate but he is afraid that if he is prescribed medication now, he will be unable to resist abusing it again, as in not being able to control himself from taking too much. He has had problems in the past with alcohol and drug abuse (including cocaine), and I think he still has some dependency issues with alcohol and marijuana -- it's not out of control, but I think he drinks and smokes more than is healthy. Anyway, I'm just wondering if others have had any experience with this sort of issue and can offer any insight. Can recreational use of ADHD meds be an indication that the disorder is indeed present? Have others had issues themselves or with spouses abusing their prescribed medications once they are diagnosed?