ADD result of drug use during adolescence?

Is there any evidence of this?

My husband has recently been diagnosed with ADD at age 42. No family history that I can see (in fact, everyone is a high achiever, professional, successful.)

My husband is very smart, well educated. He was a heavy pot smoker at a young age (12 or 13 to about 18.) He no longer smokes pot but does have some issues with alcohol.