It's also interesting how people try to establish causality for drug use with lack of mental ability.

Drugs are no good for sutpid people - the ones that get most out of them are smart people. For drugs to get the most effect being smart helps a lot.

I find it a big problem with heroin users. Anyone who knows some knows how elaborate schemes they create to acquire drugs. Also talking to addicts when they are sober (high they don't make any sense mostly) knows how complex personalities they are.

Being stupid helps one from acquiring a drug habbit IMHO. While being smart only multiplies ones problems if one manages to get into drug usage.