Substance abuse and ASPD have a remarkable amount of similarities in appearance in general, but marijuana itself doesn't have any aspects of addiction beyond an emotional attachment at most. It doesn't help that ASPD in itself can pave the way towards becoming an addict, making it harder to distinguish which may have came from which.
Kind of hilarious that they found a way to explain that weed will cause it through another means.
Edit: Second source.
"
Brain scans showed that chronic use of marijuana, smoking it 3 times a day on average, decreases the grey matter volume in orbitofrontal cortex, the part involved in decision making and mental processing, if damaged it can underpin psychopathy and personality disorders. Marijuana users also showed increased white matter which may be due to compensation for declined grey matter volume.
To learn more details about this study, click here."
http://www.newhealthadvisor.com/Smoking-Weed-Every-Day.html
Well here you have it kids, I am on my way to become a reckless manipulative alpha bastard!
Withhold the drugs until de-toxed? Another thing might be to notice just how widely their ASPD traits apply in broader circumstances. Is the dependent user only exhibiting ASPD traits related to the drug (as in the anxiety of continuing to get his fix)? If the person has ASPD prior to drug use (or in spite of it), then there may be more circumstances where they exhibit ASPD traits.
It really would require extended observation, perhaps brain scan, etc. etc. in order to uncouple the two from one another (drug use and ASPD).