Marijuana and tobacco exposure predict affect-regulation expectancies in dual users.

In order to better compare affect-related expectancies for tobacco and marijuana smoking, associations of marijuana and tobacco exposure to negative affect reduction (NAR), positive affect enhancement (PAE), and related smoking outcome expectancies were assessed in young individuals who reported smoking both marijuana and tobacco on a regular basis (dual users). More frequent smoking of a given substance was associated with expectations of greater NAR and PAE by that substance while duration of exposure did not reliably predict NAR or PAE drug expectancies. Contrary to expectations, individuals anticipating greater NAR and/or PAE for one substance did not exhibit corresponding expectancies for the other drug. These findings suggest that exposure duration may be less important than current usage levels in influencing affect expectancies and that the affect-related expectancies for tobacco and marijuana are largely independent of each other.