Several models have been proposed to explain the high rate of comorbidity between SUDs and SMIs. These include family history, ASPD, and the super-sensitivity model. The self-medication model states that specific substances are used to alleviate certain painful affects, but it is not empirically supported. The "alleviation of dysphoria" model is empirically supported, and states that people with SMIs are prone to dysphoric states that predispose them to drug use, which results in them becoming addicted to drugs.