Relationships between symptoms of schizophrenia and substance abuse.

Previous work posits that severity of substance abuse and severity of schizophrenic symptoms should be linked by either or both of two mechanisms: self-regulation of symptoms and drug-induced exacerbation of symptoms. Research on these relationships has yielded mixed results. We examined the interrelationships of schizophrenic symptoms and substance abuse in 172 patients with co-occurring disorders. Relationships were weak or nonexistent, without any consistent pattern. Our findings do not support the view that substances are used to self-regulate symptoms. In addition, our results suggest that substance abuse may lead to higher rates of institutionalization through mechanisms other than by exacerbating symptoms.