Schizophrenia, Neurocognitive Dysfunction, and Substance-Related Disorders: A Review | Psychiatric Times

I thought this was a really interesting article and its suggests that both cigarettes and weed---the use of which is high in people with schizophrenia are helpful in ability to think. I think you have to register to get the article but its free and a nice review. Nicotine is itself a cognitive enhancer for pretty much everyone whereas cannabis is typical seen as causing deficits but it's not so straight forward for people with sz.