Nicotinic acetylcholine receptors are thought to be deficient in people with schizophrenia and one of the reasons why people with this condition tend to smoke heavily may be because they are trying to stimulate these receptors. A U.S. study of 31 patients looked at the effects of a substance called DMXB-A which it was thought would have the same effect as nicotine from tobacco but without the health consequences. DMXB-A was found to alleviate anhedonia (the inability to experience pleasure) and alogia (poverty of speech) and to improve vigilance and working memory. But it had little overall effect on cognition and caused mild nausea in nearly all of the participants and mild tremor in five of them.
Freedman, Robert ... [et al] - Initial phase 2 trial of a nicotinic agonist in schizophrenia American Journal of Psychiatry August 2008, 165(8), 1040-1047