Researchers find that nicotine affects a brain receptor linked to some schizophrenia symptoms:
"Smoking is a common problem for patients with schizophrenia. The increased tendency of patients diagnosed with this disorder is to not only smoke, but to do so more heavily than the general public. This raises the possibility that nicotine may be acting as a treatment for some symptoms of schizophrenia.
Nicotine acts through two general classes of brain receptors, those with high and low affinity for nicotine. The low affinity class of nicotinic receptors contains the alpha-7 subunit, which is present in reduced numbers in people with schizophrenia."