There have been numerous studies that nicotine helps give relief to people who suffer from psychotic mental illness. The research started after there were findings that a very, very high percentage of people with psychotic illnesses smoke cigarettes. Also that the worse the psychosis, generally the more cigarettes per day would be consumed. And it did turn out eventually that nicotine somehow helps. It is also a hot topic in regards to humane treatment / human rights, like as far as denying people with schizophrenia the right to smoke cigs when they are in treatment facilities.