"Research based on internal industry documents shows a concerted effort by the industry to promote belief that schizophrenics need to smoke and that it is dangerous for them to quit. Such promotion includes monitoring or supporting research that endorsed the idea that schizophrenics are uniquely immune to the health consequences of smoking (since proved false) and that tobacco is needed for schizophrenics to self-medicate."
http://en.wikipedia.org/wiki/Schizophrenia_and_smoking#Role_of_tobacco_industry