CHRNA4 and schizophrenia: Nicotine, the primary psychoactive chemical in tobacco smoke, is a prototypical nAChR agonist and the increased prevalence of smoking in schizophrenia (∼70–80%) compared to the general population (∼20%) has been interpreted as a form of self-medication (Kumari and Postman, 2005; Winterer, 2010), perhaps to compensate for reduced expression of nAChRs observed in post-mortem hippocampal and cortical brain regions of patients (Breese et al., 2000).