Given the severe public health consequences of the comorbidity of schizophrenia with nicotine dependence, understanding the etiology of this comorbidity is clinically important. Currently, schizophrenia is diagnosed and treated independently of nicotine dependence. Prognostically, there is already evidence that schizophrenia with comorbid nicotine dependence is more severe and has worse outcomes than schizophrenia without comorbid nicotine dependence (Gage et al., 2014; Sorensen et al., 2011; Tsoi et al., 2013; Zammit et al., 2003).
