CHRNA4 and schizophrenia: A variety of hypotheses have been presented to explain this phenomenon including volitional (i.e., self-medication) attempts to overcome certain schizophrenia symptoms such as depression, anxiety, and anhedonia (see [69] for review), nAChR deficit-related impairments of information processing, psychomotor speed, and cognition [1, 53] as well as to reduce antipsychotic-related side effects.