Current theory focuses on the role of dopamine in schizophrenia, particularly how negative symptoms such as social withdrawal and apathy may be caused by a deficiency of dopamine in the prefrontal cortex while positive symptoms such as delusions and hallucinations may be caused by excess dopamine in the mesolimbic pathway. Nicotine increases release of dopamine, so it is hypothesized that smoking helps correct dopamine deficiency in the prefrontal cortex and thus relieve negative symptoms.[2][3]