It is unclear, however, how nicotine interacts with positive symptoms, as it would follow from this theory that nicotine would exacerbate excess dopamine in the mesolimbic pathway and thus positive symptoms as well. One theory argues that the beneficial effects of nicotine on negative symptoms outweigh possible exacerbation of positive symptoms. Another theory is based on animal models showing that chronic nicotine use eventually results in a reduction in dopamine, thus alleviating positive symptoms.