Depression and nicotine: preclinical and clinical evidence for common mechanisms.

Updated findings on the relationship between nicotine and depression are presented. Clinical and preclinical research on nicotine use and depression suggests that nicotine may have some properties in common with antidepressants. Updated findings involve the comorbidity of smoking and major depressive disorder (MDD), the influence of depression during withdrawal on failure to quit smoking, the course of MDD without nicotine and the neurobiology of smoking and depression.