Individuals suffering from drug addiction may also manifest features of bipolar spectrum disorders. Hyperthymic and cyclothymic temperaments may render individuals vulnerable to later development of substance abuse. Bipolar disorders themselves may be altered or precipitated by substance use, most notably by stimulants (amphetamines), alcohol, and cannabinoids.The clinical usefulness of mood stabilizers, particularly antiepileptics, has been established as safe and effective in substance abusers with and without comorbid mood disorders. Most studies on this issue have been of short duration and focused on the resolution of a currently manifest period of illness. Few studies have been conducted on the usefulness of these drugs on the long-term longitudinal course of these diseases, such as frequently encountered recurrent relapses into states of agitation, impulsivity, and/or dissatisfaction. As opposed to the clinical experience with traditional antidepressants and neuroleptics, antiepileptics do not induce counter-polar states (depressed patients abruptly turning manic or hypomanic; nor patients currently hypomanic or manic turning abruptly depressed). Many clinicians consider antiepileptic mood stabilizers to be the preferred category of medications for the treatment of such patients. Valproate appears to be a potentially fruitful medication to study in these dual diagnosis patients due to preliminary evidence demonstrating its anticraving efficacy.