RESUMEN
Although mood disorders represent a frequent psychiatric comorbidity among patients with epilepsy, data regarding bipolar disorders are still limited. However, these two conditions apparently share a number of biochemical and pathophysiological underpinnings, such as the kindling phenomenon, changes in neurotransmitters and modifications in voltage-opened ion channels and second messenger systems. Moreover, epilepsy and bipolar disorders are both episodic conditions with a time course of illness that can become chronic. Recent data suggest that mood instability is actually frequent among patients with epilepsy but is phenomenologically different from that described in bipolar disorder. The present paper reviews available evidence regarding such an intriguing comorbidity in order to discuss valuable clinical issues and to suggest novel therapeutic strategies.