Interictal dysphoric disorder (IDD) is a mood disorder sometimes found in patients with epilepsy, at a prevalence rate of approximately 17%.[1] The most common symptom of IDD is intermittent dysphoric mood in between seizures. Interictal dysphoric disorder can often be treated with a combination of antidepressant and anticonvulsant medication.[2] Its existence as a diagnostic entity is not totally established, and IDD is not included in the DSM-5.
Emil Kraepelin in 1923 first outlined a set of symptoms common in people with chronic epilepsy, the most prominent of which is intermittent depressive episodes.[3] These mood changes occur without any external triggers, during the interictal phase (between seizures). In 1949, Bleuler note a similar syndrome and in 1955, Gastaut confirmed both these observations.[4]
Later, Blumer coined the term interictal dysphoric disorder to describe a similar pleomorphic presentation of symptoms exhibited by his patients.[5] Blumer and Altshuler outlined eight affective-somatoform symptoms that characterize IDD: depressive moods, irritability, anergia, insomnia, pains, phobic fears, and euphoric moods.[6] The diagnosis of IDD should be made when at least three of the seven symptoms are present.[7]