Mood disorders in epilepsy - diagnostic and methodological considerations.

BACKGROUND Mood disorders are common in people with epilepsy (PWE) with prevalence rates ranging from 11% to 62%. The variation in epidemiological data results probably from the diversity of methodologies employed and selection of the populations across the studies. Moreover, the symptomathology of mood disorders in epilepsy is often atypical, intermittent and pleomorphic and fails to meet DSM-IV-TR categories. Several studies suggested the existence of distinct interictal dysphoric disorder (IDD) in patients with epilepsy. The majority of research studies in mood disorders in epilepsy were based on screening instruments in the diagnosis of mood disorders in PWE. However, the results in validity and reliability in detecting major depression in epilepsy using self-report inventories of mood symptoms is vague. The aim of this study was to review studies on mood disorders in epilepsy with particular focus on diagnostic methods. SUBJECTS AND METHODS The focus of this Review was on patient studies on mood disorders in epilepsy (2000-2012). We searched PubMed using the following search terms (effective date: 20th May 2012): (epilepsy (Title/Abstract) OR seizure (Title/Abstract)) AND depression (Title/Abstract) OR Dysthymia OR mania OR bipolar disorder OR affective disorder OR Interictal Dysphoric Disorder OR AND (humans (MeSH Terms) AND English (lang) AND (2000/01/01(PDAT): 2012/04/31(PDAT)). RESULTS Depression is the most frequent comorbid psychiatric disorder in epilepsy. Recent studies pointed out that bipolar disorders are not rare in epilepsy. Most of the research in PWE did not rely on standardized psychiatric measures and only about 18% of studies were based on diagnostic psychiatric interviews (mainly MINI and SCID-I). Mood disorders in epilepsy excluding the ictal or periictal symptoms can be categorized using standardized measures. CONCLUSIONS Common self-report depression measures may be used to screen for depression in clinical settings. The use of screening instruments in epilepsy must be followed by structured psychiatric interviews designed to establish a DSM-IV-TR diagnoses. Standardized psychiatric interview procedures based on DSM criteria like SCID-I or MINI provide a comprehensive way to diagnose mood disorders in patients with epilepsy.