Dysthymia is less acute and severe than major depressive disorder. The cause of bipolar disorders overlaps with major depressive disorder. Fibromyalgia is often associated with anxiety and depressive symptoms. Tweedy attributes this to comorbidity with major depressive disorder and severe panic attacks. The onset of a manic or depressive episode is often foreshadowed by sleep disturbances. Vortioxetine is used as a treatment for major depressive disorder. MK-869 (aprepitant) in patients with major depressive disorder. Desvenlafaxine is primarily used as a treatment for major depressive disorder. Other disorders need to be ruled out before diagnosing major depressive disorder. The cause of major depressive disorder is unknown. Lithium is the classic mood stabilizer to prevent further manic and depressive episodes. The prevalence of increased suicidality persisted after adjusting for depressive illness and alcohol abuse. Anhedonia occurs in roughly 70% of people with a major depressive disorder. Bonet claims that this corresponds to major depressive disorder. Amitriptyline is used for a number of medical conditions including major depressive disorder (MDD).