Mood disorders are among the most common diagnoses in psychiatry. Mood is a persistent emotional state. A mood disorder, is a condition characterized by distorted, excessive or inappropriate moods or emotions. Unlike normal fluctuations in mood, the extremes of a mood disorder can be debilitating.
There are three major categories of mood disorders: unipolar mood disorders (major depressive disorder, dysthymic disorder), bipolar mood disorders (bipolar I disorder, bipolar II disorder, and cyclothymic disorder), and mood disorders having a known etiology (substance-induced mood disorder and mood disorder due to a general medical condition)
Classified as a mental illness, mood disorders, go beyond the normal fluctuations in mood which are associated with tiredness, hunger, physical illness, stress or hormonal fluctuations. Mood disorders can have a significant negative impact upon all areas of life because of the fluctuations, which can be extreme, rapid or long-lasting, and lead to little or too much sleep, excessive or inadequate energy and changes in weight or sexual activity.
The prevalence varies from 4-6% worldwide. In the Global Burden of Disease Study conducted by the World Health Organization, unipolar major depression ranked fourth among all diseases in terms of disability-adjusted life years and was projected to rank second by year 2020. In the United States, lost productivity directly related to depression has been estimated at $44 billion per year.
Subtypes of Mood Disorders
Two of the most common mood disorders are Major Depression and Bipolar Affective Disorder, also known as Manic-Depressive illness.