Medline Medical Dictionary gives this definition
Main Entry: mood disorder
: any of several psychological disorders characterized by abnormalities of emotional state and including especially major depressive disorder, dysthymia, and bipolar disorder -- called also affective disorder
Unipolar Depression and its variants including:
Seasonal Affective Disorder (SAD)
Dysthmia and Cyclothymia
Generalised Anxiety Disorder
Phobias including Agoraphobia
Obsessive Compulsive Disorder (OCD)
Post-traumatic Stress Disorder (PTSD)
There are several types of mood disorders: major depression, bipolar disorder (also known as manic depression), dysthymia, and cyclothymia.
Symptoms of major depression include feelings of sadness, loss of interest in normally pleasurable activities (anhedonia), changes in appetite and sleep, loss of energy, and problems with concentration and decision-making. Episodes of dysthymia resemble depression but are milder and often last longer.
Bipolar disorder is characterized by alternating cycles of depression and mania. Symptoms of mania include elevated or expansive mood, inflated sense of self-esteem or self-importance, decreased need for sleep, racing thoughts, and impulsive behaviour. Episodes of hypomania are typically shorter in length and less severe than mania. Cyclothymia is marked by cycles of low-level depression and hypomania.
Women are twice as likely as men to experience major depression, while bipolar disorder occurs equally in women and men. Although the onset of these disorders can occur at any age, many individuals experience their first episode between the ages of 25 and 44.
It is important that mood disorders be accurately diagnosed and treated. Affective disorders can take an enormous toll on people’s ability to work, their relationships and family life. However, the proper treatment can not only help improve symptoms of these disorders, it can return people to a better quality of life.