"Dysthymia is a relatively recently defined category, introduced in DSM-III (the third edition of the Diagnostic and Statistical Manual of Mental Disorders, a standard psychological reference) in 1980, to refer to chronic depressions of mild-moderate severity. Although the term is new, dysthymia is based on several older clinical concepts, such as neurotic depression, depressive personality and chronic depression. It is more common among females than among males and can begin at any age, although onsets in childhood and adolescence are particularly common, especially among patients seeking treatment.
"As is true for most psychiatric disorders, knowledge of the causes and origins of dysthymia remains incomplete. We do know that it runs in families, although it is unclear whether this linkage is due to genetic or environmental factors, or both. Dysthymia seems to be closely related to major depression, which is the more severe and episodic form of depression. In other words, most people who have dysthymia do experience exacerbations that meet the criteria for major depression at some point in their lives, and there is a high rate of occurrence of major depression in the families of people with dysthymia. . Individuals with this type of depression are typically overconscientious employees but remain underachievers or maintain unfulfilling social lives. Depression is biochemical and psychological in nature. An imbalance of neurotransmitters, particularly serotonin, can be inherited. Depression can be triggered by emotional turmoil or high-stress periods. Accumulated stress can cause the brain biochemistry to be thrown out of balance in individuals biochemically predisposed to depression.
Coping with stress can reduce the amount of cortisol and adrenaline production and can give a person more energy to used toward healthy behavior, such as exercise.
Cognitive behavior therapy and interpersonal psychotherapy are short-term therapies that work well in cases of mild depression. "In terms of treatment, there is considerable evidence that dysthymia responds to all the major classes of antidepressant medications, although it may take a somewhat longer time to get a positive response than does major depression. There is also suggestive evidence that dysthymia responds to some of the focused, short-term psychotherapies that have been developed for major depression, such as cognitive therapy and interpersonal therapy. There have not been enough studies on psychotherapy treatment of dysthymia to draw any definitive conclusions at this point, however."