James Kocsis, a professor in the department of psychiatry at Cornell University, offers this definition:

"Dysthymia has been in the official nomenclature of the American Psychiatric Association since 1980. It refers to chronic depression (persistent for more than two years) of mild to moderate severity. It usually appears in childhood or adolescence, and affects about three percent of the U.S. population. Sufferers are functional but impaired, particularly in social and interpersonal relationships. Antidepressant medications are often quite helpful in treating dysthymia. Older terms for dysthymia have included 'depressive neurosis' and 'depressive personality.' A good reference is Diagnosis and Treatment of Chronic Depression by James H. Kocsis and Daniel N. Klein. Guilford Press,1995."

Steven D. Hollon, a researcher in the psychology department of Vanderbilt University, responds:

"Dysthymia essentially refers to a type of depression that is relatively mild but chronic. When I was in training, we used to think that depressions were either mild and chronic or severe and episodic, but we have since learned that view is probably not accurate. Some people seem to go through life with a mild level of dysphoria (that is, they just never feel all that good), but they are at least as likely as anyone else, if not more likely, to have superimposed episodes of major depression.

"Whether the dysthymia precedes the onset of the first episode of major depression (in which case the process is referred to as 'double depression') or develops only after the onset of the first major episode (in which case it may be referred to as 'partial remission'), it appears to be treatable with drugs or psychotherapy, although the change is usually not as dramatic or as rapid as it is after episodes of major depression alone. Dysthymia is not so much a new disorder as one that is getting more attention than it used to receive."

Daniel N. Klein of the psychology department at the State University of New York at Stony Brook adds some details:

"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.

"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.