Dysthymic Disorder is characterized by chronic depression, but with less severity than a major depression. The essential symptom for Dysthymic disorder is an almost daily depressed mood for at least two years, but without the necessary criteria for a major depression. Low energy, sleep or appetite disturbances and low self-esteem are usually part of the clinical picture as well.
People who have Dysthymic disorder will often report that they don't recall ever not feeling depressed, but they may be relatively functional in managing their life, although the symptoms are severe enough to cause distress and interference with important life role responsibilities. It is important to have a complete physical to rule out any physical illnesses that might be causing the depression.
Also, if the person has a chronic medical condition that appears to be the cause for the depression (such as any chronic debilitating condition), then the correct diagnosis might be a Mood Disorder due to a general Medical Condition, even if all the criteria for Dysthymic disorder are met. The question is whether the medical condition is physically causing the depression, rather than creating chronic psychological distress that is causing the depression.
Despite the long term nature of this type of depression, psychotherapy is effective in reducing the symptoms of depression, and assisting the person in managing his/her life better. Some individuals with Dysthymic disorder respond well to antidepressant medication, in addition to psychotherapy, so an evaluation for medication may be appropriate. You should consult your psychologist if you have questions about treatment.