model has recently surfaced in the literature regarding the HPA axis (structures in the brain that get activated in response to stress) and its involvement with dysthymia (e.g. phenotypic variations of corticotropin releasing hormone (CRH) and arginine vasopressin (AVP), and down-regulation of adrenal functioning) as well as forebrain serotonergic mechanisms. Since this model is highly provisional, further research is still needed. Diagnosis The Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV), published by the American Psychiatric Association, characterizes dysthymic disorder. The essential symptom involves the individual feeling depressed for the majority of days, and parts of the day, for at least two years. Low energy, disturbances in sleep or in appetite, and low self-esteem typically contribute to the clinical picture as well. Those with the condition have often experienced dysthymia for many years before it is diagnosed. People around them often describe them in words similar to "just a moody person". The following are the diagnostic criteria: During a majority of days for two years or more, the adult patient reports depressed mood, or appears depressed to others for most of the day. When depressed, the patient has two or more of: decreased or increased appetite; decreased or increased sleep (insomnia or hypersomnia); fatigue or low energy; reduced self-esteem; decreased concentration or problems making decisions; feelings of hopelessness or pessimism. During this two-year period, the above symptoms are never absent longer than two consecutive months. During the duration of the two-year period, the patient may have had a perpetual major depressive episode. The patient has not had any manic, hypomanic, or mixed episodes. The patient has never fulfilled criteria for cyclothymic disorder. The depression does not exist only as part of a chronic psychosis (such as schizophrenia or delusional disorder). The symptoms are often not directly caused by a medical illness or by substances, including substance use or other medications. The symptoms may cause significant problems or distress in social, work, academic, or other major areas of life functioning. In children and adolescents, mood can be irritable, and duration must be at least one year, in contrast to two years needed for diagnosis in adults. Early onset (diagnosis before age 21) is associated with more frequent relapses, psychiatric hospitalizations, and more co-occurring conditions. For younger adults with dysthymia, there is a higher co-occurrence in personality abnormalities and the symptoms are likely chronic. However, in older adults with dysthymia, the