People diagnosed with Dysthymic Disorder do not experience a full major depressive episode, and therefore cannot be said to have Major Depression. Instead, they experience a less intense, but longer duration (chronic, or long term) depressed mood that occurs for most of the day, more days than not over the course of at least two years (or one year for children and adolescents). Symptom-free periods, during which there are few or no mood symptoms, never last longer than two months.
During periods of depressed mood, at least two of the following symptoms are present: changes in appetite, changes in sleep patterns, low energy or fatigue, low self-esteem, poor concentration or difficulty making decisions, and feelings of hopelessness. In addition, the individual has never experienced a manic episode, a mixed episode, or a hypomanic episode. Mood symptoms must also occur solely during the course of the mood disorder and not as part of some other disorder that may be occurring simultaneously (such as Schizophrenia or Delusional Disorder).
Dysthymic Disorder affects between 3 and 6% of the population each year. Women are twice as likely to be diagnosed with dysthymia as men. Individuals with Dysthymic Disorder often think that they have MDD, which is often their reason for seeking treatment. Although the two disorders are similar (and both are treatable), they are also distinct; with different patterns of onset, duration, and severity.
Simply put, Dysthymia is less severe than Major Depression. People with Dysthymia are able to maintain a higher level of functioning than individuals experiencing a Major Depressive Episode. The difference in severity between the two disorders is something that individual patients can experience subjectively when they consider how they have come to define "normal mood." A Major Depressive Episode is clearly a departure from people's normal mood and behavior. In contrast, Dysthymic individuals will have generally experienced a low-grade "down in the dumps" feeling for so long that they don't remember feeling any other way. For such individuals, the low-level depressed feeling that characterizes Dysthymia is their normal mood.
Approximately 10% of people with Dysthymia will get better without treatment, and 10% will go on to develop Major Depression. The other 80% or so of people with Dysthymia may linger in a Dysthymic condition for years. Fortunately, the same treatments that work to help people suffering with Major Depression are also helpful for patients with Dysthymic Disorder.
Though Dysthymic Disorder and Major Depressive Disorder are separate conditions, they can co-occur simultaneously. When individuals experience both Dysthymia and MDD at the same time, their illness is sometimes referred to as "double depression." We provide more details about double depression towards the end of this document.
Some mental health professionals use the terms Dysthymic Disorder and Neurotic Depression interchangeably. The term "neurotic depression" was initially used to describe any type of depression that did not produce psychotic features such as hallucinations or delusions. Eventually, the term was used to describe milder forms of long-term depression (today's dysthymia). The term neurotic depression is no longer used for purposes of diagnosis.