Depression Disorder

Depression disorder is likely a loose reference to “depressive disorders,” the first of the major subcategories of mood disorders in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) published by the American Psychiatric Association (APA) and several categories of Mood (affective) Disorders in the International Classification of Diseases (ICD-10) published by the World Health Organization (WHO).

What Is a Disorder?

Although some people use the terms interchangeably, a disorder and a disease differ. A disease is a “pathological process,” with characteristic problems for the patient (called symptoms) and physical changes (called signs). Note that signs is also used colloquially to refer to any indicators of something, including symptoms. This is the use of signs made in the article “Signs of Depression” because that is believed that “indicators of any sort” is what most people mean when they search for “signs of depression. But, in point of fact, a disorder is an episode or period of abnormal or disturbed function, which is to say that characteristic physical signs are absent.

The lack of characteristic symptoms and signs is one of the key elements that makes depressive disorder and other mental disorders difficult both to diagnose and to treat. It is also a key reason why the definitions differ in different standard publications and why those definitions may be revised over time: more is still being learned as research on disorders continues.

What Are Disorders that Involve Depression?

            Depression by Itself

Whichever system one looks at (DSM-IV or ICD) for classifying mental disorders, one finds depressive disorder occurring both by itself and in combination with other disorders. When it occurs by itself, a depressive disorder may be mild, moderate or severe, and occur as a discrete episode, recurring episodes, or as a chronic condition, lasting for years. The symptoms can range from a mild, but pervasive, feeling of sadness and pessimism, to such deep despair that the depressed person contemplates or attempts suicide.

The standard medical names for these types of depression are as follows. Episodic depression that can become the most severe, whether a single episode or recurrent episodes is called “major depressive disorder” in the DSM-IV and either “depressive episode” or “recurrent depressive disorder,” as appropriate in the ICD-10. Chronic depression that is characterized as being less severe is called “dysthymic disorder” in the DSM-IV and “dysthymia” in the ICD-10.

            Depression with Mania

Disorders with the word bipolar in their name mark another common type of depression disorder. In bipolar disorders, the sadness, withdrawal, and debilitation of depression is contrasted with periods of mania that may be more or less severe (less severe ones may be called “hypomania”), in which the person feels exuberant, self-confident, and creative.

Formerly called “manic depression,” the standard medical names for these types of depression disorders are now as follows. The DSM-IV refers to Bipolar Disorder I (which is characterized by at least one manic or mixed episode) or Bipolar Disorder II (in which there are hypomanic episodes, but no manic episodes). The ICD-10 calls the disorder “bipolar affective disorder” and does not distinguish between manic and hypomanic episodes. It does, however, distinguish with how severe the depression is. Both standards recognize a chronic version, called “cyclothymic disorder” in DSM-IV and “cyclothymia” in ICD-10, which - like the chronic version of depression - is less severe.

            Depression and Psychosis

 Both the DSM-IV and ICD-10 distinguish between depression alone and bipolar depression that occur with and without psychotic symptoms. Psychotic symptoms are primarily hallucinations (experiencing things that are not real or not present) and delusions (believing things that are not true). The DSM-IV refers to the depressive disorders as occurring “with psychotic features.” The ICD-10 language is “with psychotic symptoms.”

            Depression and Other Mental Disorders

In addition to allowing for depressions that are “not otherwise specified” (or NOS - DSM-IV wording) or “unspecified (ICD-10 wording), both standards specifically refer to depression linked with other mental disorders. This is the section of the categorization of depression that is most different.

While both link depression and dementia, the other connections are unique. The DSM-IV lists the following:

  • Adjustment disorder with depressed mood
  • Adjustment disorder with mixed anxiety and depressed mood
  • Early onset Alzheimer’s dementia with depressed mood
  • Late onset Alzheimer’s dementia with depressed mood
  • Vascular dementia with depressed mood

The ICD-10 lists these disorders:

  • Depressive conduct disorder
  • Mixed anxiety and depressive disorder
  • Post-schizophrenic depression
  • Psychogenic depressive psychosis
  • Psychotic depression
  • Reactive depressive psychosis
  • Schizoaffective disorder, depressive type
  • Unspecified senile depressed dementia


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