Atypical depression

Overview
Atypical Depression (AD) is a subtype of Dysthymia and Major Depression characterized by mood reactivity — being able to experience improved mood in response to positive events. In contrast, sufferers of "melancholic" depression generally cannot experience positive moods, even when good things happen. Additionally, atypical depression is characterized by reversed vegetative symptoms, namely over-eating and over-sleeping.

Despite its name, "atypical" depression is actually the most common subtype of depression — up to 40% of the depressed population may be classified as having atypical depression.

Diagnostic criteria (DSM-IV-TR)
The DSM-IV-TR, a widely used manual for diagnosing mental disorders, defines Atypical Depression as a subtype of depression or dysthymia, characterized by Atypical Features:


 * A. Mood reactivity (i.e., mood brightens in response to actual or potential positive events)
 * B. At least two of the following:
 * Significant weight gain or increase in appetite ("comfort eating")
 * Hypersomnia (sleeping too much, as opposed to the insomnia present in melancholic depression)
 * Leaden paralysis (i.e., heavy, leaden feelings in arms or legs)
 * long-standing pattern of interpersonal rejection sensitivity (not limited to episodes of mood disturbance) that results in significant social or occupational impairment
 * C. Criteria are not met for Melancholic Depression or Catatonic Depression during the same episode.

By the ICD-10 classification, it will fall in the category of F32 or F39.

Research
In general, atypical depression tends to cause greater functional impairment than other forms of depression. Atypical depression is a chronic syndrome that tends to begin earlier in life than other forms of depression — usually beginning in teenage years. Similarly, patients with atypical depression are more likely to suffer from other psychiatric syndromes such as panic disorder, social phobia, avoidant personality disorder, or body dysmorphic disorder. Atypical depression is more common in females — nearly 70% of the atypical population are women.

Medication response differs between chronic atypical depression and acute melancholic depression. While some studies suggest that an older class of drugs, MAOIs, may be more effective at treating atypical depression, the modern SSRIs are usually quite effective, while the tricyclic antidepressants are not. In addition, SSRI response can often be enhanced with "booster" medications. And, medication treatment works best when combined with appropriate psychotherapy. It is important to remember that such co-morbid syndromes as panic disorder may not be fully treated without additional medication.

It has been noted that patients with atypical depression often suffer from intense cravings for carbohydrates. A mineral supplement, chromium picolinate, was found to assuage these cravings in one study, though the conclusion reached has not been replicated.

Some hypothesize that atypical depression may be related to thyroid dysregulation. Some studies have found subtle thyroid abnormalities in people with atypical depression. Another study suggests that patients may benefit from triiodothyronine, a medication used to treat hypothyroidism.