Atypical depression accounts for 30% of all depressions

When we speak of depression we are not referring to a single nosological entity. Depression is a medical condition in which mood disturbance predominates, accompanied by particular physical manifestations, as well as alterations in thinking, sleep-wake cycle and cognition.

Years ago, when I was in residency training in the specialty, the term “atypical depression” was frequently used, a term that is not currently used (at least in the DSM-5 classification) except as a specifier for depressive disorders in general. Atypical depression has historical significance. It was described by the British authors West and Daly in 1959 as a separate diagnosis because in pharmacological trials conducted at that time a group of patients showed a better and clearer response to monoamine oxidase inhibitor antidepressants (MAOIs) than to tricyclic antidepressants. These two groups of drugs constituted the therapeutic arsenal against depression until the late 1980s, when selective serotonin reuptake inhibitor antidepressants appeared.

Why was it called ‘atypical’ depression?

This type of depression was so called “atypical” as opposed to the presentation of endogenomorphic type of depressive symptoms. It should be noted that endogenous depression was the norm at that time when depression was rarely diagnosed in outpatients and almost never in adolescents or young adults. However, the prevalence of what would be called “atypical depression” is high and represents almost 30% of all depressions.

What is the clinical picture of this pathology?

The same term is used to describe three different clinical pictures:

  • Pictures in which anxiety and phobic aspects or other symptoms of the anxious spectrum predominate, which are accompanied by depression or phenomena that imply an underlying depression, such as diurnal variations in mood.
  • Depressive pictures with reversed functional changes with respect to those typically endogenous, such as worsening in the evenings, insomnia of conciliation and nevertheless with diurnal hypersomnia, hyperphagia instead of loss of appetite, which can go as far as bulimic behavior.
  • Depressions without the underlying features of endogenous or melancholic conditions.

What symptoms are key to its diagnosis?

The defining feature of an atypical depression is the reactivity of the mood, that is, the capacity to respond with joy or at least with an improvement of mood when positive events occur (for example, the visit of a loved one or receiving praise, gratification, in short, good news), which does not occur in melancholic depressions, which maintain a persistent anhedonia in the face of the environment and in the face of even the happiest events.

In adolescents or very young people it is quite common the fact of an improvement of the mood during the time they spend with their friends, in spite of being in a frankly depressive state. This peculiarity surprises families and can delay the diagnosis by interpreting it as another sign of adolescent arbitrariness.

But in addition to this mood reactivity, there are other important symptoms:

  • Thus, in atypical depression, the mood may become euthymic (i.e. normal, without sadness) even for prolonged periods if external circumstances remain favorable.
  • Instead of finding a decrease in appetite and weight, in atypical depression we usually find an increase in food intake that may be accompanied by a clear weight gain.
  • We will find hypersomnia that may include a prolonged period of night and daytime sleep totaling at least 10 hours a day, or at least two hours more than the subject’s usual sleep time when not depressed.
  • Another unique symptom is known as leaden paralysis defined as a feeling of heaviness or ballast, usually in the extremities (arms and legs). This annoying sensation is present – at least – one hour a day and in most cases for a longer period of time.
  • Finally, the symptom known as “sensitivity to rejection” perceived in interpersonal relationships deserves comment. This trait is of early onset and in atypical depressions will persist into adulthood. Such sensitivity to rejection is present both when the person is in full-blown depression and when he or she is not… although in the former case the symptom is exacerbated to pathological levels. Therefore, here we see a personality trait that links with a clinical syndrome in a continuum from the need to be admitted, fear of rejection, alertness to the possibility of rejection, sensitivity to the response of others and to some degree the susceptibility/suspiciousness variable.
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Can this type of depression coexist with other diagnoses or disorders?

Despite not having its own nosological entity, atypical depression is the most common form of depressive syndrome seen in psychiatric outpatient clinics. Its prevalence is about four times more common in women. Research has supported the early age of onset of symptoms in patients with atypical depression, with onset of symptoms most likely to be before the age of twenty.

To further “complicate” this picture, atypical depression is described to have a high comorbidity with other psychiatric diagnoses. These are the results of some studies:

  • Greater functional deterioration and episodes of affective instability, chronic dysphoria and “double depression” (this means that at some point one can suffer from atypical depression and superimposed on it a melancholic major depression).
  • Panic disorder/agoraphobia in more than 53% of patients.
  • Obsessive-compulsive disorder in 10% of the patients with atypical depression.
  • Generalized anxiety disorder in 10% of patients with this type of depression.
  • Bulimia nervosa in about 11% of patients.
  • Social phobia, in almost 8% of patients.

In other words, we observed a very high comorbidity with anxiety in any of its forms, OCD and eating disorders.

High prevalence, early onset and greater persistence.

As I mentioned previously, the response to pharmacotherapy was clearly in favor of non-selective MAOIs (whose use today is practically extinct, since prescription is maintained for about 70,000 people worldwide). Fortunately, however, with the introduction of SSRI (selective serotonin reuptake inhibitors) antidepressants, a good therapeutic response has been observed for this type of depression, the earlier it is treated, the better the resolution.

In colloquial speech, the term atypical is usually associated with something rare. But atypical depression, although unique in its presentation, is certainly neither uncommon nor rare in depressive disorders. Both the literature and clinical practice support the evidence that “atypical depression” is a form of depression with high prevalence, early onset, and a tendency to have greater persistence over time.

An aspect of great clinical interest is that patients experiencing early-onset atypical depression, with chronic course, long-lasting pattern of rejection sensitivity and a pervasive fatigue perception, can easily be burdened with a primary diagnosis of personality disorder. This would lead to a kind of “therapeutic nihilism” which added to the preference of “not taking medication” may cause a very useful therapeutic tool (psychopharmacological treatment) to be disdained by both the clinician and the patient in the belief that the subject “has always been like this”.

For more information or any consultation you can make an appointment with Dr. Humbert Escario, specialist in Psychiatry.