| Atypical depression | |
|---|---|
| Other names | Depression with atypical features |
 | |
| Depression subtypes | |
| Specialty | Psychiatry |
| Symptoms | Low mood, mood reactivity,hyperphagia,hypersomnia, leaden paralysis,interpersonal rejection sensitivity |
| Complications | Self-harm |
| Usual onset | Typically adolescence[1] |
| Types | Primary anxious, primarily vegetative[1] |
| Risk factors | Bipolar disorder,anxiety disorder, female sex[2] |
| Differential diagnosis | Melancholic depression,anxiety disorder,bipolar disorder |
| Frequency | 15-29% of depressed patients[3] |
Atypical depression is defined in theDSM-IV asdepression that shares many of the typical symptoms ofmajor depressive disorder ordysthymia, but is characterized by improved mood in response to positive events. In contrast to those with atypical depression, people withmelancholic depression generally do not experience an improved mood in response to normally pleasurable events. Atypical depression also often features significantweight gain or anincreased appetite,hypersomnia, a heavy sensation in the limbs, andinterpersonal rejection sensitivity that results in significant social or occupational impairment.[4]
Despite its name, "atypical" depression does not mean it is uncommon or unusual.[5] The reason for its name is twofold: it was identified with its "unique" symptoms subsequent to the identification of melancholic depression and its responses to the two different classes of antidepressants that were available at the time were different from melancholic depression (i.e.,MAOIs had clinically significant benefits for atypical depression, whiletricyclic antidepressants did not).[6]
Atypical depression is four times more common in females than in males.[7] Individuals with features of atypical depression tend to report an earlier age of onset (e.g., while in high school) of their depressive episodes. These episodes tend to be more chronic than those of major depressive disorder[2] and only have partial remission between episodes. Younger individuals may be more likely to have atypical features, whereas older individuals may more often have episodes with melancholic features.[4] Atypical depression has high comorbidity withanxiety disorders, carries more risk of suicidal behavior, and has distinct personality psychopathology and biological traits.[2] Atypical depression is more common in individuals withbipolar I,[2]bipolar II,[2][8]cyclothymia,[2] orseasonal affective disorder.[4] Depressive episodes inbipolar disorder tend to have atypical features,[2] as does depression with seasonal patterns.[9]
Significant overlap between atypical and other forms of depression has been observed, though studies suggest that there are differentiating factors within the various pathophysiological models of depression. In theendocrine model, evidence suggests theHPA axis is hyperactive inmelancholic depression, and hypoactive in atypical depression. Atypical depression can be differentiated from melancholic depression via verbal fluency tests and psychomotor speed tests. Although both show impairment in several areas such asvisuospatial memory and verbal fluency, melancholic patients tend to show more impairment than atypical depressed patients.[10]
Furthermore, regarding theinflammatory theory of depression, inflammatory blood markers (cytokines) appear to be more elevated in atypical depression when compared to non-atypical depression.[11]
Genetically, atypical depression is associated with variants related to other mental disorders (e.g., bipolar disorder, attention-deficit/hyperactivity disorder), inflammation (C-reactive protein), metabolic function and metabolic illness (insulin resistance, Type 2 diabetes), and circadian rhythms (chronotype).[12]
The diagnosis of atypical depression is based on the criteria stated in theDiagnostic and Statistical Manual of Mental Disorders (DSM-5). The DSM-5 defines atypical depression as a subtype ofmajor depressive disorder that presents with "atypical features", characterized by:
Criteria for depression withmelancholic features orcatatonic features must not be met during the same episode.
The rejection sensitivity seen in atypical depression should be differentiated from that of borderline personality disorder, though the two conditions can be comorbid.
Due to the differences in clinical presentation between atypical depression andmelancholic depression, studies were conducted in the 1980s and 1990s to assess the therapeutic responsiveness of the availableantidepressant pharmacotherapy in this subset of patients.[13] Currently, antidepressants such asSSRIs,SNRIs,NRIs, andmirtazapine, are considered the best medications to treat atypical depression due to efficacy and fewer side effects than previous treatments.[14]Bupropion, anorepinephrine–dopamine reuptake inhibitor (NDRI), may be uniquely suited to treat the atypical depression symptoms of lethargy and increased appetite in adults.[14]Modafinil is sometimes used successfully as anoff-label treatment option.[15]
Before the year 2000,monoamine oxidase inhibitors (MAOIs) were shown to be of superior efficacy compared to other antidepressants for the treatment of atypical depression, and were used as first-line treatment for this clinical presentation. This class of medication fell in popularity with the advent of the aforementioned selective agents, due to concerns of interaction withtyramine-rich foods (e.g., some aged cheese, certain types of wine, tap beer and fava beans) causing ahypertensive crisis[16] and some – but not all –sympathomimetic drugs, as well as the risk ofserotonin syndrome when concomitantly used with serotonin reuptake agents. Despite these concerns, they are still used in treatment-resistant cases, when other options have been exhausted, and usually show greater rates of remission compared to previous pharmacotherapies. They are also generally better tolerated by many patients.[17] There are also newer selective and reversible MAOIs, such asmoclobemide, which carry a much lower risk of tyramine potentiation and have fewer interactions with other drugs.[18]
Tricyclic antidepressants (TCAs) were also used prior to the year 2000 for atypical depression, but were not as efficacious as MAOIs, and have fallen out of favor with prescribers due to the less tolerable side effects of TCAs and more adequate therapies being available.[13]
One pilot study suggested thatpsychotherapy orcognitive behavioral therapy (CBT) may have equal efficacy to MAOIs for a subset of patients with atypical depression, although the sample size was small and statistical significance was not reached.[19] These are talk therapy sessions with psychiatrists or clinical psychologists to help the individual identify troubling thoughts or experiences that may affect their mental state, and develop corresponding coping mechanisms for each identified issue.[20]
Trueprevalence of atypical depression is difficult to determine. Several studies conducted in patients diagnosed with a depressive disorder show that about 40% exhibit atypical symptoms, with four times more instances found in female patients.[21]
[7] Research also supports that atypical depression tends to have an earlier onset, with teenagers and young adults more likely to exhibit atypical depression than older patients.[2] Patients with atypical depression have shown to have higher rates of neglect and abuse in their childhood as well as alcohol and drug disorders in their family.[10] Overall,rejection sensitivity is the most common symptom, and due to some studies forgoing this criterion, there is concern for underestimation of prevalence.[22]
Atypical depression was first thought of as a disorder separate from typical depression in 1959, when doctors E.D. West and P. J. Dally were studying the effects ofiproniazid, an MAOI, on patients with depression.[23] They found consistencies among the patients who responded well to the drug in comparison to those who didn't. These patients, who were displaying symptoms of "anxiety hysteria with secondary depression", responded notably well to the iproniazid.[24]
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 the teenage years. Similarly, patients with atypical depression are more likely to haveanxiety disorders, (such asgeneralized anxiety disorder,obsessive–compulsive disorder, andsocial anxiety disorder), bipolar disorder, orpersonality disorders (e.g.,borderline personality disorder,avoidant personality disorder).[4][additional citation(s) needed]
Recent research suggests that young people are more likely to experiencehypersomnia while older people are more likely to experiencepolyphagia.[25]
Medication response differs between chronic atypical depression and acutemelancholic depression. Some studies suggest that the older class of antidepressants,monoamine oxidase inhibitors (MAOIs), may be more effective at treating atypical depression.[26] While the more modernSSRIs andSNRIs are usually quite effective in this illness, thetricyclic antidepressants typically are not.[4] Antidepressant response can often be enhanced with supplemental medications such asbuspirone,bupropion, oraripiprazole.Psychotherapy, whether alone or in combination with medication, is also an effective treatment in individual and group settings.[27]
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