The differential diagnosis for MDD is broad and can be thought of from the framework of differential mood disorders (ie, other Axis I disorders that present with depressive symptoms) and depressive symptoms secondary to an identifiable medical cause.
In addition to major depression, there are other types of mood disorders that manifest in the ED. While it is not expected for the emergency clinician to have memorized the DSM-IV-TR criteria for all such mood disorders, it is critical for the emergency clinician to be aware of the diversity in the spectrum of mood disorders, as it may have significant implications for evaluation and ultimate management in the ED. Among the critical mood disorder variants seen in the ED, the following are of note: dysthmia, adjustment disorder with depressed mood, bereavement, depressive disorder not otherwise specified (NOS), bipolar disorder, and mood disorder secondary to a medical cause. A brief discussion of these disorders follows.
Dysthmia can be conceptualized as a chronic mood disorder manifesting as depressed mood for most of the day, occurring more days than not, and associated with a number of somatic/cognitive symptoms. (See Table 4.) In contrast to major depression, the disease course is more chronic in nature but less severe than in major depression. Dysthmia is important to recognize in the ED because individuals with dysthymia can be at increased risk for developing major depression, and symptoms elicited in the ED should arouse a higher degree of suspicion for signs of major depressive disorder and safety for self. For example, a 10-year follow-up study noted that among patients with dysthmia, nearly 75% experienced some period of time where they also met criteria for major depression, and that among the patients who had met criteria for depression, nearly 70% experienced a relapse into another episode of depression in the 3 years following recovery.59,60
Adjustment Disorder With Depressed Mood
Adjustment disorder is characterized as a development of emotional or behavioral symptoms in response to an identifiable stressor (or stressors) occurring within 3 months of the stressor. (See Table 5.) In the setting of this adjustment disorder, patients may also manifest some aspects of clinical depression. The key aspect of adjustment disorder with depressed mood takes place within the context of an identifiable stressor, and as such may differ in terms of management strategies. An awareness of this mood disorder in the ED may be useful for both the emergency clinician as well as any potential consulting psychiatry service in identifying tailored management strategies.
Within the DSM-IV-TR classification system, a diagnosis of bereavement encompasses a specific manifestation of psychiatric symptoms that may manifest as clinical criteria for major depression but is in the context of a loss of a loved one that has occurred within an acute time frame (in the DSM-IV-TR, this is defined as 2 months). For the emergency clinician, an awareness of bereavement is important because it is often an expected response to a significant loss, and while initiation of supportive counseling and close medical follow-up is often indicated, it may not indicate the initiation of pharmacologic intervention (assuming no severe vegetative, suicidal, or psychotic symptoms). (See Table 6.)
Patients with bipolar disorder are a frequent manifestation to the ED and often have a separate and distinct management pattern. Bipolar disorder may present with a variety of symptoms. (See Table 7.)
Depressive Disorder Not Otherwise Specified
Patients may present to the ED with depressive features that do not meet criteria for the aforementioned mood disorders (ie, major depressive disorder, dysthmic disorder, adjustment disorder with depressed mood, or bipolar disorder). Such patients may be classified under depressive disorder not otherwise specified. Variations include premenstrual dysphoric disorder, minor depressive disorder, and post-psychotic depressive disorder of schizophrenia. The key aspect of this diagnosis is the recognition that while some patients may not meet criteria for all of the characteristics for a specific mood disorder, the emergency clinician should maintain a high degree of suspicion for further evaluation and management for patients endorsing some features of a depressed affect symptomatology.
Mood Disorder Secondary To A Medical Cause
A crucial aspect in the evaluation of the patient with depressive symptoms is to identify potentially secondary causes of decreased mood. This manifestation of depressive-like symptoms is often driven by etiologies that entail different management strategies and treatment. The approach to the differential should be systematic, and this disorder should be considered in all patients in the ED presenting with depressive symptoms. Clues based on the patient’s medication regimen, medical history, and physical examination may all suggest a potentially reversible cause for acute depressive-like presentation. Among the most common causes of a reversible depression in the ED are toxic ingestions, infectious processes, toxic-metabolic causes, and trauma. (See Table 8.)
Bernard Chang; David Gitlin; Ronak Patel
September 2, 2011