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INTRODUCTION

Mood disorders, which include depressive disorders and bipolar disorders, are the most common mental health complaints presenting to the ED, accounting for about half of mental health–related visits, behind anxiety and substance use disorders (about 25% each).1 Trends for ED visits for depressive disorders, bipolar disorders, and suicide ideation are sharply increasing.2-5 The prevalence of depression and bipolar disorders in the ED patient population is twice that of the general population.6 This chapter discusses the depressive disorders, bipolar disorders, and anxiety disorders. Substance use disorders are discussed in detail in Chapter 292.

DEPRESSIVE DISORDERS

Depressive disorders appear to affect women twice as often as men. Adolescents,7 the elderly (especially nursing home patients),8 and people living below the poverty level9 appear to be particularly vulnerable populations for depression. Increased rates of depressive disorders are seen with chronic illnesses, including CNS diseases,10,11 cardiovascular disorders,12 cancer,13 and chronic obstructive pulmonary disease.14

PATHOPHYSIOLOGY

The pathophysiology of depressive disorders includes genetic, biological, and psychosocial factors. A genetic predisposition heightens susceptibility.15,16 Malfunctioning monoamine neurotransmitters (especially serotonin, norepinephrine, and dopamine)17-19 are implicated and may explain the effectiveness of some current medical therapies. Abnormal γ-aminobutyric acid and glutamate levels in various areas of the brain have been noted.20 Abnormal neurocircuitry that links the prefrontal cortex to the amygdala, ventral striatum and pallidum, medial thalamus, hypothalamus, and the periaqueductal gray areas has been shown in mood disorders.21 Early childhood stress may alter corticotropin-releasing hormone cells in the hypothalamus to heighten future stress responses.22,23

A large number of medical disorders, medications, and substances of abuse may cause depressive symptoms (Table 289-1). A thorough history, examination, and appropriate laboratory studies will help differentiate the disorders. Strongly consider medical causes of the depressive symptoms in patients with new-onset symptoms of depression, in the elderly, and in those with complex medical problems.

TABLE 289-1Differential Diagnosis of Depression

CLINICAL FEATURES OF DEPRESSION

The most common type of depressive disorder is major depressive disorder. Clinical features are listed in Table 289-2. Depressive disorders are often unrecognized in ...

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