Mood Disorders

In 1 year, about 7 percent of Americans suffer from mood disorders, a cluster of mental disorders best recognized by depression or mania (Table 4-1). Mood disorders are outside the bounds of normal fluctuations from sadness to elation. They have potentially severe consequences for morbidity and mortality.

This section covers four mood disorders. As the predominant mood disorder, major depressive disorder (also known as unipolar major depression), garners the greatest attention. It is twice more common in women than in men, a gender difference that is discussed later in this section. The other mood disorders covered below are bipolar disorder, dysthymia, and cyclothymia.

Mood disorders rank among the top 10 causes of worldwide disability (Murray & Lopez, 1996). Unipolar major depression ranks first, and bipolar disorder ranks in the top 10. Moreover, disability and suffering are not limited to the patient. Spouses, children, parents, siblings, and friends experience frustration, guilt, anger, financial hardship, and, on occasion, physical abuse in their attempts to assuage or cope with the depressed person’s suffering. Women between the ages of 18 and 45 comprise the majority of those with major depression (Regier et al., 1993).

Depression also has a deleterious impact on the economy, both in diminished productivity and in use of health care resources (Greenberg et al., 1993). In the workplace, depression is a leading cause of absenteeism and diminished productivity. Although only a minority seek professional help to relieve a mood disorder, depressed people are significantly more likely than others to visit a physician for some other reason. Depression-related visits to physicians thus account for a large portion of health care expenditures. Seeking another or a less stigmatized explanation for their difficulties, some depressed patients undergo extensive and expensive diagnostic procedures and then get treated for various other complaints while the mood disorder goes undiagnosed and untreated (Wells et al., 1989).

Complications and Comorbidities

Suicide is the most dreaded complication of major depressive disorders. About 10 to 15 percent of patients formerly hospitalized with depression commit suicide (Angst et al., 1999). Major depressive disorders account for about 20 to 35 percent of all deaths by suicide (Angst et al., 1999). Completed suicide is more common among those with more severe and/or psychotic symptoms, with late onset, with co-existing mental and addictive disorders (Angst et al., 1999), as well as among those who have experienced stressful life events, who have medical illnesses, and who have a family history of suicidal behavior (Blumenthal, 1988). In the United States, men complete suicide four times as often as women; women attempt suicide four times as frequently as do men (Blumenthal, 1988). Recognizing the magnitude of this public health problem, the Surgeon General issued a Call to Action on Suicide in 1999 (see Figure 4-1). Individuals with depression also face an increased risk of death from coronary artery disease (Glassman & Shapiro, 1998).

Mood disorders often coexist, or are comorbid, with other mental and somatic disorders. Anxiety is commonly comorbid with major depression. About one-half of those with a primary diagnosis of major depression also have an anxiety disorder (Barbee, 1998; Regier et al., 1998). The comorbidity of anxiety and depression is so pronounced that it has led to theories of similar etiologies, which are discussed below. Substance use disorders are found in 24 to 40 percent of individuals with mood disorders in the United States (Merikangas et al., 1998). Without treatment, substance abuse worsens the course of mood disorders. Other common comorbidities include personality disorders (DSM-IV) and medical illness, especially chronic conditions such as hypertension and arthritis. People with depression have a high prevalence (65 to 71 percent) of any of eight common chronic medical conditions (Wells et al., 1991). The mood disorders also may alter or “scar” personality development.

Figure 4-1. Sugeon General's Call to Action to Prevent Suicide–1999

Clinical Depression Versus Normal Sadness
People have been plagued by disorders of mood for at least as long as they have been able to record their experiences. One of the earliest terms for depression, “melancholy,” literally meaning “black bile,” dates back to Hippocrates. Since antiquity, dysphoric states outside the range of normal sadness or grief have been recognized, but only within the past 40 years or so have researchers had the means to study the changes in cognition and brain functioning that are associated with severe depressive states.

At some time or another, virtually all adult human beings will experience a tragic or unexpected loss, romantic heartbreak, or a serious setback and times of profound sadness, grief, or distress. Indeed, something is awry if the usual expressions of sadness do not accompany such situations so common to the human condition—death of a loved one, severe illness, prolonged disability, loss of employment or social status, or a child’s difficulties, for example.

What is now called major depressive disorder, however, differs both quantitatively and qualitatively from normal sadness or grief. Normal states of dysphoria (a negative or aversive mood state) are typically less pervasive and generally run a more time-limited course. Moreover, some of the symptoms of severe depression, such as anhedonia (the inability to experience pleasure), hopelessness, and loss of mood reactivity (the ability to feel a mood uplift in response to something positive) only rarely accompany “normal” sadness. Suicidal thoughts and psychotic symptoms such as delusions or hallucinations virtually always signify a pathological state.

Nevertheless, many other symptoms commonly associated with depression are experienced during times of stress or bereavement. Among them are sleep disturbances, changes in appetite, poor concentration, and ruminations on sad thoughts and feelings. When a person suffering such distress seeks help, the diagnostician’s task is to differentiate the normal from the pathologic and, when appropriate, to recommend treatment.

Assessment: Diagnosis and Syndrome Severity

The criteria for diagnosing major depressive episode, dysthymia, mania, and cyclothymia are presented in Tables 4-2 through 4-5. Mania is an essential feature of bipolar disorder, which is marked by episodes of mania or mixed episodes of mania and depression. The reliability of the diagnostic criteria for major depressive disorder and bipolar disorder is impressive, with greater than 90 percent agreement reached by independent evaluators (DSM-IV).

Major Depressive Disorder
Major depressive disorder features one or more major depressive episodes (see Table 4-2), each of which lasts at least 2 weeks (DSM-IV). Since these episodes are also characteristic of bipolar disorder, the term “major⁶ depression” refers to both major depressive disorder and the depression of bipolar disorder.

The cardinal symptoms of major depressive disorder are depressed mood and loss of interest or pleasure. Other symptoms vary enormously. For example, insomnia and weight loss are considered to be classic signs, even though many depressed patients gain weight and sleep excessively. Such heterogeneity is partly dealt with by the use of diagnostic subtypes (or course modifiers) with differing presentations and prevalence. For example, a more severe depressive syndrome characterized by a constellation of classical signs and symptoms, called melancholia, is more common among older than among younger people, as are depressions characterized by psychotic features (i.e., delusions and hallucinations) (DSM-IV). In fact, the presentation of psychotic features without concomitant melancholia should always raise suspicion about the accuracy of the diagnosis (vis-à-vis schizophrenia or a related psychotic disorder). The so-called reversed vegetative symptoms (oversleeping, overeating, and weight gain) may be more prevalent in women than men (Nemeroff, 1992). Anxiety symptoms such as panic attacks, phobias, and obsessions also are not uncommon.

When untreated, a major depressive episode may last, on average, about 9 months. Eighty to 90 percent of individuals will remit within 2 years of the first episode (Kapur & Mann, 1992). Thereafter, at least 50 percent of depressions will recur, and after three or more episodes the odds of recurrence within 3 years increases to 70 to 80 percent if the patient has not had preventive treatment (Thase & Sullivan, 1995). Thus, for many, an initial episode of major depression will evolve over time into the more recurrent illness sometimes referred to as unipolar major depression (Thase & Sullivan, 1995). Each new episode also confers new risks of chronicity, disability, and suicide.

Dysthymia
Dysthymia is a chronic form of depression. Its early onset and unrelenting, “smoldering” course are among the features that distinguish it from major depressive disorder (DSM-IV). Dysthymia becomes so intertwined with a person’s self-concept or personality that the individual may be misidentified as “neurotic” (resulting from unresolved early conflicts expressed through unconscious personality defenses or characterologic disorders) (Akiskal, 1985). Indeed, the onset of dysthymia in childhood or adolescence undoubtedly affects personality development and coping styles, particularly prompting passive, avoidant, and dependent “traits.” To avoid the pejorative connotations associated with the terms “neurotic” and “characterologic,” the term “dysthymia” is used in DSM-IV as a descriptive, or atheoretical, diagnosis for a chronic form of depression (see Table 4-3) (DSM-IV). Affecting about 2 percent of the adult population in 1 year, dysthymia is defined by its subsyndromal nature (i.e., fewer than the five persistent symptoms required to diagnose a major depressive episode) and a protracted duration of at least 2 years for adults and 1 year for children. Like other early-onset disorders, dysthymic disorder is associated with higher rates of comorbid substance abuse. People with dysthymia also are susceptible to major depression. When this occurs, their illness is sometimes referred to as “double depression,” that is, the combination of dysthymia and major depression (Keller & Shapiro, 1982). Unlike the superimposed major depressive episode, however, the underlying dysthymia seldom remits spontaneously. Women are twice as likely to be diagnosed with dysthymia as men (Robins & Regier, 1991).

Table 4-2. DSM-IV criteria for major depressive episode

Table 4-3. DSM-IV diagnostic criteria for Dysthymic Disorder

Bipolar Disorder
Bipolar disorder is a recurrent mood disorder featuring one or more episodes of mania or mixed episodes of mania and depression (DSM-IV; Goodwin & Jamison,1990). Bipolar disorder⁷ is distinct from major depressive disorder by virtue of a history of manic or hypomanic (milder and not psychotic) episodes. Other differences concern the nature of depression in bipolar disorder. Its depressive episodes are typically associated with an earlier age at onset, a greater likelihood of reversed vegetative symptoms, more frequent episodes or recurrences, and a higher familial prevalence (DSM-IV; Goodwin & Jamison, 1990). Another noteworthy difference between bipolar and nonbipolar groups is the differential therapeutic effect of lithium salts, which are more helpful for bipolar disorder (Goodwin & Jamison, 1990).

Mania is derived from a French word that literally means crazed or frenzied. The mood disturbance can range from pure euphoria or elation to irritability to a labile admixture that also includes dysphoria (Table 4-4). Thought content is usually grandiose but also can be paranoid. Grandiosity usually takes the form both of overvalued ideas (e.g., “My book is the best one ever written”) and of frank delusions (e.g., “I have radio transmitters implanted in my head and the Martians are monitoring my thoughts.”) Auditory and visual hallucinations complicate more severe episodes. Speed of thought increases, and ideas typically race through the manic person’s consciousness. Nevertheless, distractibility and poor concentration commonly impair implementation. Judgment also can be severely compromised; spending sprees, offensive or disinhibited behavior, and promiscuity or other objectively reckless behaviors are commonplace. Subjective energy, libido, and activity typically increase but a perceived reduced need for sleep can sap physical reserves. Sleep deprivation also can exacerbate cognitive difficulties and contribute to development of catatonia or a florid, confusional state known as delirious mania. If the manic patient is delirious, paranoid, or catatonic, the behavior is difficult to distinguish from that of a schizophrenic patient. Clinicians are prone to misdiagnose mania as schizophrenia in African Americans (Bell & Mehta, 1981). Most people with bipolar disorder have a history of remission and at least satisfactory functioning before onset of the index episode of illness.

In DSM-IV, bipolar depressions are divided into type I (prior mania) and type II (prior hypomanic episodes only). About 1.1 percent of the adult population suffers from the type I form, and 0.6 percent from the type II form (Goodwin & Jamison, 1990; Kessler et al., 1994) (Table 4-5). Episodes of mania occur, on average, every 2 to 4 years, although accelerated mood cycles can occur annually or even more frequently. The type I form of bipolar disorder is about equally common in men and women, unlike major depressive disorder, which is more common in women.

Hypomania, as suggested above, is the subsyndromal counterpart of mania (DSM-IV; Goodwin & Jamison, 1990). By definition, an episode of hypomania is never psychotic nor are hypomanic episodes associated with marked impairments in judgment or performance. In fact, some people with bipolar disorder long for the productive energy and heightened creativity of the hypomanic phase.

Hypomania can be a transitional state (i.e., early in an episode of mania), although at least 50 percent of those who have hypomanic episodes never become manic (Goodwin & Jamison, 1990). Whereas a majority have a history of major depressive episodes (bipolar type II disorder), others become hypomanic only during antidepressant treatment (Goodwin & Jamison, 1990). Despite the relatively mild nature of hypomania, the prognosis for patients with bipolar type II disorder is poorer than that for recurrent (unipolar) major depression, and there is some evidence that the risk of rapid cycling (four or more episodes each year) is greater than with bipolar type I (Coryell et al., 1992). Women are at higher risk for rapid cycling bipolar disorder than men (Coryell et al., 1992). Women with bipolar disorder are also at increased risk for an episode during pregnancy and the months following childbirth (Blehar et al., 1998).

Table 4-4. DSM-IV criteria for manic episode

Table 4-5. DSM-IV diagnostic criteria for Cyclothymic Disorder

Cyclothymia
Cyclothymia is marked by manic and depressive states, yet neither are of sufficient intensity nor duration to merit a diagnosis of bipolar disorder or major depressive disorder. The diagnosis of cyclothymia is appropriate if there is a history of hypomania, but no prior episodes of mania or major depression (Table 4-5). Longitudinal followup studies indicate that the risk of bipolar disorder developing in patients with cyclothymia is about 33 percent; although 33 times greater than that for the general population, this rate of risk still is too low to justify viewing cyclothymia as merely an early manifestation of bipolar type I disorder (Howland & Thase, 1993).

Differential Diagnosis
Mood disorders are sometimes caused by general medical conditions or medications. Classic examples include the depressive syndromes associated with dominant hemispheric strokes, hypothyroidism, Cushing’s disease, and pancreatic cancer (DSM-IV). Among medications associated with depression, antihypertensives and oral contraceptives are the most frequent examples. Transient depressive syndromes are also common during withdrawal from alcohol and various other drugs of abuse. Mania is not uncommon during high-dose systemic therapy with glucocorticoids and has been associated with intoxication by stimulant and sympathomimetic drugs and with central nervous system (CNS) lupus, CNS human immunodeficiency viral (HIV) infections, and nondominant hemispheric strokes or tumors. Together, mood disorders due to known physiological or medical causes may account for as many as 5 to 15 percent of all treated cases (Quitkin et al., 1993b). They often go unrecognized until after standard therapies have failed.

A challenge to diagnosticians is to balance their search for relatively uncommon disorders with their sensitivity to aspects of the medical history or review of symptoms that might have etiologic significance. For example, the onset of a depressive episode a few weeks or months after the patient has begun taking a new blood-pressure medication should raise the physician’s index of suspicion. Ultimately, occult or covert medical illnesses must always be considered when an apparently clear-cut case of a mood disorder is refractory to standard treatments (Depression Guideline Panel, 1993). Cultural influences on the manifestation and diagnosis of depression are also important for the diagnostician to identify (DSM-IV). As discussed in Chapter 2, somatization is especially prevalent in individuals from ethnic minority backgrounds (Lu et al., 1995). Somatization is the expression of mental distress in terms of physical suffering.

⁶ The adjective “major” before the word “depression” denotes the number of symptoms required for the diagnosis, as distinct, from a proposed new category of “minor depression,” which requires fewer symptoms.

⁷ Bipolar disorder is also known as bipolar affective disorder and manic depression.