Abstract
Over the years, attempts have been made to classify depressive syndromes based on various criteria. For several decades, the term reactive depression was used to describe cases involving an obvious precipitant, whereas endogenous depression lacked a recent stressor. Alternatively, the term secondary depression has been used in reference to cases related to a defined medical condition, as opposed to examples of primary depression. In the current classification scheme, the Diagnostic and Statistics Manual of Mental Disorders, 5th edition (DSM-V) lists fifteen distinct diagnoses related to disorders of mood, which are shown in Table 4.1. Eight of these disorders are considered depressive disorders, whereas seven categorize patients within the bipolar spectrum of illness.
Depressive Disorders
Classification
Over the years, attempts have been made to classify depressive syndromes based on various criteria. For several decades, the term reactive depression was used to describe cases involving an obvious precipitant, whereas endogenous depression lacked a recent stressor. Alternatively, the term secondary depression has been used in reference to cases related to a defined medical condition, as opposed to examples of primary depression. In the current classification scheme, the Diagnostic and Statistics Manual of Mental Disorders, 5th edition (DSM-V) lists fifteen distinct diagnoses related to disorders of mood, which are shown in Table 4.1. Eight of these disorders are considered depressive disorders, whereas seven categorize patients within the bipolar spectrum of illness.
| Disruptive mood regulation disorder |
| Major depressive disorder |
| Persistent depressive disorder |
| Premenstrual dysphoric disorder |
| Substance/medication-induced depressive disorder |
| Depressive disorder due to another medical condition |
| Other specified depressive disorder |
| Unspecified depressive disorder |
| Bipolar I disorder |
| Bipolar II disorder |
| Cyclothymic disorder |
| Substance/medication-induced bipolar and related disorder |
| Bipolar and related disorder due to another medical condition |
| Other specified bipolar and related disorder |
| Unspecified bipolar and related disorder |
Epidemiology and Impact of Illness
Prevalence
The prototypical depressive disorder is major depressive disorder (MDD). MDD is common, disabling, persistent, and deadly. Approximately fourteen million Americans (6.6 percent of adults) have a new or ongoing episode of MDD each year, and overall lifetime prevalence is 15 percent. The prevalence in women is thought to be approximately 25 percent, twice as high as that in men (12 percent). Prevalence of MDD in eighteen- to twenty-nine-year-old individuals is nearly three times that of those over age sixty.
Clinical Course
The onset of MDD follows a bimodal distribution, with most cases beginning in late adolescence or early adulthood, and a second peak occurring in middle-age. This latter peak approximates the onset of menopause in many women, leading to some speculation that hormonal factors may be involved. Overall, the average age of onset is in the late twenties, though more than half of cases first appear after age forty.
Though there is a common misconception that elderly patients are at higher risk for depression and many practitioners may attempt to “normalize” depression in this population, evidence suggests that the rate of clinical depression among the elderly is actually lower than that of the general population. Notably, however, rates of depression are elevated among residents of nursing homes. Further, the impact of depression may be greater in older populations, and the risk of suicide among depressed patients is thought to increase with age.
Risk factors for MDD include family history, adverse childhood experiences, stressful life events, neuroticism, chronic or disabling medical conditions, and comorbid mental illness.
Patients experiencing an episode of major depression tend to describe worsening of mood over a period of weeks. In the stress-diathesis model of depression, though some individuals have a vulnerability to developing depression related to genetics or to childhood events, the phenotype of depression may only manifest in the setting of a life stress. For others, a series of stressors culminates in an episode of depression even if no vulnerability exists. In both situations, there is an obvious precipitating stressor that contributes to early episodes of depression. Patients experiencing recurrent depressive episodes, however, may find that later episodes do not have a defined precipitant, and in fact, prior episodes of depression may represent additional life stressors that increase vulnerability. This phenomenon is referred to as kindling, similar to the phenomenon observed in epilepsy. The theory is supported by the observation that early depressive episodes are often separated by longer periods of remission that become shorter as the illness progresses. From a neurobiological perspective, prior episodes of depression may induce brain changes at a cellular level, particularly in limbic areas of the brain, that convey a vulnerability to developing future depressive episodes even without provocation.
A typical episode of MDD lasts six months if untreated. Without treatment, approximately half of patients who experience a single episode of MDD will have a recurrence, including 15 percent who experience unremitting symptoms. After two episodes, the risk of recurrence increases to 70 percent, rising to 90 percent after three episodes. Subsequent episodes tend to occur more frequently and to last longer.
The course of MDD over the lifetime is quite variable, with some patients experiencing many years without symptoms and others experiencing an unremitting course. The presence of chronic symptoms may suggest an untreated comorbid personality, anxiety, or substance use disorder.
Morbidity and Mortality
MDD leads to major functional impairment and is the second leading cause of disability in the United States and worldwide.
Patients with MDD have greatly elevated general medical costs, and the total cost of MDD in the United States (health care costs + lost productivity) is a staggering $83 billion per year. MDD has been consistently and independently linked to elevated rates of death via suicide, heart disease, and all causes. Despite this, depression is the major illness with the least NIH funding proportional to the burden of disease in the United States.
Impact on Medical Illness
In addition to morbidity and mortality related to direct effects of depression, it also has a major impact on other medical illnesses. Depression following a variety of acute cardiac conditions has been consistently associated with cardiac and all-cause mortality over the following year, independent of sociodemographic variables and traditional risk factors. In patients with diabetes, depression has been linked to decreased adherence to diet and medication, higher levels of hemoglobin A1c, and worse outcomes. Similar effects have been shown for depressed patients with human immunodeficiency virus (HIV) and cancer. Depressed patients admitted to nursing homes have an increased risk of death in the subsequent year.
Cultural Factors
While some large epidemiologic studies have suggested higher rates of depression among Caucasians than among minority individuals in the United States, others have contended equal rates across racial groups.
Cross-cultural surveys suggest a significant (sevenfold) difference globally in twelve-month prevalence rates, though with the caveat that depression is underdiagnosed in many countries and that somatic symptoms may dominate the presentation in some cultures. Gender ratios and age of onset appear to be relatively consistent across cultures.
Clinical Features and Course
Major Depression
DSM-V diagnostic criteria for MDD are shown in Table 4.2. MDD is a persistent and pervasive condition, and diagnosis of MDD requires that depressive symptoms be present nearly every day throughout the duration of the episode. The hallmark of an episode of MDD is the presence of either depressed mood or anhedonia, a marked reduction in the ability to experience interest or pleasure. To meet the criteria for MDD, a total of five symptoms must be present. These include depressed mood, anhedonia, insomnia or hypersomnia, decrease or increase in appetite or weight, fatigue or loss of energy, psychomotor agitation or retardation, feelings of worthlessness or excessive guilt, decreased concentration, or recurrent thoughts of death or suicide; depressed mood or anhedonia must be one of the five symptoms. Symptoms (except for weight change and suicidal ideation) must be present nearly every day over a period of at least two weeks.
Together, the eight symptoms of depression (not including depressed mood) are frequently referred to as neurovegetative symptoms, and are recalled via the use of the pneumonic device “SIGECAPS,” standing for “sleep, interest, guilt, energy, concentration, appetite, psychomotor activity, and suicidal ideation.” The term “SIGECAPS” is meant to evoke the idea of prescribing a boost of energy for depressed patients, stemming from the Latin “Sig” for prescribe and “E Caps” for energy capsules.
Finally, it should be noted that patients may meet criteria for a major depressive episode (with all of the features listed previously) but have bipolar disorder, by virtue of having prior manic or hypomanic episodes; this has relevance for treatment and longitudinal course of illness.
A major depressive episode can be subclassified based on specific clinical features.
With Anxious Distress
Anxiety is a common feature of depressive episodes, and may convey a higher risk of suicide and treatment-resistance. The specifier “with anxious distress” is applied to an episode of MDD if two of the following symptoms are present for the majority of the course: feeling keyed up or tense, feeling unusually restless, difficulty concentrating because of worry, fear that something awful might happen, feeling that the individual might lose control of himself. The severity of the anxious distress is rated from mild to severe on the basis of the number of symptoms present.
With Mixed Features
Though previous editions classified a mixed mood episode as one involving the simultaneous presence of both a depressive and a manic episode, the DSM-V allows for the specifier “with mixed features” to be applied to an episode of MDD. Patients with an episode of MDD involving mixed features have a higher likelihood of developing bipolar disorder. Criteria are met if three or more of the following symptoms of mania/hypomania are present for the majority of a depressive episode: elevated, expansive mood; inflated self-esteem or grandiosity; more talkative than usual or pressure to keep talking; flight of ideas or racing thoughts; increase in energy or goal-directed activity; increased or excessive involvement in activities with high potential for painful consequences; and decreased need for sleep. Activities considered to have a high potential for painful consequences include unrestrained buying sprees, sexual indiscretion, and foolish business investments. If the patient meets the full criteria for bipolar disorder but has prominent depressive symptoms in addition to mania or hypomania, they are considered to have a manic or hypomanic episode with mixed features in the setting of bipolar disorder, rather than MDD with mixed features.
With Psychotic Features
Major depression with psychotic features signifies the presence of either hallucinations or delusions accompanying mood symptoms. Psychotic features are subdivided into mood-congruent and mood-incongruent features. Commonly, psychotic symptoms in MDD are mood-congruent. Delusions in psychotic depression, for example, tend to be nihilistic, guilt-themed, or somatic. Patients may develop Cotard’s syndrome, in which they believe themselves to be dead or dying, or believe that they have lost their internal vital organs. Other patients may believe that they are emitting toxic chemicals or that they are responsible for all of the bad events in the world. Hallucinations may involve olfactory sensations of decay or rotting, or voices commenting that the patient is evil or bad. Patients who develop a major depression with psychosis are at higher risk for developing psychosis during future mood episodes.
With Melancholic Features
A major depressive episode with melancholic features is heralded by the presence of either complete loss of pleasure in activities or loss of mood reactivity to pleasurable stimuli, in addition to three of the following: quality of depression characterized by despondency or despair, morning worsening of mood, early morning awakening, psychomotor retardation or agitation, decreased appetite, or excessive guilt. Patients with melancholic features are less likely to have a comorbid personality disorder, to have a clear precipitant for the depressive episode, or to respond to placebo. They may be more likely to respond to antidepressant medication or electroconvulsive therapy (ECT). Patients who develop melancholic features tend to be older and more often develop psychosis in conjunction with their depression. Melancholic features often do not persist across multiple episodes of depression.
With Atypical Features
The hallmark of major depression with atypical features is preserved mood reactivity. On exam, these patients are often capable of smiling or even laughing appropriately, and may not appear particularly depressed. Because of their mood reactivity, these patients occasionally may not engender as much empathy from the interviewer. Other atypical features include hypersomnia and hyperphagia rather than insomnia or decreased appetite, a feeling of heaviness in the arms and legs called “leaden paralysis,” and heightened rejection sensitivity. Women more commonly exhibit atypical features of depression as compared to men. Patients with atypical features tend to have an earlier age of onset for their depression and may respond to different classes of medication. Atypical depression has been linked to higher rates of comorbidity with bipolar disorder, borderline personality disorder, and social phobia.
With Catatonia
Patients who develop a major depressive episode with catatonic features exhibit three or more signs of the syndrome of catatonia. These may include motoric immobility, excessive motor activity, peculiarities of voluntary movement (including grimacing or the maintenance of rigid positions known as posturing), negativism, mutism, or echophenomena. Negativism manifests most commonly as resistance to all instructions. Patients do not follow commands and may actively resist manipulation by the examiner, such as shutting their eyes during attempts to open them. Echophenomena may include mimicking of the examiner’s speech (echolalia) or movements (echopraxia). Though patients with catatonia are classically thought of as being rigid and mute, the syndrome occurs on a spectrum, and many catatonic patients will be able to communicate with examiners and cooperate with the examination. Patients exhibiting catatonic symptoms can sometimes appear to be “playing possum,” which may lead to doubts on the part of treaters regarding the validity of their symptoms. Indeed, one theory about catatonia is that it represents an evolutionary fear response and is similar to “playing dead” behavior in other species.
With Peripartum Onset
An episode of major depression with peripartum onset occurs during pregnancy or within four weeks of delivery and is estimated to occur in 3–6 percent of pregnancies. Women with prior episodes of depression are at the highest risk for peripartum depression, but some patients will experience the first episode of depression during the peripartum period. Peripartum depression can be distinguished from “baby blues,” a normal, transient period of increased emotionality in the first three to seven days of the postpartum period, by both persistence and severity, though having the baby blues is a risk factor for developing peripartum MDD. Depression in the postpartum period often includes severe anxiety, spontaneous crying, disinterest in the infant and insomnia. Obsessional thoughts regarding violence to the child may be present and should be inquired after. Psychotic symptoms, such as delusions regarding the infant, occurring in 1 in 500 to 1 in 1,000 deliveries, are particularly worrisome and are a significant risk factor for infanticide. They tend to occur more in primiparous women and in those with personal or family histories of bipolar disorder. The risk of recurrence following an initial postpartum psychosis is up to 50 percent.
With Seasonal Pattern
Depression with seasonal variation refers to a pattern of depression in which the onset and remission of depressive episodes occur at characteristic times of the year. Most commonly, depressive episodes begin in the fall and resolve in the spring, though a minority of patients experience an opposite pattern. In order to meet criteria for the seasonal specifier, the pattern needs to have occurred for the past two years without any non-seasonal episodes. Further, over one’s lifetime, the number of seasonal episodes must substantially outnumber non-seasonal episodes. Depressive episodes occurring with a seasonal pattern tend to have more atypical features, and there is some speculation that there is higher comorbidity with bipolar disorder. Prevalence appears to increase with higher latitudes and younger age. Though standard treatments for MDD may be effective in these patients, other treatments, such as bright light therapy, may be particularly useful in patients with a seasonal pattern of major depressive episodes.
Suicide
Patients with MDD are at increased risk for suicide. Among patients who die of suicide, depression is more common than any other psychiatric disorder. Suicidal thoughts and feelings of hopelessness are often key components of depression. Among depressed patients, symptoms that increase the risk of suicide include anxiety, panic attacks, desperation, and feeling burdensome. Additional risk factors for suicide among depressed patients are shown in Table 4.3. Suicide risk factors can be divided into static and dynamic factors. Static factors refer to elements of patients’ histories that are stable and cannot be changed or influenced, whereas dynamic risk factors represent those that are amenable to treatment or intervention. Factors that may mitigate the risk of suicide in depressed patients are shown in Table 4.4.
| Static factors |
| Past self-injurious behavior or suicide attempts |
| Family history of attempted or completed suicide |
| Personality disorder |
| History of mood disorder or psychosis |
| History of abuse |
| Male gender |
| Older age |
| Dynamic factors |
| Current or recent suicidal ideation (including plan, intent) |
| Anxiety/panic |
| Substance use |
| Current mood symptoms |
| Current psychosis |
| Access to lethal means (firearms, etc.) |
| Impulsivity |
| Social stressors |
Table 4.4 Protective factors for imminent serious self-harm in depressed patients
| Lack of prior suicide attempts |
| Access to and engagement with psychiatric providers |
| Medication compliance |
| Social supports |
| Employment |
| Children and loved ones |
| Future orientation |
It appears that patients are particularly vulnerable to suicide during the early recovery from a depressive episode. One hypothesis is that energy and motivation tend to improve prior to the resolution of other symptoms, including low mood and suicidal ideation. Patients who have been experiencing suicidal ideation for weeks to months but who have not been motivated to act on these thoughts may suddenly find themselves with greater energy and impetus to act on these ongoing thoughts.
Depression Severity
Episodes of depression are rated as mild, moderate, or severe, based on symptom severity and degree of functional impairment. Mild depression is characterized by the presence of a minimal number of symptoms that result in only minor impairment in social or occupational functioning. Severe depression is characterized by the presence of several symptoms in excess of those needed for the diagnosis, as well as marked impairment in social or occupational functioning; patients requiring hospitalization for depression are in general thought to have a severe form. Under DSM-V, the presence of psychosis no longer by definition qualifies an episode as severe, though the majority of patients with psychotic depression will meet the criteria for a severe episode.
Remission
Full remission from depression is defined as a complete resolution of depressive symptoms for a minimum of two months. Though some patients with recurrent depression experience full remission, some will only achieve a partial reduction in symptoms, during which full MDD criteria are no longer met, or experience full remission for less than two months. Both of these latter patterns are classified as partial remission. Longitudinal course specifiers for depression differentiate between single episode and recurrent episodes of depression. In order to qualify as having a recurrent MDD, patients must experience a two-month period of at least partial remission followed by a return of a full syndromal episode.
The presence of residual symptoms between episodes conveys a worse overall prognosis. Unfortunately, trials of MDD treatments have found that remission of MDD is the exception rather than the rule, and millions of Americans have residual symptoms or ongoing syndromal depression with its attendant impairment, costs, and risks. Risk of recurrence declines as the length of remission increases. Factors conveying a higher risk of recurrence, aside from treatment, include symptom severity and younger age.
Persistent Depressive Disorder
Please see Table 4.5 for the DSM-V criteria for persistent depressive disorder. Persistent depressive disorder is a consolidation of two previous entities, chronic MDD and dysthymia. It is characterized by depressed mood more often than not for a period of at least two years. In addition to low mood, patients also exhibit at least two of the following: insomnia or hypersomnia, low self-esteem, low energy or fatigue, poor concentration, poor appetite or overeating, and feelings of hopelessness. In order to qualify for a diagnosis of persistent depressive disorder, patients cannot be without symptoms for a greater than a two-month continuous period of time within the two years. Individuals who meet criteria for MDD consistently for two years should be given diagnoses of both MDD and persistent depressive disorder.
Table 4.5 DSM-V Criteria for persistent depressive disorder
|
Persistent depressive disorder occurs in approximately 2 percent of the population per year (75 percent of these patients have chronic MDD) and often has its onset in adolescence or young adulthood. Children and adolescents with persistent depressive disorder may experience irritable rather than depressed mood, and only require one year of mood and associated symptoms for the diagnosis. Earlier onset is associated with Cluster B and C personality disorders and substance use disorders. Risk factors include childhood parental loss or separation, and family history of MDD or persistent depressive disorder.
Patients with persistent depressive disorder have often grown so accustomed to their chronic mood state that they view their mood as a personality trait and do not report low mood unless specifically asked. This entity is sometimes called the “Eeyore phenomenon,” after the character from Winnie the Pooh who frequently exhibits a pessimistic, gloomy attitude. Historically, an episode of MDD superimposed on the background of dysthymia has been referred to as “double depression.” For many patients with persistent depressive disorder, as an acute episode of depression resolves, they return to their baseline dysthymia.
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
