Depression
Depression is a feeling of intense sadness; it may follow a recent loss or other sad event but is out of proportion to that event and persists beyond an appropriate length of time.
After anxiety, depression is the most common mental health disorder. An estimated 10% of people who see their doctors for what they think is a physical problem are actually experiencing depression. People who become depressed typically do so in their 20s, 30s, or 40s, although depression can begin at almost any age. Depression affects a number of children and adolescents (see Section 23, Chapter 286). People born in the latter part of the 20th century seem to have higher rates of depression and suicide than those of previous generations, in part because of higher rates of substance abuse.
An episode of depression typically lasts about 6 months if untreated, but sometimes it lasts for 2 years or more. Episodes generally tend to recur several times over a lifetime.
Causes
A number of factors may make a person more likely to experience depression, such as a family tendency (heredity), side effects of certain drugs, and emotionally distressing events, particularly those involving a loss. Despite commonly held beliefs, however, depression does not necessarily reflect a personality disorder, childhood trauma, poor parenting, or weakness of character. Depression may arise or worsen without any apparent or significant life stresses.
Social class, race, and culture do not appear to affect the chance that a person will experience depression in his or her lifetime. However, a person's sex does appear to have an effect: Women are twice as likely as men to experience depression, though the reasons are not entirely clear. Of physical factors, hormones are the ones most involved. Changes in hormone levels, which can create mood changes shortly before menstruation and after childbirth, might play some role in women. Similarly, the use of oral contraceptives or hormone (estrogen) replacement therapy may contribute to or cause mood changes. Abnormal thyroid function, which is fairly common in women, may also be a factor.
Transient depression is when someone becomes temporarily depressed in reaction to certain holidays (holiday blues) or meaningful anniversaries, such as the anniversary of a loved one's death; during the premenstrual phase (premenstrual dysphoric disorder); or during the first 2 weeks after giving birth (postpartum depression). Such reactions are normal, but people with an increased predisposition to depression may develop significant depression during such times. Depression without an apparent precipitating event is called melancholia (formerly called endogenous depression). These distinctions, however, are not very important, since the effects and treatment of the depression are similar.
Depression may occur with, or be caused by, a number of physical disorders. Physical disorders may cause depression directly (such as when thyroid disease affects hormone levels, which can induce depression) or indirectly (such as when rheumatoid arthritis causes pain and disability, which can lead to depression). Often, depression that results from a physical disorder has both direct and indirect causes. For example, AIDS may cause depression directly if the human immunodeficiency virus (HIV), which causes AIDS, damages the brain; AIDS may cause depression indirectly by having an overall negative effect on the person's life.
The use of some prescription drugs can cause depression. For unknown reasons, corticosteroids often cause depression when they are produced in large amounts as part of a disease, as in Cushing's syndrome, but they tend to cause hypomania or, rarely, mania when they are given as medication.
A number of mental health disorders can predispose a person to depression, including certain anxiety disorders, alcoholism and other substance abuse disorders, and schizophrenia.
 See the sidebar Physical Disorders That Can Cause Depression.
Symptoms
Symptoms typically develop gradually over days or weeks and can vary greatly depending on what type of depression the person is experiencing. For example, a person who is becoming depressed may appear sluggish and sad or irritable and anxious.
A person who is withdrawn, speaks little, stops eating, and sleeps little is experiencing what doctors call vegetative symptoms. In contrast, a person who appears anxious and fearful (especially in the evening), has an increased appetite resulting in weight gain, and, although initially unable to sleep, sleeps for increasingly longer periods is experiencing depression with atypical symptoms. A person who, in addition, is very restless--wringing the hands and talking continuously--is experiencing agitation.
Many people with depression cannot experience emotions--including grief, joy, and pleasure--in a normal way; in the extreme, the world appears to have become colorless and lifeless. Thinking, speech, and general activity may slow down so much that all voluntary activities stop. Depressed people may be preoccupied with intense feelings of guilt and self-denigration and may not be able to concentrate. They may experience feelings of despair, loneliness, and low self-esteem. They are often indecisive and withdrawn, feel progressively helpless and hopeless, and think about death and suicide.
Sleep problems are common. Most depressed people have difficulty falling asleep and awaken repeatedly, particularly early in the morning. A loss of sexual desire or pleasure is common. Poor appetite and weight loss sometimes lead to emaciation, and in women, menstrual periods may stop. However, overeating and weight gain are common in people with mild depression.
In some depressed people, the symptoms are mild but the disorder lasts for years, often decades. This type of depression, called dysthymia, often begins early in life and is associated with distinct changes in personality. People with dysthymia are gloomy, pessimistic, humorless, or incapable of having fun; passive and lethargic; introverted; skeptical, hypercritical, or constantly complaining; and self-critical and full of self-reproach. They are preoccupied with inadequacy, failure, and negative events, sometimes to the point of morbid enjoyment of their own failures.
Some depressed people complain of having a physical illness, with various aches and pains or fears of calamity or of becoming insane. Others think they have illnesses they believe to be incurable or shameful, such as cancer or sexually transmitted diseases, and think they are infecting other people.
About 15% of depressed people, most commonly those with severe depression, have false beliefs (delusions), or they see or hear things that are not there (hallucinations). For example, they may believe that they have committed unpardonable sins or crimes or may hear voices accusing them of various misdeeds or condemning them to death. In rare cases, they may imagine that they see coffins or deceased relatives. Feelings of insecurity and worthlessness may lead people with severe depression to believe that they are being watched and persecuted. Depression with delusions or hallucinations is termed psychotic depression.
Thoughts of death are among the most serious symptoms of depression. Many depressed people want to die or feel they are so worthless that they should die. As many as 15% of untreated depressed people end their lives in suicide. A suicide threat represents an emergency situation (see Section 7, Chapter 102). When a person threatens to kill himself, a doctor may hospitalize the person so that he is kept under supervision until treatment reduces the risk of suicide. The risk is especially high when the person with depression continues to have feelings of excessive sadness even while returning to normal activities. The risk is also high around personally significant anniversaries and among people in a mixed bipolar state (see Section 7, Chapter 101 and Section 7, Chapter 101).
Diagnosis
A doctor is usually able to diagnose depression from its signs and symptoms. A previous history of depression or a family history of depression helps to confirm the diagnosis. Excessive worrying, panic attacks, and obsession are common in depression and may lead the doctor to incorrectly think that the person has an anxiety disorder.
In older people, depression may be difficult to notice, especially among people who do not work or who have little social interaction. Depression may lead to slower thinking, decreased concentration, and memory impairment that simulates dementia. Indeed, the disorder can so resemble dementia that it is sometimes called pseudodementia (see Section 6, Chapter 83).
Standardized questionnaires are used to help measure the degree of depression. Two such questionnaires are the Hamilton Depression Rating Scale, conducted verbally by an interviewer, and the Beck Depression Inventory, a self-administered questionnaire.
Laboratory tests may occasionally help a doctor determine if depression is caused by an endocrine or other physical disorder, but no simple laboratory test exists with which to diagnose depression.
In cases that are difficult to diagnose, doctors may perform other tests to confirm the diagnosis of depression. For example, because sleep problems are such a prominent sign of depression, doctors who specialize in diagnosing and treating mood disorders may use a sleep electroencephalogram to measure the time it takes for rapid eye movement sleep (the period during which dreaming occurs) to begin after the person falls asleep. Normally, progression to this stage of sleep takes about 90 minutes. In a person with depression, however, it usually takes less than 70 minutes.
Prognosis and Treatment
An untreated depression may last for about 6 months. Although mild symptoms persist in many people, functioning tends to return to normal. Nonetheless, most people with depression experience repeated episodes of depression, an average of 4 to 5 times over a lifetime. In older people, symptoms of pseudodementia (such as confusion), if present, clear up with treatment for depression.
Depression today is usually treated without hospitalization. However, sometimes a person should be hospitalized, especially if he is contemplating suicide or has attempted it, is too frail because of weight loss, or is at risk of heart problems because of severe agitation.
Drug therapy is the cornerstone of treatment for depression. Other treatments include psychotherapy and electroconvulsive therapy. Sometimes a combination of therapies is used. Depression can usually be treated successfully and does not represent a character flaw or weakness of mental abilities.
Drug Therapy: Several types of drugs--tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs), psychostimulants, and other antidepressants--are available. Most must be taken regularly for at least several weeks before they begin to work. The chances that any given antidepressant will work for a particular person are about 65%. Side effects vary with each type of drug. Sometimes when treatment with one drug fails to relieve depression, a combination of antidepressant drugs is prescribed.
Tricyclic antidepressants, once the mainstay of treatment, are now used infrequently. They often cause sedation and lead to weight gain. They can also cause an increase in heart rate and a decrease in blood pressure when the person stands. Other side effects include blurred vision, dry mouth, confusion, constipation, and difficulty in starting to urinate. These other effects are called anticholinergic effects and are often more pronounced in older people (see Section 2, Chapter 14).
Selective serotonin reuptake inhibitors (SSRIs) are now the most commonly used class of antidepressants. SSRIs are effective in treating depression and dysthymia as well as other mental health disorders that often coexist with depression. Although SSRIs can cause nausea, diarrhea, tremor, weight loss, and headache, these side effects are usually mild or go away with continued use. Most people tolerate the side effects of SSRIs better than the side effects of tricyclics. SSRIs are safer than the tricyclics in their side effects on the heart. However, with long term use, SSRIs may cause additional side effects, such as weight gain. Abrupt discontinuation of some of the SSRIs may result in a withdrawal syndrome that includes dizziness, anxiety, irritability, and flu-like symptoms.
Monoamine oxidase inhibitors (MAOIs) represent another class of antidepressant drug. MAOIs may be effective when other antidepressants have failed but are rarely the first choice in treatment. People who use MAOIs must adhere to a number of dietary restrictions and follow special precautions. For example, they should not eat foods or beverages that contain tyramine, such as beer on tap, red wines (including sherry), liqueurs, overripe foods, salami, aged cheeses, fava or broad beans, yeast extracts (marmite), and soy sauce. They must avoid pseudoephedrine, found in many over-the-counter cough and cold remedies. This drug, when combined with MAOIs, can cause a sudden and severe rise in blood pressure with a severe, throbbing headache (hypertensive crisis). People who take MAOIs should also avoid many other types of drugs, including tricyclic antidepressants, SSRIs, bupropion, mirtazapine, venlafaxine, nefazodone, dextromethorphan (a cough suppressant), and meperidine (an analgesic).
People taking MAOIs usually are instructed to carry an antidote, such as chlorpromazine or nifedipine, at all times. If a severe, throbbing headache occurs, they should take the antidote at once and go to the nearest emergency room. Because of the risk of stroke and difficult dietary restrictions and necessary precautions, MAOIs are rarely prescribed except for depressed people whose condition has not improved with other antidepressants.
Psychostimulants, such as dextroamphetamine and methylphenidate, as well as other drugs, are sometimes used, often in combination with antidepressants.
Newer antidepressants have become available that are as effective and safe as SSRIs but may have fewer and less severe side effects for some people.
St. John's wort, an herbal dietary supplement, may help relieve mild depression. However, due to potentially harmful interactions between St. John's wort and many prescription drugs, people interested in taking this herbal supplement need to discuss possible drug interactions with their doctor (see Section 2, Chapter 18).
Psychotherapy: Individual or group psychotherapy can help people with depression gradually resume former responsibilities and adapt to the normal pressures of life, building on the improvement made by antidepressant drug treatment. Interpersonal psychotherapy can provide the people with supportive guidance while adjusting to changes in life roles. Cognitive therapy can help change hopelessness and negative thinking. Psychotherapy alone may be just as effective as drug therapy for mild depression.
Electroconvulsive Therapy: Electroconvulsive therapy is sometimes used to treat people with severe depression, particularly when the person is psychotic, is threatening to commit suicide, or is refusing to eat. This type of therapy is usually very effective and can relieve depression quickly, unlike most antidepressants, which can take up to several weeks. The speed with which electroconvulsive therapy takes effect can save lives.
With electroconvulsive therapy, electrodes are placed on the head and an electrical current is applied to induce a seizure in the brain. For reasons that are not understood, the seizure relieves depression. Usually five to seven treatments, one treatment every other day, are given. Because the electrical current can cause muscle contractions and pain, the person undergoes general anesthesia during treatments. Electroconvulsive therapy may cause some temporary (rarely permanent) memory loss.
 See the drug table Drugs Used to Treat Depression.
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