What is depression? |

Causes and Symptoms

The word “depression” is often used to describe many different things. For some, it defines a fleeting mood, for others an outward physical appearance of sadness, and for others a diagnosable clinical disorder. In any year, millions of adults suffer from a clinically diagnosed depression, a mood disorder that often affects personal, vocational, social, and health functioning. The fifth edition of the
Diagnostic and Statistical Manual of Mental Disorders
(DSM-5, 2013) of the American Psychiatric Association delineates a number of mood disorders that include clinical depression, known as major depressive disorder.

Major depressive disorder is characterized by a syndrome of symptoms, present
during a two-week period and representing a clinically significant change from
previous functioning. The symptoms include at least five of the following:
depressed or irritable mood for most of the day, diminished interest in previously
pleasurable activities, significant unintentional weight loss or weight gain,
insomnia or hypersomnia, physical agitation or slowness,
loss of energy or fatigue, feelings of worthlessness or excessive guilt,
indecisiveness or a diminished ability to concentrate, and recurrent thoughts of
death. The clinical depression cannot be initiated or maintained by another
illness or condition.

Major depressive disorder is often first recognized in the patient’s twenties,
while a major depressive episode can occur at any age. Women are twice as likely
to suffer from the disorder than are men.

There are several potential causes of major depressive disorder. Genetic factors may determine a person's susceptibility to developing depression following stressful life events. Genetic studies suggest a familial link with higher rates of clinical depression in first-degree relatives. There also appears to be a relationship between clinical depression and levels of the brain’s neurochemicals, specifically decreased monoamines—the neurotransmitters dopamine, norepinephrine, and serotonin. It is important to keep in mind, however, that anywhere from 15 to 20 percent of adults will experience major depression at some point in their lifetimes. Furthermore, not everyone has a biological cause for this depression. Common causes of clinical depression also include psychosocial stressors such as the death of a loved one, financial stress, loss of a job and unemployment, interpersonal problems, or traumatic world events such as natural disasters and war. It is unclear, however, why some people respond to a specific psychosocial stressor with a clinical depression and others do not. Finally, certain prescription medications have been noted to cause or be related to clinical depression. These drugs include muscle relaxants, heart medications, hypertensive medications, ulcer medications, oral contraceptives, painkillers, narcotics, and steroids. Thus there are many causes of clinical depression, and no single cause is sufficient to explain all clinical depressions.

Other likely risk factors for depression include past alcohol dependence, insecure attachment to parents in early adolescence, and the experience of childhood abuse or neglect. Possible risk factors for depression that have been explored include cannabis use, low birth weight, high levels of television viewing and media exposure in adolescence, and head injury.

In the DSM-5, the existence of at least three manic symptoms (which is
insufficient to satisfy the diagnostic criteria for a manic episode) within a
major depressive episode is acknowledged by the specifier "major depressive
disorder with mixed features." The presence of mixed features in an episode of
major depressive disorder increases the likelihood that the illness exists in the
bipolar spectrum, although separate criteria exist for the diagnosis of
bipolar
disorder, which can share some symptoms with major
depression.

Dysthymic disorder is another persistent depressive disorder characterized by
chronic low-level depression. In the United States, the twelve-month prevalence of
dysthymic disorder is estimated to be approximately 1.5 percent of the adult
population. Dysthymic disorder is characterized by at least a two-year history of
depressed mood and at least two of the following symptoms that cause clinically
significant impairment in social, work, or other important areas of functioning:
poor appetite or overeating, insomnia or hypersomnia, low energy or fatigue, low
self-esteem, poor concentration or decision making, or
feelings of hopelessness. The individual cannot be without the symptoms for more
than two months at a time, the disorder cannot be superimposed on another
psychotic disorder, and it cannot be initiated or maintained by another illness or
condition. Dysthymic disorder is more common in adult women, equally common in
both sexes of children, and with a greater prevalence in families. The causes of
dysthymic disorder are believed to be similar to those listed for major depressive
disorder, but the disorder is less well understood than is depression.

In order to prevent the overdiagnosis of bipolar disorder in children, the DSM-5
added a new depressive disorder called disruptive mood dysregulation disorder
(DMDD). This diagnosis is given to children up to the age of eighteen years who
exhibit persistent irritability and frequent episodes of extreme emotional
outbursts and behavioral dyscontrol. DMDD is characterized by severe and recurrent
temper outbursts that are grossly out of proportion in intensity or duration to
the situation at hand, occurring on average three or more times per week for one
year or more. Diagnosis of DMDD requires the symptoms to be present in at least
two settings (at school, at home, and/or in social settings), and the child cannot
have gone three or more consecutive months without symptoms to be diagnosed with
DMDD. Onset of DMDD must occur before the age of ten years, and diagnosis cannot
be made for the first time before the age of six years or after eighteen
years.

Also in the category of depressive disorders, the DSM-5 includes premenstrual dysphoric disorder (PMDD), which was previously categorized under Appendix B "Criteria Sets and Axes Provided for Further Study" in the DSM-IV, due to a strong body of evidence supporting its existence and the validity of the diagnostic criteria. PMDD is an extreme version of premenstrual syndrome that affects approximately 2 to 5 percent of women of reproductive age. PMDD is characterized by the presence of symptoms for most of the time during the last week of the luteal phase of the menstrual cycle; these symptoms begin to remit within a few days of the onset of the follicular phase and are not present in weeks following menstruation. For the diagnosis of PMDD, a woman must have five or more of the following symptoms for most menstrual cycles during the past one year: markedly depressed mood or feelings of hopelessness, marked anxiety or tension, persistent anger or irritability or increased interpersonal conflicts, sense of difficulty in concentrating, lethargy or fatigue, marked changes in appetite, hypersomnia or insomnia, feelings of being overwhelmed or out of control, and/or physical symptoms such as headache, joint or muscle pain, and breast tenderness. These symptoms must also cause a clinically significant impact on functioning at work, school, and social settings or within personal relationships.

A final variant of clinical depression is known as seasonal affective
disorder (SAD). Patients with this illness demonstrate a
pattern of clinical depression during the winter, when there is a reduction in the
amount of daylight hours. For these patients, the reduction in available light is
thought to be the cause of the depression. In the DSM-5, SAD is categorized as a
mood disorder with a specifier called "with seasonal pattern."

Treatment and Therapy

Crucial to the choice of treatment for clinical depression is determining the variant of depression being experienced. Each of the diagnostic categories has associated treatment approaches that are more effective for a particular diagnosis. Multiple assessment techniques are available to the health care professional to determine the type of clinical depression. The most valid and reliable is the clinical interview. The health care provider may conduct either an informal interview or a structured, formal clinical interview assessing the symptoms that would confirm the diagnosis of clinical depression. If the patient meets the diagnostic criteria set forth in the DSM-5, then the patient is considered for depression treatments. Patients who meet many but not all diagnostic criteria are sometimes diagnosed with a “subclinical” depression. These patients might also be considered appropriate for the treatment of depression, at the discretion of their health care providers.

Another assessment technique is the “paper-and-pencil” measure, or depression
questionnaire. A variety of questionnaires have proven useful in confirming the
diagnosis of clinical depression. Questionnaires such as the Beck Depression
Inventory, Hamilton Depression Rating Scale, Zung Self-Rating
Depression Scale, and the Center for Epidemiologic Studies Depression Scale are
used to identify persons with clinical depression and to document changes with
treatment. This technique is often used as an adjunct to the clinical interview
and rarely stands alone as the definitive assessment approach to diagnosing
clinical depression.

Once a clinical depression (or a subclinical depression) is identified, several types of treatment options are available. These options are dependent on the subtype and severity of the depression. They include individual and group psychotherapy, light therapy, family therapy, psychopharmacology (drug therapy), electroconvulsive therapy (ECT), and other less traditional treatments. These treatment options can be provided to the patient as part of an outpatient program or, in certain severe cases of clinical depression in which the person is a danger to the self or others, as part of a hospitalization.

Clinical depression often affects the patient physically, emotionally, and socially. Therefore, prior to beginning any treatment with a clinically depressed individual, the health care provider will attempt to develop an open and communicative relationship with the patient. This relationship will allow the health care provider to provide patient education on the illness and to solicit the collaboration of the patient in treatment. Supportiveness, understanding, and collaboration are all necessary components of any treatment approach.

For the treatment of mild to moderate depression in adults, the American
Psychiatric Association (APA) recommends psychotherapy
as the initial treatment choice. The APA also recommends antidepressant
medications as an initial treatment choice, whereas the
National Institute for Clinical Excellence (NICE) recommends antidepressants only
if the patient is unresponsive to initial psychosocial interventions. For moderate
to severe depression in adults, the APA and the NICE recommend a combination of
psychotherapy and antidepressants. The APA also recommends electroconvulsive
therapy (ECT) for the treatment of severe unresponsive major depression in adults.

For the treatment of depression in children and adolescents, the recommended
initial treatment choices include education, supportive treatment, and case
management. If depression is complicated or chronic, psychotherapy may then be
recommended. Interpersonal therapy and cognitive-behavioral therapy have been
shown to be among the best psychotherapeutic options for the treatment of
depression. If the child or adolescent with depression is unresponsive to
psychotherapy, he or she may benefit from some types of antidepressant
medications; however, in most children with depression, antidepressants do not
appear to be an effective treatment.

Psychotherapy refers to a number of different treatment techniques used to deal
with the psychosocial contributors and consequences of clinical depression. In
psychotherapy, the patients develop knowledge and insight into the causes of and
treatment for their clinical depression. In cognitive psychotherapy, symptom
relief comes from assisting patients in modifying maladaptive, irrational, or
automatic beliefs that can lead to clinical depression. In behavioral
psychotherapy, patients modify their environment such that social or personal
rewards are more forthcoming. This process might involve being more assertive,
reducing isolation by becoming more socially active, increasing physical
activities or exercise, or learning relaxation techniques or other coping skills.
Research upholds the effectiveness of these and other psychotherapy techniques for
the treatment of depression and other mood disorders.

The primary types of medications used in the treatment of clinical depression in
adults include selective serotonin reuptake inhibitors (SSRIs), serotonin
norepinephrine reuptake inhibitors (SNRIs), mirtazapine (Remeron), and bupropion
(Wellbutrin). Monoamine oxidase inhibitors (MAOIs) should be restricted to
patients who do not respond to other treatments. The health care professional will
select an antidepressant based on side effects, dosing convenience (once
daily versus three times a day), and cost.

Cyclic antidepressants represent one class of antidepressant medications. As the name implies, the chemical makeup of the medication contains chemical rings, or “cycles.” There are unicyclic (buproprion and fluoxetine, or Prozac), bicyclic (sertraline and trazodone), tricyclic (amitriptyline, desipramine, and nortriptyline), and tetracyclic (maprotiline) antidepressants. These antidepressants function to either block the reuptake of neurotransmitters by the neurons, allowing more of the neurotransmitter to be available at a receptor site, or increase the amount of neurotransmitter produced. The side effects associated with the cyclic antidepressants—dry mouth, blurred vision, constipation, urinary difficulties, palpitations, and sleep disturbance—vary and can be quite problematic. Some of these antidepressants have deadly toxic effects at high levels, so they are not prescribed to patients who are at risk of suicide. Furthermore, in some patients, antidepressants such as SSRIs are associated with increased suicidal ideation, so patients should be carefully monitored as they begin an antidepressant treatment regimen.

Newer drugs are more specific in terms of the drug action. For instance,
fluoxetine is a selective serotonin reuptake inhibitor (SSRI) and works
specifically on the neurotransmitter serotonin. Similarly, buproprion is a
norepinephrine and dopamine reuptake inhibitor (NDRI) and works specifically on
the neurotransmitters norepinephrine and dopamine. More specific drugs generally
create fewer side effects. Fewer side effects can be associated with greater
medication compliance, making these drugs a more effective treatment for many
individuals.

Monoamine oxidase inhibitors (isocarboxazid, phenelzine, and tranylcypromine) are
another class of antidepressants. They function by slowing the production of the
enzyme monoamine oxidase. This enzyme is responsible for breaking down the
neurotransmitters norepinephrine and serotonin, which are believed to be
responsible for depression. By slowing the decomposition of these transmitters,
more of them are available to the receptors for a longer period of time.
Restlessness, dizziness, weight gain, insomnia, and sexual dysfunction are common
side effects of the MAOIs. MAOIs are most notable because of the dangerous adverse
reaction (severely high blood pressure) that can occur if the patient consumes
large quantities of foods high in tyramine (such as aged cheeses, fermented
sausages, red wine, foods with a heavy yeast content, and pickled fish). Because
of this potentially dangerous reaction, MAOIs are not usually the first choice of
medication and are more commonly reserved for depressed patients who do not
respond to other treatment options.

Electroconvulsive or shock therapy is the single most effective treatment for severe and persistent depression that does not respond to other treatments. If the clinically depressed patient fails to respond to medications or psychotherapy and the depression is life-threatening, electroconvulsive therapy is considered. It is also considered if the patient cannot physically tolerate antidepressants, as with elderly patients who have other medical conditions. This therapy involves inducing a seizure in the patient by administering an electrical current to specific parts of the brain. The therapy has become quite sophisticated and much safer than when it was introduced in the mid-twentieth century, and it involves fewer risks to the patient. Patients undergo several treatments over a period of time. Some temporary memory impairment is a common side effect of this treatment.

A special treatment used for individuals with seasonal affective disorder is
light
therapy, or phototherapy. Light therapy involves exposing
patients to bright light for a period of time each day during seasons of the year
when there is decreased light. This may be done as a preventive measure and also
during depressive episodes. The manner in which this treatment approach modifies
the depression is unclear and awaits further research, but some believe it affects
the internal clock of the body, or circadian rhythm. Studies of the
effectiveness of light therapy have been mixed, but interest in this promising
treatment is strong, as it may prove useful for working with nonseasonal mood
disorders as well. It should be noted, however, that light therapy does have some
risks associated with it. Caution must be used to protect the eyes and to use the
light as directed. Additionally, the intensity of light must be correct so as to
achieve therapeutic effects and not cause other problems. Finally, some
individuals can experience manic episodes if they are exposed to too much light,
so caution must be exercised in terms of the length of time for light exposure
treatment sessions.

Surgery, the final treatment option for severe depression, is quite rare. Psychosurgery is used only after all treatment options have failed and the clinical depression is life-threatening. Vagus nerve stimulation (VNS) is a form of surgery that implants a stimulus generator on the vagus nerve; it is approved by the FDA for the treatment of severe unresponsive depression. Nonsurgical methods of creating similar stimuli have been explored as well.

Perspective and Prospects

Depression, or the more historical term “melancholy,” has had a history predating
modern medicine. Writings from the time of the ancient Greek physician Hippocrates
refer to patients with a symptom complex similar to the present-day definition of
clinical depression.

The rates of clinical depression have increased since the early twentieth century,
while the age of onset of clinical depression has decreased. Women appear to be at
least twice as likely as men to suffer from clinical depression.

While most psychiatric disorders are nonfatal, clinical depression can lead to
death. About 60 percent of individuals who commit suicide have a mood disorder
such as depression at the time. In a lifetime, however, only about 7 percent of
men and 1 percent of women with lifetime histories of depression will commit
suicide. Though these numbers are high, what this means is that not everyone who
is depressed will commit suicide. In fact, many receive help and recover from
depression. There are, however, other costs of clinical depression. Billions of
dollars are spent on clinical depression, divided among the following areas:
treatment, suicide, and absenteeism (the largest). Clinical depression obviously
has a significant economic impact on society, and major personal impacts on the
lives of individuals suffering from depression.

The future of clinical depression lies in early identification and treatment.
Identification will involve two areas. The first is improving the social awareness
of mental health issues to include clinical depression. By eliminating the
negative social stigma associated with mental health treatment, there will be an
increased level of the reporting of depression symptoms and thereby an improved
opportunity for early intervention, preventing the progression of the disorder.
The second approach to identification involves the development of reliable
assessment strategies for clinical depression. Data suggests that the majority of
those who commit suicide see a physician within thirty days of the suicide. The
field of psychology will continue to strive to identify biological markers and
other methods to predict and identify clinical depression more accurately.
Treatment advances will focus on the further development of nonpharmacological and
pharmacological strategies to increase effectiveness.

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