Depression Research Clinic  

What is Depression?

Major Depression, also known as clinical or unipolar depression, is one of the most common mental illnesses. Over 9 million American adults suffer from clinical depression each year. This estimate is likely to be higher since depression commonly remains undiagnosed and untreated in a large percentage of the U.S. population. Major Depression is more than a temporary state of feeling sad; rather, it is a persistent state that can significantly impair an individual's thoughts, behavior, daily activities, and physical health.

Major Depressive Disorder impacts all racial, ethnic, and socioeconomic groups and can occur at any age. The average lifetime prevalence of depression is 17%: 26% for women and 12% for men. The mean age for a first episode is in the thirties. Demographic differences show that rates are higher in urban rather than in rural areas. No racial significance has been noted. Along gender lines, women suffer from depression at twice the rate of men. Statistics have shown that one out of every seven women will experience at least one depressive episode in their lifetime. This gender difference is best explained by looking at the interplay between biological, genetic, psychological, social, and environmental factors.

Classified as mood disorders, major depression, along with other depressive disorders such as dysthymia (a chronic less severe form of depression), and bipolar disorder (manic depression) fall along a spectrum. On one end of the spectrum is unipolar or major depression and on the opposite is bipolar disorder or manic depression, both with varying degrees of severity and duration. Along this spectrum, there are several categories of mood disorders, such as postpartum depression, seasonal affective disorder (SAD) and psychotic depression, as well as variants of bipolar disorder. Bipolar disorder is characterized by severe and disabling cycles of depression and mania.

Mood disorders are highly treatable conditions, with each type requiring different treatment approaches and modalities. Antidepressant medications and psychotherapies offer useful treatment approaches and are commonly employed in treating the debilitating effects of depression. However, if mood disorders are left untreated for long periods of time, the debilitating effects of depression can lead to suicide.

SYMPTOMS OF MAJOR DEPRESSIVE DISORDER

Symptoms of Major Depression represent a significant change from the individual's normal level of functioning. Together the symptoms cause significant distress or impairment in the individual's life and his/her ability to function. Depression symptoms can occur with either a sudden onset or in a more gradual fashion, with the severity of symptoms ranging from mild to severe.

A Major Depressive Episode is defined as having five or more of the following symptoms present for the same two-week period, and represents a change from the individual's normal level of functioning when well. At least one of the five required symptoms must be (1) depressed mood or (2) loss of interest.

  1. depressed mood experienced most of the day, nearly every day;
  2. diminished interest or pleasure in all or almost all activities most of the day, nearly every day;
  3. significant change in appetite (increase or decrease) or weight (loss or gain);
  4. insomnia or hypersomnia nearly every day;
  5. observable psychomotor agitation (feeling restless or fidgety) or retardation (feeling slowed down) nearly every day;
  6. loss of energy or fatigue nearly every day;
  7. feelings of worthlessness, or excessive or inappropriate guilt, nearly every day (not merely self reproach about being sick);
  8. diminished ability to think or concentrate, or indecisiveness, nearly every day (either subjective account or observed by others);
  9. recurrent thoughts of death, recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide.

SYMPTOMS OF MAJOR DEPRESSION WITH PSYCHOTIC FEATURES (PMD)

Symptoms of major depression with psychotic features include all of the symptoms of major depressive disorder listed above. In addition, patients experience delusions and/or hallucinations. Examples of these latter symptoms include feelings as though other people are out to harm them, feeling as though one has special powers to do things that other people cannot do, feeling overwhelmed with guilt, or hearing voices that put one down.

In psychotic major depression, the delusions and/or hallucinations only occur when the person is also experiencing significant depression. These symptoms do not occur when the person is no longer depressed. If one experiences these psychotic symptoms when they are not depressed, there are other diagnoses that would need to be considered.

SYMPTOMS OF DYSTHYMIC DISORDER

The differentiation of dysthymic disorder from major depressive disorder can be difficult. Key features of dysthymia are a mild to moderate depressed mood that has a chronic course (greater than 2 years). Dysthymia is characterized by the following:

  1. Depressed mood for most of the day, for more days than not, for at least two years.
  2. While depressed, there must be present 2 or more of the following: poor appetite or over-eating, insomnia or hypersomnia, low energy/fatigue, low self-esteem, poor concentration or difficulty making decisions, feelings of hopelessness.
  3. During the two-year period, the patient has never been without the symptoms in number 1 or 2 for more than 2 months at a time.
  4. No history of a major depressive episode, manic episode, mixed episode, hypomanic episode or cyclothymic disorder.
  5. The symptoms cause significant impairment or distress.

SYMPTOMS OF BIPOLAR DISORDER

Bipolar Disorder is a spectrum of disorders that are distinguished from Major Depressive Disorder by the presence of manic or hypomanic episodes. During the depressed periods, patients experience symptoms of major depression (see above). Contrasted by the manic periods where patients experience mania episodes. A manic episode is characterized as follows:

Manic Episode
  1. Distinct period of abnormally and persistently elevated, expansive or irritable mood, lasting for at least one week (or any duration if hospitalization is necessary).
  2. During the period of mood disturbance, three (or more) of the following symptoms (four if the mood is only irritable) have been present to a significant degree:
    1. inflated self-esteem or grandiosity
    2. decreased need for sleep
    3. more talkative than usual or pressure to keep talking
    4. disconnected or racing thoughts
    5. distractibility
    6. increase in goal-directed activity (either socially, at work or school, or sexually) or psychomotor agitation
    7. excessive involvement in inappropriate social behavior
  3. The mood symptoms cause significant impairment or distress, or severity of illness requires hospitalization to prevent harm to self or others, or there are psychotic features.

For more information on Bipolar Disorder: http://www.ndmda.org/

CAUSES OF DEPRESSION

The exact etiology of depression is yet to be determined; however, multiple factors, including biological, psychological, and environmental factors are involved in the presentation of depression. For example, an individual who has a first-degree relative with depression has a four times higher risk of developing depression than the general population. Twin studies have shown that an individual with a monozygotic twin with depression has as high as a fifty percent chance of developing the disorder.

Major depression is caused by imbalance of certain neurotransmitters (chemical messengers) in the brain, such as serotoninresearch, norepinephrine, and dopamine. Antidepressants work either by changing the sensitivity of the receptors or by increasing the availability of neurotransmitters in the brain.

In addition to genetic components, there are many psychosocial factors that contribute to the development of mood disorders. For example, an individual with little or no social support will have fewer resources to handle stress and thereby will be at a greater risk of developing a mood disorder.

TREATMENT OF MAJOR DEPRESSION

Major depression is a highly treatable illness. Between 80 to 90% of individuals who suffer from severe depression are effectively treated and return to a normal level of functioning. Treatment of depression depends on the individual as well as the severity and duration of the illness. Basic types of treatment for depression include antidepressant medications, psychotherapy, or electroconvulsive therapy (ECT). Often these basic treatment approaches are used in combination. Antidepressants are one of the largest groups of pharmaceuticals produced in the world and the second largest produced in the United States. Currently, over two-dozen antidepressants are on the market.

Antidepressants are successful in 60-80% of patients. No single antidepressant drug has been shown to be more effective than another. Antidepressants work by correcting imbalances in neurotransmitters. Generally, antidepressants take several weeks and up to months to show efficacy and each has their own side effect profile.

For more information on antidepressant treatments: http://www.nimh.nih.gov/publicat/medicate.cfm

Additionally, several methods of short-term, goal-oriented psychotherapy have proven successful in the treatment of depression, such as cognitive behavioral therapy (CBT) and interpersonal therapy. Cognitive behavioral therapy addresses the negative thinking and behavioral patterns associated with depression, and teaches the individual to recognize and target the self-defeating behavioral patterns that contribute to their depression. In contrast, interpersonal therapy has a focus on improving disturbed or unhealthy personal relationships, which may be contributing to the individual's depression.

The final treatment approach, electroconvulsive therapy (ECT), is employed in cases of severe treatment-resistant depression. An electric current is passed through the brain to produce a seizure, thereby affecting chemical activity in all regions of the brain. It is believed that, with repeated treatments, chemical changes build upon one another to help restore the normal chemical balance in the brain and help to alleviate symptoms of depression.

For more information about ECT and other treatment approaches: http://www.mayoclinic.com/health/electroconvulsive-therapy/MY00129

Stanford Medicine Resources:

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