Depressive Disorders: Overview

Major or clinical depression (dih-FRESH-un) is a mental disorder that causes people to feel long-lasting sadness and to lose interest in activities that normally give them pleasure. It is also referred to as unipolar depression because patients have only one type of feeling: sadness.

Jodie's Story

The sun is shining brightly, but 15-year-old Jodie feels darkness all around her. She used to sleep so soundly that her father said he needed a cannon blast to wake her. In recent weeks, however, she rises unexpectedly in the gray light before dawn. She lies awake staring at reflections on the ceiling of her bedroom caused by the headlights of passing cars, and cries as the distorted shapes cross her ceiling.

Did You Know?

The onset of puberty is associated with an increase in depression among adolescent girls. According to the annual National Survey on Drug Use and Health (updated in January 2015), an annual average of 1.4 million girls age 12 to 17 (or 12%) experience a major depressive episode each year. The percentage of girls who experience a major depressive episode triples between the ages of 12 and 15 years. Researchers are not sure why girls in this age group have a higher rate of depression than boys, but some think it may be related to girls' greater vulnerability to sexual abuse.

Clinical depression affects about 7 to 18 percent of the population before the age of 40 years on at least one occasion in their lives. According to the World Health Organization, by 2020, depression is anticipated to be the second-leading cause of disability worldwide (after heart disease). The majority of people who commit suicide have a depressive disorder.

What Are Depressive Disorders?

Jodie has major or unipolar depression, a disorder that affects more than 17 million people in the United States at any given time. Although people often say they are depressed when they feel low, an occasional “blue mood” is not the same thing as the mental disorder called depression. The condition often leads to constant negative thinking and sometimes substance abuse or self-harm. Extreme depression can lead to a person's attempting or committing suicide.

Everyone feels sad at times. Perhaps a relative has died, a dating relationship ends, or the home team has lost an important game. Usually, however, in a short time, that unhappy mood passes and the person is excited about a day at the beach, a new boyfriend or girlfriend, or a good grade on a test. By contrast, people with depression have long periods when nothing seems to lift their mood. It affects their whole body and mind—how they feel, think, and behave. The good news is that if people with depression get professional help, more than 80 percent of them can feel better, often within a few weeks.

The award-winning author William Styron, who wrote the book Sophie's Choice, suffered from depression. In Darkness Visible, a book about his own depression, Styron calls the disorder a “veritable howling tempest in the brain.” He compares depression with a storm that blows away all of a person's usual good feelings and abilities to cope with life.

Depression comes in many forms. The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) established guidelines for determining which kind of depression a person may have. According to the manual, major depression or clinical depression involves excessive sadness and/or loss of interest that lasts for at least two weeks. Episodes of intense sadness may be a single occurrence or recur, when certain events happen over one's life span. In some cases, the “down” period lasts for many weeks or months. At times, a person with major depression may feel as if the disease has gone away on its own. Normal feelings return like the ones the individual used to experience. But like the tides that move in and out on a beach, the suffering usually comes back if the person does not get treatment. About 20 percent of women and 12 percent of men in the United States experience this type of depression at some point in their lives.

Adolescent depression: Percentage of U.S. youth ages 12–17 with at least one major depressive episode (MDE) in the past year who received treatment for depressiona by age, gender, race and Hispanic origin, and poverty status, 2004–2013

Adolescent depression: Percentage of U.S. youth ages 12–17 with at least one major depressive episode (MDE) in the past year who received treatment for depressiona by age, gender, race and Hispanic origin, and poverty status, 2004–2013
SOURCE: Substance Abuse and Mental Health Services Administration, Center for Behavioral Health Statistics and Quality, National Survey on Drug Use and Health. Table by Cenveo Publisher Services. © 2016 Cengage Learning®.

NOTE: MDE is defined as in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV),1 which specifies a period of at least 2 weeks when a person experienced a depressed mood or loss of interest or pleasure in daily activities and had a majority of specified depression symptoms. Respondents with unknown past year MDE were excluded. American Psychiatric Association. (1994). Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (4th ed.). Washington, DC: Author.

Bipolar disorder (sometimes called manic depression) is a very different type of depressive disorder. People with bipolar disorder have periods of almost unlimited energy, wild happiness, and hyperactivity (mania), followed by periods of depression. The mood extremes may be mild or severe, and the mood changes may occur slowly or quickly. Because this type of depression involves two different feelings, it is called bipolar depression, to distinguish it from unipolar depression. Only about 1 percent of people with a depressive disorder have bipolar disorder.


Some studies show that depression can occur in several members of the same family. Certain genes * passed from parent to child may increase the chance of becoming depressed. The strongest evidence of heredity comes from twin studies. Researchers have found that identical twins, who have the same genes, are twice as likely to experience major depression as fraternal twins, who do not have identical genes. Twin studies show that about 50 percent of the possible cause of depression is genetic; the other 50 percent is derived from other factors. Someone who has a parent or sibling with major depression has a two to three times greater risk of developing depression compared to the average person. Specific single genes do cause some diseases, such as cystic fibrosis, but researchers think that the interactions of many genes predispose some people to depression. Two genes that were identified as being associated with depression as of 2016 were the MDD1 gene on chromosome 12, linked to major depression in males; and the MDD2 gene on chromosome 15, linked to early-onset depression and recurrent episodes of depression.


Some researchers who study depression and the brain have found links between depression and an imbalance in certain chemicals in the nervous system, known as neurotransmitters. These chemicals enable brain cells to communicate with each other and allow the brain to function normally. In people with depression, the nervous system may have either too much or too little of these chemicals, especially serotonin * and norepinephrine * . Some research has suggested a link between depression and the hippocampus, a horseshoe-shaped structure in the brain that helps to regulate both mood and memory. Several other physical conditions may relate to depression:

Mental Habits

Some researchers observe that certain people seem more vulnerable to depression because of their thought patterns: how they think about themselves and their lives. For example, people with low self-esteem may be more likely to develop depression. They may think they are ugly, stupid, or always saying the wrong things, even if family and friends tell them differently. People who tend to be pessimistic can become overwhelmed by depressed feelings. Such people see only the negative aspects in many situations, and have feelings of helplessness and fatalism. Perfectionists, who often set unrealistic goals for themselves, are also prone to depression.

Personal History and Social Environment

Recent scientific research has indicated that the size of the subgenual prefrontal cortex (sub-JEN-yoo-al pre-FRONtal KOR-teks) of the brain (located behind the bridge of the nose)

Recent scientific research has indicated that the size of the subgenual prefrontal cortex (sub-JEN-yoo-al pre-FRONtal KOR-teks) of the brain (located behind the bridge of the nose) may be a determining factor in hereditary depressive disorders. This part of the brain is particularly rich in proteins that carry the neurotransmitter serotonin to other parts of the brain and also help to recycle the serotonin; thus an abnormally small subgenual prefrontal cortex would increase a person's risk of depression.
Illustration by Electronic Illustrators Group. © 2016 Cengage Learning®.

Computer-generated positron emission tomography (PET) scans show the brain of a healthy person (top) in contrast to the brain of a person with untreated depression (bottom). Doctors and researchers use PET scans to study how the brain functions.

Computer-generated positron emission tomography (PET) scans show the brain of a healthy person (top) in contrast to the brain of a person with untreated depression (bottom). Doctors and researchers use PET scans to study how the brain functions.
Science Source.

Any one of these factors may lead to depression, but depression often occurs for a combination of reasons. For example, it is normal for a teenager who loses a parent to feel sad; but if the teenager already thinks that the world is a terrible place and nothing good ever happens, the stress of the loss might be worse for this teen than for another. If the teenager also inherited a gene linked to depression, it may be difficult for the individual to bounce back from the loss without treatment.

How Common Are Depressive Disorders?

Depressive disorders are one of the most common mental health concerns. The National Institutes of Health estimates that more than 20 million people in the United States battle depression. At any time, 3 to 5 percent of people suffer from an episode of major depression.

How Do People Know They Have Depressive Disorders?

Major depression and chronic depression involve a variety of symptoms. Some people experience only a few symptoms, whereas others feel most of them. Possible symptoms include the following:

These symptoms must last for at least two weeks and be present every day for most of the day before depression is diagnosed. If the person has recently experienced a major loss, the symptoms must last for two months or longer before it is considered depression, and then it might be called reactive depression—meaning that the person is adjusting to (or reacting to) a serious loss. For people with major depression, the symptoms may occur once or return over and over. For those with chronic depression, the symptoms linger for a long time.

How Do Doctors Diagnose and Treat Depressive Disorders?


Depression is not always easy to diagnose. When a person cannot move one arm after a fall, the doctor can order an x-ray to check for a broken bone. The symptoms of depression may not be so obvious.

Sometimes, people with depression do not realize that they have the disorder. They might sense that things are wrong, but often it is a family member, friend, coworker, family doctor, or teacher who notices the problem. That is when a professional who specializes in mental health, such as a psychiatrist * or clinical psychologist * , should be consulted. Such professionals are trained to observe how a person acts and talks. They look for symptoms of depression and decide what to do based on what they see and hear from the person and the person's family.

They may also ask the person to fill out one or more short questionnaires in the office, such as the Beck Depression Inventory (BDI) or the Patient Health Questionnaire-9 (PHQ-9). These are brief screening questionnaires that help the psychiatrist evaluate the patient's symptoms. In some cases the mental health professional will also ask the patient to undergo blood or urine tests in order to rule out medical illnesses that may appear with the symptoms of major depressive disorder.


Almost all people who develop depression can be helped. Statistics show that about 8 of every 10 people who get help find that their symptoms improve. Two primary kinds of treatment are used: psychotherapy and medication.


Psychotherapy or counseling (sometimes called talk therapy) assists individuals in understanding and resolving habits or problems that may be contributing to or cause depression. Depressed people may benefit from talking with a psychiatrist, clinical psychologist, clinical social worker, or other mental health counselor. Mental health professionals can help depressed individuals learn how to cope better with such stressful situations as moving to a new town or experiencing problems at home. Family members sometimes also take part in counseling.


There are several classes of antidepressant medications that psychiatrists and other physicians can prescribe to affect the way that neurotransmitters work in the brain. These medications correct the chemical imbalance that causes the symptoms of depression and allow a person to feel better. Examples of medications that are prescribed for depression include the following:

Depression and Fame

Many famous people, both those in the distant past and those more recently, have struggled with depression. While it was difficult for people to admit to depression before the 1970s, most public figures today believe that open discussion of depression and the treatments available for it is beneficial to others wrestling with the same disorder. Here is a partial list of well-known people who have experienced depression:

Presidents of the United States: John Adams, Abraham Lincoln, Calvin Coolidge

Artists: Caravaggio, Michelangelo, Vincent van Gogh, Francisco Goya, Paul Gauguin, Edgar Degas, Henri Matisse

Writers: Hans Christian Andersen, Joseph Conrad, Edgar Allan Poe, Agatha Christie, Emily Dickinson, Ernest Hemingway, Charles Dickens, Mark Twain, Walt Whitman, Virginia Woolf

Scientists: Sir Isaac Newton, Charles Darwin, J. Robert Oppenheimer, Julian Huxley

Musicians: Wolfgang Amadeus Mozart, Robert Schumann, Vladimir Horowitz, Gustav Mahler, Sergei Rachmaninoff, Pyotr Ilyich Tchaikovsky

Athletes: Terry Bradshaw, Zack Greinke, Joey Votto, Ken Griffey Jr., Mike Tyson

Actors: Audrey Hepburn, Marilyn Monroe, Alan Alda, Bill Murray, Hugh Laurie, Angelina Jolie, Anthony Hopkins, Robin Williams, Johnny Depp, Jean Seberg, Delta Burke

If one medication does not work in a matter of weeks or has side effects, another can be tried. Medications work best for individuals who are also being treated with psychotherapy. On the other hand, medications and mental health counseling do not work for everyone. About 20 percent of people with the most severe symptoms of depression do not respond well to these treatments, either used alone or in combination.

Some severe cases of depression require the person to spend time in a hospital for more intensive observation and treatment. In addition, psychiatrists sometimes treat such severe cases with electroconvulsive therapy (ECT). This procedure involves passing a small amount of electricity through the brain after the person has been given a muscle relaxant and general anesthesia. Although ECT is a controversial procedure, many people who receive the treatment report feeling better.

About two-thirds of the people with symptoms of depression do not seek or get the proper help. The disorder often makes it hard for them to recognize what is wrong. Some people try to mask depression by using alcohol or illicit drugs, but such self-medication usually just makes the depression worse. Other people might believe their mood problem can be overcome without outside help, so they endure the symptoms without seeking assistance. Such people need to understand that depression is an illness, not a character flaw. Just as something can go wrong with the heart or lungs, people can have a chemical imbalance or structural difference in their brain.

People should seek help if they experience long periods of sadness or other symptoms of depression. A young person should talk with parents, relatives, teachers, school counselors, or a close adult friend about these feelings, especially if they include thoughts of suicide. In most cases, people with depressive disorders can be helped with proper treatment.

Can Depressive Disorders Be Prevented?

See also Aging • Alcoholism • Bipolar Disorder • Child Abuse • Chronic Illness • Death and Dying • Insomnia • Pain • Psychopharmacology • Seasonal Affective Disorder (SAD) • Sexual Abuse • Stress and Stress-Related Illness • Substance Abuse • Suicide • Trauma


Books and Articles

Korb, Alex. The Upward Spiral: Using Neuroscience to Reverse the Course of Depression, One Small Change at a Time. Oakland, CA: New Harbinger, 2015.

Solomon, Andrew. The Noonday Demon: An Atlas of Depression. Reissue edition. New York: Scribner, 2014.


American Academy of Child and Adolescent Psychiatry. “Facts for Families Guide: Depression in Children and Teens.” (accessed April 5, 2016).

National Alliance on Mental Illness. “Depression.” (accessed April 5, 2016).

National Institute of Mental Health. “Antidepressant Medications for Children and Adolescents: Information for Parents and Caregivers.” (accessed April 5, 2016).


American Psychiatric Association. 1000 Wilson Blvd., Suite 1825, Arlington, VA 22209. Telephone: 703-907-7300. Website: (accessed April 5, 2016).

Depression and Bipolar Support Alliance. 55 E Jackson Blvd., Suite 490, Chicago, IL 60604. Toll-free: 800-826-3632. Website: (accessed April 5, 2016).

National Institute of Mental Health. 6001 Executive Blvd., Room 8184, MSC 9663, Bethesda, MD 20892-9663. Toll-free: 866-615-6464. Website: (accessed April 5, 2016).

National Survey on Drug Use and Health. Toll-free: 800-848-4079. (accessed April 5, 2016).

* genes (JEENS) are chemical structures composed of deoxyribonucleic acid (DNA) that help determine a person's body structure and physical characteristics. Inherited from a person's parents, genes are contained in the chromosomes found in the body's cells.

* serotonin (ser-o-TO-nin) is a neurotransmitter, a substance that helps transmit information from one nerve cell to another in the brain. It is associated with feelings of well-being.

* norepinephrine (NOR-eh-puh- NEH-fruhn) is a body chemical that increases the arousal response, heart rate, and blood pressure.

* psychiatrist (sy-KY-uh-trist) is a medical doctor who has completed specialized training in the diagnosis and treatment of mental illness. Psychiatrists can diagnose mental illnesses, provide mental health counseling, and prescribe medications.

* clinical psychologist is a mental health professional who has earned a nonmedical doctoral degree. Clinical psychologists can perform psychological evaluations and provide mental health counseling and therapy.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)