National Alliance on Mental Illness
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What is depression?

Major depression is a mood state that goes well beyond temporarily feeling sad or blue. It is a serious medical illness that affects one’s thoughts, feelings, behavior, mood and physical health. Depression is a life-long condition in which periods of wellness alternate with recurrences of illness.

Each year depression affects 5-8 percent of adults in the United States. This means that about 25 million Americans will have an episode of major depression this year alone, but only one-half receive treatment. Without treatment, the frequency and severity of these symptoms tend to increase over time. All age groups and all racial, ethnic and socioeconomic groups can experience depression.

Some individuals may only have one episode of depression in a lifetime, but often people have recurrent episodes. More than one-half of people who experience a first episode of depression will have at least one other episode during his/her lifetime. Some people may have several episodes in the course of a year, and others may have ongoing symptoms. If untreated, episodes commonly last anywhere from a few months to many years.

Major depression is also known as clinical depression, major depressive illness, major affective disorder and unipolar mood disorder. It involves some combination of the following symptoms: depressed mood (sadness), poor concentration, insomnia, fatigue, appetite disturbances, excessive guilt and thoughts of suicide. Left untreated, depression can lead to serious impairment in daily functioning and even suicide, which is the 10th leading cause of death in the U.S. Researchers believe that more than one-half of people who die by suicide are experiencing depression. Depression is a leading cause of disability worldwide and represents a global public health challenge. According to the World Health Organization, it is the forth-leading contributor to Global Burden of Disease, and by 2020, depression is projected to be the second-leading cause. Devastating as this disease may be, it is treatable in most people. The availability of effective treatments and a better understanding of the biological basis for depression may lessen the barriers that can prevent early detection, accurate diagnosis and the decision to seek medical treatment.

Who's at risk?

All age groups and all racial, ethnic and socioeconomic groups can experience depression.

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[Download the NAMI depression fact sheet.]