Major depressive disorder (MDD) is a serious mental health condition that lasts for two or more weeks and significantly interferes with a person’s ability to carry out daily activities or enjoy previously pleasurable experiences. It affects approximately 16 million American adults, or about 6.7% of the U.S. population age 18 and older.

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What Causes Major Depression?

The exact cause of depression is not fully understood. Leading research in neuroscience suggests that depression is linked to imbalances in neurotransmitters, the chemical messengers that send signals between brain cells. Genetics, personal life history, and environmental factors may also contribute to a person’s susceptibility to depression.

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How Common Is Depression?

Depression is highly prevalent in the United States. According to the Center for Behavioral Health Statistics and Quality (2016), approximately 16 million American adults experience major depressive disorder in a given year.

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Is Depression a Serious Disease?

Yes. Major depression can have devastating effects on an individual’s personal, social, and professional life. Nearly all individuals with MDD report disruptions in family life, social interactions, or work performance.

The economic burden of depression in the U.S. was estimated at $210 billion in 2010, making it the second leading cause of disability, accounting for almost 20% of all years of life lost to disability and premature death. Depression can also be life-threatening, contributing to over 30,000 suicides annually in the U.S., with about 60% of these individuals suffering from depression.

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Who Is at Risk for Depression?

Certain factors may increase the likelihood of developing depression:

• Medical conditions such as stroke, heart attack, cancer, Parkinson’s disease, or hormonal disorders

• Genetic predisposition to depression

• Stressful life events, including serious loss, difficult relationships, financial problems, or major life changes

• Certain medications that may increase vulnerability to depression

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While these factors can predispose individuals to depression, the exact relationship between risk factors and the onset of depression continues to be studied.