Depression is a mental health condition that causes a chronic feeling of emptiness, sadness, or inability to feel pleasure that may appear to happen for no clear reason.

Depression is the leading cause of disability worldwide, according to the World Health Organization (WHO).

It can undermine a person’s relationships, make working and maintaining good health very difficult, and in severe cases, may lead to suicide. In fact, depression contributes to nearly 40,000 suicides in the United States each year.

It can affect adults, adolescents, and children. This article examines what depression is and what causes it, as well as types of depression, treatment, and more.

Depression is a mood disorder that causes persistent feelings of sadness, emptiness, and loss of joy. It is different from the mood fluctuations that people regularly experience as a part of life.

Major life events, such as bereavement or the loss of a job, can triggerTrusted Source depression. But depression is distinct from the negative feelings a person may temporarily have in response to a difficult life event.

Depression often persists in spite of a change of circumstances and causes feelings that are intense, chronic, and not proportional to a person’s circumstances.

It is an ongoing problem, not a passing one. While there are different types of depression, the most common one is major depressive disorder. It consists of episodes during which the symptoms last for at least two weeks.Trusted Source

Depression can last for several weeks, months, or years. For many people, it is a chronic illness that gets better and then relapses.

Is it curable?

While there is no cure for depression, there are effective treatments that help with recovery. The earlier that treatment starts, the more successful it may be. Some people may never experience depression again after a single period of it. Others will continue to have relapses.

Many people experiencing depression recover after a treatment plan. Even with effective treatment, however, a relapse may occur. About halfTrusted Source of people do not initially respond to treatment.

To prevent relapse, people who take medication for depression should continue with treatment — even after symptoms improve or go away — for as long as their doctor advises.

Signs and symptoms

Depression can cause a range of psychological and physical symptoms, includingTrusted Source:

• persistent depressed mood
• loss of interest or pleasure in hobbies and activities
• changes in appetite and body weight
• unusually slow or agitated movements
• decreased energy or fatigue
• difficulty sleeping or oversleeping
• excessive feelings of guilt or worthlessness
• difficulty concentrating or making decisions
• thoughts of death or suicide, or suicide attempt

Depression may also causeTrusted Source other symptoms, including irritability, restlessness, chronic pain, headaches, and digestive issues.

What causes depression?

The medical community does not fully understand the causes of depression. There are many possible causes, and sometimes, various factors combine to trigger symptoms.

Factors that are likely to play a role include:

• genetic features
• changes in the brain’s neurotransmitter levels
• environmental factors such as exposure to trauma or lack of social support
• psychological and social factors
• additional conditions, such as bipolar disorder

Interactions between various factors can increase the risk of depression. For instance, a person with a family history or a genetic risk of depression may experience symptoms of depression following a traumatic event.

The symptoms of depression can include:

• a depressed mood
• reduced interest or pleasure in activities that a person previously enjoyed
• a loss of sexual desire
• changes in appetite
• unintentional weight loss or gain
• sleeping too much or too little
• agitation, restlessness, and pacing up and down
• slowed movement and speech
• fatigue or loss of energy
• feelings of worthlessness or guilt
• difficulty thinking, concentrating, or making decisions
• recurrent thoughts of death or suicide, or an attempt at suicide