When a person has depression, it interferes with daily life and normal functioning. It can cause pain for both the person with depression and those who care about him or her. Doctors call this condition “depressive disorder,” or “clinical depression.” It is a real illness. It is not a sign of a person’s weakness or a character flaw. You can’t “snap out of” clinical depression. Most people who experience depression need treatment to get better.

Signs and Symptoms

Sadness is only a small part of depression. Some people with depression may not feel sadness at all. Depression has many other symptoms, including physical ones. If you have been experiencing any of the following signs and symptoms for at least 2 weeks, you may be suffering from depression:

  • Persistent sad, anxious, or “empty” mood
  • Feelings of hopelessness, pessimism
  • Feelings of guilt, worthlessness, helplessness
  • Loss of interest or pleasure in hobbies and activities
  • Decreased energy, fatigue, being “slowed down”
  • Difficulty concentrating, remembering, making decisions
  • Difficulty sleeping, early-morning awakening, or oversleeping
  • Appetite and/or weight changes
  • Thoughts of death or suicide, suicide attempts
  • Restlessness, irritability
  • Persistent physical symptoms

Factors That Play a Role in Depression

Many factors may play a role in depression, including genetics, brain biology and chemistry, and life events such as trauma, loss of a loved one, a difficult relationship, an early childhood experience, or any stressful situation.

Depression can happen at any age, but often begins in the teens or early 20s or 30s. Most chronic mood and anxiety disorders in adults begin as high levels of anxiety in children. In fact, high levels of anxiety as a child could mean a higher risk of depression as an adult.

Depression can co-occur with other serious medical illnesses such as diabetes, cancer, heart disease, and Parkinson’s disease. Depression can make these conditions worse and vice versa. Sometimes medications taken for these illnesses may cause side effects that contribute to depression. A doctor experienced in treating these complicated illnesses can help work out the best treatment strategy.

Research on depression is ongoing, and one day these discoveries may lead to better diagnosis and treatment. To learn more about current research, visit the NIMH website at www.nimh.nih.gov.

Types of Depression

There are several types of depressive disorders.

Major depression: Severe symptoms that interfere with the ability to work, sleep, study, eat, and enjoy life. An episode can occur only once in a person’s lifetime, but more often, a person has several episodes.

Persistent depressive disorder: A depressed mood that lasts for at least 2 years. A person diagnosed with persistent depressive disorder may have episodes of major depression along with periods of less severe symptoms, but symptoms must last for 2 years.

Some forms of depression are slightly different, or they may develop under unique circumstances. They include:

Psychotic depression, which occurs when a person has severe depression plus some form of psychosis, such as having disturbing false beliefs or a break with reality (delusions), or hearing or seeing upsetting things that others cannot hear or see (hallucinations).

Postpartum depression, which is much more serious than the “baby blues” that many women experience after giving birth, when hormonal and physical changes and the new responsibility of caring for a newborn can be overwhelming. It is estimated that 10 to 15 percent of women experience postpartum depression after giving birth.

Seasonal affective disorder (SAD), which is characterized by the onset of depression during the winter months, when there is less natural sunlight. The depression generally lifts during spring and summer. SAD may be effectively treated with light therapy, but nearly half of those with SAD do not get better with light therapy alone. Antidepressant medication and psychotherapy can reduce SAD symptoms, either alone or in combination with light therapy.

Bipolar disorder is different from depression. The reason it is included in this list is because someone with bipolar disorder experiences episodes of extreme low moods (depression). But a person with bipolar disorder also experiences extreme high moods (called “mania”).