Major Depression


What is major depression?

Major depression is a serious medical illness affecting 15 million American adults, or approximately 5 to 8 percent of the adult population in a given year. Unlike normal emotional experiences of sadness, loss, or passing mood states, major depression is persistent and can significantly interfere with an individual’s thoughts, behavior, mood, activity, and physical health. Among all medical illnesses, major depression is the leading cause of disability in the U.S. and many other developed countries.

Depression occurs twice as frequently in women as in men, for reasons that are not fully understood. More than half of those who experience a single episode of depression will continue to have episodes that occur as frequently as once or even twice a year. Without treatment, the frequency of depressive illness as well as the severity of symptoms tends to increase over time. Left untreated, depression can lead to suicide.

Major depression, also known as clinical depression or unipolar depression, is only one type of depressive disorder. Other depressive disorders include dysthymia (chronic, less severe depression) and bipolar depression (the depressed phase of bipolar disorder or manic depression). People who have bipolar disorder experience both depression and mania. Mania involves unusually and persistently elevated mood or irritability, elevated self-esteem, and excessive energy, thoughts, and talking.

What are the symptoms of major depression?

The onset of the first episode of major depression may not be obvious if it is gradual or mild. The symptoms of major depression characteristically represent a significant change from how a person functioned before the illness. The symptoms of depression include:

  • persistently sad or irritable mood
  • pronounced changes in sleep, appetite, and energy
  • difficulty thinking, concentrating, and remembering
  • physical slowing or agitation
  • lack of interest in or pleasure from activities that were once enjoyed
  • feelings of guilt, worthlessness, hopelessness, and emptiness
  • recurrent thoughts of death or suicide
  • persistent physical symptoms that do not respond to treatment, such as headaches, digestive disorders, and chronic pain


When several of these symptoms of depressive illness occur at the same time, last longer than two weeks, and interfere with ordinary functioning, professional treatment is needed.

What are the causes of major depression?

There is no single cause of major depression. Psychological, biological, and environmental factors may all contribute to its development. Whatever the specific causes of depression, scientific research has firmly established that major depression is a biological, medical illness.

Norepinephrine, serotonin, and dopamine are three neurotransmitters (chemical messengers that transmit electrical signals between brain cells) thought to be involved with major depression. Scientists believe that if there is a chemical imbalance in these neurotransmitters, then clinical states of depression result. Antidepressant medications work by increasing the availability of neurotransmitters or by changing the sensitivity of the receptors for these chemical messengers.

Scientists have also found evidence of a genetic predisposition to major depression. There is an increased risk for developing depression when there is a family history of the illness. Not everyone with a genetic predisposition develops depression, but some people probably have a biological make-up that leaves them particularly vulnerable to developing depression. Life events, such as the death of a loved one, a major loss or change, chronic stress, and alcohol and drug abuse, may trigger episodes of depression. Some illnesses such as heart disease and cancer and some medications may also trigger depressive episodes. It is also important to note that many depressive episodes occur spontaneously and are not triggered by a life crisis, physical illness, or other risks.

How is major depression treated?

Although major depression can be a devastating illness, it is highly treatable. Between 80 and 90 percent of those diagnosed with major depression can be effectively treated and return to their usual daily activities and feelings. Many types of treatment are available, and the type chosen depends on the individual and the severity and patterns of his or her illness. There are three well-established types of treatment for depression: medications, psychotherapy, and electroconvulsive therapy (ECT). For some people who have a seasonal component to their depression, light therapy may be useful. These treatments may be used alone or in combination. Additionally, peer education and support can promote recovery. Attention to lifestyle, including diet, exercise, and smoking cessation, can result in better health, including mental health

*From: www.nami.org