Definition

Depression is a mental illness marked by feelings of profound sadness and lack of interest in activities. Depression is not the same as a blue mood. It is a persistent low mood that interferes with the ability to function and appreciate things in life. It may cause a wide range of symptoms, both physical and emotional. It can last for weeks, months, or years. People with depression rarely recover without treatment.

Causes

The precise cause is not known. It can be difficult to determine if an illness causes depression or depression caused the illness. Possible causes may be mental, physical, or environmental and include:

  • Stressful life events (usually in combination with one or more of the following causes)
  • Chronic stress
  • Low self-esteem
  • Imbalances in brain chemicals and hormones
  • Lack of control over circumstances (helplessness and hopelessness)
  • Negative thought patterns and beliefs
  • Chronic pain
  • Heart disease and heart surgery
  • Genetic predisposition
  • Altered brain structure and function, including after a stroke
  • Parkinson’s disease
  • Postpartum depression occurs after childbirth
  • Seasonal affective disorder (SAD) is a type of depression or a worsening of symptoms thought to be due to the decreased exposure to sunlight that occurs during winter months
  • Hypothyroidism
  • Anemia
  • Cancer
  • Substance abuse

Researchers are studying how problems with synapses in the brain may be linked to depression.

Brain

Brain Man Face

© 2009 Nucleus Medical Media, Inc.

Risk Factors

Risk factors include:

  • Sex: female
  • Age: elderly
  • Chronic physical or mental illness, including thyroid disease, headaches, chronic pain, and stroke
  • Previous episode of depression
  • Major life changes or stressful life events (eg, bereavement, trauma )
  • Postpartum depression
  • Winter season for SAD
  • Little or no social support
  • Low self-esteem
  • Lack of personal control over circumstances
  • Family history of depression (parent or sibling)
  • Feelings of helplessness
  • Certain medicines, including medicines used to treat asthma , high blood pressure , arthritis, high cholesterol , and heart problems
  • Smoking
  • Anxiety
  • Insomnia
  • Personality disorders
  • Hypothyroidism
  • Type 2 diabetes

Symptoms

Depression can differ from person to person. Some people have only a few symptoms, while others have many.

Symptoms can change over time and may include:

  • Persistent feelings of sadness, anxiety, or emptiness
  • Hopelessness
  • Feeling guilty, worthless, or helpless
  • Loss of interest in hobbies and activities
  • Loss of interest in sex
  • Feeling tired
  • Trouble concentrating, remembering, or making decisions
  • Trouble sleeping, waking up too early, or oversleeping
  • Eating more or less than usual
  • Weight gain or weight loss
  • Thoughts of death or suicide with or without suicide attempts
  • Restlessness or irritability
  • Physical symptoms that defy standard diagnosis and do not respond well to medical treatments

Diagnosis

There is no blood test or diagnostic test for depression. The doctor will ask about your symptoms and medical history, giving special attention to:

  • Alcohol and drug use
  • Thoughts of death or suicide
  • Family members who have or have had depression
  • Sleep patterns
  • Previous episodes of depression

The doctor may also perform specific mental health exams. This will help get detailed information about your speech, thoughts, memory, and mood. A physical exam and other tests can help rule out other causes.

Treatment

Treatment may involve the use of medicine, psychotherapy, or the use of both.

Severe depression usually requires hospital care and the use of drugs.

Antidepressant Medications

Up to 70% of depressed patients find relief from their symptoms with medicine. They can take 2-6 weeks to reach their maximum effectiveness. The medicines include:

Selective Serotonin Reuptake Inhibitors (SSRIs)

Tricyclic Antidepressants

Monoamine Oxidase Inhibitors (MAOIs)

Other Antidepressants

Psychotherapy

Short-term (10-20 weeks) cognitive-behavior therapy (CBT) can help some people. Psychotherapy is designed to help you:

  • Cope with difficulties in relationships
  • Change negative thinking and behavior patterns
  • Resolve difficult feelings

Electroconvulsive Therapy (ECT)

ECT is the use of an electric stimulus to produce a generalized seizure. It may be used in people with severe or life-threatening depression. ECT is also used for people who cannot take or do not respond to medicine. It is considered a safe and effective procedure.

Exercise

A regular exercise program has been shown to relieve some of the symptoms. It should play a large role in the overall management of depression.

Bright Light Therapy

If you have SAD, your doctor may recommend bright light therapy. This involves being exposed to high levels of light from a special "light box" that has a screen on it. Light therapy may decrease melatonin , a hormone that affects sleep cycles, and reduce symptoms of depression.

Dietary Supplements and Herbal Therapy

The herb St. John's wort may be an effective alternative to standard medicines with fewer side effects. St. John's wort, though, may reduce the effectiveness of many drugs, such as antidepressants, birth control pills, blood thinners, and other medicines. It is important that you talk to your doctor first before trying this herb.

There is also some evidence that dehydroepiandrosterone (DHEA), a hormone that is available as a dietary supplement, may help some people.

Dietary Changes

Research suggests that diets high in tryptophan and certain B vitamins may be helpful. There is also mixed evidence that fish oil may reduce symptoms.

If you want to take supplements or change your diet, talk to your doctor first.

Vagal Nerve Stimulation (VNS)

VNS is used as therapy for depression when multiple trials of medicine do not work. A pacemaker-like device stimulates the vagus nerve in the neck.

Vagus Nerve

Vagus Nerve

Stimulation of the vagus nerve (yellow) at the neck is a depression therapy option.

© 2009 Nucleus Medical Media, Inc.

If you are diagnosed with depression, follow your doctor's instructions .

Transcranial Magnetic Stimulation (TMS)

TMS is still under investigation, but seems to have some issues in treatment-resistant depression. An electromagnetic coil is held against your forehead. The change in electrical field stimulates nerves, improving symptoms of depression.

Prevention

Strategies to reduce your chance of becoming depressed include:

  • Being aware of your personal risk
  • Having a psychiatric evaluation and psychotherapy if needed
  • Developing social supports
  • Learning stress management techniques
  • Exercising regularly
  • Not abusing alcohol or drugs
  • Getting adequate sleep, rest, and recreation
  • Eating a Mediterranean diet . This includes plant foods, olive oil, and fish and chicken.