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Related terms
Risk factors and causes
Author information
Types of depression

Related Terms
  • Adjustment disorder, antidepressants, antipsychotics, anxiety, atypical depression, bipolar, brain, cocaine, cognitive-behavioral therapy (CBT), computerized tomography (CT), congestive heart failure (CHF), depression, dialysis dementia, dopamine, dysthymic disorder, DSM-IV, ecstasy, electroconvulsive therapy (ECT), encephalitis, extrapyramidal, fatigue, hallucinations, hypomania, interpersonal therapy (IPT), lumbar puncture, magnetic resonance imagining (MRI), major depression, manic-depressive illness, marijuana, meningitis, methamphetamine, neurotransmitter, norepinephrine, positron emission tomography (PET), postpartum mania, premenstrual dysphoric disorder (PMDD), psychotherapy, psychosis, seasonal affective disorder (SAD), serotonin, suicidal, thyroid.

  • Depression or depressive disorder is an illness that involves the body, mood, and thoughts. Depression is considered a mood disorder. Imbalances in three neurotransmitters (brain chemicals), including serotonin, norepinephrine, and dopamine, are linked to depression. Depression affects the way a person eats and sleeps, the way one feels about oneself, and the way one thinks about life situations. Unlike normal emotional experiences of sadness, loss, or passing mood states, depressive disorders are persistent and can significantly interfere with an individual's thoughts, behavior, mood, activity, and physical health.
  • According to the National Institute of Mental Health (NIMH), depressive disorders affect approximately 18.8 million American adults or about 9.5% of the U.S. population age 18 and older in a given year. This includes major depressive disorder (severe depression), dysthymic disorder (mild to moderate depression), and bipolar disorder (manic-depressive). Among all medical illnesses, major depression is the leading cause of disability in the U.S. and many other developed countries.
  • Without treatment, symptoms can last for weeks, months, or years. Appropriate treatment, however, can help most people who suffer from depression.
  • Children and teenagers can also suffer from depression. Depression in the young is defined as an illness when the feelings of depression persist and interfere with a child or adolescent's ability to function.
  • The American Academy of Child and Adolescent Psychiatry estimates that about 5% of children and adolescents in the general population suffer from depression at any given point in time. Children under stress, who experience loss, or who have trouble with attention, learning, conduct, or anxiety disorders are at a higher risk for depression.

Risk factors and causes
  • Neurotransmitter imbalances: Studies suggest that a low or high level of neurotransmitters such as serotonin, norepinephrine, or dopamine cause depression. Studies have found evidence that a change in the sensitivity of the receptors on nerve cells to these neurotransmitters may be one issue, along with an imbalance in the amounts of neurotransmitters. Balancing neurotransmitters with drug therapy is the current focus for treatment of major depression.
  • Heredity: Researchers have identified several genes that may be involved in bipolar disorder and are looking for genes linked to other types of depression. But not everyone with a family history of depression develops the disorder, and conversely, people with no family history of the disorder can become depressed.
  • Gender: Depression occurs twice as frequently in women as in men, for reasons that are not fully understood. Hormonal changes such as menstrual cycle changes, postpartum period, pre-menopause, pregnancy, childbirth, miscarriage, and menopause are the most likely causes of depression.
  • Although men are less likely to suffer from depression than women, six million men in the United States are affected by the illness. Men are less likely to admit to depression. The rate of suicide in men is four times that of women, though more women attempt it.
  • Stress: Stressful life events, particularly a loss or threatened loss of a loved one or a job, can trigger depression.
  • Medications: Long-term use of certain medications, such as some drugs used to control high blood pressure, sleeping pills, or birth control pills, may cause symptoms of depression in some people.
  • Illnesses: Having a chronic illness, such as heart disease, stroke, diabetes, cancer or Alzheimer's disease, puts an individual at a higher risk of developing depression. Having an underactive thyroid (hypothyroidism), even mildly, also can cause depression. Physical trauma (damage) to the brain can also trigger depression.
  • Personality: Certain personality traits, such as having low self-esteem and being overly dependent, self-critical, pessimistic and easily overwhelmed by stress, can make an individual more vulnerable to depression.
  • Postpartum depression: It is common for mothers to feel a mild form of distress that usually occurs a few days to weeks after giving birth. During this time the woman may have feelings of sadness, anger, anxiety, irritability and incompetence. A more severe form of the baby blues, called postpartum depression, also can affect new mothers.
  • Hormones: Women experience depression about twice as much as men, which leads researchers to believe hormonal factors may play a role in the development of depression.
  • Alcohol, smoking, and drug abuse: Abuse of alcohol, cigarettes, and recreational drugs such as cocaine, methamphetamine (crystal meth), ecstasy, and marijuana can lead to depression.
  • Previous depression: 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.

  • Treatment for depression usually involves a combination of drug and psychological therapies.
  • Psychotherapy: Psychotherapy involves talking to a healthcare professional about one's problems and life situation. There are several types of psychotherapy that have been shown to be effective for depression including cognitive-behavioral therapy (CBT) and interpersonal therapy (IPT). Research has shown that mild to moderate depression can often be treated successfully with either of these therapies used alone. However, severe depression appears more likely to respond to a combination of psychotherapy and medication.
  • Cognitive-behavioral therapy (CBT): CBT helps to change the negative thinking and unsatisfying behavior associated with depression, while teaching individuals how to unlearn the behavioral patterns that contribute to their depression.
  • Interpersonal therapy (IPT): IPT focuses on improving troubled personal relationships and on adapting to new life roles that may have been associated with a person's depression.
  • Medications: Drugs used for depression often take two to four weeks to start having an effect, and 6-12 weeks to have their full effect. The first antidepressant medications were introduced in the 1950s. Research has reported that imbalances in neurotransmitters like serotonin, dopamine, and norepinephrine can be improved with antidepressant use.
  • Selective serotonin reuptake inhibitors (SSRIs): SSRIs act specifically on the neurotransmitter (brain chemical) serotonin. Serotonin is mainly involved with mood balance. SSRIs are the most common agents prescribed for depression worldwide. These agents increase the amount of serotonin that is available for use by the brain. SSRIs include fluoxetine (Prozac®), sertraline (Zoloft®), paroxetine (Paxil®), citalopram (Celexa®), escitalopram (Lexapro®), and fluvoxamine (Luvox®).
  • Serotonin and norepinephrine reuptake inhibitors (SNRIs): SNRIs are the second-most popular antidepressants worldwide. These agents increase the amount of both serotonin and norepinephrine. SNRIs include venlafaxine (Effexor®) and duloxetine (Cymbalta®). SSRIs and SNRIs tend to have fewer side effects than other types of antidepressants. Side effects include nausea, nervousness, insomnia, diarrhea, rash, agitation, or sexual side effects (problems with arousal or orgasm).
  • Norepinephrine-dopamine reuptake inhibitor (NDRI): NDRIs acts by increasing the amounts of dopamine and norepinephrine available to the brain. Bupropion (Wellbutrin®) is commonly used as an antidepressant in this class.
  • Tricyclic antidepressants (TCAs): TCAs are older antidepressants that are not used as frequently now. They work similarly to the SNRIs, but have other properties that result in very high side effect rates, as compared to almost all other antidepressants. They are sometimes used in cases where other antidepressants have not worked. TCAs include amitriptyline (Elavil®), desipramine (Norpramin®), doxepin (Sinequan®), imipramine (Norpramin®, Tofranil®), nortriptyline (Pamelor®, Aventyl®), and protriptyline (Vivactil®). TCAs cause side effects that include dry mouth, constipation, bladder problems, sexual problems, blurred vision, dizziness, drowsiness, skin rash, and weight gain or loss.
  • Monoamine oxidase inhibitors (MAOIs): MAOs are seldom used now for depression. They also increase amounts of serotonin, norepinephrine, and dopamine for the brain to use in mood stabilization. They can sometimes be effective for people who do not respond to other medications or who have atypical depression with marked anxiety, excessive sleeping, irritability, hypochondria (health anxiety), or phobic (obsessive) characteristics. However, they are the least safe antidepressants to use, as they have important medication interactions, including causing dangerously high blood pressure, and require adherence to a diet free of tyramines, chemicals found in certain foods such as fish (especially dried and salted), chocolate, alcoholic beverages (chianti wine), and fermented foods such as cheese and soy sauce, sauerkraut, and processed meat. MAOIs include phenelzine (Nardil®), isocarboxazid (Marplan®), and tranylcypromine sulfate (Parnate®). A range of other, less serious side effects occur including weight gain, constipation, dry mouth, dizziness, headache, drowsiness, insomnia, and sexual side effects (problems with arousal or satisfaction).
  • Other: Mirtazapine (Remeron®) is an antidepressant used commonly in the elderly that helps cause weight gain. A common side effect is drowsiness. Often psychiatrists will combine antidepressants with each other or with agents that are not antidepressants themselves. A class of drugs called atypical antipsychotic agents, including aripiprazole (Abilify®), olanzapine (Zyprexa®), quetiapine (Seroquel®), ziprasidone (Geodon®), and risperidone (Risperdal®) may be used. Side effects for these drugs are high, including excessive sedation and tardive dyskinesia (a nervous system disorder causing facial grimaces, lip smacking, and uncontrollable shaking). According to the American Diabetes Association (ADA), certain antipsychotic drugs may increase the risk of diabetes, obesity and high blood pressure.
  • Stimulants, such as methylphenidate (Ritalin®) or dextroaphetamine (Dexedrine®) can be added. Stimulants may cause dry mouth, disturbances in sleep patterns, nervousness, anxiousness, and weight loss.
  • Lithium and mood-stabilizing medications may be prescribed, including lithium (Eskalith®, Lithobid®), valproic acid (Depakene®), divalproex (Depakote®), and carbamazepine (Tegretol®) to treat bipolar depression. Medications called atypical antipsychotics such as olanzapine (Zyprexa), risperidone (Risperdal) and quetiapine (Seroquel) were initially developed for treatment of psychotic disorders.
  • Hormone therapy: For women with postpartum depression or premenstrual dysphoric disorder (PMDD), hormonal replacement with estrogen and/or progesterone may help with depression. However, there is an increased risk of heart disease and cancer (breast and ovarian) with the use of these medications.
  • Electroconvulsive therapy:Electroconvulsive therapy (ECT) involves the use of electrical current to stimulate various parts of the brain, and is used mainly in people who have episodes of major depression associated with suicidal tendencies, or in people whose medication has proved to be ineffective. ECT profoundly affects brain metabolism and blood flow to various areas of the brain. How that correlates to easing depression remains unknown, but this therapy is often highly effective. Safety of ECT is controversial, and adverse effects such as confusion, memory loss, headache, hypotension (low blood pressure), and tachycardia (increased heart rate) may occur.
  • Light therapy: This therapy may help if the individual has seasonal affective disorder (SAD). This disorder involves periods of depression that recur at the same time each year, usually when days are shorter in the fall and winter. Scientists believe fewer hours of sunlight may increase levels of melatonin, a brain hormone thought to induce sleep and depress mood. Treatment in the morning with a specialized type of bright light, which suppresses production of melatonin, may help with this disorder. Melatonin is a hormone for the sleep-wake cycle and may be decreased during depression.
  • Mild depression: If mild depression is diagnosed, antidepressant drugs are not usually recommended as a first treatment. Exercise seems to help some people with depression. Talking through feelings using counselling may also be helpful for mild depression. Talking to a friend or relative, self-help reading material, or a local self-help group are good choices. If the depression is mild but there is a past history of depression, antidepressants may be used.
  • Chronic (long term) mild depression or dysthymia (present for two or more years) is more likely in people over 55 years and can be difficult to treat. Individuals diagnosed with dysthymia are usually started on a course of antidepressants.
  • Moderate depression: If mild depression does not improve, antidepressants or talking treatments are generally used. Research has shown that antidepressants and psychological therapies are equally effective in treating mild or moderate depression but having the two types of treatment together does not seem to offer any extra benefits.
  • Severe depression: If severe depression is diagnosed, both antidepressant therapy together with psychotherapy are usually used in combination.
  • Although major depression can be a devastating illness, it is highly treatable. Between 80-90% of individuals diagnosed with major depression can be effectively treated and return to their usual daily activities and feelings.
  • Hospitalization: Depression is a serious medical illness. Urgent care and hospitalization may be necessary when someone seems to be a danger to themselves or others, or if they are psychotic. A person experiencing extreme major depression should be brought to the hospital immediately to prevent suicide or possible violence to another person. An acute episode is treated with medications and a low-stimulation environment. Depending on the individual's symptoms and history, longer-term hospitalization may be required.

Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. American Academy of Child and Adolescent Psychiatry. .
  2. American Academy of Family Physicians. .
  3. American Psychiatric Association. .
  4. Mental Health America.
  5. National Alliance on Mental Illness. .
  6. National Institute of Mental Health. .
  7. Natural Standard: The Authority on Integrative Medicine. .

Types of depression
  • Major depression: This type of depression lasts more than two weeks. Symptoms may include overwhelming feelings of sadness and grief, loss of interest or pleasure in activities usually enjoyed, and feelings of worthlessness or guilt. This type of depression may result in poor sleep, a change in appetite, severe fatigue and difficulty concentrating. Severe depression may increase the risk of suicide.
  • Atypical depression: Individuals with atypical depression, as opposed to major depression, experience improved mood when something good happens. In addition, two of the following symptoms occur to have atypical depression: an increase in appetite or weight gain (as opposed to the reduced appetite or weight loss of "typical" depression), excessive sleeping (as opposed to insomnia), leaden paralysis (a severe form of fatigue or tiredness), and sensitivity to rejection.
  • Dysthymia: Dysthymia is a less severe depression (mild to moderate) than major but a more chronic form of depression. Signs and symptoms usually are not disabling, and periods of mild depression can alternate with short periods of feeling normal. Having dysthymia places an individual at an increased risk of major depression. To be considered having dysthymia, the first two years of depressed mood cannot include any episodes of major depression. In addition, no underlying cause of depressed mood, such as a general medical condition (PMS, menopause, or coronary heart disease) or substance abuse may be present. The symptoms of dysthymia and the associated signs of depression cause significant distress or impairment in social, occupational, and other important areas of functioning. When a major depressive episode occurs on top of dysthymia, healthcare professionals may refer to the resultant condition as double depression.
  • Adjustment disorders: Having a loved one die, losing a job, or receiving a diagnosis of cancer or another disease can cause an individual to feel tense, sad, overwhelmed, or angry. Eventually, most people come to terms with the lasting consequences of life stresses, but some do not; this is called an adjustment disorder. Adjustment disorders are forms of depression that occur when the response to a stressful event or situation causes signs and symptoms of depression. Some people develop an adjustment disorder in response to a single event such as a parent or spouse dying. In others, it stems from a combination of stressors. Adjustment disorders can be acute (lasting less than six months) or chronic (lasting longer). Doctors classify adjustment disorders based on the primary signs and symptoms of depression.
  • Bipolar disorder: Having recurrent episodes of depression and elation (mania) is characteristic of bipolar disorder. Because this condition involves emotions at both extremes (poles), it's called bipolar disorder or manic-depressive disorder. Mania affects judgment, causing individuals to make unwise decisions. Some people have bursts of increased creativity and productivity during the manic phase. The number of episodes at either extreme may not be equal. Some people may have several episodes of depression before having another manic phase, or vice versa.
  • Seasonal affective disorder: Seasonal affective disorder (SAD) is a pattern of depression related to changes in seasons and a lack of exposure to sunlight. SAD usually occurs in winter. It may cause headaches, irritability and a low energy level. SAD is not a chronic (long term) depressive disorder.
  • Postpartum depression: According to the American College of Obstetricians and Gynecologists, about 10% of new moms experience postpartum depression, a more severe form of depression that can develop within the first six months after giving birth. For women with postpartum depression, feelings such as sadness, anxiety and restlessness can be so strong that they interfere with daily tasks. Rarely, a more extreme form of depression known as postpartum psychosis can develop. Symptoms of this psychosis include a fear of harming oneself or one's baby, confusion and disorientation, hallucinations and delusions, and paranoia.
  • Premenstrual dysphoric disorder (PMDD): PMDD occurs when depressive symptoms, such as crying, tiredness, and sadness, occur one week prior to menstruation and disappear after menstruation.

Copyright © 2011 Natural Standard (

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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