Depression is a medical condition that can cause a wide variety of psychological and physical symptoms. Extreme sadness is often the most pronounced symptom. Some people experience loss of interests or pleasure rather than sadness. Depression can be distinguished from occasional blues and grief because depression is persistent, often interfering with daily activities and relationships.
In the past, depression was poorly understood and carried an unfortunate social stigma. However, depression occurs commonly; the risk of suffering from a major depressive episode at some time during a person's life is up to 12 percent for men and 25 percent for women. The condition can affect people of all ages, including children and older adults.
Depression is a treatable condition. Psychotherapy (counseling), drug therapy, and other treatments can alleviate symptoms and help people with depression return to rich and productive lives. Treatment is most successful in people who are open to being helped and willing to participate in treatment.
This article discusses the causes, risk factors, signs and symptoms, and diagnosis of depression. A separate article discusses the treatment of depression. (See "Patient information: Depression treatment options for adults (Beyond the Basics)".)
More detailed information about depression is available by subscription. (See "Clinical manifestations and diagnosis of depression" and "Diagnosis and management of late-life depression" and "Unipolar major depression in adults: Choosing initial treatment" and "Unipolar depression in adults: Treatment of resistant depression".)
Articles that discuss depression in adolescents are available separately. (See "Patient information: Depression in adolescents (Beyond the Basics)" and "Patient information: Depression treatment options for adolescents (Beyond the Basics)".)
Research has helped clarify the complex biologic basis of depression, although the exact cause of depression is still uncertain. Studies suggest that depression is accompanied by changes in neurochemicals in the brain, including serotonin, norepinephrine, and dopamine. These neurochemicals allow cells to communicate with each other and play an essential role in all brain functions, including movement, sensation, memory, and emotions. That depression affects the brain is supported by the results of genetic studies and the response of depression to drug therapy and other therapies that alter levels of brain neurochemicals.
In addition, social factors may be involved, including isolation and criticism from family members. Psychological factors include repeated negative thoughts (for example, “I’m no good,” “The future is hopeless,” or “There is nothing I can do”). Losses and interpersonal problems may also contribute to onset of depression.
DEPRESSION RISK FACTORS
Although anyone can develop depression, certain factors increase a person's risk for this condition, including:
- Female sex
- A history of depression in a parent, sibling, or child
- A prior episode of major depression
Other factors have been identified as secondary (weaker) risk factors for depression:
- A history of depression in a family member who is not a parent, sibling, or child
- Lack of social supports
- Significant stressful life events
- Current alcohol or substance abuse
Depression and other medical conditions — Many people with chronic medical or neurological disorders, as well as some people with short term conditions, have difficulty with depression. The number of people with depression may be particularly high in diseases of the brain (eg, stroke, traumatic brain injury, Parkinson disease), heart conditions, cancer, and conditions that affect the immune system (eg, lupus).
The risk of depression is not related to any specific disease or organ system. However, depression can worsen the outcome of many conditions, and even increases the risk of death from medical causes as well as suicide. This may be related to the fact that some people with depression are not motivated to take their medications on schedule, attend medical appointments, and/or exercise.
Fortunately, recognizing and treating depression can improve a person's sense of health and well-being, and can also improve a person's interest in caring for him or herself.
Extreme sadness may be the best known symptom of depression, although depression also includes other psychological and physical symptoms. The hallmark of depression is that symptoms are persistent and interfere with daily activities and relationships.
Unfortunately, there is no single sign or symptom that serves as a marker for depression, and the condition can be tricky to identify. In fact, many people do not recognize that they are depressed or that their physical symptoms (aches and pain, appetite and sleep changes) are related to depression. One study revealed that 29 percent of people visiting their doctors for a physical symptom had a depressive disorder or an anxiety disorder .
The symptoms of the three types of depression (major depression, dysthymia, and atypical depression) will be discussed here.
Major depression — Major depression is the medical term for depression that includes five of the symptoms listed below. A person can have mild, moderate, or severe major depression.
- Sadness most of the day, particularly in the morning
- Markedly diminished pleasure or loss of interest in almost all activities nearly every day
- Significant weight loss or weight gain
- Insomnia or excessive sleep
- Agitated movements or very slow movement
- Fatigue or loss of energy
- Feelings of worthlessness or guilt
- Impaired concentration and indecisiveness
- Recurring thoughts of death or suicide
The symptoms must be present during the same time period and must persist for at least two weeks. One of the symptoms must be either depressed mood or loss of interest.
Dysthymia — Dysthymia is a low-grade depression that persists for a long period of time. Dysthymia is usually diagnosed when a person has had depressive symptoms for at least two consecutive years. The most common symptoms of dysthymia include an absence of pleasure or interest in activities, low self-esteem, and low energy.
Atypical depression — Atypical depression is a common type of depression. People with atypical depression have some of the same features of major depression listed above, but do not have five of the nine symptoms required for a diagnosis of major depression. Instead, they often have prominent physical symptoms, including weight gain and sleep disturbances, especially excessive sleep.
Seasonal affective disorder — Seasonal affective disorder (SAD) is a form of major depression that varies with the seasons. Most patients with SAD have episodes of depression that begin in the fall and continue through the winter.
SAD is characterized by several features:
- Symptoms of depression that regularly appear during a particular time of year (unrelated to stressful events associated with specific seasons)
- Full remission of depression (or a change from depression to mania) during other times of year
- Two major episodes of depression during the associated season in the last two years and an absence of depression during other times of the year
Grief — Grief is a normal reaction to many situations, following the death of a loved one, loss of a close relationship or job, or the loss of health or independence. This section discusses one of the most common types of grief that occurs after the death of a family member or friend.
Grief following death — Immediately following death, whether or not the death has been anticipated, survivors usually experience feelings of numbness, shock, and disbelief. Intense feelings of sadness, yearning for the deceased, anxiety about the future, disorganization, and emptiness commonly arise in the weeks after the death.
"Searching behaviors," including visual and auditory hallucinations of the deceased person, are common and may lead the bereaved person to fear that he or she is "going crazy." Despair and sadness are common as it becomes clear that the deceased will not return. Sleeplessness, appetite disturbances, agitation, chest tightness, sighing, and exhaustion are common.
These reactions are usually transient and resolve in over 90 percent of people by 13 months after the loss. However, losses can trigger depression in some people; as an example, 15 to 35 percent of people who lose their spouse develop depression in the following year .
Some patients who grieve may develop complicated grief (or traumatic grief), which is defined as persistence of at least four of the following feelings for six months or more:
- Feelings that life is empty without the deceased
- Trouble accepting the death
- A sense that the future holds no meaning without the deceased
- Being on edge or agitated
- Difficulty trusting others since the loss
Grief versus depression — It is often difficult to know if a person who is grieving also suffers from depression. Patients who have feelings of hopelessness, helplessness, worthlessness, and guilt, as well as severe symptoms of early grief may be depressed. Patients whose grief is complicated by depression often benefit from an antidepressant medication in addition to individual or group psychotherapy. Group therapy in a bereavement group can be particularly useful for patients with grief and depression. In contrast, persons suffering only with grief are more likely to benefit from psychotherapy alone.
Bipolar depression — People with bipolar I disorder (manic depression) have periods of mania (feeling excessively elated, impulsive, irritable, or irrational), and may also experience periods of major depression. Bipolar II disorder involves periods of depression interspersed with periods of "hypomania," which are milder forms of mania with periods of high energy, decreased sleep, and some agitation. People with bipolar II disorder may have a poor response to antidepressant medications; consultation with a psychiatrist is recommended to assist in the treatment of people with this disorder. (See "Patient information: Bipolar disorder (manic depression) (Beyond the Basics)".)
The diagnosis of depression is based upon a patient's symptoms, the duration of symptoms, and the overall effects of these symptoms on a patient's life. There is currently no medical test that identifies depression, although blood tests are often done to rule out other medical conditions that could be causing depression (such as hypothyroidism).
A diagnosis of major depression requires that symptoms are severe enough to interfere with a person's daily activities, and the ability to take care of oneself, maintain relationships, engage in work activities, and to support oneself. A diagnosis also requires that the symptoms have occurred on a daily basis for at least two weeks. The diagnosis should be made by a physician or advanced clinician, based upon the patient’s history and findings from an examination (sometimes also supplemented with laboratory testing).
A separate topic review discusses treatment options for adults with depression. (See "Patient information: Depression treatment options for adults (Beyond the Basics)".)
WHERE TO GET MORE INFORMATION
Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: Depression (The Basics)
Patient information: Premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD) (The Basics)
Patient information: Medicines for depression (The Basics)
Patient information: Electroconvulsive therapy (ECT) (The Basics)
Patient information: Anorexia nervosa (The Basics)
Patient information: Bulimia nervosa (The Basics)
Patient information: Post-traumatic stress disorder (The Basics)
Patient information: Postpartum depression (The Basics)
Patient information: Paraplegia and quadriplegia (The Basics)
Patient information: Antisocial personality disorder (The Basics)
Patient information: Seasonal affective disorder (The Basics)
Patient information: When you have depression and another health problem (The Basics)
Patient information: Serotonin syndrome (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: Depression treatment options for adults (Beyond the Basics)
Patient information: Depression in adolescents (Beyond the Basics)
Patient information: Depression treatment options for adolescents (Beyond the Basics)
Patient information: Bipolar disorder (manic depression) (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Monoamine oxidase inhibitors (MAOIs) for treating depressed adults
Serotonin-norepinephrine reuptake inhibitors (SNRIs): Pharmacology, administration, and side effects
Antidepressant medication in adults: Switching and discontinuing medication
Assessment and management of depression in palliative care
Clinical manifestations and diagnosis of depression
Depression in adolescents: Epidemiology, clinical manifestations, and diagnosis
Depression in pregnant women: Clinical features and consequences
Diagnosis and management of late-life depression
Diagnosis of psychiatric and psychologic disorders in patients with cancer
Unipolar major depression in adults: Choosing initial treatment
Management of psychiatric disorders in patients with cancer
Overview of psychosis
Postpartum psychosis: Epidemiology, clinical manifestations, and assessment
Treatment of postpartum psychosis
Seasonal affective disorder
Tricyclic and tetracyclic drugs: Pharmacology, administration, and side effects
Unipolar depression in adults: Treatment of resistant depression
The following organizations also provide reliable health information.
- National Library of Medicine
- National Institute of Mental Health
- American Psychiatric Association
- American Psychological Association
- American Academy of Child and Adolescent Psychiatry
- Depression and Bipolar Support Alliance (DBSA)
- National Foundation For Depressive Illness
- National Mental Health Association
- National Alliance for the Mentally Ill