Major depressive disorder

Causes and Risk Factors

– The biopsychosocial model suggests biological, psychological, and social factors contribute to depression.
– The diathesis-stress model indicates preexisting vulnerability activated by stressful events.
– Negative thoughts about self, world, and future can lead to depressive symptoms.
– Genetics play a major role in depression development, with 40% of the risk for major depressive disorder explained by genetic factors.
– Genome-wide studies have identified genetic variants linked to depression risk.
– Adverse childhood experiences, childhood trauma, and genetics are key environmental and biological factors influencing depression.
– Substance use in early age increases the risk of developing depression later in life.
– Seasonal affective disorder is associated with seasonal changes in sunlight and hormonal changes after giving birth.

Symptoms and Diagnosis

– Symptoms of major depressive disorder include low mood, inability to experience pleasure, and physical symptoms like fatigue and headaches.
– Diagnosis involves assessing current circumstances, biographical history, symptoms, family history, and substance use.
– Mental state examinations evaluate mood, thought content, and presence of suicidal thoughts.
– Rating scales like the Hamilton Rating Scale for Depression are used to indicate symptom severity.
– Primary-care physicians may miss cases due to accompanying physical symptoms and various barriers.
– DSM-5 and ICD-10 criteria provide guidelines for diagnosing different types of depression, ensuring standardized diagnosis and treatment.
– Differential diagnoses include dysthymia, bipolar disorder, and other disorders like depression due to physical illness or substance use.

Biological Mechanisms

– The monoamine theory suggests insufficient activity of monoamine neurotransmitters as the primary cause of depression.
– Evidence supports the involvement of serotonin, dopamine, and other monoamines in depression.
– Immune system abnormalities, HPA-axis dysfunction, and neuroimaging models propose abnormalities in specific brain regions contributing to depression.
– Increased monoamine oxidase activity is linked to depression.
– Challenges to the monoamine theory include inconsistent observations and effects of antidepressants.

Treatment and Management

– Psychotherapy, medication, and electroconvulsive therapy are common and effective treatments for depression.
– Collaborative care by a team of health care practitioners produces better results.
– Psychotherapy is the treatment of choice for individuals under 18.
– Antidepressants should not be used for the initial treatment of mild depression.
– Lifestyle interventions like physical exercise, sleep, diet, and smoking cessation can complement conventional methods.
– Psychological therapies like cognitive-behavioral therapy (CBT) and mindfulness-based programs are effective in treating and preventing depression.

Assessment and Prevention

– Diagnostic assessments involve evaluating current mood, thought content, and suicidal thoughts.
– Screening for depression is recommended by the USPSTF among those over the age of 12.
– Preventive efforts may result in decreases in rates of depression.
– Routine use of screening questionnaires has little effect on detection or treatment.
– Behavioral interventions like interpersonal therapy and cognitive-behavioral therapy are effective in preventing new onset depression.

Major depressive disorder (Wikipedia)

For other types of depression, see Mood disorder.

Not to be confused with Depression (mood).

Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Introduced by a group of US clinicians in the mid-1970s, the term was adopted by the American Psychiatric Association for this symptom cluster under mood disorders in the 1980 version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III), and has become widely used since.

Major depressive disorder
Other names	Clinical depression, major depression, unipolar depression, unipolar disorder, recurrent depression
Sorrowing Old Man (At Eternity's Gate), an 1890 portrait by Vincent van Gogh
Specialty	Psychiatry, clinical psychology
Symptoms	Low mood, low self-esteem, loss of interest in normally enjoyable activities, low energy, pain without a clear cause, disturbed sleep pattern (insomnia or hypersomnia)
Complications	Self-harm, suicide
Usual onset	Age 20s
Duration	> 2 weeks
Causes	Environmental (e.g. adverse life experiences), genetic predisposition, psychological factors such as stress
Risk factors	Family history, major life changes, certain medications, chronic health problems, substance use disorder
Differential diagnosis	Bipolar disorder, ADHD, sadness
Treatment	Psychotherapy, antidepressant medication, electroconvulsive therapy, transcranial magnetic stimulation, exercise
Medication	Antidepressants
Frequency	163 million (2017)

The diagnosis of major depressive disorder is based on the person's reported experiences, behavior reported by relatives or friends, and a mental status examination. There is no laboratory test for the disorder, but testing may be done to rule out physical conditions that can cause similar symptoms. The most common time of onset is in a person's 20s, with females affected about twice as often as males. The course of the disorder varies widely, from one episode lasting months to a lifelong disorder with recurrent major depressive episodes.

Those with major depressive disorder are typically treated with psychotherapy and antidepressant medication. Medication appears to be effective, but the effect may be significant only in the most severely depressed. Hospitalization (which may be involuntary) may be necessary in cases with associated self-neglect or a significant risk of harm to self or others. Electroconvulsive therapy (ECT) may be considered if other measures are not effective.

Major depressive disorder is believed to be caused by a combination of genetic, environmental, and psychological factors, with about 40% of the risk being genetic. Risk factors include a family history of the condition, major life changes, certain medications, chronic health problems, and substance use disorders. It can negatively affect a person's personal life, work life, or education, and cause issues with a person's sleeping habits, eating habits, and general health. Major depressive disorder affected approximately 163 million people (2% of the world's population) in 2017. The percentage of people who are affected at one point in their life varies from 7% in Japan to 21% in France. Lifetime rates are higher in the developed world (15%) compared to the developing world (11%). The disorder causes the second-most years lived with disability, after lower back pain.