A major depressive episode (MDE) is a period characterized by depressed mood for a duration of at least two weeks and/or loss of interest or pleasure in everyday activities, as well as symptoms such as negative thoughts and emotions, changes in appetite, cognitive difficulties, or suicidal ideation or attempts. Major depressive episodes are the defining characteristic of major depressive disorder (MDD), are part of the diagnostic criteria for bipolar II disorder, and are common (but not required for diagnosis) in bipolar I disorder.
Socioeconomic status, life experience, genetics, and personality traits are believed to be factors in the development of depression and may represent an increased risk of developing a major depressive episode. According to the Nordic Journal of Psychiatry, there is a direct correlation between a major depressive episode and unemployment.
Possible treatments for a major depressive episode include psychotherapy and antidepressants. Electroconvulsive therapy and transcranial magnetic stimulation may be used in cases that do not respond to other treatment. Recovery chance is higher when medication and therapy are combined in moderate-to-severe cases, although in more severe cases, hospitalization or intensive outpatient treatment may be required.
Signs and symptoms A major depressive episode is defined by either depressed mood or a loss of interest or pleasure in everyday activities, present for at least two weeks. At least four additional depressive symptoms are also required for diagnosis. Depressed mood is the most common symptom, and is often manifested by observable changes in mood or affect (such as tearfulness) or negative emotions (such as feeling sad, anxious, empty, hopeless, indifferent, pessimistic, numb, or irritable). Irritability is a common presentation of depressed mood in children and adolescents in particular. Withdrawal from social settings and neglect of personal relationships often accompany depressed mood, and may be noticed by those close to the person.
Major depressive episodes are known to cause sleep disturbances such as insomnia or, less frequently, hypersomnia. Symptoms of insomnia include trouble falling asleep, trouble staying asleep, or waking up too early in the morning. Hypersomnia may include sleeping for prolonged periods at night or increased sleeping during the daytime. Sleep may not be restful, and the person may feel sluggish despite many hours of sleep, which may be a factor in the worsening of their depressive symptoms, which interfere with other aspects of their lives. This type of sleep disorder may make it harder to fall and stay asleep at night than during the day. Hypersomnia is often associated with atypical depression as well as seasonal affective disorder.
A general lack of energy, fatigue, and tiredness that cannot be otherwise explained is also a symptom of a major depressive episode. A person may feel tired without engaging in any physical activity, which may cause day-to-day tasks, such as showering, to become unmanageable. This may also lead to difficulties with everyday decisions or trouble thinking or concentrating. This criterion requires this difficulty to cause significant difficulty in functioning for those involved in intellectually demanding activities, such as school and work, especially in difficult fields. Individuals with depression often describe a slowing of thought, an inability to concentrate and make decisions, and being easily distracted. In the elderly, the decreased concentration caused by a major depressive episode may present as deficits in memory. This is referred to as pseudodementia and often goes away with treatment. Decreased concentration may be reported by the patient or observed by others.
Changes in motor activity by individuals in a major depressive episode that is slower or faster than normal levels may be noticed by those around them. People with depression may be overly active (psychomotor agitation) or very lethargic (psychomotor retardation). Psychomotor agitation is marked by increased body activity, which may result in restlessness, an inability to sit still, pacing, hand wringing, or fidgeting with clothes or objects. Psychomotor retardation results in a decrease in body activity. In this case, a depressed person may demonstrate a slowing of thinking, speaking, or body movement. They may speak more softly or say less than usual. To meet diagnostic criteria, changes in motor activity must be so abnormal that it can be observed by others. Personal reports of feeling restless or slow do not count towards the diagnostic criteria.
In a major depressive episode, appetite is often decreased without a conscious effort to diet. A person experiencing a depressive episode may have a marked loss or gain of weight (5% of their body weight in one month), which may be the result of a lack of energy. In children, failure to make expected weight gains may be counted towards this criterion. Some individuals also experience increased appetite due to coping through self-soothing and eating. Overeating is often associated with atypical depression.
Individuals suffering from a major depressive episode may have excessive feelings of guilt that go beyond an average level and which are not linked to guilt about being depressed. Major depressive episodes are often accompanied by a significant drop in self-esteem without an obvious reason. The guilt and worthlessness experienced in a major depressive episode can range from subtle guilt to delusions of wrongdoing, shame, and humiliation. Additionally, self-loathing is a common symptom exhibited in patients with clinical depression. Many patients with major depressive disorder exhibit distorted thought patterns and may believe they are not worthy of care from those around them and that their lives have no meaning or purpose. For someone to be diagnosed with a major depressive episode, they must have been feeling this drop of self-esteem and worthlessness for most of the day, multiple days in a row. A short sense of guilt for a minor wrong-doing or the feeling of sadness that goes away after a few hours does not count as a major depressive episode.
A person going through a major depressive episode may have repeated thoughts about death, other than the fear of dying; suicide, with or without a plan; or may have made a suicide attempt. The frequency and intensity of thoughts of suicide can range from believing that friends and family would be better off if one were dead to frequent thoughts about suicide to detailed plans about how the suicide would be carried out. These thoughts may not represent a desire to die, but to stop the emotional pain.
Causes The cause of a major depressive episode is not well understood. Despite its longstanding prominence in pharmaceutical advertising, the idea that low serotonin levels cause depression is not supported by scientific evidence. One interpretation is that depression manifests due to an imbalance of neurotransmitters in the brain, resulting in feelings of worthlessness and despair. Magnetic resonance imaging shows that the brains of people diagnosed with depression may have a hippocampus up to 10% smaller than those who do not exhibit signs of depression. A family history of depression increases the chance of being diagnosed.
There are usually a combination of biological, psychological, and social factors that play into a person's depression. A major depressive episode can often follow acute stress in someone's life, such as the death of a loved one or being fired from a job. Evidence suggests that psychosocial stressors play a larger role in the first 1–2 depressive episodes while having less influence in later episodes. People who experience a major depressive episode often have other mental health issues. Children with generalized social anxiety disorder may be more likely to experience a major depressive episode.
Other risk factors for a depressive episode include: Early childhood trauma Family history of a mood disorder Lack of interpersonal relationships Personality (insecure, worried, stress-sensitive, obsessive, unassertive, dependent) Postpartum Recent negative life events Presence of non-mood-related mental disorders
The cause of depression is believed to be due to a combined effect of genetic and environmental factors. Other medical conditions, for example hypothyroidism, may cause people to experience similar symptoms as a major depressive episode. However, according to the DSM-5, this would be considered a mood disorder due to a general medical condition, not a major depressive episode.
Diagnosis The criteria below are based on the formal DSM-5 criteria for a major depressive episode. A diagnosis of a major depressive episode requires the patient to have experienced five or more of the symptoms below, one of which must be either a depressive mood or a loss of interest or pleasure (although both are frequently present). These symptoms must be present for at least 2 weeks, represent a change from the patient's normal behavior, and cannot be attributed to another medical conditionDiagnostic and Statistical Manual of Mental Disorders, Fourth Edition or substance use. Symptoms must also cause clinically significant distress in important areas of everyday life (e.g. social or occupational).
While they are the defining characteristic of MDD, the DSM-5 also includes the presence of major depressive episodes in the diagnostic criteria for bipolar disorder (specifically bipolar II, though they are commonly present in bipolar I as well). Therefore, the presence of a major depressive episode is not necessarily synonymous with a diagnosis of major depressive disorder; additional factors, such as the presence or absence of manic, hypomanic, or mixed episodes, must also be considered and will affect the ultimate diagnosis.
Criteria The two main symptoms of a major depressive episode are a depressed mood and a loss of interest or pleasure. From the list below, one bold symptom and four other symptoms must be presented for at least 2 weeks for a diagnosis of a major depressive episode. Weight loss or gain Change in body activity (psychomotor changes) Change in sleep Depressed mood Feelings of worthlessness and excessive or inappropriate guilt Indecisiveness, confusion, or a decrease in concentration Loss of energy Loss of interest or pleasure Suicidal ideation
Differential diagnosis
Differential diagnoses include, but are not limited to: Adjustment disorder Anxiety disorder (Generalized anxiety, PTSD, obsessive-compulsive disorder) Depression due to a general medical condition Disruptive mood dysregulation disorder Dysthymia Gender dysphoria Personality disorder with depressive symptoms Premenstrual dysphoric disorder Substance abuse or Substance use disorder
Testing No labs are diagnostic of a depressive episode, but some labs can help rule out general medical conditions that may mimic the symptoms of a depressive episode. Healthcare providers may order blood work, including routine blood chemistry, CBC with differential, thyroid function studies, and Vitamin B12 levels, before making a diagnosis.
Healthcare providers may screen patients in the general population for depression using a screening tool, such as the Patient Healthcare Questionnaire-2 (PHQ-2). If the PHQ-2 screening is positive for depression, a provider may then administer the PHQ-9. The Geriatric Depression Scale is a screening tool that can be used in the elderly population.
Treatment