Major Depressive Disorder
Definition and Classification
Major depressive disorder (MDD), also known as clinical depression, is a significant medical condition that can impact many areas of a person's life. It is characterized by a persistent feeling of sadness or a lack of interest in outside stimuli. The unipolar connotes a difference between major depression and bipolar depression, which refers to an oscillating state between depression and mania. Instead, unipolar depression is centered on a single phase of major depression. Major depressive disorder is a debilitating illness that affects more than 264 million people worldwide according to the World Health Organization (WHO).
Symptoms
The symptoms of major depressive disorder are highly variable among individuals. They may include persistent feelings of sadness, emptiness, or hopelessness, loss of interest or pleasure in activities, significant weight loss or gain, insomnia or hypersomnia, psychomotor agitation or retardation, fatigue or loss of energy, feelings of worthlessness or excessive guilt, diminished ability to think or concentrate, and recurrent thoughts of death or suicide. These symptoms must cause significant distress or impairment in social, occupational, or other important areas of functioning, and they cannot be attributed to the physiological effects of a substance or another medical condition.
Causes
The exact cause of major depressive disorder is not well understood, but it is believed to involve a combination of genetic, biochemical, environmental, and psychological factors. Some people may be genetically predisposed to developing depression, while others may be triggered by a significant life event or stressor. Other potential causes include certain medical conditions, medications, and substance abuse.
Diagnosis
The diagnosis of major depressive disorder is typically made based on a thorough clinical interview, including a detailed personal and family psychiatric history, and a mental status examination. There are no laboratory tests to diagnose MDD, but some medical conditions and medications can cause symptoms similar to those of depression, so doctors often want to rule out these possibilities before making a diagnosis.
Treatment
Treatment for major depressive disorder typically involves a combination of psychotherapy and medication. Cognitive-behavioral therapy (CBT) and interpersonal therapy (IPT) are among the most effective forms of psychotherapy for this condition. Antidepressant medications, such as selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs), are commonly used to treat MDD. In some cases, other treatments, such as electroconvulsive therapy (ECT) or transcranial magnetic stimulation (TMS), may be considered.
Prognosis
The prognosis for individuals with major depressive disorder is variable. Some people may experience only a single episode of depression in their lifetime, while others may have recurrent episodes. With appropriate treatment, most people with MDD can achieve a significant reduction in symptoms and improved quality of life. However, some individuals may continue to experience residual symptoms or have a partial response to treatment.
Epidemiology
Major depressive disorder is one of the most common mental health disorders in the United States and worldwide. According to the National Institute of Mental Health, an estimated 17.3 million adults in the United States had at least one major depressive episode in the past year. This represents 7.1% of all U.S. adults. The prevalence of MDD is higher in women than in men, and the median age of onset is 32.5 years old.