Meyahealth
HomeGeneticsConditionDepression
Back to Condition
Depression
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Depression

Depression is a common but serious psychiatric disorder that profoundly impacts mood, behavior, and physical health. Characterized by persistent feelings of sadness and a loss of interest in daily activities, it arises from a complex interplay of genetic and environmental factors.

Overview

Depression (also known as major depression or major depressive disorder) is a psychiatric disorder that affects mood, behavior, and overall health. It causes prolonged feelings of sadness, emptiness, or hopelessness, and a loss of interest in activities that were once enjoyed.

People with depression may experience a variety of symptoms, including:

  • Changes in appetite (leading to overeating or not eating enough)
  • Changes in sleeping patterns (sleeping too much or insomnia)
  • Loss of energy
  • Difficulty concentrating
  • Physical features such as headaches, unexplained aches and pains, unusually slow or fast movements, and digestive problems

To receive a diagnosis of depression, an individual must exhibit signs and symptoms nearly every day for at least 2 weeks. However, the features of this condition vary widely. Depression most commonly begins in late adolescence or early adulthood, though it can appear at any age. If untreated, episodes can last for weeks, months, or years, and can recur. Affected individuals may have difficulty functioning in daily life, school, or work, and have a higher risk of substance abuse and dying by suicide than the general population.

Related Conditions

Several health conditions are closely related to depression or feature it as a characteristic characteristic:

  • Dysthymia: Long-lasting symptoms that are similar to, but less severe than, those of major depression.
  • Perinatal or postpartum depression: Depression that occurs around or following the birth of a child.
  • Seasonal affective disorder: Depression triggered by the changing of the seasons.
  • Bipolar disorder: A condition that can include both "highs" (manic episodes) and depressive episodes.
  • Generalized anxiety disorder
  • Schizoaffective disorder: A condition where depression or another mood disorder occurs alongside features of schizophrenia.

Frequency

Depression is one of the most common mental health disorders in the United States, affecting more than 19 million American adolescents and adults. In 2016, 6.7 percent of adults and 12.8 percent of adolescents reported having at least one episode of depression. The condition is about twice as common in women as in men, which may be related in part to hormonal factors.

Causes & Risk Factors

Depression is known to run in families, suggesting that genetic factors contribute to the risk. However, research into the genetics of depression is in its early stages, and very little is known for certain about its specific genetic basis. Studies suggest that variations in many genes, each having a small effect, combine to increase overall risk.

Determining genetic risk factors is challenging because what is currently classified as "depression" may actually be multiple distinct disorders with similar symptoms but different genetic underpinnings. Additionally, genetic variations related to depression may differ between men and women.

The genes thought to be associated with depression have diverse functions in the brain:

  • Some genes may control the production, transport, and activity of chemicals that relay chemical signals, allowing nerve cells (neurons) to communicate with one another.
  • Other genes may influence the growth, maturation, and maintenance of neurons, as well as synaptic plasticity—the ability of connections between neurons to change and adapt over time in response to experience.

Environmental Factors

Nongenetic (environmental) factors play critical roles in a person's risk of developing depression. The disorder can be triggered by:

  • Substance abuse
  • Certain medications
  • Stressful life events (such as divorce or the death of a loved one)
  • Relationship difficulties or social isolation
  • Unemployment or financial problems
  • Childhood abuse or neglect
  • Physical illnesses, such as cancer, thyroid disease, and chronic pain

It is highly likely that environmental conditions interact with genetic factors to determine an individual's overall risk of developing the disease.

Inheritance

Depression does not have a clear pattern of inheritance in families. People who have a close relative (such as a parent or sibling) with depression appear to have a two to three times greater risk of developing the condition than the general public. However, many people who develop depression have no family history of the disorder, and many with an affected relative never develop it.

Other Names for This Condition

  • Clinical depression
  • Depressive disorder
  • Major depression
  • Major depressive disorder
  • MDD
  • Unipolar depression

Frequently Asked Questions

Supporting someone with depression involves encouraging them to seek and adhere to professional treatment, listening without judgment, and offering practical help with daily tasks if needed. It's important to educate yourself about depression, avoid minimizing their feelings, and help them maintain social connections. For severe symptoms or suicidal thoughts, immediate professional intervention is crucial.
If left untreated, depression can lead to significant impairment in daily life, affecting work, school, and relationships. It increases the risk of substance abuse, chronic physical health problems, and can lead to recurrent episodes that become more severe over time. Most critically, untreated depression significantly elevates the risk of suicide.
While sadness is a normal human emotion, clinical depression involves persistent feelings of sadness, emptiness, or hopelessness, along with a loss of interest in activities, nearly every day for at least two weeks. Other symptoms like significant changes in appetite or sleep, low energy, or difficulty concentrating are also common. Professional help should be sought if these symptoms are severe, interfere with daily functioning, or if thoughts of self-harm or suicide are present.
Initial treatment for depression typically involves a combination of psychotherapy (talk therapy) and medication, such as antidepressants. The specific approach depends on the severity of symptoms and individual needs. Lifestyle adjustments, including regular exercise, a balanced diet, and consistent sleep patterns, are also often recommended as supportive measures.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

Meyahealth

Ⓒ 2026. All rights reserved by MEYA

About UsTerms & PolicyFAQ