Depression

What is it?

According to the WHO: a common mental disorder “characterised by depressed mood or loss of pleasure or interest in activities for long periods”. MedlinePlus says: “Depression is more than feeling sad or upset for a few days. It is a serious mood disorder” and affects about 7% of American adults. The NIMH says it can cause severe symptoms that affect how you feel, think and handle daily activities such as sleeping, eating and working.

The NHS stresses that depression is “a real illness with real symptoms” and not weakness, and that it differs from passing sadness in that sadness lasts weeks or months, not a few days.

Types according to the NIMH: major depression (depressed mood of at least two weeks with functional impact), persistent depressive disorder (milder symptoms for two years or more), seasonal affective disorder, depression with psychosis, perinatal depression (during pregnancy or after birth), and premenstrual dysphoric disorder. Bipolar disorder is listed with episodes of depression and mania.

According to the WHO: about 4% of the general population had depression in 2023, and 5.2% of adults (4.1% men and 6.2% women), it is 1.5 times more common in women, and it affects more than 10% of pregnant women and those who have recently given birth.

Causes

According to the WHO: depression results from “a complex interaction of social, psychological and biological factors”. The NIMH and MedlinePlus say genetic, biological, environmental and psychological factors contribute. The NHS lists major life events such as bereavement, losing a job or childbirth, and genetic predisposition, and it may occur without an obvious cause.

Risk factors

The WHO lists: adverse life events (unemployment, bereavement or trauma), physical inactivity, harmful alcohol use, and co-existing medical conditions such as heart disease, diabetes and cancer. MedlinePlus states that women are often more affected, with hormonal changes (the menstrual cycle, pregnancy and menopause). The NIMH and MedlinePlus point to its co-occurrence with chronic diseases such as diabetes and heart disease.

Related pages here: type 2 diabetes, coronary artery disease, and obesity (the NHS lists depression among conditions that may contribute to weight gain, and among the daily challenges of obesity).

Symptoms

According to the NIMH: a persistent sad, anxious or “empty” mood, feelings of hopelessness or pessimism, loss of interest or pleasure in hobbies, exhaustion and low energy, difficulty concentrating, remembering and making decisions, disturbed sleep and appetite, physical aches without a clear cause, and thoughts of death or self-harm may appear. The WHO adds excessive guilt or low self-worth, MedlinePlus lists social withdrawal and increased substance use, and the NHS lists tearfulness, anxiety and low sex drive and pain.

The WHO states that an episode lasts at least two weeks, and MedlinePlus says symptoms must occur most of the day, nearly every day for at least two weeks for it to be diagnosed. Severity ranges from mildly lowered mood to severe episodes (NHS).

How is it diagnosed?

The sources indicate that assessment is done by a care provider or mental health professional (MedlinePlus: “see your care provider or mental health professional”), and an episode is classified according to the number and severity of symptoms and their functional impact (WHO). This page does not cover depression screening tools or tests to rule out physical causes.

Treatment

The treatment categories usually used are listed here; this is not a prescription. The doctor chooses the plan according to each person's condition; do not change any medicine or dose without a specialist.

According to MedlinePlus: “most treatments include medicines and/or psychotherapy (talk therapy)”. The WHO lists psychological interventions as a first option: behavioural activation, cognitive behavioural therapy, interpersonal therapy and problem solving, with antidepressants (including the SSRI class) added in moderate and severe cases, not advised for children and requiring caution in adolescents.

The NIMH says antidepressants usually take 4–8 weeks to work, that esketamine (a nasal spray) is used in some resistant cases, and that brain stimulation (electroconvulsive therapy and transcranial magnetic stimulation) is used when other treatments fail. Do not stop or change a medicine without the doctor.

The NHS states that the plan varies by severity: in mild depression watchful waiting with lifestyle changes and guided self-help, in moderate to severe depression talking therapies (such as cognitive behavioural therapy) with antidepressants, and in severe depression referral to a specialist. The condition is supported by exercise, reducing alcohol, quitting smoking, healthy eating and support groups. The NHS says most people treated appropriately reach “full recovery”.

Prevention

The WHO states that effective prevention includes school programmes for coping skills for young people, interventions for parents, and exercise programmes for older people. This page does not cover other individual prevention methods.

Living with it

Depression is not weakness (NHS), and asking for help early improves outcomes: the NHS says “the earlier you see a doctor, the closer you are to recovery”. Nearby mental health services can be found through local health authorities, and you can talk to someone you trust. This page does not cover advice for family and companions.

If you or someone you know has thoughts of death or self-harm, seek emergency help immediately from your country's emergency services, and do not stay alone: tell a trusted person or call the nearest emergency service or a mental health professional. (A general notice that does not include local numbers.)

Common questions