Persistent depressive disorder (dysthymia) !

A long-lasting depression, milder or as severe as major depression, present most days for at least 2 years in adults (1 year in children and adolescents).

Updated 2026-11-01

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What it is

A chronic depressive disorder in which depressed mood is present on most days for at least 2 years in adults, or 1 year in children and adolescents (where mood may be irritable). It includes what was formerly called dysthymia and chronic major depression. The person may feel that low mood is simply part of their personality.

Who gets it

Lifetime prevalence is around 3–6% in general-population surveys and it is more common in women. It often begins in childhood, adolescence or early adulthood. It is frequently missed in primary care in Latin America because people consult for physical complaints, insomnia or fatigue rather than mood.

Causes

Genetic vulnerability to depression
Early adversity: childhood abuse, neglect or loss of a parent
Chronic stress and long-term medical illness
Personality traits such as high neuroticism

Risk factors

Family history of depression
Female sex
Adverse childhood experiences
Chronic physical illness or chronic pain
Substance use disorders
Anxiety disorders and personality disorders

Pathophysiology

Like other depressive disorders, it is thought to involve dysregulated serotonin, noradrenaline and dopamine signalling, an overactive stress axis and altered activity between prefrontal and limbic regions such as the anterior cingulate cortex and amygdala. Early-onset forms are linked to lasting effects of childhood stress on these circuits.

Classification

Pure dysthymic syndrome: never meets full criteria for major depression during the 2 years
With persistent major depressive episode: full criteria met throughout
With intermittent major depressive episodes (so-called double depression when a major episode is superimposed on dysthymia)
Early onset (before age 21) or late onset (21 or older)

Symptoms and signs

Depressed mood most of the day, more days than not
Poor appetite or overeating
Insomnia or hypersomnia
Low energy or fatigue
Low self-esteem and poor concentration or difficulty making decisions
Feelings of hopelessness

Diagnosis

Clinical: Depressed mood for at least 2 years in adults (1 year in young people) plus at least two of: appetite change, sleep change, low energy, low self-esteem, poor concentration or hopelessness, without symptom-free periods longer than 2 months. There must be no history of mania or hypomania. Screening with the PHQ-9 and suicide risk assessment are part of the evaluation.
Tests: No test confirms the diagnosis. Thyroid function, complete blood count, glucose and, where indicated, vitamin B12 to exclude medical causes of fatigue and low mood; review of medicines and substances.
Imaging: Not needed unless neurological signs or atypical features suggest another cause.

Differential diagnosis

Major depressive disorder (episodic, shorter, more severe)
Bipolar disorder or cyclothymic disorder
Hypothyroidism and other medical causes
Substance- or medicine-induced depressive disorder
Personality disorders

Goal of treatment

Achieve full remission rather than partial improvement, restore daily functioning and prevent superimposed major depressive episodes and suicide.

Treatment

Conservative: Psychotherapy, especially cognitive behavioural therapy, interpersonal therapy or CBASP, which was designed for chronic depression.
Medical: Antidepressants (SSRIs first-line; SNRIs or other classes as alternatives) for an adequate period; the combination of medicine and psychotherapy works better than either alone.
Lifestyle: Regular physical activity, sleep routine, reducing alcohol and building social activity.
Follow-up: Follow-up of symptoms with rating scales, suicide risk review and attention to treatment adherence, since response is slower than in episodic depression.

Complications

Superimposed major depression (double depression)
Suicidal behaviour
Substance use disorders
Poor work, academic and social functioning
Worse outcomes of chronic medical illness

Prognosis

It tends to be long-lasting, and many people are not treated because the low mood is seen as part of their character. With adequate treatment many improve, but relapse is common, and early onset and comorbid personality or substance use disorders predict a poorer course.

Test yourself

Think of the answer, then tap the question to see it.

What is the minimum duration of depressed mood required for persistent depressive disorder in adults?

At least 2 years (1 year in children and adolescents).

What is 'double depression'?

A major depressive episode superimposed on persistent depressive disorder.

What history excludes the diagnosis and suggests another disorder?

Any manic or hypomanic episode (bipolar disorder) or cyclothymic disorder.

Which treatment approach gives the best results?

The combination of psychotherapy and an antidepressant such as an SSRI.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Persistent depressive disorder (MedlinePlus (U.S. National Library of Medicine), 2025).

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Representative model, for educational purposes only.

Frontal lobe highlighted on the Durgical 3D model