Mental HealthICD-10: F34.1Fairly common; affects a meaningful proportion of adults over a lifetime, often unrecognized

Persistent Depressive Disorder

Also known as: Dysthymia, Chronic depression

Persistent depressive disorder (PDD), formerly called dysthymia, is a long-lasting form of depression in which a low mood is present most of the day, on most days, for at least two years in adults (one year in children and teenagers). The symptoms are often milder than in a major depressive episode, but their sheer duration means they can quietly erode self-esteem, relationships, and ambition. People with PDD frequently describe themselves as having 'always been this way' and may not recognize it as an illness. Episodes of major depression can occur on top of it, sometimes called double depression. PDD responds to psychotherapy and medication, usually in combination, though improvement can take longer than with shorter-term depression.

At a Glance

Common symptoms
Low, sad, or 'empty' mood most days for two years or more, Low self-esteem or feelings of inadequacy, Hopelessness or pessimism
Main treatments
Psychotherapy, particularly CBT, interpersonal therapy, or CBASP, which was designed for chronic depression, Antidepressant medication (commonly SSRIs or SNRIs), often combined with therapy, Longer-term treatment and relapse-prevention planning, because the condition is chronic by nature
Category
Mental Health · Fairly common; affects a meaningful proportion of adults over a lifetime, often unrecognized
See a doctor if
Low mood has lasted for months and is affecting daily functioning

Symptoms

Low, sad, or 'empty' mood most days for two years or more
Low self-esteem or feelings of inadequacy
Hopelessness or pessimism
Poor appetite or overeating
Sleeping too little or too much
Low energy and fatigue
Trouble concentrating or making decisions

Causes

  • Genetic factors; depression often runs in families
  • Differences in brain chemistry and stress-hormone regulation
  • Early adversity, loss, or trauma
  • Ongoing stressors such as chronic illness, financial strain, or isolation
  • Personality traits such as high self-criticism or negative thinking styles

Risk Factors

  • Family history of depression
  • Chronic medical conditions
  • Childhood neglect or abuse
  • Other mental health conditions such as anxiety or substance use
  • Lack of social support

Diagnosis

  • Clinical interview establishing the duration and persistence of symptoms
  • Depression questionnaires such as the PHQ-9 to measure severity
  • Assessment for episodes of major depression, bipolar disorder, and other conditions
  • Physical examination and blood tests to exclude medical causes such as thyroid disease or anemia

Treatment

  • Psychotherapy, particularly CBT, interpersonal therapy, or CBASP, which was designed for chronic depression
  • Antidepressant medication (commonly SSRIs or SNRIs), often combined with therapy
  • Longer-term treatment and relapse-prevention planning, because the condition is chronic by nature
  • Treatment of coexisting conditions such as anxiety or substance use
  • Supportive: regular exercise, which has antidepressant effects in its own right
  • Supportive: structured daily routines, social contact, and activities that provide a sense of achievement (behavioral activation)
  • Supportive: consistent sleep and a balanced diet

Prevention

  • Seek help early when low mood persists rather than waiting it out
  • Maintain exercise, sleep, and social connections during stressful periods
  • Continue treatment as advised even after feeling better
  • Learn to recognize early signs of relapse
  • Limit alcohol, which worsens mood over time

When to See a Doctor

  • Low mood has lasted for months and is affecting daily functioning
  • You have lost interest in things you used to enjoy
  • Symptoms are getting worse or you feel you are sinking into a deeper depression
  • You are relying on alcohol or drugs to cope
  • You have thoughts of self-harm or suicide (seek urgent help)

Frequently Asked Questions

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