Unipolar depression: symptoms and features

Symptoms (DSM-5 major depressive disorder)

At least 5 of these 9 symptoms during the same 2-week period, nearly every day, and at least one must be depressed mood or loss of interest or pleasure:

1. Depressed mood (in children and adolescents, may be irritability)

2. Markedly reduced interest or pleasure

3. Significant weight loss or gain, or appetite change

4. Insomnia or sleeping too much

5. Agitation or slowed movement

6. Fatigue or loss of energy

7. Feelings of worthlessness or excessive guilt

8. Difficulty thinking, concentrating or deciding

9. Recurrent thoughts of death or suicide

Also: clinically significant distress or impairment; not due to a substance or medical condition; never a manic or hypomanic episode.

ICD-11

ICD-11 (6A70 single episode depressive disorder; 6A71 recurrent depressive disorder, at least two episodes separated by several months) requires a depressive episode of at least 2 weeks, with low mood or loss of interest most of the day, nearly every day, plus symptoms such as poor concentration, excessive guilt, hopelessness, thoughts of death, changes in appetite or sleep, slowed or restless movement, and low energy. There must never have been a manic, hypomanic or mixed episode.

Both systems therefore agree closely on core symptoms and the 2-week duration.

Features

• WHO estimated 322 million people had depression in 2023, including 43 million children and adolescents.
• About a third of people with depression receive formal mental health care (WHO).
• DSM-5 removed the bereavement exclusion, so depression can now be diagnosed soon after a death, a change some argue medicalises normal grief.
• In the DSM-5 field trials, test-retest reliability for major depressive disorder was only kappa 0.28 (Regier et al., 2013).
• Diagnosis rates differ by gender and culture; in some cultures distress is expressed more through physical symptoms, which may affect diagnosis.

If you are struggling with low mood or thoughts of harming yourself, please talk to someone you trust, such as a parent, teacher, school counsellor or doctor. If you or someone else is in immediate danger, contact your local emergency services. Find A Helpline (findahelpline.com) lists free, confidential helplines in many countries.

Worked example

Amira has felt low, lost interest in her hobbies, sleeps badly and feels worthless for 3 weeks. Does she meet the DSM-5 criteria?

1. Core symptoms: depressed mood and loss of interest (two of the nine, including the required core).
2. Other symptoms: insomnia and worthlessness, making 4 symptoms in total.
3. DSM-5 needs at least 5 symptoms, so she does not yet meet the criteria, even though the duration (over 2 weeks) is met.
4. A clinician would check for other symptoms such as fatigue or poor concentration.

Answer: Four symptoms is one short of the five DSM-5 requires.

Check yourself

1. How many of the nine DSM-5 symptoms must be present for major depressive disorder?
   Show answer

   5. At least 5 of 9.

2. For how many weeks must the symptoms be present (DSM-5 and ICD-11)?
   Show answer

   2 weeks. At least 2 weeks.

3. Which symptom must be one of the five under DSM-5?
   • Insomnia
   • Weight loss
   • Poor concentration
   • Depressed mood or loss of interest or pleasure
   Show answer

   Depressed mood or loss of interest or pleasure. At least one core symptom is required.

4. What does 'unipolar' mean?
   • Depression without any episodes of mania
   • Depression in one season only
   • A single symptom
   • Depression caused by one gene
   Show answer

   Depression without any episodes of mania. Unipolar contrasts with bipolar, which includes mania.

5. Using WHO's 2023 figures, 43 million of the 322 million people with depression were children and adolescents. What percentage is that? Give your answer to 1 decimal place.
   Show answer

   13.4 %. 43 / 322 x 100 = 13.4%.

6. Explain why removing the bereavement exclusion from DSM-5 was controversial.
   Show answer

   Critics argued it could lead to normal grief after a death being diagnosed as depression, medicalising an ordinary reaction and possibly leading to unnecessary treatment.. It risks treating normal grief as a disorder.

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Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Psychology specification (issue January 2026)
• Pearson IAL Psychology component guide: WPS04 (Issue 2, November 2024)
• NCBI Bookshelf: DSM-5 criteria for major depressive disorder (table)
• WHO ICD-11 for Mortality and Morbidity Statistics: 6A70 Single episode depressive disorder
• WHO ICD-11 for Mortality and Morbidity Statistics: 6A71 Recurrent depressive disorder
• WHO fact sheet: Mental disorders (Global Burden of Disease figures for 2023)
• Regier et al. (2013), DSM-5 field trials in the United States and Canada, Part II: test-retest reliability of selected categorical diagnoses, American Journal of Psychiatry
• American Psychiatric Association: highlights of changes from DSM-IV-TR to DSM-5
• Find A Helpline (ThroughLine): free directory of verified helplines in 175+ countries

Last updated 8 November 2026. Spotted a mistake? Tell us.