What are the key diagnostic criteria for major depressive disorder according to NICE guidelines?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 14 August 2025Updated: 14 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

According to NICE guidelines, the diagnostic criteria for major depressive disorder refer to those outlined in the International Classification of Diseases-11 (ICD-11) or the Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5) .

  • DSM-5 Criteria: A diagnosis of depression requires the presence of five or more symptoms from a list of nine, occurring during the same two-week period . At least one of these symptoms must be depressed mood or a loss of interest or pleasure, present most of the day, nearly every day . The nine symptoms include:
    • Depressed mood (indicated by subjective report or observation by others) .
    • Loss of interest or pleasure in almost all activities (indicated by subjective report or observation by others) .
    • Significant (more than 5% in a month) unintentional weight loss or gain, or a decrease or increase in appetite .
    • Sleep disturbance (insomnia or hypersomnia) .
    • Psychomotor changes (agitation or retardation) severe enough to be observable by others .
    • Tiredness, fatigue, or low energy, or decreased efficiency with which routine tasks are completed .
    • A sense of worthlessness or excessive, inappropriate, or delusional guilt (not merely self-reproach or guilt about being sick) .
    • Impaired ability to think, concentrate, or make decisions (indicated by subjective report or observation by others) .
    • Recurrent thoughts of death (not just fear of dying), suicidal ideation, or suicide attempts .
    The symptoms must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning .
  • ICD-11 Criteria: Depression is defined as the presence of depressed mood or diminished interest in activities occurring most of the day, nearly every day, for at least two weeks, accompanied by other symptoms such as reduced ability to concentrate, beliefs of low self-worth or excessive guilt, hopelessness, recurrent thoughts of death or suicidal ideation, significantly disrupted sleep, significant changes in appetite or weight, psychomotor agitation or retardation, and reduced energy or fatigue .

A comprehensive assessment for depression should not rely simply on a symptom count, but also take into account the degree of functional impairment and/or disability associated with the possible depression, and the duration of the episode ,.

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