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What is depression?

  • Depression is a mood (affective) disorder
  • It can be unipolar depression (first occurrence or recurrent) or bipolar (with reoccurrences of mania and depression)
  • The onset of individual episodes is often related to stressful events or situations
  • It usually runs a relapsing and remitting course


In depression, aetiology is typically multifactorial. The usual way of presenting aetiological factors in psychiatry is by considering a “3 by 3 table” of:

  • Biological-Psychological-Social factors
  • Predisposing-Precipitating-Perpetuating factors
  • These can (and commonly do) overlap
Depression aetiology table
Depression aetiology table


Protective factors must also be considered (factors that lower an individual’s risk of developing a disorder).

Protective factors for depression
Protective factors for depression


Examples of Aetiologies


  • Genetics (e.g. family history of depression in the nuclear family increases the risk to almost 30-40% and up to 50% in monozygotic twins)
  • Personality (e.g. dependent, anxious and avoidant traits)
  • Physical illness (e.g. hypothyroidism or chronic illnesses)
  • Biochemical theories, monoamine deficiency (e.g. serotonin imbalance causes depressive symptoms)
  • Neuroendocrine (hypothalamic-pituitary-adrenal axis)
  • Co-morbid substance misuse
  • Medication use (e.g. beta-blockers, steroids)
  • History of other mental illnesses (e.g. anxiety)



  • Negative automated thoughts– cognitive theory of Beck (e.g. helplessness, hopelessness, worthlessness)
  • Life events
  • Environmental factors (e.g. support)
  • Lack of education



  • Social support
  • Poor economic status or support

Diagnostic Hierarchy

Just as with every case in psychiatry, there is a diagnostic hierarchy to consider before coming to a definite diagnosis (Greg Lydall, 2009):

Diagnostic hierarchy
Diagnostic hierarchy


Clinical assessment and investigations can help rule out various differential diagnoses:

  • Thyroid function tests (TFTs) for hypothyroidism (an organic cause of low mood).
  • Urine drug screen for ongoing substance misuse
  • Medication review

Clinical Presentation

Depression is graded as mild, moderate or severe. A diagnosis of a depressive episode requires:

  • Symptoms present for at least 2 weeks (this may be less if depression is severe)
  • Symptoms are not attributable to other organic or substance causes (e.g. normal bereavement)
  • Symptoms impair daily function and cause significant distress

These “symptoms” are known as the core/main and cognitive symptoms:

Core or Main symptoms (“MIE”)

  • Mood is low
  • Interest is lost (Anhedonia)
  • Energy is low (Anergia)


Cognitive Symptoms

  • Decreased concentration
  • Impaired memory
  • Pessimistic and self-blaming
  • Nihilistic


  • Mild depression requires 2 core or main plus at least 2 cognitive symptoms.
  • Moderate depression requires 2 core or main plus at least 3 or 4 cognitive symptoms.
  • Severe depression requires all 3 core of main plus at least 5 cognitive symptoms.

Taking this one step further, the ICD-10 criteria (1994) for unipolar depression is as follows:

  1. Mild depressive episode, with or without somatic symptoms
  2. Moderate depressive episode, with or without somatic symptoms
  3. Severe depressive episode, with or without psychotic symptoms – these may be mood-congruent or incongruent psychotic symptoms


Somatic Symptoms

  • Marked loss of appetite or weight loss (some people experience the opposite)
  • Marked loss of libido
  • Sleep disturbances with early morning awakening (usually 2 hours or more before the usual time)
  • Diurnal variation of mood (worse in the mornings)
  • Psychomotor retardation or agitation – objective evidence, remarked on or reported by other people

The table below provides a clearer description of when with or without somatic symptoms is used, as per the ICD-10 classification.

ICD-10 classification of depression severity
ICD-10 classification of depression severity


Symptoms of Psychosis

The two main symptoms of psychosis to consider are hallucinations (commonly auditory, less commonly olfactory; visual; tactile) and delusions (e.g. nihilistic or persecutory).

These symptoms of psychosis can be:

  • Mood-congruent (delusions/hallucinations that are consistent with typical depressive themes of e.g. guilt)
  • Mood-incongruent (delusions/hallucinations that are not consistent with typical depressive themes; including more first rank symptoms e.g. thought insertion).

Risk Assessment

  • Risk to self: self-harm, suicide or neglect (commonest in depression)
  • Risk to others: technically low-risk – unless psychotic features such as command hallucinations are present


Management is based on the bio-psycho-social model and is divided into short-term and long-term strategies. “Treatment and care should take into account people’s individual needs and preferences. Good communication is essential, supported by evidence-based information, to allow people to reach informed decisions about their care”. (NICE, 2009)

Management is dependent on symptoms the individual has (e.g. difficulty sleeping: practising good sleep hygiene and having a sleep diary).

Depression management
Depression management

Mild depression: Psychological and Social


  • First line: Low-intensity psychosocial interventions (NICE, 2009):
    • Computerised cognitive-behavioural therapy (CCBT)
    • Individualised CBT or individual guided self-help based on CBT principles
    • Structured group physical activity programme
  • Psychoeducation of disease

Exceptional cases to consider starting on biological therapy (i.e. antidepressants):

  • Past history of moderate or severe depression
  • Presence of mild depression that has been present for at least 2 years
  • Presence of mild depressive symptoms after other interventions


  • Risk assessment
  • Ongoing review – response to low-intensity psychosocial intervention, compliance, symptoms etc.
  • Measurement scales to assess response to treatment and quality of life
  • Relapse prevention plan
  • Assess for social support and previous issues flagged up during consultations
  • If they are on antidepressant therapy – review compliance, use, side effects and adjust doses if appropriate

Moderate or Severe depression: Biological, Psychological and Social


  • First line: a combination of antidepressant therapy (biological treatment) and high-intensity psychosocial interventions (NICE, 2009) which will depend on if they have/do not have a chronic physical health problem (see below).
  • If they are presenting with a severe depressive episode with psychotic symptoms, then augmenting treatment with an antipsychotic (aripiprazole, risperidone, quetiapine or olanzapine)
  • Psychoeducation of disease

For people without a chronic physical health problem:

  • Individual CBT
  • Interpersonal therapy
  • Behavioural activation
  • Behavioural couples therapy

For people with a chronic physical health problem:

  • Group-based CBT
  • Individual CBT
  • Behavioural couples therapy


  • Risk assessment
  • Review their response to high-intensity psychosocial intervention compliance, symptoms, etc
  • Review their response to antidepressant therapy, compliance, side effects and adjust doses if appropriate.
  • Measurement scales to assess response to treatment and quality of life
  • Relapse prevention plan
  • Assess social support and previous issues flagged up during the consultation


Dr Nusrat Khan

Clinical Associate Professor and Consultant Psychiatrist

Newcastle University


  1. Greg Lydall, M.D., Noreen Jakeman, Sheena Webb (2009) ‘Affective Disorders’, in Sarah Stringer, L.C., Susan Davison, Maurice Lipsedge (ed.) Psychiatry P.R.N. Oxford University Press.
  2. ICD-10 (1994) ICD-10 Churchill Livingstone.
  3. M Justin Coffey, M. (2017) Catatonia: Treatment and prognosis. Available at: https://www.uptodate.com/contents/catatonia-treatment-and-prognosis (Accessed: 23/01).
  4. NICE (2009) Depression in adults: recognition and management.

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