Diagnosis of Depression

Full notes on the clinical diagnosis, reliability and validity of depression.

AQA A Unit 4 exam

  • Created by: charlotte
  • Created on: 28-04-12 14:06

What is Depression

Depression; physical, mental, emotional and behavioural experiences more prolonged, severe and damaging

It is an affective disorder and the most common mental disorder in world.

24% of women; higher risk due to hormones and social reasons

15% men; more likley undiagnosed as less likley to seek help

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Classification & Diagnosis

Classification; system differentiating between different disorders

Diagnosis; clinical judgement of suffering from a disorder leading to treatment

There is no clinical/medical tests for diagnosis, only detailed interviews and questioners biased on two classifications;

  • DSM IV; system of all know symptoms associated with a mental condition. GP will ask patient if have symptoms which enables them to identify the condition
  • ICD; similar system which covers all diseases

Systems are based around;

  • A common cause
  • Require similar treatment
  • Progress similarly if left untreated
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Characterists of Depression

Person must have a depressive mood consistently for 14 days and 4 other characterists of depression for a diagnosis

  • Insomnia
  • Loss of interest
  • Weight gain/loss
  • Fatigue
  • Thoughts of death
  • Hopelessness and despair
  • Social withdrawal
  • Loss of sex drive

There are different types of depression;

  • Major Depressive Disorder (14 days or more)
  • Chronic Depression (2 years or more)
  • Bi-polar Disorder (episodes of both manic and depressive moods)
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Reliability of Diagnosis

Reliability; how consistent measures are

  • Symptom classifications overlap and some categories are questioned - depression is normally present with other mental disorders ('co-morbidity')
  • 10% of people diagnosed with unipolar develop bipolar - if the distinction between depressive types clear?

If patients are given the diagnosis or many different diagnosis they recieve the wrong treatment

  • Goldberg and Huxley; half of people who go to GP have depressive symptoms and these are not recognised
  • Beck; 2 psychiatrists 153 patients to diagnose and they only agreed 54%
  • Rosenham; found reliability in first study but warned of impostors not reliable in second study

Reliability is objective and goes on perception so people with same symptoms don't always recieve the same diagnosis

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Reliability of Diagnosis

  • Keller; used DSMIV with 524 patient interviews and then 6 months later (test-retest reliability, inter-rater reliability was high but the diagnosis was not consistent of fair to poor
  • Large sample of participants so representative sample but with a longnitudinal study may have drop-outs resulting in bias of co-operative participants only
  • However! there had been time for the patients to improve/get treatment, or in some cases get worse, so its difficult to establish whether reliability is being tested
  • Zanharini; inter-rater reliability was 0.8 for MDD but 0.61 a week later
  • Reliability may deteriorate over time
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Validity of Diagnosis

Validity; extent a diagnostic system measures what is claims to measure

Difficult to study validity as specialists may be biased by actively looking for symptoms or patient may be having a particularly bad day leading to a bias outcome

  • Van Weel-Baumgarten; GP diagnosis of depressive less ojective than other specialists as basing diagnosis on previous patient knowledge
  • Stirling et al; average consultation for GP was 8 minutes compared to 1 hour for a psychiatrists. 50% increase in GP consultation resulted in 32% increase in diagnosis accuracy

Main diagnosis is based on observation of behaviour in an interview so judgements of clinician (subjective)

Imposed artificially on behaviour to help understand but may not be valid

  • McCullough et al; compared 681 patients diagnosed with depression (MMD & dsythymia) found overlap in symptoms, responses to treatment and other variables made difficult to justify distinct forms of depressive illness
  • Miller and Goldberg; GPs more skilled in detection of mental disorders such as depression were able to elicit more cues from distressed patients
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Other issues of diagnosis


  • Diagnosis is affected by Western values of normality and abnormality and therefore is culturally biased
  • Approaches and treatments vary between cultures e.g. Africa called 'ants in brain'
  • China see depression as problem with living rather than a medical problem

Karasz; described depressive symptoms to south Asian and european Americans. South Asians identified social and moral problems, needing self management and European American's emphasised biological explanations

Naturally occurring groups but may not be representative as may have been westernised by living in New York


  • Females more likely diagnosed (may be from biological or life stress differences than biased clinician)
  • Expectation of gender stereotyping with women being expected to be more emotional and unstable and men less likely to admit having symptoms
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