Classification of OCD

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Classification & Diagnosis (4 marks AO1)


  • Obsessions: recurrent, intrusive thoughts (e.g. germs are everywhere) or impulses (e.g. to shout obscenities).. perceived inappropriate/forbidden
  • Compulsions: repetitive behaviours/mental acts that aim to reduce the anxiety caused by obssession --> Compulsive behav. not connected in realistic w/what they designed to neutralise/prevent


  • Person MUST recognise that the obsessional thoughts/impulses=Product of their OWN mind --> distinguishes from other mental disorders (schizophrenia)
  • OCD cannot be caused by other medical conditions/substance use (alcohol/drug dependancy)
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Issues relating to the diagnosis of OCD (4+16)

Reliability= consistency of a measuring instrument

Measured: are the test items consistent (internal relaibiltity)? or whether two independent assesors give similar scores (inter-rater reliability measures external relaibility)

Goodman: Y-BOCS= semi-structured interview --> Assesses symptom severity and monitors response to treatment --> First 2 sections: obsessions experienced now & past --> Final section: how OCD interferes w/everyday life & patient ability to control/resist symptoms

SUPPORT RUSH: 'best available measure' --> Goodman: devised new variant Florida Obsessive-Compulsive Inventory --> Further SUPPORT: Woody found good internal consistency --> Improved if items related to ppls ability to resist/control symptoms were removed--> DC's .. SD lowered b/c P's more likely answer truthfully to non-personal Q's --> Ppl may not b aware of how severe mental illness is --> Further SUPPORT: children's version (CY-BOCS) good inter-rater reliability --> H/W must caution .. children answering the questions :/

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Issues.. (cont)

Although good test-retest 2 weeks (supports external reliability of YBOCS short term), CONTRADICTORY 48.5 days lower .. lower external validity long term --> H/W computerised versions = similar scores to interview-administered versions .. provides support external reliability YBOCS .. DCs dont affect either method - may affect both equally?

Validity= does the diagnosis rep. somethin real and distinct from other disorders & does it measure what it sets out to measure --> 2 aspects --> Discriminant validity: how well OCD distinguished other condt. -->SUPPORT: YBOCS does distinguish b/twn OCD & other disorders --> H/W CONTRADICTION: does not discriminate well w/depression --> Both OCD & dep. presnt anxiety .. strong evidence for BIOLOGICAL AETIOLOGY of OCD & suugests OCD NOT separate disorder but one type of dep. --> Nevertheless, internal valid. strengthened by fact interviews done= clinician distinguish b.twn obsessions & 'simple worries' that we all have --> Patient may not distinguish b/twn these & overexaggerate symptoms --> Therefore provides SUPPORT for internal validity of YBOCS

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Issues ... (cont II)

2nd aspect: Validity of diagnosis: SD & fear of 'labelling' .. incorrect answers given to YBOCS= confounding any diagnosis --> SUPPORT: don't wanna handle Questionnaire cause dirty --> Further limitation: lack awareness of how severe symptoms .. better diagnosed parents/friends

Incidence of OCD same in most countries/cultures (2-3%). --> H/W symptoms/manifestation shaped by 'sufferers' culture --> If endemic = bio. tendency to be very nervous but b/c compulsions culturally specific (China #4 UK #13) suggests compulsions are environ. in its aetiology --> Diathesis = interactionist approach to treat --> Imposed etics: symptom checklisk culturally biased? --> SUPPORT: signif. diffs. b/twn White and Black Americans in scores for contamination obsessions --> Diagnosis of OCD needs to be devel. more complexly in order to address cultural/racial diffs. in OCD otherwise tools such as the YBOCS, used to diagnose symtoms of OCD, lack in internal validity and reliability

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