schizophrenia

positive symptoms

• appear in addition to ordinary experiences

• thoughts/ behaviour the person with SZ did not experience before they became ill

negative symptoms

• lack or absence of normal function/behaviour

• behaviour that a person experience before they now can no longer do

hallucinations

Sensory experiences that are not based in reality

e.g hear voices

delusions

disturbances in content of thought, irrational beliefs, commonly linked to paranoia

e.g persecutions- people are out to get you

disorganised speech

shift themes, word salad, meaningless words

-affective flattening

poor range of emotional expression

-speech poverty

reduction in quantity and quality of speech

diagnostic reliability

the consistency of a measuring instrument to assess the severity of the SZ symptoms

inter-rater reliability

• whether 2 independent assessors give similar diagnosis of the same person independently

• Soderberg found 81% agreement using the DSM

• Jakobsen tested the reliability of the ICD-10, 100 patients were assessed finding a concordance rate of 98%, demonstrating high reliability

test-retest reliability

• whether tests used to deliver these diagnoses are consistent over time allowing a clinician to make the same diagnosis on separate occasions

• osario reported excellent test-retest reliability in 180 individuals using the DSM5 of +0.95

factors affecting reliability

• is too broad- two patients could have completely different symptoms

• subjectivity- diagnostic requirements lack sufficient reliability to distinguish between sz and non sz patients

• cultural differences- variation between countries- 69% of us psychaitrists diagnoses sz whereas only 2% diagnosed sz 

diagnostic validity

the extent that sz represents something that is real and distinct from other disorders- do the classification systems measure what it claims to measure

criterion validity

the extent to which using different classification systems produce the same diagnosis in the same patients

• cheniaux- 100 patients- 68 diagnosed using ICD and 39 diagnosed with DSM- validity is low

factors affecting validity

comborbity- the extent that 2 or more conditions co occur in the same individual 

• buckley- comborbity depression occurs in 50% of sz patients 

symptom overlap- symptoms of SZ are also found in other conditions

• ellason found people with DID have more first rank symptoms than sz

family studies in SZ- GOTTESMAN

• children with two sz parents have concordance rate of 46%, one parent 13% and siblings 9%

-research suggests that sz runs in families, however is it down to environmental factors

twin studies in SZ

JOSEPH

Showed concordance rate of mz twins of 40% and 7% for DZ

+all twin studies show higher concordance in MZs- more reliable argument

-these studies assume MZ AND DZ have equivelant environments- which is flawed because they do not consider socio psychological factors