Diagnosis & Classification Flashcards
Outline diagnosis & classification for schizophrenia
-Diagnosis & classification interlinked
-According to medical approach, to diagnose specific disorder, we need to distinguish one from another
-This is done by identifying clusters of symptoms that occur together & classifying this as 1 disorder
-2 major systems for classification of mental disorders:
WHO Int. Classification of Disease (ICD-10)
American Psychiatric Association’s Diagnostic & Statistical Manual (DSM-5)
-DSM-5 — 1 positive symptom for diagnosis/ 2+ negative symptoms for ICD
-Previous editions of ICD&DSM recognised subtypes of Schiz but both dropped as they’re inconsistent
Outline positive symptoms
HALLUCINATIONS (Unusual sensory experiences)
-Some related to events in environment whereas others have no relationship to what senses picking up from environment, e.g. voices heard
-Can be experienced in relation to any sense, e.g. distorted facial expressions
DELUSIONS (AKA paranoia or irrational beliefs)
-Common delusions involve being important figure, e.g. Jesus or being persecuted, e.g. by governments
-Delusions can make person behave in ways making sense to them but bizarre to others
-Vast majority of people with delusions aren’t aggressive & more likely to be victims
Outline negative symptoms
SPEECH POVERTY (Changes in patterns of speech)
-Seen as negative as emphasis on reduction in amount & quality of speech in schiz
-May include delay in person’s verbal responses during conversation
-Nowadays more emphasis placed on speech disorganisation - speech is incoherent/changing topics mid sentence — classified as positive symptom in DSM-5 but speech poverty still negative
AVOLITION (AKA ‘APATHY’)
-Finding it difficult begin/keep up with goal-directed activity
-Schizos often have sharply reduced motivation to carry out range of activities
-Andreasen (1982) identified 3 signs of avolition: poor hygiene & grooming, lack of persistence in work/education & lack of energy
Outline inter-rater reliability
Different diagnosing clinicians reach same diagnosis for same individual
Outline test-retest reliability
Same clinician reaches same diagnosis for same individual on two occasions
Outline validity
Whether we assess what we’re trying to assess
Outline the issues in diagnosis & classification of Schizophrenia
STRENGTH - Good Reliability - relating to consistency
E.g. - Psychiatric diagnosis is reliable when it has I-R & T-R reliability
Before DSM-5, reliability for Schiz diagnosis was low, but now improved
Osorio et al. (2019) report great reliability for diagnosis of Schiz in 180 individuals using DSM-5, pairs of interviewers got I-R reliability of +0.97 & T-R reliability of +0.92
E.x. - We can be reasonably sure that diagnosis of Schiz consistently applied
LIMITATION - Low Validity
E.g. - One way to assess validity of psychiatric diagnosis is criterion validity
Cheniaux et al. (2009) had 2 psychiatrists independently assess same 100 clients using ICD-10 &
DSM-4 criteria - 68 diagnosed with Schiz under ICD system & 39 under DSM
Ex. - Suggests Schiz is either over- or under diagnosed according to diagnostic system, either way this suggests criterion validity is low
HOWEVER - In Osorio’s study there was great agreement between clinicians when using 2 measures to diagnose both derived from DSM
Means criterion validity for diagnosing Schiz actually good provided take place within single diagnostic system
LIMITATION - CO-MORBIDITY
E.g. - If conditions occur together lot of time this questions validity of diagnosis & classification bc they might actually be single condition - Schiz commonly diagnosed with other conditions
For example, review found about half of Schizos also had diagnosis of depression or substance abuse
Ex. - Problem for classification as Schiz may not exist as distinct condition & problem for diagnosis as at least some people diagnosed with Schiz may have unusual cases of conditions like depression
