DIAGNOSIS AND CLASSIFICATION

• PREVALENCE 


  Serious mental disorder affecting 1% of population. more common in males, city-dwellers and lower socio-economic groups
• CLASSIFICATION 


  identify symptoms that go together to make a disorder
• DIAGNOSIS 


  Identify symptoms and use classification system to identify the disorder
• CLASSIFICATION SYSTEMS 


  • DSM-5 = one positive symptom must be present
  • ICD-10 = two or more negative symptoms are sufficient for diagnosis
• TYPE 1 SZ 


  acute form/short episodes, characterised by positive symptoms and responsive to medication.
• TYPE 2 SZ


  chronic form/long-lasting episodes, characterised by negative symptoms and unresponsive to medication.
• HALLUCINATIONS (POSITIVE)


   Sensory experiences of stimuli that have either no basis in reality or are distorted perceptions of things that are there.  Bizarre, unreal perceptions, e.g. auditory - hearing voices, visual - seeing lights, objects, olfactory - smells, tactile - feeling bugs crawling on or under the skin.
• DELUSIONS (POSITIVE)

  Beliefs that have no basis in reality, a false belief that is resistant to confrontation with the truth, e.g. paranoid - believing they are a victim of a conspiracy, delusions of grandeur - believing they are famous or have special powers, delusions of reference - events in the environment are related to them, messages communicated through the TV.
• DISORGANISED SPEECH (POSITIVE)

  abnormal thought processes, leading to problems organising thoughts and speech.
• CATATONIC BEHAVIOUR (POSITIVE) 


  reduced reaction to the immediate environment, rigid postures, aimless motor activity.
• POSITIVE SYMPTOMS 


  Atypical symptoms experienced in addition to normal experiences.  Displaying an excess or distortion of normal functions, involving loss of touch with reality.
• NEGATIVE SYMPTOMS 


  Atypical experiences that represent the loss of a usual experience, behaviours involving disruption of normal emotions and actions.
• SPEECH POVERTY - ALOGIA (NEGATIVE)

  Reduced frequency and quality of speech, excessively brief replies to questions, minimal elaboration, less complex syntax, e.g. fewer clauses, shorter utterances.
• AVOLITION (NEGATIVE)


  Loss of motivation, lowered activity levels, apathy, poor hygiene and grooming, lack of persistence in goal-directed behaviour, lack of energy, lack of sociability and affection.
• AFFECTING FLATTENING (NEGATIVE)


   a reduction in the range and intensity of emotional expression, including facial expression, voice tone, eye contact and body language.
• RELIABILITY 


  It means ‘consistency’ of symptom measurement, e.g. a classification system - DSM.

  • Inter-rater reliability - the extent to which different assessors (mental health professionals) agree on their assessments (identical, independent diagnosis).
  • Test-retest reliability - clinicians make the same diagnosis on separate occasions from the same information.

  It is measured by a statistic called a kappa score (1 = perfect inter-rater agreement, 0 = zero agreement).  A score above 0.7 is considered good.  DSM trials have a score of 0.46.
• VALIDITY 


  It concerns how accurate diagnosis is - the extent to which we are measuring what we intend to measure.

  • Criterion validity - do different assessment systems arrive at the same diagnosis for the same patient? 
  • Predictive validity - if diagnosis leads to successful treatment, then diagnosis is seen as valid.
  • Descriptive validity - to be valid, patients with schizophrenia should differ in symptoms from patients with other disorders.
  • Aetiological validity - to be valid, all schizophrenics should have the same cause for the disorder.
• CULTURE BIAS 


  Tendency to over-diagnose members of other ethnic groups.  African Americans and English people of Afro-Caribbean origin are 7x more likely than white people to be diagnosed with schizophrenia.  They are also more likely to be perceived as ‘dangerous’ and placed in secure hospitals. Cultural traditions - positive symptoms; hearing voices is more acceptable in African cultures, as a way of communicating with ancestors.  Psychiatrists tend to over-interpret symptoms and distrust the honesty of black people.
• GENDER BIAS 


  The tendency for diagnostic criteria to be applied differently to males and females, either ignoring or exaggerating the difference.  Men are more likely to be diagnosed (up to 50%)

  • Men = suffer more negative symptoms and have higher levels of substance abuse.  
  • Women =  better recovery rates and lower relapse rates.  Women have better interpersonal functioning (work & family relationships), which mask the symptoms.
• SYMPTOM OVERLAP 


  Many symptoms of schizophrenia are found in other disorders.

  E.G - bipolar disorder, which have positive symptoms like delusions and negative symptoms like avolition.

  This suggests they might not be separate conditions.
• CO MORBIDITY 


  The co-existence of two separate conditions or illnesses at the same time, e.g. schizophrenia with substance abuse, anxiety, depression or OCD.  

  It also raises issues of descriptive validity, as having simultaneous disorders suggests that schizophrenia may not be a separate disorder.
• (+) DIAGNOSIS - GOOD RELIABILITY

  
  

  A reliable diagnosis is consistent between clinicians (inter-rater) and between occasions (test-retest). OSORIO ET AL report excellent reliability for sz diagnosis (DSM-5) - inter rater agreement of +.97 and test retest of +.92 = diagnosis of sz is consistently applied
• (-) DIAGNOSIS - LOW VALIDITY

  
  

  criterion validity involves seeing whether different procedures used to assess the same individuals arrive at the same diagnosis. CHENIAUX ET AL had 2 psychiatrists independently assess the same 100 clients. 68 were diagnosed with sz with ICD and 39 with DSM = sz is either over or under diagnosed, suggesting that criterion validity is low
• (-) DIAGNOSIS - CO MORBIDITY 


  if conditions ofter co-occur then they might be a single condition. sz is commonly diagnosed with other conditions. E.G BUCKLEY ET AL concluded that sz is comorbid with depression and substance abuse of OCD. = sz may not exist as a distinct condition
• (-) DIAGNOSIS - GENDER BIAS 


  men are diagnosed with sz more often than women. this could be because men are more genetically vulnerable, or women have better social support, masking symptoms = that some women with sz are not diagnosed so miss out on helpful treatment
• (-) DIAGNOSIS - CULTURE BIAS

  some symptoms e.g hearing voices are accepted in some cultures e.g afro-caribbean societies 'hear voices' from ancestors. afro-caribbean british men are up to 10x more likely to receive a diagnosis than white british men, probably due to over interpretation of symptoms by UK psychiatrists = afro-caribbean men living in the UK appear to be discriminated against by a culturally-biased diagnostic system.
• (-) DIAGNOSIS - SYMPTOM OVERLAP

  there is overlap between the symptoms of sz and other conditions e.g both sz and bipolar disorder involved delusions and avolition. sz and bipolar may be the same condition (a classification issue). sz is hard to distinguish from bipolar (diagnosis issue) = sz may not exist as a condition and if it does it is hard to diagnose