Diagnosis and classification

• What is schizophrenia?

  • A severe psychotic disorder characterised by the loss of contact with reality
  • Experienced by about 1% of the world population yet more commonly diagnosed in men and those of lower socio-economic classes
  • Symptoms can interfere severely with everyday tasks, so most patients end up homeless or hospitalised
• What is the difference between positive and negative symptoms of schizophrenia?

  • Positive symptoms are distortions of normal function, which tend to have greater weight during diagnosis but are harder to measure objectively and can be affected by cultural differences
  • Negative symptoms are a lack of normal function, they start a lot earlier (sometimes even years before positive ones), can be much more objectively measured, and are less affected by cultural differences BUT can be implicated in co-morbidity
• What are hallucinations?

  • Hallucinations are unusual sensory experiences, which can be either distorted perceptions of the environment or related to people. Can also be experienced in relation to any sense
  • Auditory: hearing voices/sounds others can't
  • Visual: seeing things others can't
  • Olfactory: smelling things others can't
  • Tactile: feelings things on skin/body other's can't
• What are delusions?

  • Also known as paranoia, delusions are irrational beliefs about the environment that aren't real but seem real
  • These can be delusions of grandeur which are inflated beliefs about an individual's power or importance e.g. being historical, political or religious figures like Jesus or Napoleon
  • Or delusions of reference like believing external events in the environment are directly related to them e.g. personal messages being communicated through TV or radio
• What is disorganised speech?

  • When an individual has trouble organising their thoughts due to dysfunctional thought processes, which shows up in their speech
  • Can experience derailment which is quickly slipping from one topic to another, as well as 'word salad' which is incoherent speech with a lack of fluency, sounding like a child's gibberish
• What are the positive symptoms of schizophrenia?

  • Hallucinations
  • Delusions
  • Disorganised speech
• What are the negative symptoms of schizophrenia?

  • Speech poverty (alogia)
  • Avolition
  • Affective flattening
  • Anhedonia
• What is speech poverty?

  • Also known as alogia, it is a reduction in the amount and quality of fluent speech, thought to reflect slow or blocked thoughts
  • May produce fewer words or only speak in response to others
• What is avolition?

  • Finding it difficult to keep up with goal-directed behaviour as people with schizophrenia have sharply reduced motivation to initiate activities
  • This can be seen in poor hygiene and grooming, lack of persistence in work or education, and lack of energy
• What is affective flattening?

  • Reduction in outward expression of emotions, with less co-verbal behaviour
  • Can show a deficit in prosody - less paralinguistic features like strength, tone, or pitch of voice with no facial expressions
• What is anhedonia?

  • A lack of reactivity to normally pleasurable stimuli. This can manifest as feeling no pleasure from physical stimuli like food or human contact, or feeling no pleasure from interpersonal interactions, known as physical and social anhedonia
  • Less reliable symptom as it can overlap with disorders like depression
• What are the DSM-5's requirements for diagnosis of schizophrenia?

  • Must show 2 or more positive or negative symptoms present during a 1 month period
  • Must show social/occupational dysfunction for a significant portion of time since the onset of the disturbance
  • Continuous signs of disturbance must persist for at least 6 months, including 1 month of symptoms that meet the criterion
  • Signs and symptoms should not be better accounted for by another disorder or medical condition
• What are the ICD-10's requirements for diagnosis of schizophrenia?

  • Must show 2 or more positive or negative symptoms that are not a manifestation of other medical conditions/disorders
  • 2 negative symptoms will suffice as opposed to the DSM-5's requirement for at least 1 positive symptom
  • Recognises sub-types like catatonic or paranoid schizophrenia
• What is reliability and validity in diagnostic tools?

  • Inter-rater reliability: for a diagnostic tool to be reliable, different diagnosing clinicians should reach the same diagnosis for the same individual
  • Test-retest reliability: when the same clinician uses the same diagnostic tool to reach the same diagnosis on 2 separate occasions
  • Criterion validity: whether different assessment systems arrive at the same diagnosis for the same patient on the same disorder
• What is one strength of the diagnosis of schizophrenia?

  • Good reliability: Osorio et al. (2019) reported excellent reliability for the diagnosis of schizophrenia using the DSM-5
  • Pairs of interviewers achieved +.97 inter-rater reliability and +.92 test-retest reliability in 180 individuals, showing we can be reasonably sure that the diagnosis of schizophrenia is consistently applied
• What is one limitation of the diagnosis of schizophrenia?

  • Low validity: Cheniaux et al. (2009) had 2 independent psychiatrists assess the same 100 patients and found that 68 were diagnosed with schizophrenia under the ICD-10 but only 39 under the DSM-5
  • Suggests that schizophrenia in general is either under or over diagnosed - either one of the diagnostic tools is too lenient or the other is too strict, showing low criterion validity
• What is one limitation of the classification of schizophrenia?

  • Co-morbidity: when two or conditions occur together, calling into question the validity of their diagnosis and classification of symptoms
  • According to Buckley et al.'s review, 50% of people diagnosed with schizophrenia also have depression, 47% have substance abuse issues and 23% also have OCD
  • This suggests people are being wrongly diagnosed and that people being diagnosed with schizophrenia may just have unusual cases of depression
• What is another limitation of the classification of schizophrenia?

  • Symptom overlap: when symptoms of schizophrenia are also found in other conditions e.g. positive symptoms can also be found in bipolar disorder
  • Ellason & Ross (1995) pointed out that people with dissociative identity disorder experience much more symptoms of schizophrenia than those actually diagnosed, sufficient enough to receive an entire other diagnosis
  • Suggests classifications are not coherent enough to be associated distinctly to one order -> low accuracy and validity
• What is a social limitation of the diagnosis of schizophrenia?

  • Gender bias: Fischer & Buchanan (2017) found that men are more commonly diagnosed with schizophrenia than women in a ratio of 1:4:1, suggesting they are more vulnerable because of genetic factors
  • Cotten et al. (2009) suggests it is more likely that women are undiagnosed because they have closer relationships and get support from these, therefore meaning women may not be receiving the treatment or services that benefit them
• What is another social limitation of the diagnosis of schizophrenia?

  • Culture bias: some symptoms have different meanings in different cultures, like in Haiti people believe hearing voices are actually communications from ancestors
  • Pinto and Jones (2008) found that African-Caribbeans in Britain are 9x more likely to be diagnosed with schizophrenia than white people in Britain, but those living in African-Caribbean countries are not
  • Shows a culturally biased diagnostic system leading to discrimination against British African-Caribbeans and an over-interpretation of symptoms in them leading to wrong and vindictive diagnosis'