Schizophrenia

• Schizophrenia


  A mental disorder characterized by a disintegration of the personality, involving a range of psychotic symptoms such as delusions, hallucinations, and disorganized thinking and behavior
• Schizophrenia

  • Involves a split between thinking and feeling
  • Patients lack insight into their condition and don't realize they are ill
• The onset of schizophrenia is typically in late adolescence or early adulthood
• Positive symptoms


  Excess or distortion of normal functions, such as delusions, hallucinations, and changes in behavior
• Delusions

  • Paranoid delusions - belief that something or someone is deliberately trying to harm them
  • Delusions of grandeur - belief that they have some imaginary authority or power
• Hallucinations

  • Auditory hallucinations - hearing voices that are not real
  • Visual, olfactory, and tactile hallucinations - seeing, smelling, and feeling things that are not there
• Catatonic or disorganized behavior


  Inappropriate or strange behaviors, such as aimless motor activity, rigid posture, increased time at rest, forced grasping, and resistance to instructions
• Disorganized speech


  Speech that is incomprehensible, with sentences that don't make sense and topics that change with little or no connection
• Negative symptoms


  Reduction or loss of normal functions, such as flattened emotions, inability to enjoy things, social withdrawal, apathy, and speech poverty
• Diagnostic reliability


  Clinicians must be able to reach the same conclusion about a diagnosis when assessing the same patient at different points in time or when different clinicians assess the same patient
• Inter-rater reliability


  Measure of the extent to which different clinicians reach the same conclusion about a diagnosis when assessing the same patient
• A kappa statistic of 1 indicates perfect inter-rater agreement, a score of 0 indicates no agreement. A score generally considered good is above 0.70
• With the recent edition of DSM-V, the diagnosis of schizophrenia had a kappa score of 0.46
• Validity


  The extent to which a diagnosis reflects an actual disorder
• The two most widely used classification systems for diagnosis of schizophrenia are the DSM and the ICD-11
• The DSM-V is produced by the American Psychiatric Association, the ICD-11 is produced by the WHO
• Cultural factors influence the diagnostic process, and there are significant variations between cultures in the diagnosis of schizophrenia
• Cultural differences in diagnosis

  • A study found 69% of US psychiatrists diagnosed schizophrenia, but only 2% of British psychiatrists gave the same diagnosis for the same patient description
• Older editions of the DSM and ICD had more differences, but they are now more aligned (but not completely)
• Symptom perception may vary culturally - a study found Ghanaian and Indian participants reported more positive experiences with voices, while US participants reported only negative experiences
• The DSM has been criticized for being biased towards pathologizing one gender over the other
• Many of the symptoms used to identify and diagnose schizophrenia are also found in other disorders, affecting the validity of the diagnosis
• Schizophrenia patients often have co-morbidities such as substance abuse, anxiety, and depression, which also affects the validity of the diagnosis
• The DSM encourages clinicians to make multiple diagnoses when appropriate, rather than just one
• Longenecker et al (2010)

  Concluded that maybe men with schizophrenia have lower inter-personal functioning than schizophrenic women, who are able to have good family relationships
• High-functioning


  May explain why some women have not been diagnosed with schizophrenia
• Masking the symptoms doesn't help in diagnosing schizophrenia
• A diagnosis of schizophrenia tells us little about the chances of improvement (prognosis)
• Research indicates that whilst some with schizophrenia show improvement from the disorder, others don't
• There is much variation in outcomes for patients diagnosed with schizophrenia (20% recovering to previous functioning and 30% showing sone improvement but with intermittent relapse)
• A diagnosis of schizophrenia has little 'predictive validity' in terms of a person's recovery from the disorder
• Symptom overlap and co-morbidity

  Can have negative consequences for people diagnosed with schizophrenia
• Weber (2004) found that patients with schizophrenia who were co-morbid with medical problems had a lower standard of care
• Lack of inter-rater reliability is a major issue when diagnosing schizophrenia
• Inter-rater reliability


  The degree of agreement among raters (clinicians) when diagnosing a condition (schizophrenia)
• Perfect agreement between clinicians yields a Kappa score of 1
• Whaley (2001) Regier (2013) reported Kappa scores of 0.11 and 0.46 respectively when diagnosing schizophrenia
• Lack of inter-rater reliability suggests that schizophrenia cannot be reliably diagnosed by clinicians
• Gottesman - Family studies: Concluded that if your parents suffer from schizophrenia, you have a 46% chance of developing it. Concordance rated are 8-12% if only one parent has schizophrenia
• Joseph (2004) meta analysis of twin studies


  1. If identical twins (monozygotic) have schizophrenia, the other twin has a 40% chance

  2. If non-identical twins (dizygotic) have schizophrenia, the other twin has around a 7% chance