Schizophrenia Flashcards
What are hallucinations
Positive symptom of schizophrenia. They are sensory experiences that have either no basis in reality or are distorted perceptions of things that are here
What are Delusions
Positive symptom of schizophrenia. Involve irrational beliefs that have no basis in reality.
What is Avolition
Negative symptom of schizophrenia. A loss of motivation to carry out tasks and results in lowered activity
What is speech poverty
Negative symptom of schizophrenia. Involves reduced frequency and quality of speech
What is Schizophrenia
a severe mental disorder where contact with reality and insight are impaired, an example of psychosis
What are positive symptoms
Atypical symptoms experienced in the addition to normal experiences. Include delusions and hallucinations.
What does the DSM-5 about diagnosing schizophrenia
Patients must display at least 2 main symptoms of schizophrenia for at least 6 months
What was Rosenhans method
Conducted an observation study. 8 volunteers, who pretended to have schizophrenia, admitted into hospital. Rosenhan tested how long it took doctors to declare that the volunteers were healthy
What were Rosenhans results
Took doctors between 7-52 days to realise the diagnoses were wrong, and that the volunteers were healthy. Study showed the diagnosis of schizophrenia can lack validity
Evidence for inter-rater reliability
In 1962, a researcher called Beck found diagnoses for schizophrenia were 52% similar. In 2005, researchers found that for schizophrenia were 81% similar. This shows diagnoses of schizophrenia are becoming more reliable over time
What are AO3 points for diagnosis and classification of schizophrenia
Good reliability
Low validity
Co-morbidity
Diagnosis: Reliability
-Reliability means consistency. A diagnosis is said to be reliable when different diagnosing clinicians reach the same diagnosis for the same individual (inter-rate reliability) and when the same clinician reaches the same diagnosis for the same individual on two occasions.
-Prior to DSM-5 the reliability for diagnosing schizophrenia was low but has now improved.
-Osório et al report excellent reliability for the diagnosis of schizo in 180 patients using DSM-5. Pairs of interviews had a inter-rater reliability of +97.
-This means we can reasonably sure that the diagnosis of schizophrenia is consistently applied.
Diagnosis: Low validity
-Validity concerns whether we assess what we are trying to assess. We assess validity of psychiatric diagnosis via criterion validity.
-Cheniaux et al had two psychiatrists independently assess same 100 clients using ICD-10 & DSM-4 criteria
-68 diagnosed with schizo under ICD and <39 under DSM
-Suggests schizo either over or underdiagnosed. Suggests hat criterion validity is low
Diagnosis: Low validity counter point
-Osório et al study reported excellent agreement between clinicians when using two measures to diagnose schizo both derived from DSM
-Means criterion validity for diagnosing is actually good provided it takes place within a single diagnostic system
Diagnosis: Co-morbidity
-when co-morbidity occurs this questions the validity of their diagnosis as it might be a single condition.
-Schizo is commonly diagnosed with other conditions. For example, half of those diagnosed had a diagnoses with depression or substance abuse.
-This is a problem as it means schizophrenia may not exist as a distinct condition, and is a problem for diagnosis as some people diagnosed may have unusual cases of conditions like depression
Schizophrenia: family studies
Family studied have shown risk of schizophrenia increases with genetic similarity to a relative with the disorder. MZ twins have higher concordance rates (48%) than DZ (17%), general population is 1%
Candidate genes for schizophrenia
-Schizophrenia was believed to be monogenetic but is polygenetic. Most likely genes would be those coding for neurotransmitters including dopamine.
Ripke et al
Combined all previous data from genome wide studies. The genetic make up of 37,000 schizos against 113,000 controls, 108 separate genetic variations associated with slightly increased risk of schizo. Different studies identified different candidate genes it also appears schizophrenia is aetiologically heterogeneous
Role of mutation
Schizophrenia can still arise When a family has no history of it. One explanation for this is mutation in parental DNA caused by radiation, poison or viral infection.
Neural correlates
Patterns of structure or activity in the brain that occur in conjunction with an experience and may be implicated in the origins of that experience
Original DA hypothesis
Hyperdopaminergia in subcortical brain areas may explain schizophrenia. This leafs to acute episodes and positive symptoms.
Updated DA hypothesis
Abnormally hypodopaminergia in cortex leads to hyperdopaminergia in subcortical areas. Explain cognitive problems and negative symptoms.
Evaluation points for biological explanations
Research support
Environmental factors
Evidence for dopamine
Biological explanation: Research support
Strong evidence base for the genetic explanation. Gottesman’s family study shows risk increases with genetic similarity to a family member with schizophrenia. Teinari et al adoption study shows that biological children of paretns with schizophrenia are at heightened risk. Hilker et al showed with a twin study concordance rate of 33% for MZ twins and 7% for DZ. This shows that some poeple are more vulnerable to schizophrenia as a result of their genetic make up.