Schizophrenia Flashcards
Schizophrenia
Schizophrenia is a serious mental disorder suffered by about 1% of the world population. More in men than women, more in cities than the countryside and more in working class rather than middle class. The symptoms can interfere with everyday tasks, many end up homeless or hospitalised. Contact with reality and insight are impaired.
Classification of schizophrenia
Schizophrenia doesn’t have a single defining characteristic, it is a cluster of symptoms. They use the ICD-10 and the DSM-5(America). These differ slightly in their classification. In the DSM-5 one of the positive symptoms or speech disorganization must be present, where as two or more negative symptoms are sufficient in the ICD-10.
ICD-10
Recognises a range of subtypes of schizophrenia. Paranoid schizophrenia- characterised by powerful delusions and hallucinations, but relatively few other symptoms.
Hebephrenic schizophrenia- mostly negative symptoms.
Catatonic schizophrenia- disturbance to movement- immobile or overactive.
Positive symptoms of schizophrenia
Additional experiences beyond those of ordinary existence. Include hallucinations and delusions.
Hallucinations
A positive symptom, these are sensory experiences of stimuli that have either no basis in reality or are distorted perceptions of things that are there. Can be any sense, hearing voices or seeing things.
Delusions
A positive symptom. Also known as paranoia. They involve irrational beliefs that have no basis in reality, for example, that the sufferer is someone else or that they are the victim of a conspiracy. Eg. think that aliens are after them, or that they are jesus. Suffers behave in a way that make sense to them but bizarre to others.
Negative symptoms of schizophrenia
Involve the loss of usual abilities and experiences. Avolition, speech therapy
Avolition
Finding it difficult to begin or keep up with goal directed activity. They usually have reduced motivation to caryy out a range of activities. Andreason identified 3 signs of avolition; poor hygiene and grooming, lack of persistence in work/education and lack of energy.
Speech poverty
Changes in patterns of speech. ICD-10- emphasis on reduction in the amount and quality of speech. Sometimes a delay in the sufferers verbal responses.
DSM-5- speech disorganisation, speech becomes incoherent or the speaker changes topic mid sentence.
Diagnosis and classification of schizophrenia- evaluation (Reliability)
Reliability- Cheniaux et al has 2 psychiatrists independently diagnose 100 patients using both the DSM and ICD criteria. Inter-rater reliability was poor. One diagnosed 44 using the ICD and 26 with the DSM and the other diagnosing 24 using the ICD and 13 with the DSM. This is a weakeness of diagnosis of schizophrenia.
Diagnosis and classification of schizophrenia- evaluation (validity)
From the Cheniaux et al study, it is more likely for schizophrenia to be diagnosed using the ICD rather than the DSM. This suggests that schizophrenia is either over diagnosed in the ICD or under diagnosed in the DSM. So poor validity.
Diagnosis and classification of schizophrenia- evaluation (co-morbidity)
Morbidity- how common a medical condition is. Co-morbidity is the phenomenon that 2 or more conditions occur together. Buckley et al, concluded that around half of patients with a diagnosis of schizophrenia also have a diagnosis of depression or substance abuse. PTSD and OCD occurred in around 25% of schizophrenia diagnosis’s. Maybe we’re bad at telling the difference between the 2 conditions.
Diagnosis and classification of schizophrenia- evaluation (symptom overlap)
There is considerable overlap between the symptoms of schizophrenia and other conditions. E.g. both schizophrenia and bipolar involve positive symptoms like delusions and negative symptoms like avolition. ICD may diagnose as schizophrenic and DSM as bipolar. Lacks validity.
Biological explanations for schizophrenia- Genetic basis and candidate genes
Schizophrenia runs in families, however this is week evidence for a genetic link as they often share aspects of their environment. However, we do share 100% genes with MZ twins and 50% with DZ twins, siblings and parents.
Candidate genes are believed to be associated with risk of inheritance. Genes associated with increase risk included those coding for the functioning of a number of neurotransmitters including dopamine.
Biological explanations for schizophrenia- the dopamine hypothesis
Neurotransmitters (the brain’s chemical messengers) appear to work differently in the brain of schizophrenic. Dopamine is believed to be involved.
Biological explanations- the dopamine hypothesis- Hyperdopaminergia in the subcortex
High levels of activity of dopamine in the subcortex (central areas of the brain). Eg. an excess of dopamine receptors in Broca’s area may be associated with poverty of speech or the experience of auditory hallucinations.
Biological explanations- the dopamine hypothesis- Hypodopaminergia in the cortex
Goldman-Rakic et al identified a role for low levels of dopamine making in the negative symptoms of schizophrenia. It may be that both Hyper and Hypodopaminergia are correct explanations as both high and low levels of dopamine in different brain regions are involved in schizophrenia.
Biological explanations- Neural correlates
Neural correlates are measurements of the structure or function of the brain that correlate with an experience, in this case schizophrenia. Both positive and negative symptoms have neural correlates.