What is a strength of diagnosis and classification in schizophrenia ?
Reliability
A psychiatric diagnosis is said to be reliable if it has inter-raterreliability as well as test-retestreliability (same diagnosis , same individual multiple occasions)
Flavia Osario et al (2019) report good reliability for schizophrenia diagnosis in 180 individuals using the DSM-5
Pairs of interviewers achieved inter-rate reliability of +97 and test-retest of +92
Why is validity a limitation in the diagnosis of shizophrenia ?
One way to assess validity of a psychiatric diagnosis is criterion validity
Elie Cheniaux et al(2009) had two psychiatrists independently assess the same 100 clients using ICD-10 and DSM-IV criteria found that 68 were diagnosed with schizophrenia under the ICD system but only 39 under DSM
Why is gender bias a limitation in the diagnosis of schizophrenia ?
Since the 1980s men have been diagnosed with schizophrenia more commonly than women
Fischer and Buchanan 2017 ( ratio of 1 : 4.1 )
One explanation for this is women are less vulnerable than men , perhaps due to genetic factors.
Or women are underdiagnosed because they have closer relationships and hence get support ( Cotton et al 2009) which leads to women with schizophrenia often functioning better than men
- WOMEN may not be recieving treatment and services that might benefit them
Why is co - morbidity a problem when diagnosing schizophrenia
If conditions occur together a lot of the time then this calls into question the validity of their diagnosis and classification because they might actually be a singlecondition.
Eg one review found that about half of those diagnosed with schizophrenia
also had a diagnosis of depression or substanceabuse
schizophrenia may not exist as a distinct condition, and at least some people diagnosed with schizophrenia may have unusual cases of conditions ike depression
The probability that one member of a given group (a sibling, a cousin, a MZ twin, a DZ twin, etc.) will develop a disorder given that the other member already has it
- Originally , the dopamine hypothesis was based on the discovery that anti psychotics caused symptoms similar to those with Parksinsons disease(low DA) ( Seeman 1987)
- Because of this, it was thought that schizophrenia was due to too high levels of dopamine in subcortical areas of the brain
- Davis et al (1991) proposed the additiion of too low DA in the cortex which can also explain symptoms
- Its been suggested that cortical HYPOdopamingeria can lead to HYPERdopaminergia so they both play a part
- both genetic variations and early experiences of stress make people more sensitive to fluctuating DA levels
Describe the role of mutation in the genetic basis of schizophrenia
- Can also have a genetic origin in the absence of a family history of the disorder
-mutation in parental DNA which can be caused by radiation , poison or viral infection
-Evidence for mutation comes from positive correlations between paternal age ( increased risk of sperm mutation ) and risk of schizophrenia increasing from 0.7% with fathers under 25 to over 2% in fathers over 50
Describe the role of neural correlates of schizophrenia
- Dopamine is important in functioning of several brain systems related to the symptoms of schizophrenia
- Originally , the dopamine hypothesis was based on the discovery that antipsychotics caused symptoms similar to those with Parksinsons disease(low DA) ( Seeman 1987)
- Because of this, it was thought that schizophrenia was due to too high levels of dopamine in subcortical areas of the brain
- Davis et al (1991) proposed the additiion of too low DA in the cortex ( hypodopaminergia) which can also explain symptoms
- Its been suggested that cortical HYPOdopamingeria can lead to HYPERdopaminergia so they both play a part
- both genetic variations and early experiences of stress make people more sensitive to fluctuating DA levels
Outline a strength in the genetic explanation for schizophrenia
+ Family studies such as Gottesman show that risk increases with genetic similarity to a family member with schizophrenia
Adoption studies such as Tienari et Al 2004 show that biological children of parents with schizophrenia are at a heightened risk even if they grow up in an adoptive family
Hilker et Al 2018 showed a concordance rate of 33% for identical twins and 7% for nonidentical twins
People are more vulnerable to schizophrenia as a result of their genetic makeup
Outline a weakness in the genetic explanation for schizophrenia
Environmental factors
Environmental factors (biological and psychological) increase the risk of developing schizophrenia
Morgab et Al 2017 said Biological risk factors include birth complications and smoking THCrichcannabis in teenage years ( Di forti et Al 2015)
Psychological risk factors include childhoodtrauma which leave people more prone to adult mental health problems
Nina Morkved et Al 2017 found 67% of schizophrenics had at least one childhood trauma compared to 38% matched geoup with non psychotic mental health issues
Describe a strength of using antipsychotics to treat schizophrenia
+ Evidence for effectiveness
Thornley et al(2003) reviewed studies comparing the effects of chlorpromazine to control conditions
Data from 13 trials - 1211 participants showed drug associated with better functioning and reduced symptom severity as compared to placebo
Meltzer (2012) concluded clozapine is more effective than typical antipsychotics and has been effective 30-50% of treatment resistant cases where typical antipsychotics have failed
HOWEVER
Healy (2012) suggested serious flaws
Most studies are of short term effects and some successful trials have had their data published multiple times , exaggerating the size of evidence
Also because antipsychotics have a calming effect , which may have a positive effect but not actually reduce severity of psychosis
Describe debates and research into the appropriateness of drug therapy when treating schizophrenia ( side effects)
- 20 to 25% of sufferers experience serious side effects and will suffer from some form of disordered motor movements like tremors and involuntary tics ( eg TardiveDyskenisia)
- Causes 50% of sufferers to stop taking within the first year