diagnosis and classification of shizophrenia evaluation

Question 1

what is co-morbidity

Answer 1

the occurence of two disorders or conditions together, e.g. a person has schizophrenia and a personality disorder

Where two conditions are frequently diagnosed together it calls into question the validity of classifying the two disorders separetley

Question 2

what is symptom overlap

Answer 2

occurs when two or more conditions share symptoms this calls into question the validity of classifying the two disorders separately

Question 3

what is reliablity

Answer 3

reliability = consistency
an important measure of reliability is inter-rater reliability - the extent to which different assessors agree on their assessments

Question 4

what does reliability mean for schizophrenia diagnosis

Answer 4

in the case of diagnosis, this means the extent to which two or more mental health professionals arrive at that same diagnosis for the same individual

Question 5

what study shows that schizophrenia diagnosis and classification has poor reliability

Answer 5

Ellie Cheniaux et al had two psychiatrists independently diagnose 100 people uding both DSM and ICD criteria

Inter - rarter reliability was poor, with one psychiatrist diagnosing 26 with schizophrenia to DSM and 44 according to ICD, and the other diagnosing 13 according to DSM and 24 according to ICD.

This poor reliability is a weakness of the diagnosis of schizophrenia as it means that some people are misdiagnoses/overdiagnosed with one and undersiagnosis with the other.

Question 6

what is validity

Answer 6

it is the extent to which we are measuring what we are intending to measure

Question 7

what does validity mean for the diagnosis of schizophrenia

Answer 7

in the case of the mental disorder like schizophrenia there are number of validity issues to consider

Question 8

how do we asses validity for schizophrenia diagnosis

Answer 8

one standard way to assess the validity of diagnosis is by seeing whether different assessment systems arrive at the same diagnosis for the same person

If we consider the figures in Cheniaux et al study, we can see that schizophrenia is being more likely diagnosed using ICD than DSM.

This suggests that schizophrenia is either over-diagnosed in ICD or underdiagnosed in DSM. Either way, this poor validity is a weakness for the diagnosis of schizophrenia

Question 9

why is co-morbidity a limitation for schizophrenia diagnosis

Answer 9

if conditions occur together a lot of the time then this calls into question the validity of their diagnosis and classification because they might be a single condition

e.g. Peter Buckley et al (2009) concluded that around 1/2 of people with a diagnosis of schizophrenia have a diagnosis of depression (50%) or substance abuse (47%)

PTSD also occurs in 29% of cases and OCD in 23%

Question 10

what do Buckley et al findings suggest

Answer 10

this poses as a challenge for both classification and schizophrenia are also diagnosed with depression as maybe we are just quite bad at telling the difference between the two conditions

In terms of classification, it may be that, if very severe depression looks like schizophrenia and vice versa, then they might be better seen as one single condition.
This confusing question is a weakness of the diagnosis and classification of diagnosis

Question 11

why is symptom overlap a limitation for schizophrenia

Answer 11

there is considerable overlap between the symptoms of schizophrenia and other conditions

this calls into question the validity of the classification and diagnosis of schizophrenia

Under ICD a person might be diagnosed with schizophrenia; however, many of the same individuals would receive a diagnosis bipolar disorder according to DSM criteria

This is unsurprising given the overlap of symptoms. It even suggests that schizophrenia and bipolar disorder may not be two different conditions but one

Question 12

why is cultural bias a limitation for schizophrenia

Answer 12

African American (AA) and English people of Afro - Carribean origin (A-C) are 7 times more likely to be diagnosed with schizophrenia

the rates in Africa and West Indies are not particularly high this is almost certainly not die to genetic vulnerability

Diagnosis seems to be beset with issues of culture bias

Javier Escobar has pointed out that (overwhelmingly white) psychiatrists may tend to over interpret symptoms and distrust the honesty of a Afro - Caribbeans during diagnosis

Question 13

what are the genetic biological explanations for schizophrenia

Answer 13

• the genetic basis of schizophrenia
• the dopamine hypothesis
• neural correlates

Question 14

what is the genetic basis of schizophrenia

Answer 14

1. schizophrenia runs in the family

2. candidate genes

Question 15

what does it mean when we say that schizophrenia runs in the family

Answer 15

schizophrenia runs in the family is relatively weak evidence in itself for a genetic link as family members tend to also share aspects of their environment as well as genes

However, there have been systematic investigations of the extent to which greater genetic similarity between family members is associated with the likelihood of both developing schizophrenia

Question 16

what is some evidence to the genetic link of schizophrenia

Answer 16

we share 100% of our genes with identical twins and 50% with parent/sibling

There is a strong relationship between the degree of genetic similarity and shared risk of schizophrenia demonstrated in Grottesman study - as genetic similarity increases so does the probability if sharing schizophrenia

Question 17

what are candidate genes

Answer 17

individual genes are believed to be associated with risk of inheritance because a number of genes each appear to confer a small increased risk of schizophrenia it appears that schizophrenia is polygenic - it requires a number of factors to work in combination

because different studies have identified different candidate genes it also appears schizophrenia to be aetiologically heterogeneous

Question 18

what is aetiologically heterogeneous

Answer 18

different combinations of factors lead to the condition

Question 19

what is a study to show that schizophrenia is polygenic

Answer 19

Ripke et al (2014) carried out a huge study combining all previous data from genome - widestudies of schizophrenia

The genetic make - up of 37,000 people diagnosed with schizophrenia was compared to 113,000 controls, 188 genetic variations were associated with increased risk of schizophrenia

Genes associated with increased risk included those coding for the functioning of a number of neurotransmitters

Question 20

what is the dopamine hypothesis

Answer 20

it involves neurotransmitters which are brain’s chemical messenger’s appear to work differently in the brain of a person with schizophrenia

In particular dopamine (or DA) is widely believed to be involved
Dopamine is important in the functioning of several brain systems that may be implicated in the symptoms of schizophrenia

Question 21

what are the two dopamine hypothesis

Answer 21

HYPERdopaminergia in the subcortex

HYPOdopaminergia in the subcortex

Question 22

HYPERdopaminergia in the subcortex

Answer 22

this is the original version of the dopamine hypothesis focused on the possible role of high levels or activity of dopamine (hyperdoperminergia) in the subcortex, i.e, the centrak areas of the brain

e.g. an excess of dopamine receptors in Broca’s area (which is responsible for speech production) may be associated with poverty of speech and/ or experience of auditory hallucinations

Question 23

HYPOdopaminergia in the subcortex

Answer 23

this is the more recent version of the dopamine hypothesis have focused instead on abnormal systems in the brains cortex

Goldman- Rakic et al (2004) have identified a role for low levels of dopamine (HYPOdopamiergia) in the prefrontal (responsible for thinking and decision making) in the negative symptoms of schizophrenia

it may be that both hyper and hypodopaminergia are correct explanations - both high and low levels of dopamine in different brain regions are involved in schizophrenia

Question 24

what are neural correlates of schizophrenia

Answer 24

neural correlates are a measurements of the structure/ function of the brain that correlate with an experience, in this case schizophrenia schizophrenia

positive and negative symptoms have neural correlates

Question 25

neural correlates of negative symptoms

Answer 25

an example of negative symptoms is avolition which is the loss of motivation

motivation involves the anticipation of a reward, and certain regions of the brain

motivation involves the anticipation of a reward, and certain regions of the brain
e.g. Ventural straitum are believed to be particularly involved in this

Question 26

how is the ventral staitum linked to avolition

Answer 26

ventral striatum are believed to be particularly involved in this anticipation. It therefore follows that abnormality of areas like the ventral striatum may be involved in the development of avolition

Question 27

who conducted a study looking at activity levels in the ventral striatum

Answer 27

Juckel et al (2006) have measured activity levels in the ventral striatum in schizophrenia and found lower levels of activity than those observed in controls in controls

Juckel et al observed a negative correlation between activity levels in the ventral striatum and the severity of overall negative symptoms
Thus activity in the ventral striatum is a neural correlate of negative symptoms

Question 28

neural correlates of positive symptoms

Answer 28

positive symptoms also have neural correlates

Allen et al (2007) scanned the brains of people experiencing auditory hallucinations and compared them to a control group whilst they identified pre-recorded soeech as their or others

Lower activation levels in the separate temporalgyrus and anterior cingulate gyrus were found in the hallucination, which also make more errors than the control group.
We can thus say that reduced activity in these two areas of the brain is neural correlate of auditory hallucination