Schizophrenia Flashcards
Schizophrenia definition
Schizophrenia is a chronic, severe mental disorder that affects the way a person thinks, acts, expresses emotions, perceives reality, and relates to others.
•Schizophrenia is most often diagnosed between the ages of 15-35
•Schizophrenia affects about 1% of the population at some point in their lives.
•It is more commonly diagnosed in men, in cities and in the working-class population
Classification
A classification is a list of the symptoms of a disorder. Psychiatrists then use this list of symptoms to diagnose the disorder.
Diagnosis
Diagnosis is the process of identifying a specific type of mental health disorder.
The two major systems for the classification of mental disorder are
- ICD-11
- DSM-5
Why is schizophrenia problematic to diagnose
- does not have one defining characteristic but rather a cluster of seemingly unrelated symptoms.
- In addition, the ICD-11 and DSM-5 differ in their diagnosis
How does ICD-11 diagnose
Two or more negative symptoms for at least a one month
How does DSM-5 diagnose
At least one positive symptom for at least six months
Positive symptoms
refer to atypical symptoms experienced in addition to normal experiences
Examples of positive symptoms
- Hallucinations
- delusions
Hallucinations
Unusual sensory experiences
Delusion
Irrational beliefs
Negative symptoms
atypical symptoms that represent a loss to normal experiences
Examples of negative symptoms
- avolition
- speech poverty
Avolition
(apathy) is finding it difficult to begin or keep up with goal-directed activity.
Speech poverty
(alogia) is the lessening of speech fluency and productivity reflecting slow or blocked thoughts.
reliability in the diagnosis of schizophrenia
Reliability refers to the consistency.
There are two ways to assess reliability:
- Inter-rater reliability
-Test-retest reliability
validity in the diagnosis of schizophrenia
Validity refers to the extent that a diagnosis represents something that is real and distinct from other disorders and the extent that a classification system such as ICD-10 or DSM-5 measures what it claims to measure.
Inter-rater reliability when diagnosing schizophrenia
the extent to which psychiatrists can agree on the same diagnosis of schizophrenia when independently assessing patients
Test-retest reliability was diagnosising schizophrenia
the extent to which the same diagnostic tool e.g. DSM or ICD provides the same outcome over a period of time
5 Issues with the validity of classification and diagnosis for schizophrenia
- comorbity
- symptom overlap
- gender bias
- culture bias
- criterion validity
Comorbidity
When a person has a diagnosis of two different conditions
Symptom overlap
When a disorder shares its symptoms with other disorders
Gender bias
When the diagnostic system favours or misrepresents one gender.
Culture bias
When the diagnosis system favours or misrepresentations a culture
Criterion validity
Whether the DSM and ICD reach the same outcome
Family studies (genetic explantiom)
- schizophrenia runs in families through the inheritance of genes passed down through DNA.
- People do not inherit schizophrenia, but they inherit a genetic predisposition to the disorder.
Concordance rates
- Concordance rates describes the presence of the same trait in both members of a pair of twins
- Evidence shows there is a strong relationship between the genetic similarity of family members and likelihood of both developing schizophrenia (concordance rate).
Gottesman 1991
Gottesman (1991) carried out a family study and found the followingconcordance rates for schizophrenia:
- MZ = 48%
- DZ = 17%
- siblings = 9%
The results show that the closer the degree of genetic relatedness, the greater the risk of developing schizophrenia.
why can schizophrenia be classed as polygenic
•no single gene is thought to be responsible.
•polygenic meaning many genes are involved. Each individual gene presents a small increased risk of schizophrenia.
- Ripke et al studied patients with schizophrenia and compared them to control group.108 separate genetic variations associated with increased of schizophrenia.
why can schizophrenia be classed as aetiologically heterogenous
Different combinations of these genes in different people can lead to schizophrenia. It is therefore aetiologically (caused) heterogeneous (by different things).
how can schizophrenia be caused by genetic mutations?
When people develop schizophrenia without any genetic link in their family it has been suggested it is caused a genetic mutation in sperm cells.
Eg. through radiation, poison or viral infections.
this risk is more likely if the father is older:
under 25 = 0.7%
over 50 = 2%
Neural correlates
Neural correlates are when the structure or functioning of the brain is correlated (associated) with positive and negative symptoms of schizophrenia.
Dopamine hypothesis
Research suggests that schizophrenia is caused by abnormal levels of the neurotransmitter dopamine.
Original dopamine hypothesis (hyperdopaminergic)
- The original dopamine hypothesis stated that schizophrenia was caused by excessive activity of dopamine (hyperdopaminergia) in the subcortex.
- An excess of DA receptors in pathways from the sub cortex to Broca’s area may explain specific symptoms of schizophrenia, such as speech poverty and auditory hallucinations.
Updated dopamine hypothesis (hypodopaminergic)
- Davis et al (1991) proposed that schizophrenia may also be caused by low activity of dopamine (hypodopaminergia) in the prefrontal cortex.
- This can explain more of the negative symptoms of schizophrenia such as avolition as the prefrontal cortex is responsible for thinking and decision making.
- It is suggested that hypodopaminergia leads to subcortical hyperdopaminergia. The updated dopamine hypothesis suggests that both high and low levels of dopamine in different brain regions is the most likely explanation for schizophrenia.
Enlarged ventricles
One theory is that schizophrenia is caused byenlarged ventricles (fluid-filled gaps betweenbrain areas). Enlarged ventricles are especially associated withdamage to central brain areas and theprefrontal cortex.Such damage is often associated with negative symptoms.