Schizophrenia Flashcards
What is schizophrenia?
A psychotic disorder
A severe mental disorder where contact with reality and impaired
What does schizophrenia affect?
Thought processes and ability to determine reality
Which groups are more likely to receive a diagnosis of schizophrenia?
Men
City dwellers
Lower class
How do you diagnose a specific disorder by distinguishing one from another? How is schizophrenia diagnosed?
- Identify clusters of symptoms that occur together, classify as one disorder
- Diagnose by identifying symptoms and deciding what disorder a person has
For schizophrenia…
ICD-11 says 2 negative symptoms sufficient for diagnosis
DSM-5 says must have at least 1 positive symptom
What are the 2 broad types of symptoms of schizophrenia?
Positive or negative
What are positive symptoms?
Additional experiences beyond those of ordinary experience
Hallucinations and delusions
What are negative symptoms?
Loss of usual abilities and experiences
Speech poverty and avolition
What are hallucinations?
Bizzare, unusual sensory experiences
They are
- either distorted/exaggerated perceptions
OR
- have no basis in reality
What are 4 types of hallucinations? Give an example for each
Auditory- eg: hearing voices others can’t
Visual- eg: distorted facial expressions
Olfactory- eg: smelling burning
Tactile- eg: bugs crawling on skin
What are delusions?
Firmly held (yet false) irrational belief held by the person that have no basis in reality
What are 4 types of delusions? Give an example for each
Delusions of grandeur- eg: believing you have superpowers
Paranoia- eg: paranoia that you are under executive control
Delusions of persecution- eg: claims people are hiding to find you
Delusions of reference- eg: personal message communicated through TV
What is speech poverty?
Reduction in the frequency and quality of speech, may also be a delay in verbal responses
Do people with schizophrenia know the same words as people without schizophrenia?
Yes, but they have difficulty producing information → slowed or blocked thoughts
What is speech disorganisation?
A positive symptom in DSM-5
Speaker changes topic mid-sentence or speech is jumbled/incoherent
What is avolition?
Sometimes called apathy
Difficult to begin/keep up with goal-directed and self-initiated activity
Who named the 3 signs of avolition? What are they?
Andreasen
- Poor hygiene and grooming
- Lack of motivation and persistence in work/education
- Lack of energy
Comment on reliability and validity for the diagnosis of schizophrenia
Good reliability for diagnosis
- high diagnostic reliability (test-retest), the diagnosis of schizophrenia is consistent/repeatable at 2 different points in time
- high inter-rater reliability, different clinicians reach the same conclusions about the same patient
- reliability has improved with DSM-5
- Osório et al found excellent reliability for diagnosis of sz- IR +0.97 and TRT +0.92
Certain that the diagnosis is consistently applied
Low criterion validity for diagnosis
- whether different assessment systems arrive at the same diagnosis for the same patient
- Cheniaux et al found that out of same 100 patients, 68 diagnosed with sz under ICD, only 39 under DSM
Either over or under diagnosed in the diagnostic system, so criterion validity is low
What is the issue with comorbidity in the diagnosis/classification of schizophrenia?
Sz has comorbidity with other conditions
- if occurs frequently, validity is questioned as it may be a single condition
- sz commonly diagnosed with other conditions, Buckley found that about half also had depression/substance abuse
Problem for classification, may not be a distinct/precise condition, some people may just have unusual cases of eg: depression
What is the issue with gender bias in the diagnosis/classification of schizophrenia?
Gender bias in diagnosis
- 1.4:1 ratio of men diagnosed to women
- women may be just less vulnerable to women bcos of genetics
- but Cotton et al found that women are underdiagnosed as they have closer r/ships, and hence get support, so escape diagnosis
The underdiagnosis means that men and women with similar symptoms may experience differing diagnosis, and women may not receive services/treatment to benefit them
What is the issue with culture bias in the diagnosis/classification of schizophrenia?
Culture bias in diagnosis
- some symptoms have different meanings in different cultures (eg: hearing voices)
- Pinto and Jones found that African-Caribbean Brits are up to 9x as likely to receive a diagnosis than white Brits
- through Western lens, overinterpretation of symptoms, thus over-diagnosis
Maybe discriminated against by a culturally biased diagnostic system, more/less likely to be diagnosed just because of ethnicity- questions reliability
What is the issue with symptom overlap in the diagnosis/classification of schizophrenia?
Symptom overlap with other conditions
- symptoms may not be unique, may be found in other disorders
- sz and bipolar both have positive symptoms (eg: delusions) and negative symptoms (eg: avolition)
- in terms of classification, sz and bipolar may just be variations of a single conditions
Classification and diagnosis flawed as hard to diagnose/distinguish, and may not even be its own condition
What are the 2 biological explanations to schizophrenia?
Genes
Neural correlates
What do family studies show about the likelihood of developing schizophrenia?
Risk of schizophrenia increases in line with genetic similarity to a relative with it
Who did large-scale family studies for schizophrenia?
Gottesman
According to Gottesman, what is the risk of developing schizophrenia for the general population?
1%
According to Gottesman, what is the risk of developing schizophrenia if your aunt/uncle has it?
2%
According to Gottesman, what is the risk of developing schizophrenia if your sibling has it?
9%
According to Gottesman (and Sheild), what is the risk of developing schizophrenia if you have a dizygotic twin who has it?
17%
According to Gottesman (and Sheild), what is the risk of developing schizophrenia if you have a monozygotic twin who has it?
48%
What does the correlation/high concordance rate in Gottesman’s family study represent?
How families share genes (and environment)
Who did an adoption study for schizophrenia?
Tienari et al
164 adoptees whose biological mothers had diagnosed schizophrenia
Strong evidence for a genetic basis to schizophrenia as the adoptees cannot be influenced by their biological parents’ environment
What are candidate genes?
Number of different genes involved in schizophrenia, so the condition is polygenetic
What type of candidate genes are involved in sz?
Ones coding for dopamine (links to dopamine hypothesis)
What is the study into the candidate genes for schizophrenia?
Ripke et al combined all previous data from genome-wide studies of schizophrenia
Very large sample size
108 separate genetic variations associated with increased risk of schizophrenia
Because so many candidate genes identified, schizophrenia is aetiologically heterogenous, so causes vary
How can mutations play a role in the development of schizophrenia?
Can have a genetic origin in the absence of family history
May be due to mutation in parental DNA from things like radiation/poison/viral infection
What is the study into how mutation plays a role in the development of schizophrenia?
Brown et al
Positive correlation between parental age (associated with increased risk of sperm mutation) and risk of schizophrenia
Fathers over 50 = 2% risk
Fathers under 25 = 0.7% risk
What are neural correlates?
Measurements/patterns of the structure and function of the brain that corresponds with an experience and may be implicated in the origins of the experience
What is a strength and weakness of the genetic (biological) explanation for schizophrenia?
Research support
- family studies (Gottesman) show risk increases with genetic similarity
- Tienari et al, genes heighten risk
People more vulnerable to schizophrenia because of genetic makeup
Clear that environmental factors also increase risk
- birth complications, smoking TNC-rich cannabis in teens
- Mørkved et al 67% with schizophrenia had childhood trauma
Genetic factors alone not a complete explanation for schizophrenia, interactionist approach better
What is the best-known neural correlate of schizophrenia?
Dopamine
What type of neurotransmitter is dopamine?
An excitatory neurotransmitter, so increases rate of firing between neurons
What does the original dopamine hypothesis suggest?
Antipsychotics reduce dopamine caused similar symptoms to Parkinson’s disease, associated with low dopamine levels
Thus, schizophrenia may result from high levels of dopamine (hyperdopaminergia) in subcortical areas of the brain
Excess dopamine receptors in pathways from subcortex to Broca’s area (responsible for speech production) explains symptoms such as auditory hallucinations
–> As more dopamine binds, so more neurons fire
Who devised the updated dopamine hypothesis?
Davis et al