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Schizophrenia - Coggle Diagram
Schizophrenia
Symptoms
- Symptoms are traditionally divided into positive (abnormal by their presence > hallucinations, delusions) and negative symptoms (abnormal by their absence > lack of motivation, cognitive decline)
- Factor analysis studies suggest a 3-factor model:
Disorganisation
- Disorganisation refers to disconnected or incomprehensible thought and speech, bizarre behaviour.
- Formal thought disorder
- Loose associations > between sentences, changing rapidly between concepts
- Word salad > sentences don’t make sense.
- Inappropriate affect
- Bizarre dress
Negative symptoms
- Negative symptoms represent deficits in normal behaviour and cognition
- Flat affect
- Alogia (poverty of speech)
- Avolition (poverty of will)
- Cognitive deterioration
Reality distortions (psychotic symptoms)
- Schizophrenia is a psychotic disorder (characterised by the presence of hallucinations (false perceptions) and delusions (false beliefs)
- The presence of psychotic symptoms does not necessarily imply schizophrenia
- Substance use, bipolar 1 disorder, and various neurological disorders.
Hallucinations
- “Hallucinations are perception-like experiences that occur without an external stimulus” > DSM5
- Auditory hallucinations are the most common in schizophrenia, but visual, tactile and olfactory also occur
- Certain types of auditory hallucinations are especially characteristic
- Auditory verbal > hearing voices
- Third person: The patient hears voices discussing them and/or commenting on their actions
- Audible thoughts > hearing a voice say your thoughts to you
- Command hallucinations > voices that tell you to do certain actions
- Auditory verbal hallucinations activate identical brain regions to real voices
- There is nothing inherent in real sounds that enables them to be distinctions from hallucinations
Delusions
- “Delusions are fixed beliefs that are not amenable to change in light of conflicting evidence” > DSM5
- Paranoid delusions: a person believes that others are trying to harm them
- Grandiose delusions: a person believes they have special powers or they are on a special mission
- Delusions of reference: a person believes that the words or actions of strangers have special reference to them.
- Delusions of control: a person experiences their actions as being controlled by an outside force.
- Thought insertion: a person believes that thoughts are coming into their mind from an outside source.
- Thought broadcast: the person believes that thoughts are leaving their minds and entering the minds of others.
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Intro
- Severe mental illness affecting approx 0.7% of the population.
- Similar prevalence across different cultures
- Approx equal gender distribution
- Some evidence that it’s more prevalent in men
- Somewhat better prognosis in women
- The age of onset is typically 18-30 years
- Tends to occur earlier in men
- Typically lifelong condition.
Costs of schizophrenia
- Score lower on every measure of the quality of life > rate of employment, rate of marriage, number of children, number of friends, self-reports of quality of life
- Suicide rate >10x the general population
- Financial cost billions per year > hospitals, community mental health, lost productivity, prisons (~3% of prisoners suffer from schizophrenia)
- Approx 11% of homeless people have schizophrenia
Causes
- Freudian conceptions
- schizophrenia as a defence mechanism against latent homosexuality.
- “In order to defend himself from his homosexual desires, the patient reacts with persecutory delusions”
- Schizophrenogenic mother
- Fromm-Riechmann noticed that schizophrenia runs in families > schizophrenogenic mother is one who is simultaneously overprotective and hostile to her children.
Schizophrenia is a brain disorder
- Grey matter abnormalities
- Abnormalities at baseline
- progressive > at least over the first few years of illness
- White matter abnormalities
- Glial cells
- Glial cells are all non-neuronal supporting cells of the brain
- Implanting human glial cells from individuals with schizophrenia into mice led to the development of behaviours and traits associated with schizophrenia
- Microglial cells > like immune cells for the brain
- Oligodendrocyte > make the myelin sheath for neurons
- Why does schizophrenia often occur during adolescence
- Large differences in the brain during this time; grey matter volume reduces (synaptic pruning), and white matter volume increases (myelination)
Treatments
Pharmacological
- Antipsychotic medications (neuroleptics) are currently the most effective and widely used treatments for SZ.
- Chlorpromazine (Thorazine) was developed as an anaesthetic in 1952.
- Thorazine was the first of the typical (1st gen) antipsychotics
- Antipsychotic effect related to dopamine antagonism.
- Atypical (2nd gen) antipsychotics like Clozapine were developed in the mid-70s.
- Block dopamine receptors but also act as serotonin agonists (more effective against negative symptoms
- Both 1st and 2nd gen antipsychotics have unpleasant side effects leading to a low compliance rate
- side effects
- Extrapyramidal symptoms: tardive dyskinesia (involuntary movements of face/body, etc. rarely reversible but may improve after drug is stopped)
- Agranulocytosis: loss of white blood cells (very dangerous)
- Weight gain
- Sedative and dysphoric effect (may worsen negative symptoms)
Psychotherapy
- Medications, while relatively effective against psychotic symptoms, are relatively ineffective against negative symptoms.
- Many SZ patients show residual psychotic and disorganised symptoms after medication
- Psychotherapy is an effective adjunct to pharmacotherapy in SZ.
- Rather than resolving psychotic symptoms per se, psychotherapy instead aims to minimise distress, increase quality of life, teach coping skills, etc.
- CBT for auditory hallucinations doesn’t deny or prevent the patient from hearing voices but rather aims to
- Change patient’s attitudes towards their voices
- Identify and avoid situations that exacerbate the voices.
History
- Hippocrates: the voices ordered her to jump up and throw herself into the well and drown”
- Emile Kraeplin (1899):
- Dementia praecox > dementia in youth
- Disorganisation was central
- Eugen Bleuler (1908): first to introduce the term schizophrenia
- Schizo = split, phrene = mind
- Referring to the split between emotion and cognition (flat affect) characteristic of the disorder.
Risk Factors
Genetic
- Highly heritable > 48% MZ, but there is no single gene.
- Lots of risk genes of small affect each
- Gene-environment reactions (COMT gene)
- Velocardiofacial syndrome (VCFS) occurs when there is a deletion of a piece of the long arm of chromosome 22 > 24 genes, ~3 mil bases.
- Very high rates of schizophrenia in VCSF > ~25%
- COMT gene is one of those deleted and is involved in breaking down dopamine.
- Environmental
- Some recreational drugs increase the risk of developing schizophrenia
- According to some studies, amphetamine increases the risk by about 10x.
- Amphetamine is a dopamine agonist > increasing the levels of synaptic dopamine.
Dopamine and
Psychosis
- Dopamine is undoubtedly involved in the etiology of schizophrenia-like psychotic symptoms
- dopamine agonists produce symptoms similar to the psychotic symptoms characteristic of SZ.
- All antipsychotic medications block dopamine receptors > therapeutic dose strongly related to the drug’s binding affinity for D2 receptors.
Dopamine hypothesis of SZ
- Psychotic symptoms of SZ are caused by hyperactivity of the dopaminergic system
- Antipsychotic drugs all block D2 receptors
- Dopamine agonists can cause SZ-like symptoms
- SZ patients show abnormally high levels of dopamine synthesis
- SZ patients show high levels of dopamine receptors.
- Explanatory gap: the explanation that psychotic symptoms are caused by abnormally high levels of dopamine is incomplete
- Leaves a gap between the biological and psychological levels of description
First Rank Symptoms
- Kurt Schneider identified the FRS as the most characteristic symptoms of SZ
- Audible thoughts (thought echo)
- Voices arguing
- Voices commenting on one’s actions
- Delusions of control
- Thought withdrawal, insertion, broadcast
- The FRS are actually diagnostic of SZ according to some criteria
- Empirical studies suggest FRS are NOT unique to SZ but are far more common in SZ than in other psychotic disorders (like Bipolar 1).