L14 - Biological basis of Schizophrenia Flashcards
What makes Sz a complex disorder?
It has a wide and diverse range of symptoms
Cause unknown
It’s response to treatment is often unsatisfactory
What are the 3 main symptoms categories of Sz?
Positive
Negative
Cognitive
What are positive symptoms of Sz?
Hallucinations
Delusions
Thought disorder
What are negative symptoms of Sz?
Emotional flattening
Anhedonia (inability to feel pleasure)
Avolition (Lack of motivation/ ability to start activity)
Withdrawal
Motor/ behavioural abnormalities like catatonia
what are cognitive symptoms of Sz?
Impairments in attention, memory and executive cognitive function
What diagnostic tools are used for diagnosing Sz?
DSM-5-V (USA)
International Classification of Diseases - ICD (Europe)
What are key diagnostic criteria for Sz?
Symptoms such as thought insertion, delusions, hallucinatory voices and catatonia persisting for more than a month
What are exclusion criteria for Sz diagnosis?
Mood disorders, drug use and neurological conditions
What is the prevalance rate of Sz?
Approx. 0.5% (5 per 1000 people surveyed per year)
At what age does Sz typically onset?
Late adolescence to early adulthood (between 20-39)
How do genetic factors influence Sz risk?
Family history significantly increases risk, with higher concordance in MZ twins (approx. 40-60%) compared to DZ twins (approx 10-15%)
What are environmental risk factors for Sz?
Prenatal exposure to viruses, pregnancy/ delivery complications, and social factors like family dynamics
What structural brain changes are associated with Sz?
Reduced temporal lobe volume
Enlarged ventricles
Hypofrontality (reduced frontal cortex activity)
What’s the dopamine hypothesis of Sz?
Sz may be associated with increased dopamine function, particularly linked to positive symptoms
How do amphetamines and dopamine antagonists relate to Sz?
Amphetamines mimic positive symptoms
Dopamine antagonists alleviate them
What role does serotonin play in Sz?
Increased serotonin function may be linked to Sz, supported by drug-induced psychosis studies (e.g., LSD)
What’s the glutamate theory of Sz?
Decreased glutamate function, evidenced by reduced glutamate levels and receptor changes.
This may contribute to symptoms
How do positive symptoms relate to brain function?
They may result from impaired function in the temporal lobes
How do negative and cognitive symptoms relate to brain function?
They may result from prefrontal cortex dysfunction and disconnection between temporal and frontal lobes
What is the role of serotonin-dopamine antagonists in Sz treatment?
They treat both positive and negative symptoms by modulating multiple neurotransmitter systems
What are examples of typical antipsychotics and how do they work?
Dopamine D2 receptor antagonists e.g., Chlorpromazine
Treat positive symptoms but have severe motor side effects
What are typical antipsychotics less effective negative symptoms?
they may exacerbate negative symptoms by reducing dopamine function in the mesocortical pathway
What are extrapyramidal side effects?
Severe motor side effects that resemble Parkinson’s disease caused by dopamine blockade in the nigostriatal pathway
What makes clozapine an atypical antipsychotic?
It has a fewer motor side effects, treats negative symptoms but requires blood monitoring due to risks like leukopenia
What is the advantage of atypical antipsychotics?
They act on dopamine and serotonin receptors, reducing both positive and negative symptoms with fewer motor side effects.
What are the limitations of atypical antispychotics?
They don’t work in all patients, can cause side effects and may take longer to act.
What are common issues with antipsychotic treatment compliance?
Adverse side effects often lead to medication miscontinuation and relapse
What’s the relapse rate for untreated Sz?
approx 10% per month after discontinuing treatment
What are psychological therapy options for SZ?
CBT
Family therapy
Particularly effective when combined with medication
What is the prognosis for Sz without Pharmacological intervention?
Approx 20% of parients show near-full recovery
How does pharmacological treatment improve prognosis?
Recovery rates rise to approx 50% with antispsychotic use
Why is reducing antipsychotic side effects an important goal?
To improve compliance and reduce relapse rates in patients.
How does the serotonin theory relate to schizophrenia?
Increased serotonin function, supported by the effects of LSD, may contribute to symptoms.
How does the glutamate theory explain schizophrenia?
Decreased glutamate levels and receptor changes are linked to symptoms, although data is inconsistent.
What evidence supports the glutamate theory of schizophrenia?
Reduced glutamate in cerebrospinal fluid, increased cortical glutamate receptors postmortem, and decreased glutamate uptake sites in the cingulate cortex.
What is the main limitation of the dopamine hypothesis?
It cannot account for negative and cognitive symptoms of schizophrenia.
How do temporal lobe deficits contribute to schizophrenia symptoms?
Impaired temporal lobe function is associated with positive symptoms like hallucinations and delusions.
How do frontal lobe deficits contribute to schizophrenia symptoms?
Impaired prefrontal cortex function is linked to negative and cognitive symptoms.
What is the “disconnection syndrome” in schizophrenia?
It refers to inappropriate communication between temporal and frontal lobes, contributing to symptomatology.
