Antipsychotics Flashcards
Five symptom domains of schizophrenia
positive, negative, cognitive, aggressive, anxiety/depression
As disease progresses, which symptoms become more dominant in schizophrenia?
Negative symptoms
Examples of positive symptoms for schizophrenia
Hallucinations, delusions, thought disorders, abnormal behaviors
Negative symptoms in schizophrenia
Withdrawal from social contacts, flattening of emotional responses
How do negative symptoms arise in schizophrenia?
Primary deficit of the illness Secondary to depression Secondary to extrapyramidal symptoms Secondary to environmental deprivation Secondary to positive symptoms
What are cognitive dysfunction in schizophrenia?
Impairment of selective attention
Impairment of working memory
What is used to predict the prognosis of schizophrenia?
Social and vocational functioning (and hence treatment outcome) is predicted by cognitive dysfunction better than positive symptoms
Patient with low cognitive dysfunction but with positive symptoms, good or bad prognosis?
Good prognosis.
Aetiology of schizophrenia
Genetic factors (50% risk in monozygotic twin of affected individual) Environmental factors: maternal viral infections during pregnancy, obstetric complications can predispose neurodevelopmental abnormalities Onset in late adolescence/early adulthood is consistent with neurodevelopmental abnormality involving myelination of cortico-cortical pathways
What are the neurochemical theories proposed for positive symptoms of schizophrenia?
Alterations in:
Dopamine, serotonin, glutamate
Describe what led to the dopamine theory?
Amphetamine (a D2 agonist) produces symptoms similar to acute schizophrenia → hence antipsychotics are D2 antagonists
The smaller the Kd value, the higher or lower the affinity to the D2 receptor?
Higher affinity
Fluphenazine → haloperidol → trifluoperazine → clozapine → chlorpromazine
Dopamine pathways of the brain
Nigrostriatal pathway
Mesocortical/mesolimbic pathways
Tuberoinfundibular pathway
What is the nigrostriatal pathway?
Important in Parkinson’s (schizo is not a movement disorder)
Starts at the substantia nigra and ends in the dorsal striatum
Involved in voluntary movement
When nigrostriatal pathway is not doing well, patient has extrapyramidal symptoms → off-target effects
What is the mesocortical/mesolimbic pathway?
Ventral tegmental area to prefrontal cortex and limbic brain
Involved in emotion, cognition and attention
Mesolimbic: reward and emotion
Mesocortex: cognition and attention
What is the tuberoinfundibular pathway?
Pathway from hypothalamus to anterior pituitary regulates prolactin secretion into the blood circulation
Off target effect
Describe what led to the serotonin theory of schizophrenia?
LSD (5HT2 agonist) produces symptoms similar to acute schizophrenia → hence antipsychotics have 5HT2 antagonism
Describe what led to the glutamate theory of schizophrenia?
Drugs which block NMDA receptor channel (eg ketamine) produce symptoms similar to acute schizophrenia → hence antipyschotics which have NMDA agonism are likely to be effective
What are the 2 types of antipsychotic drugs?
Typical antipsychotics
Atypical antipsychotics