Week 6: Beyond the dopamine hypothesis of schizophrenia Flashcards
What does the updated hypothesis of psychosis propose?
Psychosis involves neural networks beyond the classical dopaminergic mesolimbic pathway, including serotonin and glutamate systems.
What has been a classic and enduring idea in psychopharmacology regarding psychosis?
The dopamine hypothesis, especially as it relates to schizophrenia.
What other neurotransmitters are implicated in psychosis besides dopamine?
Serotonin and glutamate networks.
What is the classical dopamine hypothesis of psychosis?
Dopamine hyperactivity at D2 receptors in the mesolimbic pathway causes psychosis.
How does amphetamine use support the dopamine hypothesis of psychosis?
Amphetamine releases dopamine and induces a paranoid psychosis similar to schizophrenia.
What is a recent example of a treatment that challenges the dopamine hypothesis?
Pimavanserin, a serotonin 2A antagonist, treats Parkinson’s disease psychosis without blocking dopamine D2 receptors.
What are the three major hypotheses of psychosis?
Dopamine hyperactivity, NMDA receptor hypoactivity, and serotonin 5-HT2A receptor hyperactivity.
Why is it likely that multiple pathways contribute to psychosis?
Because different forms of psychosis may involve different neurotransmitter imbalances and interconnected pathways.
How do different drugs model different psychoses?
Psychostimulants (dopamine), dissociative anesthetics (NMDA antagonists), and psychedelics (serotonin agonists) induce different types of hallucinations and delusions.
How do symptoms differ between schizophrenia and Parkinson’s disease psychosis?
Schizophrenia mainly causes auditory hallucinations and paranoid delusions, while Parkinson’s psychosis primarily leads to visual hallucinations and persecutory delusions.
What is the main side effect of blocking D2 receptors in the nigrostriatal pathway?
Movement disorders like akathisia, drug-induced parkinsonism, and tardive dyskinesia.
What does the NMDA receptor hypoactivity theory propose?
Hypofunctional NMDA receptors on GABA interneurons in the prefrontal cortex lead to excessive glutamate release, activating the mesolimbic dopamine pathway and causing psychosis.
What is the proposed mechanism for serotonin-induced psychosis?
Hyperactivation of 5-HT2A receptors on glutamate neurons leads to increased glutamate release and downstream activation of the mesolimbic dopamine pathway.
How does serotonin hyperactivity contribute to Parkinson’s disease psychosis?
Excess serotonin activation at 5-HT2A receptors leads to glutamate release, which stimulates the ventral tegmental area, activating dopamine pathways and inducing psychosis.
What is a major conclusion regarding the three hypotheses of psychosis?
Dopamine, serotonin, and glutamate pathways are interconnected, and treatments targeting multiple neurotransmitter systems may be effective.
