Schizophrenia Flashcards
Positive symptoms of schizophrenia?
Disorders of thought/disorganised behaviour
Hallucinations
Paranoia
Negative symptoms of schizophrenia?
Blunted emotions/anhedonia
Social withdrawal
Apathy/loss of energy
Cognitive impairment
Environmental causes of schizophrenia
Family stress Poor social interaction Poor maternal nutrition Infection/virus at an early age Early trauma Obstetric complication
Action of amphetamines
They get into the neurones in the presynaptic terminal. They push out dopamine, so more is available for the synapse.
How is dopamine made?
Phenylalanine -> tyrosine -> L-DOPA -> Dopamine
What is dopamine made form?
Amino acids
Where is dopamine released?
At the synapse
Where does dopamine act when it is released into the synapse?
The post-synaptic receptors (D1-D5)
Which post-synaptic receptor is the pharmacological target for schizophrenia?
D2 receptor
How do D2 receptor antagonist work?
It binds to the D2 receptor so dopamine cannot
What is the D2 receptor?
It acts as a negative feedback mechanism, regulating the release of dopamine from the pre-synaptic neurone.
What dopamine pathways is the target for schizophrenia?
Mesolimbic and Mesocortical
What happened if other dopamine pathways are acted on?
Causes side effects
What is the mesocortical responsible for?
Cognition, memory, attention, emotional, behaviour, and learning
What is the nigrostriatal responsible for?
Movement and sensory stimuli
What is the mesolimbic responsible for?
Pleasure and reward, seeking behaviours. Addiction, emotion. And perception.
What does hyperactivity in the mesolimbic pathway cause?
Creates positive psychotic symptoms. The pathway may also mediate aggression.
What does blockade of the D2 receptors in the mesolimbic dopamine pathway cause?
This has the effect of reducing the hyperactivity in this pathway that is postulated to cause the positive symptoms of psychosis.
What can also happen when some parts of the mesolimbic pathway are blocked?
Can also block reward mechanisms, leaving patients apathetic, anhedonic, lacking motivation, interest, and joy from social interactions.
What can the D2 receptors in the mesolimbic dopamine system mediate?
Positive symptoms of psychosis and the normal reward system of the brain (pleasure centre).
What would the ideal drug do for schizophrenia?
Decrease dopamine in the mesolimbic pathway
Increase dopamine in the mesocortical pathway.
AND leaving dopaminergic tone unchanged in both the nigrostriatal and tuberoinfundibular dopamine pathways to avoid side effects.
What does and increase in dopamine in the mesocortical dopamine pathway cause?
Treatment for negative and cognitive symptoms
What does and decrease in dopamine in the mesolimbic dopamine pathway cause?
Treatment for positive psychotic symptoms
