Schizophrenia

What does the dopamine theory of schizophrenia propose?

Excess dopamine activity contributes to schizophrenia symptoms especially positive symptoms

How does amphetamine support the dopamine theory?

Amphetamine increases dopamine release and can produce behaviour similar to an acute schizophrenic episode

How does amphetamine increase dopamine release?

It competes with dopamine for uptake into dopaminergic vesicles

What evidence from Parkinson's disease supports the dopamine theory?

L-dopa and dopamine agonists can cause hallucinations

What are dopamine antagonists used for in schizophrenia?

To control positive symptoms

What symptoms are considered positive symptoms of schizophrenia?

Hallucinations delusions and disorganised thinking

How do dopamine antagonists affect amphetamine-induced symptoms?

They block amphetamine-induced effects

What is VGluT?

Vesicular glutamate transporter

What happens when VGluT is reduced?

Less glutamate is released

What is the effect of reduced glutamate on NMDA receptors?

Reduced activation of NMDA receptors

How does reduced NMDA activation affect mesocortical dopamine activity?

It decreases dopaminergic activity in the mesocortical pathway

What brain region shows reduced dopamine in negative symptoms?

Prefrontal cortex PFC

What are negative symptoms of schizophrenia?

Social withdrawal flat affect lack of motivation and reduced speech

How can reduced glutamate contribute to positive symptoms?

Reduced NMDA activation decreases GABA inhibition leading to excessive dopamine signalling

What ions normally enter through NMDA receptors?

Sodium and calcium

How does reduced NMDA activity affect GABA release?

It reduces GABA release

What is the role of GABA in schizophrenia theories?

GABA normally provides inhibitory control over dopamine pathways

Which brain area is involved in loss of inhibitory control in positive symptoms?

Ventral tegmental area VTA

What is sensory filtering?

The brain's ability to ignore irrelevant stimuli

How are glutamate and GABA linked to sensory filtering?

Dysfunction in these systems may impair sensory filtering and contribute to psychosis

What does the neurodegeneration hypothesis suggest about schizophrenia?

Schizophrenia may involve progressive brain degeneration over time

Are schizophrenia symptoms usually present in childhood?

No symptoms are usually absent in childhood

Which symptoms often appear first in schizophrenia?

Positive symptoms

What happens to schizophrenia symptoms over time according to the neurodegeneration hypothesis?

Symptoms worsen and response to drugs may decrease

What severe cognitive problem may develop in schizophrenia over time?

Dementia-like cognitive decline