The dopamine hypothesis

AO1 - theory

• dopamine hypothesis states that schizophrenia is caused by excessive dopamine activity - leading to characteristic symptoms of schizophrenia
• schizophrenics have abnormally high numbers of D2 receptors on receiving neurons - resulting in more dopamine binding and therefore more neurons firing
• Comer (2003) -> certain D2 receptors play a key role in guiding attention - disturbances in this process could lead to problems thought to be found in schizophrenics i.e. attention, perception and thought related problems

Evidence

Amphetamines

• dopamine agonist - stimulates nerve cells containing dopamine causing the synapse to be flooded with this neurotransmitter
• large doses can cause hallucinations and delusions - characterisitc of schizophrenic episode

Anti-psychotics

• dopamine antagonist - block activity of dopamine in the brain
• eliminate symptoms such as hallucinations/delusions by reducing stimulation of dopamine system
• the fact these drugs alleviated many of the symptoms of schizophrenia strengthened the case for dopamine being a significant contributory factor in this disorder

Parkinson's disease

• low levels of dopamine activity are found in those…