Biological Explanations: Dopamine Hypothesis Flashcards
What is the relationship between dopamine levels and schizophrenia (SZ)?
High levels of dopamine in the brain are associated with symptoms of SZ.
High dopamine levels correlate with overactive neuron firing and increased symptoms.
What is the role of dopamine receptors in schizophrenia?
Patients with SZ have abnormally high levels of dopamine receptors, resulting in more dopamine binding and increased neuron firing.
This overactivity is linked to the symptoms of SZ.
What is the dopamine hypothesis?
The dopamine hypothesis suggests that symptoms of SZ are due to excess dopamine activity in the brain.
It explains the effectiveness of antipsychotic drugs that reduce dopamine levels.
How do phenothiazines help treat schizophrenia?
Phenothiazines reduce dopamine levels, which alleviates symptoms of SZ.
They block dopamine receptors in the brain.
What side effect is associated with phenothiazines?
Muscle tremors similar to those seen in Parkinson’s disease.
This side effect indicates the complex relationship between dopamine levels and motor control.
What is L-Dopa used for?
L-Dopa is a treatment for Parkinson’s disease.
It addresses symptoms caused by overactive levels of dopamine.
What is a criticism of the dopamine hypothesis?
The effectiveness of antipsychotic drugs in alleviating symptoms is found in only 1/3 of people, suggesting dopamine is not the sole cause of SZ.
This indicates a more complex etiology of schizophrenia.
What is a reductionist explanation for schizophrenia?
It increases dopamine levels as the primary cause of symptoms.
This perspective is criticized because it simplifies the multifactorial nature of SZ.
What happens to Parkinson’s patients who develop schizophrenia?
They may develop symptoms of schizophrenia due to excess dopamine from treatment.
This illustrates the delicate balance of dopamine in various neurological conditions.
Who revised the dopamine hypothesis?
Davis and Kahn.
They proposed that symptoms arise from an excess of dopamine in subcortical areas of the brain.
What is the revised view of the dopamine hypothesis regarding symptoms?
Symptoms are caused by an excess of dopamine in subcortical areas, particularly the mesolimbic pathway.
This shifts focus from a simplistic cause to specific brain pathways.
What percentage of patients relapsed on placebo within 12 months?
64% of patients relapsed on placebo within 12 months.
This highlights the importance of drug treatment in managing schizophrenia symptoms.
What does the reduction of dopamine levels in schizophrenia patients suggest?
It suggests that the original dopamine hypothesis may lack validity.
This is evidenced by the observation of dopamine levels in the prefrontal cortex.
What is observed about dopamine levels in the prefrontal cortex of schizophrenia patients?
Dopamine levels are low in the prefrontal cortex in SZ patients.
This suggests the dopamine hypothesis may not accurately apply to all aspects of schizophrenia.
Leucht (strength of dopamine hypothesis)
Found that drug treatments that work via normalising dopamine levels were more effective than a placebo. The efficacy of treatments directly influencing the dopamine system supports the dopamine hypothesis biological theory of sz
Leucht, patients who relapsed within 12 months on antipsychotics
27%
Limitation of revised hypothesis: lacks validity
Howes and Kapur
Hypothesis not substained in studies, lacks direct evidence for low levels of dopamine in prefrontal cortex in sz patients. Suggest D hypothesis is un accurate when applying to sz patients
Limitation, overactive levels of dopamine not only source for positive symptoms
Noll
A: tested effectiveness of antipsychotics in removing symptoms
F: 1/3 people did not remove H + D (positive symptoms)
Reductionist explanation, dopamine not sole cause of positive symptoms
Dopamine Hypothesis
The dopamine hypothesis suggests that high levels of dopamine (D) in the brain contribute to schizophrenia symptoms. Research indicates that individuals with schizophrenia have an excessive number of D2 receptors, making them more sensitive to dopamine activity. Phenothiazines, a type of antipsychotic medication, help treat schizophrenia by reducing dopamine levels and blocking D2 receptors in the brain. However, these drugs can cause side effects, such as muscle tremors, similar to those seen in Parkinson’s disease. Additionally, L-Dopa, a treatment for Parkinson’s, can induce schizophrenia-like symptoms if administered in excessive amounts. This supports the idea that dopamine levels play a crucial role in both conditions.
Revised Hypothesis
A revised hypothesis by Davis and Kahn proposes that schizophrenia symptoms arise from excess dopamine in subcortical brain areas, particularly in the mesolimbic pathway, while other symptoms may result from dopamine deficits in different brain regions.
