Parkinson's disease affects over 1.1 million people in the United States and gradually destroys the brain cells that control movement. By the time symptoms such as tremor appear, patients have already lost around half of the affected brain cells, so earlier detection is important.
Researchers used positron emission tomography (PET) to measure two brain markers: dopamine transporters, which are involved in uptake of dopamine, and synaptic density, which reflects the health and number of connections between brain cells. The study included 30 patients with Parkinson's disease and 13 healthy volunteers. Each person underwent two PET scans: one tracer measured dopamine transporters as an index of dopamine neurons, and a second tracer measured synaptic density. The team compared these measurements in the brain regions most affected by Parkinson's.
The researchers found that in healthy participants the two markers correlated in the striatum, but that relationship deteriorated in people with Parkinson's. They also observed that dopamine neuron loss was greater than synaptic loss and that differences were larger at more advanced stages. Combining imaging markers gives a clearer view of disease development and may help target the underlying biology. The work appears in Movement Disorders and was supported by the National Institutes of Health, Yale University and AbbVie.
Difficult words
- positron emission tomography — brain imaging method that uses radioactive tracersPET
- dopamine transporter — protein involved in uptake of dopaminedopamine transporters
- synaptic density — amount and health of connections between neurons
- striatum — brain region involved in movement and reward
- correlate — show a relationship between two measurementscorrelated
- tracer — small radioactive substance used in PET scans
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Discussion questions
- How could earlier detection of Parkinson's change patient care or daily life? Give two reasons.
- Why might combining two imaging markers give a clearer view of disease development?
- What problems do you think doctors face when trying to detect Parkinson's earlier?
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