Parkinson's disease affects over 1.1 million people in the United States and progressively destroys the brain cells that control movement. Because patients often have already lost about half of the affected cells by the time tremor appears, researchers stress the need for earlier and more complete detection methods.
The new study used positron emission tomography (PET) to measure two complementary brain markers: dopamine transporters, which index dopamine neurons and their ability to take up the neurotransmitter, and synaptic density, which indicates the number and health of connections between brain cells. In healthy participants the two markers rose and fell together in a predictable pattern within the striatum, the region most affected by Parkinson's. The research team scanned 30 patients with Parkinson's and 13 healthy volunteers, giving each person two tracers to measure the separate markers in the same brain regions.
The authors report that in Parkinson's the usual correlation between dopamine transporter availability and synaptic density breaks down. They observed greater loss of dopamine neurons than of synapses, and changes intensified at more advanced stages. As the coauthors note, existing dopamine imaging can be reliable but may miss early changes; combining multiple imaging markers therefore gives a clearer picture of disease progression. The study appears in Movement Disorders and was supported by the National Institutes of Health, Yale University and AbbVie.
Difficult words
- neurotransmitter — chemical that carries signals between nerve cells
- synaptic density — number and health of connections between cells
- dopamine transporter — brain protein that helps neurons reabsorb a signalling chemicaldopamine transporters
- striatum — brain region involved in movement control
- correlation — a relationship where two things change together
- tracer — substance used in scans to show structurestracers
- intensify — become stronger or more extremeintensified
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Discussion questions
- What practical advantages might earlier and more complete detection of Parkinson's bring for patients and families?
- How could combining two different imaging markers change the way doctors monitor disease progression?
- The study found greater loss of dopamine neurons than of synapses. What might this difference mean for developing treatments?
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