Scientists have discovered that positron emission tomography (PET) scans of the heart might be able to identify those at risk of developing Parkinson’s disease or Lewy body dementia. Both these conditions are associated with abnormal accumulations of alpha-synuclein protein in the brain, and the ability to detect early changes could improve our understanding and potential intervention for these diseases.

In a small study, researchers at the National Institutes of Health (Bethesda, MD, USA) conducted PET scans on 34 individuals who were considered at risk for Parkinson’s due to various factors. They were looking at the heart to measure the activity of norepinephrine, a messenger in the nervous system that is linked to dopamine—a chemical that is known to be at low levels in Parkinson's patients. Previous studies had already indicated that those suffering from Lewy body conditions experience a marked reduction of norepinephrine in the heart.

The latest study revealed that at-risk individuals with lower levels of 18F-dopamine-derived radioactivity in the heart were more likely to be diagnosed with Parkinson’s or Lewy body dementia over time. The participants underwent heart PET scans using a radioactive tracer at 18-month intervals for a maximum of about 7.5 years, or until they were diagnosed. Initially, out of nine people with lower levels of cardiac radioactivity from the dopamine tracer, eight went on to develop Parkinson’s or Lewy body dementia. In contrast, among those who showed normal levels of radioactivity on their first scan, only one later developed these conditions. Notably, all nine individuals who eventually were diagnosed with a Lewy body disease had displayed low radioactivity at or before their diagnosis.

The findings suggest that Parkinson’s and Lewy body dementia might impact the nervous system that controls automatic body functions, including the heart rate and blood pressure. The aggregation of synuclein, a process common to both disorders, also occurs in the nerves leading to other organs. By using PET scans to recognize those who might be in the preclinical stages of Lewy body diseases, there may be opportunities to explore preventive strategies that could involve lifestyle changes, dietary supplements, or other medical therapies.

“Imagine the scans are frames of a movie,” said David S. Goldstein, M.D., Ph.D., NINDS Principal Investigator. “The frame at 8 minutes during the first evaluation is already enough to identify the people who are likely to go on to develop a central Lewy body disease years later.” 

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