COVID-19 Linked to Increased Risk for Parkinson's
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One of the neurologic complications of COVID-19 may be the development of Parkinson's disease, new data suggest.

At least three case reports have been published of relatively young COVID-19 patients who developed clinical parkinsonism, either in isolation or with other neurologic deficits, within 2 to 5 weeks of contracting the disease. A fourth case has not yet been published.

They report that the three patients in the published cases were aged 35, 45, and 58 years. All had severe respiratory infection that required hospitalization. For two of three patients, symptoms of parkinsonism diminished upon administration of traditional dopaminergic medication. The third patient recovered spontaneously.

In all cases, brain imaging revealed reduced function of the nigrostriatal dopamine system, as is seen in Parkinson's disease. None of them had a family history of Parkinson's disease nor any history of signs of prodromal Parkinson's. One patient underwent genetic testing and was not found to carry any Parkinson's risk variants.

Three Possible Mechanisms: "A Perfect Storm"

The authors describe three possible mechanisms that could explain the link between COVID-19 and Parkinson's.

First, the virus may cause hypercoagulation. Small infarcts in multiple organs, including the brain, could trigger Parkinson's. Alternatively, the virus may a trigger defence response in nerve cells that leads to an increase in alpha-synuclein and its clumping ? a hallmark of Parkinson's. Finally, a massive systemic inflammation may trigger the condition.

These mechanisms together may produce "a perfect storm" for the development of Parkinson's, author suggests.

"There is a growing body of evidence to suggest that alpha-synuclein is involved in the immune system and can be affected by viral infections," he explained. This includes studies showing that in mice infected with West Nile virus ? which causes encephalitis ? there is an increase in alpha-synuclein and clumping of alpha-synuclein.

"It would be interesting to find out if there are neuroinflammatory changes or increases in alpha-synuclein in the brains of patients who have died from COVID-19, but so far, there are few neuropathology reports available," the author added.