A Viral Cause of Parkinson's

There are so many causes of Parkinson-like symptoms that as a whole, they're known as Parkinson's Diseases. One that has puzzled scientists in recent years makes up about fifteen percent of the world's ten million cases. Now they've connected these cases to a shared trait: many are survivors of encephalitis from decades ago.

Encephalitis is brain inflammation. Scientists found that many survivors of the nineteen-eighteen Spanish flu who got encephalitis developed Parkinson's. Then in recent years they saw half the survivors of West Nile encephalitis and a quarter of Western Equine encephalitis survivors developed what is now called Viral Parkinsonism.

To explain this, they infected mice and found the animals lost nerve cells that make dopamine, typical of Parkinson's. MRI scans showed the virus in two brain structures involved in dopamine production. The mice had forty-six percent more microglial cells which are immune cells that fight viral infections as well as seventy nine percent more astrocytes. These cells promote energy and blood flow in neurons during infection. The mice brains also had alpha-synuclein protein clumps typical of Parkinson's.

Scientists think the surge of these immune cells in the brain may cause damaging inflammation. Combine that with less dopamine producing cells and years after encephalitis, some develop viral parkinsonism. Perhaps this new lead will produce much needed therapies.