Study Shows Influenza May Increase Risk of Developing Parkinson’s

New research suggests a certain strain of influenza virus predisposes mice to developing pathologies that mimic those seen in Parkinson’s disease. This new study built on previous research at St. Jude Children’s Research Hospital in Memphis, Tenn., that showed a deadly H5N1 strain of influenza (bird flu) that has a high mortality rate (60 percent) was able to infect nerve cells, travel to the brain and cause inflammation that would later result in Parkinson’s-like symptoms in mice. In the new study, researchers looked at a less-lethal strain, H1N1 (swine flu), that does not infect neurons, but still causes inflammation in the brain via inflammatory chemicals or cytokines released by immune cells involved in fighting the infection. Using a model of Parkinson’s disease in which the toxin MPTP induces Parkinson’s-like symptoms in humans and mice, they found that mice infected with H1N1, even long after the initial infection, had more severe Parkinson’s symptoms than those who had not been infected with the flu. And, when mice were vaccinated against H1N1, or were given antiviral medications at the time of flu infection, the increased sensitivities to MPTP were eliminated.

“The H1N1 virus that we studied belongs to the family of type A influenzas, which we are exposed to on a yearly basis,” said Richard J. Smeyne, PhD, professor of neuroscience in the Sidney Kimmel Medical College at Thomas Jefferson University and director of the Jefferson Parkinson’s Disease Center in the Vickie and Jack Farber Institute for Neuroscience. “Although the work presented here has yet to be replicated in humans, we believe it provides good reason to investigate this relationship further in light of the simple and potentially powerful impact that seasonal flu vaccination could have on long-term brain health.”