RELATED: 96 Percent of People With Parkinson’s Have This in Common, Study Says. A recent study published in JAMA Neurology used data from Danish health care databases that included 10,231 men and women diagnosed with Parkinson’s disease between 2000 and 2016. Researchers then carefully analyzed each patient’s information against 51,196 control patients by matching them by age and sex while also tracking flu infections dating back all the way to 1977 through referencing hospital records, The New York Times reports. Analysis revealed that those who had contracted the flu at some point were 70 percent more likely to develop Parkinson’s disease within ten years compared to those who were never infected with the virus. Within 15 years, the likelihood increased to 90 percent more likely.
The latest research comes after decades of speculation in the scientific community that there could be an association between Parkinson’s disease and contracting the flu. While it’s been linked to genetics and certain environmental conditions such as exposure to toxic chemicals and pesticides, studies have also probed the noted increase in diagnoses of the neurodegenerative condition in the wake of the 1918 flu pandemic. And due to the extended onset of the disease, it can take much longer to be diagnosed, making any research into an association with the flu difficult. “The association may not be unique to influenza, but it’s the infection that has gotten the most attention,” Noelle M. Cocoros, MPH, the study’s lead author and a research scientist at the Harvard Pilgrim Health Care Institute, told The Times. “We looked at other infections as well, and there are several specific ones—hepatitis C and others—that may be associated with Parkinson’s. But we didn’t have large enough numbers to analyze them.” Others speculated that the findings might affect which vaccines get recommended to patients by their doctors. “There are many other good reasons to get a flu shot,” Cocoros said. “But if there is an association with Parkinson’s, then vaccination would lessen your risk. Still, it’s pretty evident that Parkinson’s can be caused by many things. Infection may be one of the many causes.“ae0fcc31ae342fd3a1346ebb1f342fcb
RELATED: For more up-to-date information, sign up for our daily newsletter. The study’s results have helped add evidence to the theory that the inflammation caused by certain infections such as the flu could affect the central nervous system, leading to a higher likelihood of Parkinson’s disease. But the researchers were also cautious to point out that more work had to be done before a definite link between the two could be made. “We’ve couched our findings with appropriate limitations,” Cocoros told The Times. “This is not evidence of a causal link between flu infection and Parkinson’s. Our study adds to a broader literature, and we shouldn’t overstate the results.” Besides a long theorized connection with the flu, other research has looked into other possible early signs that someone could be at risk of developing Parkinson’s. For example, an oft-cited 2009 study published in Neurology looked to see if constipation could precede the onset of the cardinal motor symptoms of the neurodegenerative disease, such as tremor and rigidity. The researchers studied data for nearly 200 patients who had developed the disease between 1976 and 1995, and 200 control subjects without Parkinson’s. According to the study, the patients with Parkinson’s were nearly two times more likely to have a history of constipation than those without the disease—with the association being evident decades before patients were officially diagnosed. “Indeed, the association remained significant when restricted to constipation documented more than 20 years before the onset of Parkinson’s disease,” the researchers concluded. “In Parkinson’s, constipation can be part of the disease process. [Parkinson’s disease, or PD,] can affect the autonomic nervous system, a network of nerves that directs bodily functions we don’t consciously control, such as blood pressure and digestion,” the Michael J. Fox Parkinson’s Foundation states on its website. “When digestive tract movement slows in PD, constipation can happen. Recent research also has linked changes in gut bacteria (the microbiome) with Parkinson’s disease; these disruptions may contribute to constipation.” RELATED: If You Notice This When You Walk, It Could Be an Early Sign of Parkinson’s.
