Serious falls that result in injury may indicate the person should look out for Parkinson’s disease (PD) in the future, according to researchers from Umea University in Sweden.

Published in PLOS medicine, the study found patients with PD were more likely to have experienced serious injuries, like hip fractures, from falling in the years preceding their diagnosis than controls without PD. The reverse was true as well — participants who suffered falls were more likely to be diagnosed with Parkinson’s in the following years than controls who hadn’t injured themselves from falling. Lead author Peter Nordstrom and his colleagues from the university say the findings could provide insights in the earliest stages of PD.

The team collected data from the Swedish National Patient Register and identified 24,412 people who had been diagnosed with PD between 1988 and 2012. They matched each case up with 10 controls, and adjusted for other factors that could affect a person’s risk of a fall. Parkinson’s was associated with a 19 percent higher risk of injurious falls up to 10 years before diagnosis, and a 36 percent higher risk of hip fracture more than 15 years before diagnosis. The closer to diagnosis, the stronger the association.

In a second part of the study, researchers matched 622,333 patients who had a record of injurious falls with control individuals who never fell and got seriously injured. After adjusting for outside factors, they found an 18 percent greater risk of a Parkinson’s diagnosis in the 10 years following an injurious fall.

Parkinson’s disease is a progressive disorder that affects the nervous system, with movement problems being the most well-known signs. Recognized early signs of the condition include lack of expression on the face, no arm swinging while walking, and barely-noticeable tremors. These symptoms worsen over time to cause stiffness and slowing movement to the point of incapacitation. There is currently no cure and the exact cause of Parkinson’s remains unknown.

The researchers behind the study recognize the experiment was preliminary, and stress that the findings need to be confirmed in other populations and settings. Still, the results are important for researchers digging into the initial stages of Parkinson’s, since they identify potential markers of the disease more than 10 years before a clinical diagnosis.

“These findings suggest that clinically relevant neurodegenerative impairment could be present many years before the clinical onset of the disease,” the authors wrote. “The findings… need to be confirmed in other settings but provide new insights into the earliest, hitherto unrecognized, stages of PD.”

Source: Nystrom H, Nordstrom A, Nordstrom P. risk of Injurious Fall and Hip Fracture up to 26 y Before the Diagnosis of Parkinson disease: Nested Case-Control Studies in a Nationwide Cohort. PLOS Medicine. 2016.