As reported in Parkinson’s News Today,  a new study published in Family Medicine and Community Health has looked into the relationship between concussions and certain other neurological disorders that patients have anecdotally linked to such head injuries.  The researchers analyzed insurance information that had data on nearly the whole population of Manitoba, a province in Canada, including over 47,000 Manitobans who’d had concussions.  They found that people who had a concussion were 57% more likely to be diagnosed with Parkinson’s disease.

Parkinson’s disease is a neurological disease that causes progressive difficulty with movement. The progressive disease tends to begin with mild tremors and shaking, and progress into difficulty walking, balancing, speaking, and then in later stages, hallucinations. The disorder affects the central nervous system, damaging communication between the body and the brain. It usually begins after age 50, and progresses with time.

Concussions are caused by blows to the head, often resulting in headaches, tension, memory issues, difficulty with balance, and overall brain functioning. While the short term symptoms tend to clear up after about a week, there are echoes of long-term neurological effects; the full extent is not yet known. While anecdotal evidence and some studies suggest they are linked to neurological disorders, studies to date have not been rigorous enough to be considered reliable.

The current team of researchers have used data from the Manitoba Population Research Data Repository, which is fully equipped with information from nearly the entire province. Manitoba is made up of nearly 1.4 million residents as of 2019.  They matched the 47,483 people who had been diagnosed with concussions from 1990 to 2015 to three people who had not been diagnosed with concussions with similar demographic features. The models also adjusted for the socioeconomic status and co-existing health conditions that may also play a role.

The study searched for the relative risk to find the correlation between those who had a concussion and later were diagnosed with Parkinson’s disease, attention deficit/hyperactivity disorder (ADHD), mood and anxiety disorders (MADs), and dementia. A history of a concussion had different effects on the various disorders, but it was shown to increase the likelihood of all of them. People who’d had one concussion were found to be 57% more likely to develop Parkinson’s later in life. That risk was raised to 200% if they’d had four or more concussions.

While their findings still has caveats- notably the methodology using insurance data meant it did not come with a family history of the neurological disorders- it clearly finds a heightened risk associated with concussions. The data was widespread and thorough, and is beginning to show real proof of the tangible ways concussion effects live on.