Three co-stars of Back to the Future actor Michael J Fox were also diagnosed with Parkinson's - leading researchers to speculate whether a virus is responsible for the disease diagnosis.
A 15-year-old Fox first starred in the 1970s sitcom Leo and Me in Vancouver - a hilarious series about an Italian adventurer who lived on a yacht with his orphaned nephew (played by Fox).
According to a CBC report, three fellow actors on the hit Canadian series have since developed early-onset Parkinson's disease - a brain disorder that Fox was originally diagnosed with in the early 90s. It has been theorized that the disease can be brought on by genetic or environmental factors years after initial exposure.
Per the NHS, signs and symptoms of Parkinson's can include tremors, muscle stiffness, and slowness of movements. Other physical symptoms can extend to dizziness, nerve pain, cognitive impairment, and even dementia.
Researchers in Japan have found that a form of the flu, which is caused by a virus, attacks the same part of the brain that Parkinson's affects.
Two years ago, a then-59-year-old Fox revealed to The Guardian that these diagnoses were not enough to be defined as a cluster and therefore have not properly been researched.
"But believe it or not, that's not enough people to be defined as a cluster, so there hasn't been much research into that. But it is interesting. I can think of a thousand possible scenarios: I used to go fishing in a river near paper mills and eat the salmon I caught; I've been to a lot of farms; I smoked a lot of pot in high school when the government was poisoning the crops. But you can drive yourself crazy trying to figure it out," he stated.
Soon after Fox's diagnosis, he struggled immensely with depression and turned to alcohol. "My first reaction to it was to start drinking heavily. I used to drink to party, but now I was drinking alone and every day. Once I did that it was then about a year of like a knife fight in a closet, where I just didn't have my tools to deal with it," he stated, per People.
The Canadian-born actor's symptoms eventually caused him to quit working on his award-winning sitcom, Spin City - which he won three Golden Globes and an Emmy for. Soon after, he established The Michael J Fox Foundation, which was dedicated to Parkinson's research.
In 1999, Fox spoke to a Senate committee on assisting with government funding to help fight Parkinson's.
In his first book, Lucky Man, he wrote about that experience, stating: "It seemed to me that this occasion demanded that my testimony about the effects of the disease, and the urgency we as a community were feeling, be seen as well as heard."
The Guardian reported that, in the past 20 years, Fox has managed to raise an astonishing $1 billion for Parkinson's research.