Brett Favre says he was diagnosed with Parkinson's disease after having issues with his right arm and hand. What to know about the condition's symptoms, causes and risk factors.

NFL Hall of Famer Brett Favre was recently diagnosed with Parkinson’s disease. The 54-year-old shared the news on Tuesday during a testimony at a congressional hearing on federal welfare reform.

The hearing was held to discuss guardrails for distributing Temporary Assistance for Needy Families funds, which distributed millions to Favre’s alma mater, the University of Southern Mississippi, and Prevacus, a drug company he backed that is no longer in existence.

“Sadly, I also lost my investment in a company that I believed was developing a breakthrough concussion drug I thought would help others,” Favre said. “As I’m sure you’ll understand, while it’s too late for me — I’ve recently been diagnosed with Parkinson’s — this is also a cause dear to my heart.”

Favre played in 20 NFL seasons and previously shared on The Bubba Army radio show that he sustained “thousands” of concussions during his football career. “Every time my head hit the turf, there was ringing or stars going, flash bulbs, but I was still able to play,” he said in the interview. “That’s what’s kind of frightening about the concussion thing. It’s the ones that seem minor that do the damage, because you’re able to keep going, and still today there’s probably guys that have them, they’re [saying] ‘I’m not going out.’” Favre also produced the new Apple TV movie Concussed: The American Dream.

Favre later spoke to TMZ Sports about his diagnosis, which he said he received on Jan. 3, 2024. According to the former football star, he met with five specialists, who, he claims, told him the same thing: "If [Parkinson's is] not in your family — and there's none on either side of my family — then the first thing we look at is head trauma." Says Favre: "Well, hell. I wrote the book on head trauma."

Favre added that he had "very minor symptoms" prior to his diagnosis. "I had two symptoms, and they went on for about a year," he told TMZ Sports. The first was his right arm raising up and being "stuck" in a right-angle position by his side. Favre, who is right-handed, said the strength in both his arms and hands are "fine," but he noticed that he would need to use two hands to, say, use a screwdriver. "The weirdest one was, like, a long-sleeved shirt or a jacket," he said. "I would go put my right arm in it, and I couldn't get it through the hole for nothing. ... I felt my arm, the strength was there, but I could not guide it. And it was the most frustrating thing."

On Tuesday night the ex-Green Bay Packer took to X to thank fans for their support regarding his diagnosis, which he said has "been an ordeal."

Favre’s revelation has raised a lot of questions about Parkinson’s disease, including a potential connection to concussions. Here’s what neurologists want you to know.

What is Parkinson’s disease?

Parkinson’s disease is a brain disorder that causes symptoms such as unintended or uncontrollable movements, including shaking, stiffness and trouble with balance and coordination, according to the National Institute on Aging (NIA). “One of the key features of the disease is slowness in movement,” Dr. Gian Pal, a neurologist and movement disorders specialist at Rutgers Health Robert Wood Johnson Medical School, tells Yahoo Life. “There can also be stiffness, balance problems and tremors, but moving slowly is common.”

The disease, which actor Michael J. Fox also has, is progressive, meaning symptoms get worse over time. About 500,000 Americans are diagnosed with Parkinson’s disease, although the National Institute of Neurological Disorders and Stroke (NINDS) says the actual number of those who have it is likely much higher.

What causes Parkinson’s disease?

The exact cause of Parkinson’s disease is unknown. However, there are a few risk factors linked with the development of the disease. According to Johns Hopkins Medicine, those include:

• Age. Most people develop the condition as they get older, with 60 being the average age of onset.

• Gender. Men are more likely to develop the condition than women.

• Genetics. Those with a parent or sibling with Parkinson’s disease are two times as likely to develop the condition.

• Environmental causes. These include exposure to pesticides and herbicides; working with heavy metals, detergents and solvents; and being exposed to Agent Orange during the Vietnam War era.

Can concussions raise your risk of Parkinson’s disease?

That’s not entirely clear at this point. Research has found a link between head trauma and the risk of developing Parkinson’s disease. One study published in the journal Neurology found that even having a mild brain injury raised the risk of developing Parkinson’s disease by up to 56%. Another study published in the journal Family Medicine and Community Health found that people who had experienced a concussion were 57% more likely to develop Parkinson’s disease.

“There is a potential link,” says Dr. Daniel Truong, a neurologist and medical director of the Truong Neuroscience Institute at MemorialCare Orange Coast Medical Center in Fountain Valley, Calif.

But Parkinson’s disease is a complicated condition, and not everyone who has a concussion goes on to develop the disease, Pal points out. “The association is not conclusive. It warrants further research,” he says.

"Parkinson's disease is linked with higher levels of tau, a protein, in the brain," Dr. Amit Sachdev, medical director in the Department of Neurology at Michigan State University, tells Yahoo Life. "It is hard to know for sure if concussion is associated with elevated tau and, if so, if this deposits on the brain in a pattern to cause the disease."

Pal also notes that a JAMA study that was released last year found that playing football was linked with a greater chance of having a diagnosis of parkinsonism (a group of conditions that cause similar Parkinson’s-like symptoms) or a Parkinson’s disease diagnosis — and the odds were greater the longer a person played the sport. Still, this link isn’t definitive. “Playing football might be a risk factor for Parkinson’s, but the evidence is still mixed,” Pal says.

Parkinson’s disease symptoms

Symptoms of the disease can vary by person, but the NIA says these are the four main symptoms of Parkinson’s:

• Tremor in hands, arms, legs, jaw or head

• Muscle stiffness

• Slowness of movement

• Trouble with balance and coordination

People with Parkinson’s disease may also experience depression and other emotional changes; trouble swallowing, chewing and speaking; urinary issues; constipation and skin issues, according to the NIA.

How is Parkinson’s disease diagnosed?

There are no blood or lab tests used to diagnose nongenetic Parkinson’s disease. As a result, doctors will usually give a diagnosis based on medical history and a neurologic exam, according to the NIA. They may also try a short, low-dose treatment of medicines used to treat Parkinson’s disease to see if symptoms improve, according to the Mayo Clinic. However, “that is not required for diagnosis,” Pal says.

Parkinson’s disease treatments

“One of the main issues with Parkinson’s disease is that there is low dopamine in the brain — that causes a lot of the physical symptoms of the disease,” Pal says. “We have good medicines to replace that dopamine.”

But, in the early stages of the disease, Pal says that someone may not need treatment. Instead, a patient and their doctor will typically decide together if the symptoms are disabling enough that they need medication. “If it’s causing functional limitations in their day, then they would think about medication,” he says.

Aside from medication, physical activity can also be helpful for managing symptoms, Pal says.

If you’re having symptoms of Parkinson’s disease, Pal recommends getting an evaluation with a movement disorder specialist as soon as possible to see if it could be the disease or something else entirely. “Then they will better understand what the long-term outlook would look like,” he says.

"Parkinson's is a progressive disorder with many features," adds Sachdev. "Early diagnosis is important."

Pal stresses that there are medications and treatments to help. “Generally, Parkinson’s is a slow, progressive disease,” he says. “We have a lot of treatments available.”

This article was originally published on Sept. 24, 2024 and has been updated with Favre's statements.