Michael J. Fox experienced a fall on stage at a fan event, prompting him to admit he was in "intense pain" due to Parkinson's disease.

The actor, 61, recently shared the story behind his ongoing health battle with the condition in a Netflix documentary. He was first diagnosed with early onset Parkinson's in 1991, dealing with it privately to begin with.

"It’s such a shitty disease," he told Variety in an interview last month. "I didn’t want to think about it. I didn’t want to deal with it. It didn’t fit my story. I just shut down." In 1998, he shared the news publicly.

After initially fearing he'd made the wrong decision due to scrutinising tabloid headlines, the father of four eventually found peace in going public. He officially retired in 2020 after struggling to learn lines – though this far exceeded the timeline doctors had originally given him.

Despite his acceptance of his diagnosis, he said honestly, "Parkinson’s is still kicking my ass. I won’t win at this. I will lose." But, he added, "there’s plenty to be gained in the loss."

Other celebrities who have spoken about living with Parkinson's disease include Jeremy Paxman, Ozzy Osbourne and Billy Connolly.

What is Parkinson's disease?

Parkinson's disease is a condition where parts of the brain become progressively damaged over many years, explains the NHS website.

It is caused by a loss of nerve cells in the substantia nigra (a part of the brain), which leads to a reduction in dopamine (known as one of the 'happy hormones').

More specifically, dopamine also helps to regulate the movement of the body, with a lack of it responsible for many of the symptoms of the disease.

Who is most at risk of Parkinson's disease?

It is unclear exactly what causes the loss of nerve cells that leads to Parkinson's, but many experts think it is a result of a combination of genetic and environmental factors.

While Parkinson's can run in families due to 'faulty genes' being passed on by a parent, it is rare for it to be inherited this way.

Parkinson's disease affects roughly one in 500 people, according to the health service. Most people with the condition start to develop symptoms when they're over 50. That said, around one in 20 people also first experience symptoms when they're under 40.

Men are slightly more likely to get the disease than women are.

Parkinson's disease symptoms

There are three main symptoms of Parkinson's, which are:

• involuntary shaking of particular parts of the body (known as a tremor)

• slow movement

• stiff and inflexible muscles

Someone with Parkinson's disease can also experience a variety of other physical and psychological symptoms, including:

• depression and anxiety

• balance problems (this may increase the chances of a fall, which could help to explain Paxman's accident, for example)

• loss of smell (known as anosmia)

• sleeping problems (insomnia)

• memory problems.

The 'Parkinson's mask' - previously referred to by Paxman - is known as 'facial masking' or 'hypomimia', which links to the stiffness of muscles some people experience. Nurse Linda, from the Parkinson's UK helpline, explains on the charity's website that the lack of dopamine in the brain can stop your facial muscles from working how they used to.

She added that when this happens, people can look like they have a blank expression, even if they are experiencing a strong emotion. Having a Parkinson's mask is a common symptom and it doesn't mean someone with the condition is necessarily feeling low or depressed - they just can't use their facial muscles to correctly express themselves.

Many people with Parkinson's also report problems with apathy (lack of interest) and motivation, which means they might not respond to emotions like they used to.

Help with Parkinson's disease

If you are concerned you have any Parkinson's disease symptoms, see a GP who can speak to you about the problems you're experiencing, and if needed, refer you for further tests.

While there is no cure, you can help manage Parkinson's by:

• taking medication

• staying active

• monitoring your symptoms

• exploring different therapies

• in some cases brain surgery

For more information on the condition:

• visit the NHS website's section on Parkinson's disease

• visit the Parkinson's UK website, the main support and research charity for the disease or contact them on the free helpline 0808 800 0303 or email on hello@parkinsons.org.uk

Parkinson's disease: Read more

• Michael J. Fox says cure for Parkinson’s disease is ‘closer than it’s ever been’ – Evening Standard, 2-min read

• Hearing loss early sign of Parkinson’s – Evening Standard, 2-min read

• Mum diagnosed with Parkinson's at 44 shares surprising symptoms – including loss of smell and OCD – Yahoo Life UK, 6-min read

Additional reporting PA.

Watch: Billy Connolly on dealing with Parkinson's disease: Comedian says he has learnt to 'hypnotise' his hand when it shakes