Jeremy Paxman's doctor diagnosed him with Parkinson's disease after noticing he was less "exuberant" and had facial symptoms while on University Challenge, the broadcaster has revealed.
The presenter, 72, who also previously hosted Newsnight, said he was diagnosed with the condition when in hospital after collapsing while walking his dog.
It was during treatment for his injuries that one of the doctors pointed out that while watching him on television he'd noticed it looked like his face had acquired a "Parkinson's mask".
"Well, it was completely out of the blue," commented Paxman, referring to the bombshell news about his health.
"I was having a walk in the square across the way," he recalled. "There was ice around and I had the dog with me – the dog was on a lead.
"The first thing I knew was when somebody was sitting on a bench. I'd fallen over and I made a terrible mess of my face."
Of course, he had no idea what was coming next.
“I’d gone straight down on my hooter, which, as you can see, is not small – cuts all over the place. I was a real mess. And when I was in A&E, a doctor walked in and said, ‘I think you’ve got Parkinson’s,'" explained Paxman.
“And it turned out that he had been watching University Challenge and had noticed that my face had acquired what’s known as the Parkinson mask.
“I wasn’t as effusive and exuberant as normal. I had no idea.”
Paxman first shared in May last year that he had been diagnosed with Parkinson's and that he had been receiving treatment for his mild symptoms at the time.
He then announced in August that he would be stepping down as host of University Challenge after nearly 29 years. "It’ll become obvious that there’s something funny about me – and I mean unusual, not funny funny. So I don’t want to spoil it for them," he explained at the time.
While he credited his time there as brilliant and said he'll be sad to give it up, he was firm in his decision. “I always think that if you’re scared of making a decision, do it," he added.
However, he is now due to present a one-off special about his diagnosis, Paxman: Putting Up With Parkinson’s, to be broadcast at 9pm on Tuesday October 4 on ITV.
But what exactly is the condition Paxman's been 'putting up with' and what are the symptoms?
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.
It is unclear exactly what causes the loss of nerve cells 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 1 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 1 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)
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), loss of smell (known as anosmia), sleeping problems (insomnia) and memory problems.
The 'Parkinson's mask' Paxman refers to 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. Apparently 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 like apathy (lack of interest) and motivation, which means they might not respond to emotions like they used to. "It may seem like there is a link in some cases, but it may be two common aspects of Parkinson's, happening at the same time," the website states.
If you are concerned you have any symptoms of Parkinson's disease, 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 disease with medication, staying active, monitoring your symptoms, exploring different therapies and in some cases brain surgery.
As well as Paxman, other celebrities who have spoken about living with Parkinson's disease include Ozzy Osbourne and Billy Connolly.
For more information on the condition, visit the NHS website's section on Parkinson's disease.
You can also 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 email@example.com.
Additional reporting PA.
Watch: Billy Connolly on dealing with Parkinson's disease: Comedian says he has learnt to 'hypnotise' his hand when it shakes