Almost two fifths of people with Parkinson's disease have felt the need to hide their symptoms or lie about having the condition, new research has revealed.
It's estimated that 42,000 people in the UK have delayed sharing their diagnosis with a friend or family member.
When asked why they chose to not share their diagnosis with loved ones, patients said they didn't want people to feel awkward or embarrassed around them.
They also said they feared being judged and felt like their symptoms were "not socially acceptable".
The research, collected by ComRes on behalf of Parkinson's UK, has been released publicly to mark the start of Parkinson's Awareness Week.
A spokesperson for Parkinson's UK said hiding a diagnosis from a loved one can have a "devastating" impact on a person's emotional health.
David Plummer, 47, is a wildlife cameraman from Henfield in West Sussex.
After six months of testing he was diagnosed with Parkinson's, but he didn't take the news well.
"I ended up walking round and round a square in London, completely dazed," he said. "Then I went to a bar in Victoria Station and drank too much before getting the train home.
"And so I entered the dark days. Panic, claustrophobia and no sleep.
"Parkinson's is not a flag I wave. There are a few people I told quickly but after that I didn't announce it."
He added: "I'll often try to hide it if my symptoms are showing, as sometimes it's embarrassing. I'm single at the moment and when going out on dates it's not something you want to say first off. A part of me wants to hide it."
Research also found that many Parkinson's patients expressed a worrying level of emotional repercussions.
Some experienced negative emotions in the year after their diagnosis, with younger patients with Parkinson's being the worst affected.
Others reported feeling "like their world had ended", "like they were grieving" or "like they didn't know who to turn to".
Steve Ford, chief executive at Parkinson's UK, said: "It's worrying that many people with Parkinson's, for a wide range of reasons, are not able to access the help they need - and it's having a devastating impact on their emotional health.
"We are determined that each and every person with Parkinson's is aware of the support available so they can feel equipped to have these difficult conversations.
"We know that the right support, whether through family, friends or Parkinson's UK, is vital for those with the condition, to help them come to terms with their diagnosis and know that they're not alone.
"We are here to help people find the support they need, when they need it."