More than a third of people in the UK with Parkinson's disease feel the need to hide their symptoms or lie about having the condition, a survey for a charity suggests.
They feel the symptoms are not socially acceptable and may embarrass those close to them, Parkinson's UK said.
It added it was concerned that too many people were struggling alone with their diagnosis, affecting emotional health.
The disease affects 127,000 people in the UK - about one in 500 people.
The main symptoms are tremor, slowness of movement and rigidity.
The charity surveyed 1,868 people with the disease to find out how they dealt with their diagnosis.
Fear of stigma
One in three with the condition said they had delayed telling friends and family about their diagnosis with some of the main reasons including the fear of being stigmatised.
The charity said the findings also revealed a worrying level of emotional repercussions for people diagnosed with Parkinson's.
Younger people reported being hardest hit by the diagnosis to the extent that many said they felt "like their world had ended" and said "they didn't know who to turn to".
Steve Ford, chief executive at Parkinson's UK, said not getting help for the degenerative neurological condition was having a devastating impact on people's 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."
He added: "We are here to help people find the support they need, when they need it."