EVERY few seconds Jonathan Mars lets out a yelp, punctuating his sentences with a strangled squeal.
He blinks rapidly, like a rabbit frozen in headlights, his eyes darting around the room.
Jonathan, aged 26, from Gleadless, has Tourette Syndrome, a neurological disorder that leads to involuntary vocal tics and physical movements.
“If I’m on the bus people sitting near me get up out of their seats and move,” he said.
“People are making fun of me every day of my life. I’ve just had enough.”
Jonathan is speaking out to raise awareness of a disease which affects around one in every hundred children.
And he wants to get in touch with other people in South Yorkshire who suffer from the condition.
“If we form a group we might be able to help each other,” he said.
“There are a lot of people who have this problem.”
The condition is best known for causing uncontrollable swearing – but that aspect of Tourette, known as coprolalia, is not actually that common, affecting only 10 per cent of sufferers.
In Jonathan’s case his condition means frequent yelps, uncontrollable eye movements, loud shouting, and severe obsessive-compulsive disorder (OCD).
Although Tourette Syndrome is a recognised medical condition, most people Jonathan encounters think he is simply being rowdy.
He has been thrown out of supermarkets, kicked off buses, and is frequently victimised.
And, more seriously, he has been beaten up and robbed and is increasingly worried about his safety.
“I’m sick of being targeted,” he said. “I’m getting on the bus and I’m constantly worrying about who is going to get on.
“I make noises and people make them back, mimicking me.”
He tries to take himself out of problematic situations, but it is not always possible.
“I try and stay out of shops if it’s busy. I don’t want to shock anyone,” he said.
“My grandad is in hospital at the moment, but I can’t visit him.
“I don’t know if I might start shouting – I don’t want that to happen on a ward of elderly people.
“Everywhere I go people stare. I carry a card explaining what Tourette Syndrome is – but even when I show it some people don’t care.
“That’s why I want people to understand what it means.”
Until Jonathan was 19, growing up in Leeds and then Barnsley, he was fine, a normal child living a normal life.
But then his mum started to notice something was wrong.
“I started making odd noises and making odd movements, and my eyes started going,” he said.
“I’ve had it seven and a half years now, and it is getting worse.”
Dr Aijaz Khan, consultant neurologist at the Royal Hallamshire Hospital, says Jonathan has an extreme form of the condition.
“Tourette Syndrome is under-recognised – there are a lot of people who have the condition but don’t realise it.
“It often starts in childhood and can get better. But in some cases it gets worse.
“For many people it means a combination of a mild tic and OCD – and in very mild cases it might even be an advantage because mild OCD can give people a drive in their career.
“But in extreme cases it can become a real problem.”
He added: “Jonathan’s symptoms are worse than average – he has it more severely than most people.
“It is constantly impacting on his life.”
“And in certain situations that makes him vulnerable.
“When he makes certain noises, for example when he is in the pub, people might think he has learning difficulties or is a vulnerable person.
“And that means predatory people think they can take advantage of him.”
Dr Khan has referred Jonathan for cognitive behavioural therapy, to try and reduce the impact of his OCD.
And he is being seen by a psychiatrist.
But Jonathan’s biggest hope at the moment is an unlikely drug, usually used for people with epilepsy.
Dr Khan said: “Jonathan has found gabapentin is quite helpful.
“It’s not something we’d usually use, but there has been evidence elsewhere of other epileptic drugs working in the past, so we are continuing to use it and seeing how he gets on.”
For Jonathan, it’s time to reach out to others.
“I’m 26 and I’ve had enough.
“ I want people to realise what this means, that it is a medical condition and it is terrible to live with.
“There are other people who have this problem – we can help each other out.
“And the more people who know about Tourette Syndrome, the better.”
If you are interested in taking part in Jonathan’s new support group, contact Ben Spencer on 0114 2767676 ext 3103, or email email@example.com.