SIMON Bent was in the pub when the truth first hit him. He'd gone for a pint with the actors after rehearsals for his play Sugar Sugar. What he really wanted to know was where one actor had got his characterisation from. What was his inspiration for such a slow, stuttering and incoherent performance? The other actors found it hilarious. Couldn't the playwright tell? At length, the actor confessed. He'd based his interpretation on Bent himself.
Slow, stuttering and incoherent? Was that how people saw him? He was still a young man in his late 30s, not some doddery old boy incapable of lighting a match. He was a successful writer of hit comedies - Wasted, Bad Company and Goldhawk Road - at pr
estigious venues such as London's Bush Theatre. He wasn't some washed-up old codger at the end of his career.
The conversation shook him up. But he had to admit he'd noticed his handwriting getting smaller and had been finding it harder to do up buttons. Was something wrong? He visited his doctor, who put him through months of tests. Eventually came the Movement Disorder Clinic - "It sounded like the Ministry of Silly Walks" - where he was given the diagnosis. Simon Bent had Parkinson's Disease.
"The character I'd written in Sugar Sugar had something wrong with him but he didn't know what it was," says Bent. "I looked at the actor and realised there was something wrong with me. I was writing about myself without knowing it. I was telling a story back to myself."
For a while, he couldn't tell anyone the news. He was frightened and didn't understand enough about it. He did masses of research, looking for miracle cures, trying to get his head around it. "It was really hard," he says. "You have to accept you've lost control. You have to accept you need help. You go to a restaurant and have to ask them to cut up the meat for you. At 39 you feel you've been reduced to being a child. You feel vulnerable."
Eight years later, Bent is sitting in Glasgow's Tramway while rehearsals are under way for The Escapologist, his first collaboration with Suspect Culture. To meet this soft-spoken and warm-hearted man today, you'd have no reason to suppose anything was wrong. Sometimes he struggles to get to the end of a sentence, but it's no worse than a shy person with a bit of a stammer.
His symptoms have been more prominent in the past - he says he's better now than he was five years ago - and they're likely to get worse in the future. For now, the drugs are keeping the disease under control, but they can't halt it. Also, he has the perennial problem of side-effects, especially if he drinks alcohol. At least he now knows this: when the drugs were first prescribed no one thought to mention what they might do to him.
"The medication was very powerful and had psychotic side-effects, but nobody told me," he recalls. "I became more and more paranoid and disturbed. I became the centre of a conspiracy by the Yardies to assassinate me. It got to the point where I stood up for 24 hours one night with a plank in one hand, a hammer in the other and a set of step ladders because I knew there was an assassin in the window opposite and a getaway car round the corner. I didn't realise there was something wrong with me."
That he has got through these years so well has a lot to do with therapy. He'd first been to counselling - with great reluctance - during a rocky patch in a relationship and had kept at it for two years. He'd given it up and for a time got "completely lost" but had been drawn back into the fold by his counsellor who suggested group therapy.
"That was about the time I found my voice as a writer," says the Scarborough-born playwright. "I started making sense of the story of my life and became a more serious playwright. I was going to leave, but then I got Parkinson's and I needed therapy to come to terms with the illness."
Does he recommend it? "Yes, as long as you've got a good therapist. Group therapy that isn't proscriptive and is non-judgemental but is very tough and makes you face up to responsibility for yourself is a good thing."
PARKINSON'S DISEASE or not, Bent has become an ever bigger name on the English theatre scene since that first trip to the doctor. Accomplices was staged at the Sheffield Crucible, The Country of the Blind at London's Gate Theatre and The Associate and an adaptation of John Irving's A Prayer for Owen Meany at the National.
Being cast under a medical life sentence, he admits, has affected his work rate. "I've worked so much harder since I got Parkinson's," says Bent, 47, whose first screenplay, Christie Malry's Own Double Entry, was nominated for a Bafta. "Time has taken on a different meaning to me. I'm trying to do as much as I can before it gets to the point when I can't physically do something."
This background makes him the ideal candidate for the Suspect Culture job. The Escapologist is based on Houdini's Box, the 2001 book by pop psychotherapist Adam Phillips, which juxtaposes the story of Harry Houdini's restless quest to escape with anecdotes from the therapist's couch about clients who feel compelled to escape from the things they desire.
"There are people who can be defined by what they escape from," writes Phillips. "And people who are defined by the fact that they are forever escaping."
All escape, he argues, is a displacement activity from dealing with the things that frighten us. Houdini was forever on the run from the failures of his immigrant father in go-getting America. His miraculous escapes were a defiant demonstration of his ability to survive against the odds. But having escaped, all he could do was escape again.
The decision to create a piece of theatre from this unsettling, if not obviously dramatic book, was made by artistic director Graham Eatough. "I was in a rehearsal room for another show a couple of years ago and we realised, rather alarmingly, that six out of seven of us sitting round the table had had direct experience of therapy," he says. "It confirmed for me that the role therapy now assumes in our society is more ubiquitous than it used to be and less of a taboo. The dynamics of therapy, that dialogue, are ripe for exploration."
Working with the National Theatre in London to develop the theme, Eatough was put in contact with Bent and the relationship was sealed. "My life is bound up in my art, whether that's madness, therapy or telling stories," says the playwright. "To work with Suspect Culture has enabled me to explore the psychotherapeutic dynamic between the patient and the therapist."
Although Phillips' book provides the potentially powerful theatrical imagery of Houdini's stunts - the publicity image is of a man in a straitjacket hanging upside down by a chain - Bent felt it would take a greater leap to dramatise the author's themes. Psychotherapy is necessarily in the past tense - it's the patient reflecting from the comfort of a couch - whereas theatre is always in the present.
His solution was to make a free adaptation with new characters whose stories a therapist uses to understand the dilemmas in his own life.
"The presentation on a stage of therapy or confession is anti-theatrical because it's reflective and it means you're on the back foot," says Bent. "Good drama should be constantly pushing forward. The challenge was to get inside the process of therapy between the client and the therapist as well as telling a story. The book is all about the dialogue, the conversation, not the intellectualisation or the analysis. It's about connections, being truthful, and that's what happens on stage."
That might not sound like the stuff of Bent's trademark black comedy but he says therapy always gives rise to funny situations. Comedians and therapists all get their material from our prejudices and fears. "Laughter is an important part of the analytical process," he says. "What we laugh at is based on what's acceptable, what's unacceptable and our taboos."
For Bent himself, increasingly aware of his body's weaknesses, escape is found in writing. "I can do things imaginatively that I can't do physically," he says. "My body's changing all the time. Just as I think I'm on one even plain, I'll drop and start to have difficulty on another level. I can't use notebooks any more, so I've learnt to expand my memory. And even if I have to tap it out with my nose, I'll still write - it's such an integral part of my survival."
• The Escapologist, Tramway, Glasgow, Friday and Saturday (previews) then January 17-28