THE kids used to call him Dickhead. They came by his house, often after dark, and threw stones. He lived alone. They smashed in at least one window. Once, a few of them tried to set fire to the place.

Mary Rose Callaghan was a neighbour of the man, on the street on which they lived, in Bray. She could see that he was mentally unwell, a vulnerable type who was easy prey for the butt-end of children's cruelty.

Schizophrenia was his burden.

He endured enough suffering within his own head, now he had to deal with the slings and arrows being thrown at him from without as well.

Callaghan tried to reason with the children, told them to go home to their mammies, weren't they too old to be carrying on like that? She went to the guards.

"They said that they were too busy, " she remembers. "They said that you would have to see them doing something before they could be charged with it.

That wasn't of much use to my neighbour."

The terror continued for a while, but then, as is the way with these things, it abated. "One young lad then came around to do his lawn and help him out so they weren't all bad, " Callaghan says. "It's just the way children can be sometimes. It's human nature to pick on the most vulnerable." So it goes in life.

In art, it goes a little differently.

Callaghan's latest novel is Billy, Come Home and the Billy in question is helped through his illness by a loving sister, Angie. But Billy is subject to much the same prejudice and stigma which dogged the author's neighbour in real life. Angie narrates the reader through Billy's story.

"Billy's condition was as basic as epilepsy or Alzheimer's, yet there are no moral agendas with those illnesses, whereas people with schizophrenia are stigmatised. Everyone assumes they are like Anthony Perkins in Psycho or have dual personalities like Doctor Jekyll and Mr Hyde."

Schizophrenia is only the beginning of Billy's troubles. As the story unfolds, he is accused of the brutal murder of a girl from the Travelling community on a dark night in the south Co Dublin suburb of Shankill. A nightmare ensues for the siblings as Billy's condition is used by the cops as a signpost for his guilt. What follows is a story of endurance amidst attitudes borne by ignorance and prejudice.

Billy is a fictional character, but it was her neighbour's experience that prompted Callaghan to turn her attention to the issue of schizophrenia. It's a long, long way from there to her practised art of penning comic fiction (she has also written a biography of Kitty O'Shea, Parnell's love interest).

Billy, Come Home works. It exposes the blatant prejudice against sufferers and their families, but retains the structure of a dramatic story.

Callaghan refrains from polemics, but offers insight through the narrator's voice.

Here's Angie mulling over the burden carried by a family member of a schizophrenic. "I was in the habit of keeping his troubles to myself. It was something learned over the years. No successful person in today's Ireland would dare admit that they suffered from depression and people with schizophrenia were pariahs.

Psycho was the word frequently used in the press."

Callaghan is old-school when it comes to writing novels. "A novel should say something, " she says.

"Shaw said that. It should have a point of view without being didactic. That's what I tried to do.

I wanted to give information but retain the story.

"And there still is huge social stigma around mental illness.

We've seen this recently in Dublin and Cork when mental-health bodies wanted to get some housing. Even though it's 2007 we're still living with an old mentality."

Around one per cent of the population in the developed world is estimated to suffer from schizophrenia. That makes around 40,000 with the condition in this state. It usually manifests itself in adolescence or early adulthood and can be characterised by hallucinations, delusions or disorganised thinking or behaviour. Other symptoms are withdrawal or loss of motivation or feelings.

The severity of the condition can broadly be divided into thirds. One-third have a psychotic episode, which can last three to four months, and make a full recovery. One-third have periodic relapses but in between can function fairly normally.

And the final third never make a full recovery.

Genetic or environmental factors are usually the cause. The myths surrounding the condition are such that Schizophrenia Ireland includes on its website the detail that, "bad parenting, poverty or sinful behaviour" does not cause it.

John Saunders, director of SI, says the myth that parents were responsible persisted until recent years. "It has been established that genetic and environmental stress factors are responsible. The environmental factors are usually outside the home, such as in school, college or during early career development."

Of all mental illnesses, schizophrenia has been particularly susceptible to myths of ignorance. Two recur time and again and succeed in heaping insult on the injury being endured by sufferers.

The first is that those afflicted have a tendency towards violence. "This simply does not tally with the research, " Saunders says. "If you look at the statistics worldwide, 99.6% of all killings are done by rational people, which is proportionately greater than the numbers who have schizophrenia. I know hundreds of people for whom aggression is not a factor.

"Unfortunately there are some who do turn their aggression inwards. Around 10% of people diagnosed will die by suicide, " he says. "What happens is when somebody with the condition is violent, it tends to get highlighted out of proportion."

Callaghan concurs. She was in Germany on a grant, writing Billy, Come Home, when the Swedish foreign minister Anna Lindh was shot by a schizophrenic. "It was all over the papers in Europe, " she recalls. "The fact that he had the condition was seen as some sort of explanation. But in reality they tend to be less violent than rational people."

The other principal myth is that sufferers have a split personality, a little Dr Jekyll, a little Mr Hyde. Again, the truth tells a vastly different tale.

"It's a myth of literature, " Saunders says. "Look at Superman, Batman, going from ordinary to superhuman, just like Jekyll and Hyde.

"The idea came from the man who introduced the term 'schizophrenia', a German psychiatrist named Bleuler. He took the name from the Classical Greek, which literally translates as 'split of mind'. What he actually meant was split from reality, but it went on from there."

In terms of treatment, there have been improvements with new - what are called "clean" - drugs that don't have the same severity of side effects as the previous generations of chemicals. Ideally, the best results are achieved through stabilisation with drugs, then complemented with psychotherapy. Overall, the prognosis has improved greatly.

Attitudes, however, have hardly kept up with the advances.

Saunders believes there has been only slight improvement in this department among the general populace in the last few, allegedly enlightening, decades.

For Callaghan, the project of a novel and the journey on which it took her has been rewarding.

Things didn't work out too great for Billy, as becomes apparent early on in the novel. Callaghan's neighbour, meanwhile, eventually moved to a nursing home a few years ago.

She is already embarking on her next venture, a book on clerical celibacy. "It's not about paedophilia or that, but just the celibacy issue, " she says, glad to be returning to her more usual fare of comic fiction.

Her brief foray into more serious literature may well end up doing some service for the tens of thousands and their families who must carry on through the ignorance.

'Billy, Come Home' will be published by Brandon on 27 February.

The Schizophrenia Ireland helpline is 1890 621 631; www. sirl. iex