Up to 150,000 Scots suffer from Borderline Personality Disorder (BPD), according to the SeeMe campaign. Three- quarters are women.

Yet the term is controversial - viewed by many professionals and patients as a "dead-end" diagnosis. Studies have shown that many psychiatrists and psychiatric nurses view it as untreatable.

This is critically important, as those diagnosed with BPD have a hugely increased suicide risk - 50 times greater than the general population, according to one study.

The Mental Welfare Commission in Scotland has launched an investigation into the recent suicide of a woman in the Highlands who was alleged to have a personality disorder. But the MWC already believes the situation must change. It carried out an investigation following another case in 2003 where a man with a personality disorder, known as Mr G, was left to languish in prison with an "untreatable" personality disorder.

Mr G was discovered to be suffering from a type of dementia, which had gone untreated. His low mood, suicidal thoughts and inappropriate behaviours were disregarded. Even the fact he was now incontinent hadn't prompted the doctors charged with his care to review their diagnosis, until the commission intervened.

Dr Donald Lyons, director of MWC Scotland, says, "The problem with the diagnosis of personality disorder is that it can be used as a way to exclude people from services. Where somebody has that diagnostic label attached to them, mental health professionals can become blinkered to other mental health problems which are going on with that individual."

"The trouble is that people who are perceived as behaving in difficult or troublesome ways often get this label - and it might be that they are behaving in a troublesome or difficult way because they are actually ill."

Mr G's case showed clearly that evidence of other conditions was sometimes being overlooked, Lyons says, while a BPD diagnosis also appeared to make it difficult for other agencies to get help for their clients from mental health services.

"When we went to see Mr G in prison, the prison mental health records actually contained the information that we needed to think, wait a minute this isn't right - this diagnosis can't explain everything that's happening with this person.' "In the course of examining the case we interviewed a number of health care, social care, homeless agencies and voluntary sector providers and we were often told of the difficulty they experienced in accessing a mental health service where someone was given a diagnosis of personality disorder."

Now Lyons believes psychiatrists and those in related professions must change their attitude: "A lot of work has to be done to ensure mental health professionals are aware of the possibilities for treatment. You don't just say, person- ality disorder - as far as mental health services are concerned, case closed, there's nothing we can do'."

Last year Scotland took a lead within the UK by including BPD in a list of mental health conditions professionals are now obliged to approach in a systematic, comprehensive manner as part of NHS strategies to integrate care.

Some psychiatrists do accept the need for a new approach. Research supports the view that poor parenting and traumatic early experience can lead to BPD. Dr Linda Treliving is a consultant psychiatrist in psychotherapy based at Cornhill Hospital in Aberdeen and chair of the Scottish Personality Disorder Network.

She says, "There is a lot of work showing that people with BPD actually do have physiological brain changes you can measure and see there are developments that haven't occurred because they haven't had the right opportunity."

Fortunately it is now known there is hope for recovery for BPD sufferers like Kaye. Approximately 40% of those diagnosed no longer meet the criteria for BPD after five or six years, and recovery rates can be even higher with effective intervention, Treliving says.

"There is a real sense that the ability of the brain to adapt and for the individual to respond to experience never ends. It's almost like when a person has a stroke and other neural pathways can come in to compensate."

Despite these discoveries, many patients with BPD still feel they are dismissed as manipulative and beyond help. Challenging behaviours such as self-harming, which have been developed as coping strategies, are not always understood.

Many patients feel they have been written off by medics and do not understand why they can't be admitted to hospital, even when they feel desperate or suicidal. But the situation is complex. Dr Treliving says, "Research shows that admitting people with BPD to hospital is not helpful. People can regress and start behaving impulsively and chaotically. We should still be coming up with alternative packages of care."

Planned, time-limited admissions to hospital are an option now being evaluated in the Highlands. Meanwhile, a range of interventions have been proven to be helpful. Medication can play an important role in managing symptoms, while talking treatments such as Cognitive Behavioural Therapy or Psychodynamic Therapy have been shown to be effective in addressing root causes. A new therapy from the USA called Dialectic Behavioural Therapy which incorporates intensive one to one and group work is available in some parts of Scotland. Meanwhile, Dr Treliving and a few colleagues are qualified in a validated technique known as Mentalisation Therapy.

It will take time for old prejudices to fade and there is an ongoing issue with poor provision of psychological therapies. Legislation and research alone cannot create the culture change the Mental Welfare Commission and tens of thousands of sufferers would like to see.