AS a new service is set up at The Retreat in York for people with personality disorders, we look at the condition estimated to affect as many as one in ten people and how severe cases can be treated.

ACCORDING to an expert, as many as one in ten of us could have a personality disorder.

Prof Eddie Kane, of the Institute of Mental Health, went on the record as saying four per cent of people have a personality disorder, with some studies suggesting it's as high as 13 per cent.

They vary in severity and type - including borderline, anti-social, paranoid and narcissistic - with statistics showing people with personality disorders are more likely to commit suicide, be in prison and have mental health problems.

But given their prevalence few people know much about personality disorders, with experts saying the condition is often misunderstood or stigmatised which can lead to people with severe cases being misdiagnosed or offered ineffective treatment.

So what is a personality disorder? They are defined as conditions in which an individual deviates significantly from an average person, in terms of how they think, perceive, feel or relate to others. People may be overwhelmed by negative feelings such as distress, anxiety, worthlessness or anger, or exhibit odd behaviour, or struggle to connect with people and maintain relationships.

And while many people have who have personality disorders suffer mild symptoms and live their lives without coming to the attention of mental health services, some people can behave repeatedly in a way that is not acceptable to the community that they live in and they can cause distress to themselves, or others.

It is people with severe conditions, a new inpatient service called The Kemp Unit at The Retreat in Heslington Road aims to help. The unit will offer help to up to ten women at a time with very severe and complex personality disorders.

Due to open in April, NHS commissioners from all over the country - but especially from York and the surrounding areas - can refer patients to have specialist treatment lasting an average of six months to help cope with their problems.

"People might be very anxious and very fearful and they might have been let down by services in the past," Jodie Roberts, pathway development manager at The Retreat said about the patients they will be welcoming to the unit.

"They may have had to wait a long time for the treatment offered and they may have been in a lot of services and if people have got problems with forming positive relationships moving from service to service can impede on their progress. Also, the chaos a lot of the ladies experience, particularly with borderline personality disorder, will have been increased with difficulty of access to services.

"Because of the lack of understanding it is a specialist area. It is unknown and the expertise is not readily available.

"We want to be able to give people the skills to manage their personality disorder."

Tailored packages of care will be given to women on the unit, who will primarily have borderline personality disorder and may have overwhelming feelings of distress, anxiety, worthlessness or anger and may have difficulty managing their feelings without self-harming – for example, by abusing drugs and alcohol or taking overdoses.

A specialist team led by psychiatrist Dr Mel Temple will work with patients to offer dialectical behaviour therapy (DBT) to help patients cope with emotional instability, while at the same time encouraging them to behave in a more positive way.

They will also be offered compassion focused services to help build more positive relationships and eye movement desensitisation to help treat women who may have suffered trauma.

Most of the women will have had a trauma in their lives that has made them unable to cope and has exacerbated their problems.

"Someone may have had a personality disorder for most of their life but not experienced difficulty with it and they may have the traumatic episode and they are unable to cope," Ms Roberts said, "The ladies we will see may have gone through a life event. A marriage may have broken down... they may have had a violent traumatic relationship which comes to an end. There was an example of lady whose husband had understood her personality and what she needed to respond and he formed that attachment and provided stability. When he died, she lost that stabilising effect and struggled to cope."

When women leave the unit it is hoped they may continue to receive help as outpatients from the Tuke Centre to continue their recovery.

She said it's the kind of service The Retreat, which has a long history of innovative mental health care, is proud to offer. "People have presented with these problems and not been diagnosed for a number of years, which is why this service is needed, particularly in this area as there's nothing similar in Yorkshire."

What is a personality disorder?

Personality disorders are conditions in which an individual differs significantly from an average person, in terms of how they think, perceive, feel or relate to others.

Changes in how a person feels and distorted beliefs about other people can lead to odd behaviour, which can be distressing and may upset others.

Common features include: - being overwhelmed by negative feelings such as distress, anxiety, worthlessness or anger - avoiding other people and feeling empty and emotionally disconnected - difficulty managing negative feelings without self-harming (for example, abusing drugs and alcohol, or taking overdoses) or, in rare cases, threatening other people - odd behaviour - difficulty maintaining stable and close relationships, especially with partners, children and professional carers - sometimes, periods of losing contact with reality - Symptoms typically get worse with stress.

- People with personality disorders often experience other mental health problems, especially depression and substance misuse.

When and why do personality disorders occur?

Personality disorders typically emerge in adolescence and continue into adulthood.

They may be mild, moderate or severe, and people may have periods of "remission" where they function well.

Personality disorders may be associated with genetic and family factors. Experiences of distress or fear during childhood, such as neglect or abuse, are common.

What are the different types of personality disorder?

Several different types of personality disorder are recognised. They have been broadly grouped into one of three clusters – A, B or C – which are summarised below.

Read about the symptoms of personality disorders for a full list of the main types and signs of personality disorders.

- Cluster A personality disorders A person with a cluster A personality disorder tends to have difficulty relating to others and usually shows patterns of behaviour most people would regard as odd and eccentric. Others may describe them as living in a fantasy world of their own.

An example is paranoid personality disorder, where the person is extremely distrustful and suspicious.

- Cluster B personality disorders A person with a cluster B personality disorder struggles to regulate their feelings and often swings between positive and negative views of others. This can lead to patterns of behaviour others describe as dramatic, unpredictable and disturbing.

An example is borderline personality disorder, where the person is emotionally unstable, has impulses to self-harm, and has intense and unstable relationships with others.

- Cluster C personality disorders A person with a cluster C personality disorder struggles with persistent and overwhelming feelings of fear and anxiety. They may show patterns of behaviour most people would regard as antisocial and withdrawn.

An example is avoidant personality disorder, where the person appears painfully shy, socially inhibited, feels inadequate and is extremely sensitive to rejection. The person may want to be close to others, but lacks confidence to form a close relationship.