Issues in assessing people with intellectual disability for personality

disorder

There is little research about personality disorders in people with intellectual disability, however the presentation of personality disorder in people with intellectual disability is not thought to be significantly different to its presentation in the general population. The diagnosis of personality disorder can be made in people with mild and moderate intellectual disability but it is unlikely that it would be made in someone with severe or profound intellectual disability. There is no single cause of personality disorder, rather personality disorder results from a complex interplay between genetic factors, early life experiences, family culture, social and environmental factors, abuse and trauma, temperament and education. However, people with intellectual disability are more likely to be exposed to a range of risk factors. They are more likely to be subject to abuse and social deprivation; they may have a limited opportunity to learn new skills; overprotection by carers may result in dependence; institutionalisation can prevent the development of secure relationships; repeated exposure to failure and low expectations of success and aspiration may impaire their self esteem. Personality disorders originate in childhood and continue throughout adulthood. They are said to be lifelong. In some people difficulties with personal and social function will be most apparent at times of stress or during episodes of mental illness (anxiety, depression etc.). Personality disorders are generally not diagnosed in a person under the age of 18 years, although features would have been present for some time. This reflects the fact that personality continues to develop through adolescence and maladaptive personality traits may not continue in to adulthood. In people with intellectual disability personality development can be significantly delayed. For this reason diagnosis of personality disorder in people with intellectual disability is not usually made until the person is over 21 years of age. There is an overlap between a number of personality disorders and features of autism. People with pervasive developmental disorders who have deficits in social interaction, theory of mind, empathy and communication may be inaccurately diagnosed with a personality disorder. Other untreated mental illnesses may also present with long term symptoms and may be misunderstood as personality disorders. (Anxiety disorders are common in people with developmental disabilities and may be incorrectly diagnosed with an avoidant personality disorder.) It is also important to consider whether a person has a specific syndrome causing a specific behavioural presentation International research varies widely with reported prevalence rates of between 5 and 91% for personality disorder in people with intellectual disability. Figures of around 20 to 30 % are likely to be more realistic. In a local study, 22% of patients referred to a clinical service over a 5 year period met criteria for a personality disorder. The problems at referral included self-harm, aggression, substance abuse, inappropriate sexual behaviour, hallucinations and mood disturbance.