The Validity of a Personality Disorder Diagnosis for People with an Intellectual Disability

Background It has long been appreciated that people with intellectual disabilities experience mental health problems. Studies into the prevalence of personality disorder in the population of people with an intellectual disability indicate significant variations, which have no clear explanation. Method Work on personality disorder and personality is reviewed. Results This article will outline some of the reasons for the variations in the reported prevalence figures including the impact of diagnostic overshadowing, problems inherent within the diagnostic classification systems and instruments that have a significant impact upon the reliability of a diagnosis. It will also argue that there are some fundamental issues relating to the validity of the construct of personality disorder and its application to the population of people with intellectual disabilities. The article notes that the model of personality, which in itself is not without critics, is derived from research on the general population and has not been integrated with personality research conducted within the population of people with an intellectual disability. Conclusion It is suggested that the current diagnostic systems need to be reviewed in the context of an existing evidence base from within the field of intellectual disabilities. There are grounds to be cautious with the current diagnostic process and to question its clinical utility. Furthermore, diagnosis may only serve as an intermediate step and as part of a more detailed nomothetic approach.