NADD Bulletin Volume VII Number 1 Article 2

Complete listing

Practice Guidelines for the Assessment and Diagnosis of Mental Health Problems of Adults with Intellectual Disability

Shoumitro Deb, Geraldine Holt, & Nick Bouras

These practice guidelines (Deb, Matthews, Holt, & Bouras, 2001a) were published under the auspices of the European Association of Mental Health and Mental Retardation in 2001. It appears that although the rate of functional psychiatric illness among adults with intellectual disability is similar to what is expected in the general population, the overall rate of mental disorder (psychopathology) including that of behavioural disorder is significantly higher in this population (Deb, Thomas, & Bright, 2001b; c). It appears that many psychiatric illnesses that are present in the general population could also be detected among adults who have intellectual disability. Furthermore, certain childhood onset psychiatric disorders such as autistic spectrum disorder and attention deficit hyperactivity disorder are not uncommon among adults with intellectual disability. Similarly, certain neuropsychiatric conditions that are prevalent amongst the elderly general population, such as dementia are more prevalent amongst adults with intellectual disability in their presenium (before age 65).

Controversy exists regarding the diagnosis and classification of psychiatric disorders amongst adults with intellectual disability. It is not clear whether it is better to apply the psychiatric diagnostic classification used for adults in the non-intellectually disabled general population or whether there should be a completely different classification system used for adults with intellectual disability. It is also not clear whether diagnosis such as schizophrenia can be made in a person who has severe or profound intellectual disability. For practical purposes, it may sometimes be useful, particularly in cases of adults who have severe and profound intellectual disabilities, to manage and treat target behaviours rather than a specific psychiatric syndrome.

Because of the above-mentioned uncertainties, we felt that it is timely to produce evidence and consensus based guidelines for the clinicians working in the field to help them with the diagnosis and assessment of psychiatric illness in adults with intellectual disability. The guidelines are presented in the following sections; introduction: epidemiology, assessment procedure, particular psychiatric disorders, and appendix. In the introduction we have emphasised that although these guidelines are primarily developed as a reference for practising clinicians working in this field, these guidelines are written in a user friendly way so that even the carers of adults with intellectual disability should be benefited from this document. This document is focused on the description of psychiatric illnesses that affect adults with intellectual disability. The issues related to the diagnosis of psychiatric illness among children with intellectual disability are somewhat different, and therefore have not been covered in this document. Similarly, aspects of treatment, diagnosis of pervasive developmental disorders and behaviour disorders are not covered either. It is hoped that these topics will be covered in future guidelines.

The document is based primarily on the ICD-10 diagnostic criteria, but we have highlighted the areas where the manifestation of psychiatric illnesses could differ in adults with intellectual disability. This document is extensively referenced. In synthesising the evidence we have used Cochran library conventions Type I-V evidence.

'Type I evidence' - good systematic review and meta-analysis (including at least one randomised controlled trial)

'Type II evidence' - randomised controlled trials

'Type III evidence' - well designed interventional studies without randomisation

'Type IV evidence' - well designed observational studies

'Type V evidence' - expert opinion, influential reports and studies

We have also revised the document in the light of comments received from an international panel of experts in the field of mental health and intellectual disability.

These practice guidelines provide detailed practical advice regarding history-taking, examination of patients, and interviewing of patients and carers. We have highlighted many areas where emphasis is different compared with that in the general adult population. The guidelines cover the following specific psychiatric illnesses; schizophrenia, delusional disorder, schizoaffective disorder, affective disorders including depressive disorder, bipolar affective disorder, dysthymia and cyclothymia, anxiety related disorders such as generalised anxiety disorder, phobic anxiety disorder, panic disorder, and obsessive compulsive disorder (OCD), other neurotic and stress related disorders such as acute stress reactions, post-traumatic stress disorder, and adjustment disorders, somatoform (hypochondriacal) disorders, eating disorders, sleep disorders, psychosexual dysfunction, disorders due to psychoactive substance use, dementia, delirium, and personality disorders. For each of these disorders, the publication provides diagnostic guidelines, differential diagnoses and evidence. We have also referred to the recently developed Diagnostic Criteria in Learning Disability (DC-LD) (The Royal College of Psychiatrist, 2001). In the appendix we have provided rating instruments with references for the diagnosis of psychiatric illness, behaviour disorders and dementia in adults who have intellectual disability.


Deb, S., Matthews, T., Holt, G., & Bouras, N. (2001a). Practice guidelines for the assessment and diagnosis of mental health problems in adults with intellectual disability. Pavilion Press, London.

Deb, S., Thomas, M., & Bright, C. (2001b). Mental disorder in adults with intellectual disability. 1: Prevalence of functional psychiatric illness among a community-based population aged between 16-64 years.Journal of Intellectual Disability Research, 45, 495-505.

Deb, S., Thomas, M., & Bright, C. (2001c). Mental disorder in adults with intellectual disability. 2: The rate of behaviour disorders among a community-based population aged between 16-64 years. Journal of Intellectual Disability Research, 45, 506-514.

The Royal College of psychiatrists (2001). DC-LD: Diagnostic Criteria for Psychiatric Disorders for use with adults with Learning Disabilities/ Mental Retardation. London: Gaskell Press.

For further information:

Shoumitro Deb, M.D.

Department of Psychiatry, Division of Neuroscience

University of Birmingham, Queen Elizabeth Psychiatric Hospital

Mindelsohn Way, Birmingham B15 2QZ, UK.