Diagnostic Manual—Intellectual Disability: A Textbook of Diagnosis of Mental Disorders in Persons With Intellectual Disability

The editors of Diagnostic Manual—Intellectual Disability (DM-ID) have set out to complete the difficult task of compiling the evidence base on mental disorders in the field of intellectual disability (ID) into one reference book while modifying DSM-IV diagnostic criteria for use in persons with the disorder who present with mental and behavioral disorders. A similar manual was developed in the United Kingdom that adapts International Classification of Diseases–10 (ICD-10) criteria. The Royal College of Psychiatrists’ Diagnostic Criteria for . . . Learning Disabilities (DC-LD)¹ focuses on modifying diagnostic criteria through a multi-axial approach; however, it does not include the current evidence base on topics such as etiology and risk factors.

I believe that DM-ID represents a significant step forward in helping clinicians apply diagnostic criteria in a systematic way to persons with ID. However, the true test of its utility will be whether most clinicians begin to use this manual on a day-to-day basis. DC-LD has not been able to achieve this goal, partly because information systems within the health care organizations in the United Kingdom are developed for ICD-10 diagnoses and are not for modified diagnostic systems pertaining to specific groups of the population. This is probably the right approach because most clinicians need to recognize disorders that occur across the population. Adapted diagnostic criteria systems remain more useful in research so that an agreed-on consensus in identifying disorders can be achieved and etiological and risk factors can be identified with more confidence. The experienced clinician can adapt the criteria of the recognized diagnostic systems of ICD-10 and DSM-IV in his or her daily practice.

There is variation in the quality of the sections within DM-ID; for example, mood disorder, schizophrenia, and behavioral phenotypes are covered comprehensively, whereas the section on pervasive development disorders was less helpful (eg, there was no discussion on the utility of diagnostic interviews).

I would recommend that all researchers use this diagnostic manual when studying mental health and behavioral problems in persons with ID. I think this text will be most useful to those clinicians who employ DSM-IV criteria in their daily practice and for those who treat patients with ID regularly.

In sum, this reference book is a very useful source for finding the evidence base for the diagnosis and etiology of mental disorders in persons with ID.