DSM-5 and disability learning

The Diagnostic and Statistical Manual is one of the most controversial books in publishing. The latest edition redefines learning disorders. Rosemary Tannock explains.

Teacher helping pupil in classDSM-5, the fifth edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, was published in May to a storm of controversy and criticism. It has a significant impact on lives of individuals, on public perceptions of mental health disorders, on health care and educational systems, and on public policy.

First published in 1952, the DSM is used in the United States and many other countries as the universal authority for the diagnosis of mental health disorders. It was created to enable clinicians to communicate about mental health disorders using a common language: it specifies what constitutes a mental health disorder, codifies these disorders, and specifies the criteria for their diagnosis. It has a major influence on how mental health disorders are conceptualised and treated in many countries; on how medical insurance companies help cover treatment costs for mental health conditions; and on research agendas and access to research funding.

The DSM category of Learning Disorders underwent substantial change between DSM-IV and DSM-5. Many people experience difficulties learning in school, but not all such difficulties constitute a Specific Learning Disorder (SLD), as defined in DSM-5. According to DSM-5, SLD is a type of neurodevelopmental disorder that impedes a person’s ability to learn and use specific academic skills, such as reading, writing and arithmetic, which serve as the foundation for most other academic learning. SLD is a clinical diagnosis and is not necessarily synonymous with ‘learning difficulties’ identified by the education system. The difference is in the degree, frequency, intensity, and persistence of the symptoms, as well as in the resultant impairments. Genetic research shows that it runs in families, is heritable, and implicates both genetic and environmental factors, such as smoking during pregnancy and prematurity. Neuroimaging studies reveal that SLD is associated with alterations in brain structure and function.

By contrast to the DSM-IV criteria for SLD, which were child-centric, DSM-5 takes a lifespan perspective of SLD. Evidence from longitudinal studies of children with SLD shows that their learning difficulties typically persist into adulthood. Learning difficulties in adults may look different. Perhaps adults read slowly, but no longer struggle to sound out words. Adults may also learn to compensate for their difficulties. They can avoid reading by getting information from other media, use specialised software to assist with reading and writing, or use calculators or another person to assist with numbers. Thus the diagnostic criteria for SLD also needed to be relevant for adults who seek help for their learning difficulties.

DSM-IV listed different types of learning difficulty, defined by the domain of academic learning that was impaired, such as problems learning to read, spell and write, and to do arithmetic. By contrast, DSM-5 lumps them into one overarching disorder. This decision was based on research evidence from twin studies that these types of disorder have a common genetic basis. Epidemiological studies reveal that these subtypes co-occur. The majority of youngsters with Written Expression Disorder also have a Reading Disorder and 50 per cent of children with Mathematics Disorder also have Reading Disorder. Longitudinal studies reveal, too, that one type of disorder often leads to other types as learning demands increase.

One contentious issue is the failure of DSM-5 to code Dyslexia as a distinct type of SLD. The American Psychiatric Association received a litany of complaints demanding that ‘Dyslexia be put back in the DSM’, even though the term has never been used formally in earlier editions. In contrast to the term ‘Dyscalculia’ (a learning disability specific to mathematics, which is recognised in Europe but not in the US and which lacks advocacy), the term ‘Dyslexia’ has become highly politicised by advocacy groups lobbying the government for services. The DSM-5 acknowledges its prevalence, impairments, and need for services, as well as the remarkable research advances in its neuroscientific understanding. But its compilers chose not to use this label to codify learning disorders in reading, because it means a very different constellation of learning difficulties in different countries.

Another major change is the elimination of the ‘IQ-achievement discrepancy’ criterion required in DSM-IV and by many school systems. This decision was based on two decades of research evidence demonstrating that this criterion was statistically and conceptually flawed. Instead, DSM-5 requires four criteria to confirm a clinical diagnosis of SLD. The difficulties must have persisted for at least six months, despite the provision of intervention to target them; the affected academic skills must be well below what is expected for the person’s age and impair that person’s functioning at school, work, or in the activities of daily living; the difficulties must have started in the school years, even though they may not become fully manifest until later; and the learning difficulties must not be attributable to other factors, such as uncorrected vision or hearing, or lack of proficiency in the language of  instruction.

It is hoped that the DSM-5 criteria for SLD will be reflected in education and healthcare policies. They recognize a subgroup of people who experience difficulties learning the foundational academic skills but do not meet the IQ-achievement discrepancy required by DSM-IV and by some clinicians and school boards. As a result, they have been denied access to special educational services or workplace facilities. In the short term, providing these facilities may mean that educational costs increase. But the longer-term gains from lowered rates of school drop-out, un- or under-employment, and additional psychiatric problems will outweigh any short-term pain!

Rosemary Tannock is professor emerita at the University of Toronto’s Ontario Institute for Studies in Education, Canada.

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