Neurodevelopmental Disorders: Learning Disorders

Learning disorders are defined by persistent and clinically impairing difficulties learning and using academic skills despite adequate educational opportunity. Current diagnostic systems recognize learning disorders in reading, writing, and math. The chapter reviews current evidence for the validity of learning disorders in basic literacy skills (word reading accuracy, reading fluency, and spelling), reading comprehension, written expression, and math. The chapter focuses on the two best validated diagnoses, namely, dyslexia (learning disorder in basic literacy) and math disability, including current evidence on their etiology, brain bases, neuropsychology, cross-cultural manifestations, and treatment. Three common quandaries are discussed: (1) How severe must academic problems be to diagnose a disorder? (2) How specific must the problems be? (3) How can clinicians distinguish a learning disorder from linguistic difference or environmental disadvantage? Academic skills are normally distributed due to their multifactorial etiologies, so individual diagnosis requires placing a partly arbitrary cutoff on an underlying continuum. Early definitions of learning disorders emphasized specificity and focused on individuals with isolated problems in one academic area. Substantial evidence indicates that learning disorders arise from a mix of general and specific influences and that children with broad-based learning challenges benefit from many of the same interventions as children with an isolated weakness. Finally, distinguishing a neurodevelopmental disorder from environmental disadvantage is complex and challenging, and the risks of both over- and underidentification for children from historically oppressed groups are discussed. Case studies of children with dyslexia and math disability are included.