This chapter deals with two separate, but linked, lines of research. First, is the historic relationship between neuropsychology and learning disability (LD): the accumulating evidence of neurological impairment is reviewed, as well as theories about the role of neurological deficit. Second, the question of subtypes of LD is discussed. Surprisingly, subtype research has, for the most part, proceeded in isolation from the search for a neurological substrate of LD. An attempt is made to show that a convergence of these two types of research may contribute greatly to our knowledge of the field.
The relationship between neuropsychology and LD is built into most definitions. For example, the National Joint Committee on Learning Disabilities (1998) describes LD as a ‘heterogeneous group of disorders manifested by significant difficulties in the acquisition and use of listening, speaking, reading, writing, reasoning, or mathematical skills … These disorders are intrinsic to the individual, presumed to be due to central nervous system dysfunction.’
The stress is on ‘presumed.’ In contrast, detailed descriptions, assessments, and often also treatment protocols have been developed for many childhood disorders of neurological origin, but LD are still based on a presumed neurological origin — the same is true for pervasive developmental disorders and attention deficit hyperactivity disorder (ADHD).