Developmental Dyslexia: The Role of the Cerebellum

Abstract

Specific developmental dyslexia is normally identified by unexpected problems in learning to read for children of average or above average intelligence ---``a disorder in children who, despite conventional classroom experience, fail to attain the language skills of reading, writing and spelling commensurate with their intellectual abilities'' (from the definition by the World Federation of Neurology, 1968, p26). A typical estimate of the prevalence of dyslexia in Western school populations is 4% (Badian, 1984; Jorm, Share, Maclean, & Matthews, 1986), with roughly four times as many boys as girls being diagnosed, though other investigators (Shaywitz, Shaywitz, Fletcher and Escobar, 1990) have reported incidence as high as 10%. Dyslexia is genetic in origin (Smith, Kimberling, Pennington, & Lubs, 1983), and cannot therefore be `outgrown' in adulthood, even if the reading difficulties are largely overcome.