HYPERLEXIA AND DYSLEXIA IN AUTISM: HITTING A MOVING TARGET

Abstract

The diagnostic histories of autism, dyslexia, and hyperlexia are complex. Because these conditions share both convergent and diver­gent properties, it is important to under­stand these relationships, especially in the case of research and how we interpret bodi­es of work which span decades of fluc­tuating criteria. It is also important to syn­the­size what we already know about the morpho­logy of these con­di­tions and pinpoint what we still don’t. Autism and dyslexia, for instance, share antipodal cerebral morpho­logies, such as minicolumnar den­sity, neuropil width, cell size, corpus callo­sal volume, gyral complexity, gyral window size, and cerebral volume, while hyperlexia has not been studied in this fashion, although it sha­res much in common with autism. Mean­while,  the  fluctuation  in  criteria  of  dyslexia over the years, means that older studies, such as some of the most highly cited in post­mortem research, have potentially used more heterogeneous groups of subjects than dys­lexia research typically uses today. Con­sider­ably, these older studies are often the basis of current animal model and genetics research. In conclusion, in consideration of the continued flux in criteria, particularly the proposed change from “Reading Disorder” to the broa­der “Specific Learning Disorder” within the DSM-5, we strongly recommend a separation of the various reading disorders under their own headings to promote specificity of diag­nosis and treatment, and to support better research.