Dyslexia in Children and Young Adults: Three Independent Neuropsychological Syndromes

TLDR

The study reviews clinical descriptions of dyslexia syndromes and discusses existing dyslexia models. The authors argue that future dyslexia studies should include brain‑damaged readers as a control group. They divided 113 children and young adults into three groups—brain‑damaged readers, brain‑damaged dyslexics, and dyslexics without brain damage—and administered a battery of neuropsychological tests to each. The results revealed three independent dyslexia syndromes—language disorder, articulation/graphomotor dyscoordination, and visuo‑perceptual disorder—without significant differences between dyslexic groups, supporting a multi‑defect model of dyslexia.

Abstract

In an attempt to delineate causal factors in dyslexia, 113 children and young adults (age-range eight to 18 years) were divided into three groups: those with brain damage who could read (n=31), those with brain damage who were dyslexic (n=53), and those without brain damage who were dyslexic (n=29). A battery of neuropsychological tests was presented to each participant. No significant differences were found between the two dyslexic groups. Three syndromes--language disorder, articulation and graphomotor dysco-ordination, and visuo-perceptual disorder--were found among the great majority of those with dyslexia. The results support a model of dyslexia as being caused by multiple independent defects in higher cortical functioning, as opposed to the theory of a single causal defect. A clinical description of each syndrome is given and models of dyslexia are discussed. The authors stress the desirability of including brain-damaged readers as a control group in any future study on causal factors in dyslexia.