DEVELOPMENTAL DYSLEXIA AND ATTENTION DYSFUNCTION IN ADULTS - BRAIN POTENTIAL INDEXES OF INFORMATION-PROCESSING

Event-related brain potentials (ERPs) were recorded from a group of 13 men with severe developmental dyslexia and 15 matched normal controls . Auditory and visual stimuli, presented in separate reaction time tas ks of graded difficulty, were used to elicit ERPs. No group difference s in P300 were seen under relatively undemanding task conditions. Howe ver, as task demands increased, visual P300 was reduced in the dyslexi c men as compared with the normal readers. An Abbreviated Conners Pare nt Rating Scale was used to assess retrospectively childhood symptoms of attention-deficit hyperactivity disorder (ADHD). Additional analyse s revealed that the dyslexics with a history of many symptoms of ADHD in childhood (high ADHD) accounted for the group differences in P300; the dyslexics with a history of few or no such symptoms (low ADHD) wer e indistinguishable from the controls at all electrode sites. Furtherm ore, whereas the low-ADHD dyslexics showed the same hemispheric asymme try in auditory P300 as did the controls (right > left), auditory P300 was more symmetrically distributed in the high-ADHD dyslexics. The re sults are interpreted as suggesting that a distinct brain organization may characterize dyslexic men with a history of concomitant deficits in attention.