Cognitive event-related potentials in attention deficit disorder

Cognitive event-related potentials (ERPs) have been used to aid in the interpretation of findings that children with Attention Deficit Disorder (ADD) make more errors and react more slowly than nondisabled controls in tests of sustained attention. Coincident with their abnormally poor performance, children with ADD have smaller late positive components of the ERP (especially a wave known as P3b) than their peers with psychiatric diagnoses. Notably, stimulant administration improves the performance of children with ADD and enlarges the amplitude of the late positive waves of their ERPs. These findings are interpreted as reflecting reduced capacity allocation, which, in turn, is increased by stimulant medications. Research on memory scanning suggests that children with ADD are deficient in energetic aspects of information processes and that their excessive slowness in reaction time tests involves stages following memory search and decision, that is, motor processes. The same factors seem to be involved in the amelioration of performance by stimulants, which speed up motor responses but do not affect the latency of P3b. Research on ERPs during selective attention also points to possible disturbances in this aspect of processing, but further research in this area is needed.