Auditory evoked brain potentials as a function of interstimulus interval in adults with Down's syndrome.

Auditory-evoked potentials (AEP) to repeated binaural tone pips of several interstimulus intervals (ISIs) greater than or equal to 1 s were recorded from the vertex of young adults with Down's syndrome (DS; trisomy 21) and normal young adults. The following results were obtained: (1) AEP amplitudes, as well as one latency measure, of both experimental groups increased with the lengthening of ISI. (2) AEP peak latencies of the DS group were longer than AEP peak latencies of the normal group for all the ISIs employed. (3) AEP amplitudes of the DS group tended to be larger than AEP amplitudes of the normal group. These findings are discussed in relationship to issues of attention.