Cognitive evoked potentials (P300) in early Huntington's disease.

The P3 component of both auditory-event- and visual-event-related potentials of 13 patients with Huntington's disease was studied and compared with the P3 component of normal patients. The latencies of the patients' P3 components were compared with the latency-age regression lines generated by the normal population in both modalities. A P3 latency was considered abnormal if it fell above the 2-SE limit for the latency-age regression line. The incidence of normal or abnormal P3 latencies in the two modalities was compared with the results of computed tomography, electroencephalography, and neuropsychological testing. Nine patients had abnormal P3 latencies and ten patients had abnormal visual P3 latencies, with seven having abnormal latencies on both tests and 12 having abnormal latencies on one of the two tests. An abnormal P3 latency in one modality did not imply an abnormal P3 latency in the other. An abnormality of the P3 latency did not correlate with an abnormality in results from computed tomography, electroencephalography, or neuropsychological testing.