Event-related potentials in patients with Huntington's disease and relatives at risk in relation to detailed psychometry.

Event-related potentials (ERPs) were studied in patients with Huntington's disease (HD) and their offspring at risk in a simple auditory oddball paradigm requiring the counting of the rarer of two stimulus categories. Group statistical analysis revealed prolongation of latencies of components P2, N2 and especially P3 in HD patients and to a lesser extent in at-risks. In a large population of normals the age-latency relationship for component P3 showed a non-linear shape with increasing slope and scatter in the older age groups. A bipartate linear regression analysis splitting the normal population at age 50 was used for detection of abnormalities of P3 latency in individual cases. Abnormal P3 latencies were present in the majority of HD patients and also in 25% of clinically normal at-risks. Correlation analysis of ERP components with detailed psychometry revealed a particularly high association of P3 latencies with measurements requiring speeded information processing in non-verbal tasks. P3 amplitude did not covary with performance scores but unlike P3 latency showed association with depression and psychosis scores. From the results it appears that analysis of ERPs is a useful electrophysiological tool for an objective assessment of cognition both in clinically definite and subclinical stages.