The auditory event-related potential is a stable and reliable measure in elderly subjects over a 3 year period.
OBJECTIVE
Valid markers of psychobiological processes, including changes over the lifespan, must be reliable. This study investigated the reliability of the auditory event-related potential (ERP) over a 3 year period.


METHODS
Predictable and unpredictable rare tones were embedded in common-to-rare sequences at 3 different ratios (2:3, 2:5 and 2:8). Forty-six older (mean age 72.3 years) volunteers pressed a key to the rare tones, and ERPs (Fz, Cz and Pz) and reaction time (RT) were measured. Reliability across years was assessed using 3 methods: (1) determination of the stability of waveform components (P1, N1, P2, N2 and P3); (2) cross-correlation of successive 15 ms epochs of within-subject ERPs; and (3) cross-correlation of 15 ms epochs of between-subject ERPs.


RESULTS
With all analyses, the ERP was stable. Analysis of the scored components indicated that P3 was especially stable in the unpredictable rare (2:8) condition. Earlier components were equally stable across all conditions. Analysis of 15 ms ERP epochs indicated significant ERP stability 60 ms after stimulation, lasting over 640 ms.


CONCLUSIONS
Robust within-subject reliability of the ERP strengthens its potential use for detecting preclinical changes in at-risk elderly populations.
Sandman
C A
CA
Department of Psychiatry, University of California, CA, Irvine, USA. casandma@uci.edu
Patterson
J V
JV
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013997:Time Factors