The impact of age-related changes in event-related P300 potentials on detecting early cognitive dysfunction

Event-related P300 potentials that closely reflect cognitive brain functions show significant age-related latency prolongations. This aging-P300 interaction can best be approximated by third-order polynomial regressions. To delineate the clinical impact this special kind of regression function may have on detecting early cognitive dysfunction, we applied visual P300 potential data of healthy subjects (n = 344; age range, 18-98 years) to nondemented patients with either (i) chronic liver disease (n = 104; age range, 19-74 years) or (ii) cerebral arteriosclerosis (n = 80; age range, 38-80 years). As compared with linear regressions, third-order polynomial regressions for the age-related changes in P300 potential latencies showed a smaller latency increase during middle age, with an accelerating latency prolongation from age 60 onward. In patients with liver cirrhosis, third-order polynomial regressions yielded a rate of abnormal P300 potential latencies exceeding that of linear regressions absolutely by 17-21%, and relatively by 67-71%. Although the rate of P300 abnormalities was much lower in the CAD patients with either regression model, the relative increase in P300 abnormalities due to third-order polynomial regressions was 40-112.5%. In conclusion, normal data for the latencies of P300 potentials based on third-order polynomial regressions result in a higher sensitivity of P300 potentials for detecting early cognitive dysfunction. This gain in diagnostically important information is not offset by a loss in specificity, and may depend on the kind as well as stage of the disease, the age distribution of the patients and the degree of the P300 potential abnormalities.