[Effect of age on cognitive potentials using auditory and colored visual stimulation].

Abstract

Cognitive potential using two-tone auditory discrimination task has been widely used as a standard and useful test to quantify the severity of cognitive dysfunction. According to our experience, however, this method (the T method), sometimes cannot be performed even in normal elderly subjects because of difficult discrimination between these two different tone bursts. In order to overcome this disadvantage, we developed two other methods which had easier discrimination tasks: one using a tone burst and click sound (the C method), and the other using red and green color (the V method). We adopted these three methods to 64 normal adults and aged subjects whose age ranged from 20 to 88 years old. As a result, most of the P3 latency and amplitude in all subjects tested correlated significantly among these three methods. Any peak latency of P3 correlated significantly (p < 0.05) and positively with age, but the rate of increment of latency per year differed. For example, the value recorded from the Cz scalp site was 0.77 ms/year in the T method, 1.05 ms/year in the C method, and 1.67 ms/year in the V method, respectively. The rate of undetected P3 potential in aged subjects more than 60 years old was higher in the T method (3/18 subjects = 17%) than by both the C and V methods (1/19 subjects = 5%). In conclusion, the effect of age on P3 latency varied according to method and our new technique was sufficiently applicable to elderly subjects.