Interrelations of age, sensory functions, and human brain signal processing

Disturbances of sensory functions may additionally impair cognitive functions in elderly persons. To delineate the impact of visual sensory functions on brain signal processing during normal aging from an electrophysiological perspective, we investigated 289 fit community-dwelling subjects (162 men [56%] and 127 women [44%]; age range, 18-98 years) by means of visual event-related P300 potentials. By taking age, visual acuity, and stimulus-dependent components of visual-evoked potentials (PVEPs) into account, we found age to be the single most important factor for P300 variability (partial F > 10.0, p < .0001 for all P300 parameters; stepwise regression analysis). Furthermore, both the N75 (partial F = 12.415) and P100 latencies (partial F = 4.850) of the PVEPs were independently correlated with the P300 latencies, whereas the P300 amplitudes revealed additional correlations with the P100 amplitudes (partial F = 8.576; p < .0001, for all). Sex, however, did not influence these age-related P300 changes. Aging itself accounts for the largest proportion of variability in human brain signal processing as reflected by P300 potentials. Visual sensory functions, however, also provide an independent, but minor, contribution to P300 variability. Therefore, it seems prudent to take parameters of sensory functions into account especially for clinical P300 applications in the elderly population.