P300 and the effects of aging: relevance to the diagnosis of dementia.

A tone discrimination task was used to elicit the P300 component of event related potentials in 55 normal subjects aged between 15 and 89 years. The age/latency relationship in the total sample was significant, but contrary to the reports of some others was statistically better described at CZ by a linear and not a curvilinear age regression function. Adults over 45 had steeper age regression slopes and larger age/latency correlations frontally and centrally than younger adults, but there was no difference in amplitude between these groups. The effect of age on latency seemed slightly more pronounced frontally in older adults, and there was significantly more latency variability in this group. Overall, the age/latency relationship in adults was statistically best described by separate linear age regression functions for adults less than or equal to 45 and greater than 45. It is suggested that latency variability may account for some of the discrepancy in the age/P300 literature, and the clinical implications of this are discussed.