THE PATTERN OF AGE-RELATED DIFFERENCES IN ELECTROPHYSIOLOGICAL ACTIVITY OF HEALTHY-MALES AND FEMALES

Age-related differences in quantified electrophysiological measures were examined in 202 subjects (109 females; 93 males) ages 30-80 all of whom were judged to be optimally healthy on a wide variety of criteria. The study utilized both absolute and relative measures from EEG spectral analysis as well as additional measures from long latency-evoked potentials. The same findings were noted for the 109 newly studied females as were reported for 63 previously studied male subjects. Results indicate that there is a broad trend for decreased EEG slow and increased fast activity with age, however, some of the measures change linearly and others are best represented by nonlinear functions. There is no decade where activities remain stable- Overall the pattern of change for males and females is similar, however, gender differences in both the EEG and EP data were present. The females had higher magnitudes for almost all absolute spectral and fast relative spectral measures. However. females demonstrated lower absolute alpha amplitude, lower relative slow activity, and lower late-latency EP data. Moreover, the absolute slow activity measure showed a gender X age interaction, indicating that the females had a different change in pattern of activity with increasing age than the males. Thus, gender-related findings were complex and could not be expressed as simple differences in overall amplitude. Age-related change is not a simple linear process but differs for differing EEG spectral bands, relative, and absolute spectral measures and for males and females. The overall findings contradict the common wisdom that EEG and alpha slow with age and that age related EEG change is on a continuum with findings in Alzheimer's disease where increased slowing predominates.