Quantitative EEG correlates of normal aging in the elderly.

To clarify the effect of normal aging on the EEG in the elderly, relative EEG power and coherence were studied in 68 elderly subjects (age range 61-90 years) as well as in 20 young subjects (age range 23-38 years). Relative beta power was significantly higher in the elderly subjects, while no significant differences were seen among the elderly groups. Therefore it may be assumed that EEG power in the centrooccipital region among the normal elderly remains almost unchanged. Also, age had no effect on interhemispheric coherence. However, intrahemispheric coherence was found to decrease with age in all bands almost linearly. Thus, intrahemispheric coherence is a more sensitive indicator of normal aging than relative power.