Orthostatic changes in the EEG power spectra of normal subjects: effect of aging.

EEG power spectra in fronto-central, centro-parietal, parieto-occipital and occipito-temporal regions were analysed during an orthostatic test performed on 60 normal volunteers aged 22-82 years. Resting EEGs were taken lying down and compared with the records made immediately after tilting and at 15 min. Two age groups were formed, each comprising 30 subjects, mean age 38.3 +/- 8.8 and 65.4 +/- 8.1 years, respectively. No differences were found between the 2 groups in the baseline power spectra, except for a lower alpha power in the elderly group. In orthostatism, alpha activity increased, significantly at 15 min after head-up change. Beta 1 and beta 2 wavebands were also increased, although to a smaller degree. This orthostatic EEG reactivity was blunted in the elderly group. Mechanisms possibly involved in these phenomena have been discussed and the effect of aging has been stressed.