EEG activity in the 13-15 Hz band correlates with intelligence in healthy elderly women

Thirty-five elderly women in excellent health received a neuropsychological battery and resting electroencephalograms (EEGs) from bilateral parietal scalp electrodes. Spectral density analysis of the EEGs was designed to evaluate two levels each of slow activity (delta, 0.2-3.8 Hz and theta, 4.0-7.8 Hz), alpha activity (slow alpha, 7.0-9.8 Hz and fast alpha, 10.0-12.8 Hz) and fast activity (sigma, 13.2-14.8 Hz and beta, 15.0-20.0 Hz). There was no relationship between alpha slowing and cognitive impairment. However, significant correlations emerged between sigma activity and Wechsler Adult Intelligence Scale Scores. This association was strongest between right parietal sigma activity and WAIS Performance Scale weighted scores.