EEG alpha rhythm frequency and intelligence in normal adults

The electroencephalogram (EEG) reflects stable individual differences in brain function and therefore can be a powerful instrument for exploring the biological basis of intelligence. However, the question of whether the EEG, and, in particular, the alpha rhythm frequency (AF) is related to intelligence in normal adults remained unclear. We analyzed EEG spectra and performance on different intelligence rests in 101 healthy males aged 20 to 45 (M IQ = 119.2; SD = 9.4) with a special regard to brain region and specific mental abilities. Scores on Raven's Standard Progressive Matrices (SPM) correlated positively with AF in prefrontal and frontal regions. Verbal abilities factors derived from the verbal subtests of Amthauer's Intelligence Structure Test (IST) and Horn's LPS test of mental performance correlated positively with both mean and peak AF factors (r = .34 and .35, correspondingly; p < .001). However, AF did not show any significant relationship with the factors of general (g factor), spatial, and arithmetic abilities.