Quantitative analysis of EEG effects following experimental marginal magnesium and boron deprivation

Magnesium (115 and 315 mg/d) and boron (0.23 and 3.23 mg/d) were fed in a double-blind Latin squares design to 13 healthy postmenopausal women (aged 50-78 years) living on a metabolic unit. An eight-channel electroencephalogram (EEG) was recorded during the last week of each of four 6-week dietary periods. Power and coherence measures were determined for each of four EEG frequency bands: delta (1-3 Hz), theta (4-7 Hz), alpha (8-12 Hz), and beta (13-18 Hz). Compared to high dietary magnesium, the low magnesium intake increased total power in the frontal regions and right temporal and parietal regions and resulted in frequency-specific increases in left occipital delta power, theta power in all but the left temporal region, alpha power in the right frontal and right temporal regions, and beta power in the frontal regions. The proportion of theta to total power in the parietal regions also increased with the low magnesium intake. While magnesium effects were observed primarily during eyes-closed conditions, effects of dietary boron on EEG power were found only during eyes-open conditions. Relative to high dietary boron, the low boron intake increased delta power in the left parietal and left occipital regions, increased the proportion of delta to total power in the frontal regions, and decreased relative right frontal theta, right frontal alpha, and left frontal beta power. Additional magnesium and boron effects were evident in the measures of EEG coherence. Thus relatively short periods of marginal magnesium and boron deprivation can affect brain function in healthy older women. The findings extend previous qualitative observations of increased CNS activity following severe magnesium deprivation and deficiency to cases of experimentally induced marginal magnesium deficiency, and verify CNS hyperexcitability by quantitative analysis of the EEG.