Effect of lithium on the EEG of healthy males and females. A probability mapping study.

This study is based on 20 healthy volunteers (10 males and 10 females). Between 675 and 1,225 mg lithium carbonate per day was applied for 10 days. EEG was recorded before (day 0) and after lithium intake (day 10) with 19 electrodes and quantified by spectrum analyses. Absolute power and coherence values, between adjacent electrodes and between electrodes on homologous sites of both hemispheres, were computed for five frequency bands. For the evaluation of differences of the EEG parameters obtained on days 0 and 10, a nonparametric paired permutation test was applied. The obtained descriptive error probabilities were presented in topographic maps. Under lithium, the absolute power increased in the entire frequency range, but most distinct in the theta and beta 1 band. The local coherence analyses revealed a clear lateralization: increase in the left hemisphere and decrease in the right. The interhemispheric coherence decreased occipitally and frontally. A comparison of the EEG changes under lithium in males and females showed clear differences in the topographic distribution of power as well as coherence changes.