Effect of nimodipine upon electroencephalographic vigilance in elderly persons with minor impairment of brain functions

Abstract

10 volunteers (61-78 years) with minor impairment of brain function were given placebo, 40 mg and 60 mg nimodipine (Nimotop) in single doses with intervals of 3 medication-free days between medications under double-blind conditions. Consecutive 2-s epochs of a 10-min EEG record (resting conditions) of F3/C3-F4/C4-P3/01-P4/02 were subjected to FFT (Fast Fourier Transform). Using the information given by the 4 leads for each minute of recording the number of epochs which correspond to a stage A or non-A were determined. In order to evaluate subtle effects on electroencephalographic vigilance within stage A, also the anterior-posterior and left-right relations of absolute alpha-power were calculated. Since previous findings suggested that a nimodipine effect can only be demonstrated when individual differences in the baseline-EEG are considered, the subjects were subdivided in equal subgroups according to the number of non-A epochs under placebo. The rationale for this is the finding that in geriatric patients two electroencephalographically distinguishable forms of dissolution can be observed. Under both 40 mg and 60 mg nimodipine the subgroup with a prevalence of non-A epochs (poor alpha-activity) showed a decrease of non-A epochs; the subgroup with a prevalence of A-epochs (abundant alpha-activity), an increase. Opposite results for the two subgroups were also obtained for the left-right relations of alpha-power over the anterior regions. Under 40 mg nimodipine the subgroup with poor alpha-activity showed a shift to the left; the subgroup with abundant alpha-activity to the right. Under 60 mg nimodipine both subgroups showed a shift to the left. The results confirm findings that nimodipine stabilizes electroencephalographic vigilance at a medium level. Moreover they suggest a dose dependence of the effect, i.e., at higher doses nimodipine seems to act as a sedative.