Comparison of electroencephalogram waveforms in older patients with/without dementia after administration of midazolam: a prospective, observational comparative study

Background: Sedation with midazolam in older patients with severe dementia can cause reactions that differ from those encountered in healthy individuals. We hypothesized that one reason for this is that electroencephalogram (EEG) responses to midazolam in patients with severe dementia may differ from those encountered in healthy individuals. In this study, we aimed to examine the effects of midazolam on EEG findings in older patients with severe dementia and compare them with those observed in older adults without dementia. Methods: We included 25 patients aged ≥ 60 years, and allocated them to either the dementia (13 patients) or non-dementia (12 patients) group. Participants with a Mini-Mental State Examination score of ≤ 23, Functional Assessment Staging of Alzheimer's disease stage 6 or 7, and/or Clinical Dementia Rating of being "severe" were considered to have severe dementia. EEG electrodes were attached to patients' frontal pole (Fp2). Midazolam was administered until a modified Observer's Assessment of Alertness/Sedation (OAA/S) score of 2 was attained. Chi-square test, Mann-Whitney U test, and Wilcoxon signed-rank test were performed to assess between-group differences. Differences were considered statistically significant at P < 0.05. Results: The power of the delta wave at baseline and immediately before treatment was higher in patients with dementia than that in the patients without dementia. Conversely, the power of the alpha wave was lower in the dementia group in the sedated state of the OAA/S 2. Regarding the changes within each group, the theta and beta waves in the dementia group decreased after midazolam administration. Conclusion: Regarding EEG waveforms in the frontal pole, administration of midazolam significantly decreased the power of the fast wave (alpha wave) and increased the power of the slow wave (delta wave) in older patients with severe dementia compared with that in older patients without cognitive decline.