P40: Memantine effects on resting-state EEG sources in Alzheimer’s disease

Abstract

Objectives: Several studies have shown that acetylcholinesterase inhibitors (AChEIs) decrease delta or theta activity, increase alpha activity on Electroencephalography (EEG) in Alzheimer’s disease (AD) patients. The effects of memantine on EEG in AD patients are not as well understood as those of AChEIs. The present study investigated the electrocortical effects of 3 months memantine medication in AD patients.

Methods: EEG was recorded in 28 patients with AD (mean age 83.3 ± 4.6 years, 19 females) before and 3 months after the onset of memantine medication. Source localization was applied to the EEG using exact low-resolution brain electromagnetic tomography (eLORETA) in 8 frequency bands (delta, theta, alpha-1, alpha-2, beta-1, beta- 2, beta-3, gamma). Differences in source strengths from before to after memantine treatment were compared per frequency band using t-statistics (corrected for multiple testing over frequency bands and voxels).

Results: Theta activity significantly decreased in bilateral anterior cingulate gyrus, bilateral posterior cingulate gyrus, right parahippocampal gyrus, right insula, right fusiform gyrus, bilateral precuneus, right uncus and right temporal gyrus. Alpha-1 and alpha-2 activity decreased in the anterior cingulate gyrus. Beta-1 activity significantly decreased in the anterior and posterior cingulate gyrus. There were no areas of increased EEG activity in any frequency bands.

Conclusions: We found that memantine reduced theta activity similarly to AChEIs. This finding may be related to the cognitive improvements of memantine. Whereas the decrease of beta-1, alpha-1 and alpha-2 activity in the anterior cingulate gyrus was different from AChEIs. Further studies are required to elucidate these differences.