Neurophysiological Biomarker of Mild Cognitive Impairment

Abstract

Mild cognitive impairment is sometimes regarded as related to aging. However, statistically every second case turns into full dementia, which still is resistant to any treatment. It is therefore desirable to recognize deviations from normality as early as possible. This might be feasible by using quantitative EEG analysis in the presence of mental work. The present retrospective data analysis revealed a new quantitative biomarker indicating the degree of impairment. Current source density was calculated from 16 channel EEG using CATEEM ® software. Four different conditions were analyzed: relaxed state, performing a d2-concentration test, a calculation performance test and a memory test for 5 min each. Subjects older than 40 years were divided into two groups according to their DemTect score: 13 -18 (HC; n = 44) or 8 -12 (MCI; n = 45). Spectral power was chopped into six frequency ranges (delta, theta, alpha 1, alpha 2, beta 1 and beta 2). Average spectral power was enhanced in the MCI group in comparison to healthy subjects with respect to delta (p = 0.05) during relaxed state when all electrode positions were regarded. With respect to EEG recording during performance of three different psychometric tests it was recognized that mainly spectral changes during performance of the d2-concentration test were related to mild cognitive impairment. With regard to all electrode positions statistically significantly lower spectral power values were reached during the d2-test for delta (p = 0.001), theta (p = 0.0001) and alpha 1 waves (p = 0.08) in impaired subjects in comparison to healthy subjects. Regarding regions of interest increases of delta and theta power were seen in the fronto-temporal brain during performance of the d2-concentration test. These increases disappeared when looking at MCI data. In the centro-parietal region decreases of alpha and beta 1 power emerged, which were even larger in MCI subjects. No MCI-dependent changes were observed in the other two tests. A correlation was found between psychometric performance of the d2-test and the DemTect score (r = 0.51). MCI subjects had statistically significant worse performance in all three mental challenges in comparison to healthy volunteers. It is concluded that MCI can be characterized at an early stage by EEG recording in the relaxed state. High spectral delta and theta power in general and specifically at fronto-

Psychophysiological Effects of a Combination of Sideritis and Bacopa Extract (memoLoges<sup>®</sup>) in 32 Subjects Suffering from Mild Cognitive Impairment. A Double-Blind, Randomized, Placebo-Controlled, 2-Armed Study with Parallel Design

“…Furthermore, it has been shown, that mental challenges induce higher spectral power in the beta range. However, subjects suffering from mild cognitive impairment produced clearly less beta power during for example the d2-test [2]. Therefore, the statistically significant increase of beta power as observed in the presence of memoLoges ® in comparison to placebo in this study during mental performance (arithmetic calculation test and memory test) must be regarded as a sign of restoration to normal functioning.…”

“…One discriminates between recording in the relaxed state (eyes open or closed) or during performance of mental challenges. In the relaxed state it has been shown earlier that subjects suffering from mild cognitive impairment have higher delta and theta spectral power in the frontal brain [2]. This higher spectral power of these slow waves prevents further increases during mental performance due to a ceiling effect (during performance of psychometric tests massive increases of focal delta and theta power were observed in healthy subjects [13].…”

“…"Mild Cognitive Impairment (MCI) describes the cognitive state of non-demented individuals who report memory deficits, which should preferably be corroborated by an informant, and measurable by objective testing" [1]. Objective testing has been performed on two levels: performance of psychometric tests and concomitant recording of quantitative EEG [2]. In this earlier publication, the d2-concentration test had turned out to be more sensitive than an arithmetic calculation or memory test.…”

Quantitative Objective Assessment of Websites by Neurocode-Tracking in Combination with Eye-Tracking

“…A combination of Eye-Tracking and EEG has been used during natural reading [4]. Meanwhile, even very short epochs of 364 ms duration of the electroencephalogram (EEG) are accessible for frequency analysis and were reported as Neurocode-Tracking in combination with Eye-Tracking [5]. The present investigation aimed at the proof of the concept of using this new methodology for assessment of websites during Internet surfing.…”

V20. Gender differences in the quantitative EEG in relaxed states and during cognitive or emotional challenges

“…The present retrospective analysis of several clinical studies was undertaken in order to sort out if there are gender dependent quantitative differences in the absolute spectral power in different brain regions. EEG recordings were taken using the CATEEM Ò technology as described earlier based on 17 electrode positions (Dimpfel, 2014). Spectral power -averaged during recordings of 5 min duration -was compared during relaxed states ''eyes open'' and ''eyes closed'' as well as during different cognitive tasks (concentration test, memory test or math calculation) or watching different videos (animal film, comedy film, Disney film, erotic and sex film) or several TV commercials.…”