Thanks to Jay Gunkelman who made a very informative post on January 27 on this forum entitled Dementia and Alzheimer’s Disease. There he described the EEG patterns that we should expect and detect when evaluating for AD or other dementias.
I’d like to just throw out there a few other findings that were discovered in a few exploratory investigations while working on some studies with our colleague Alicia Townsend, at the time at Univ. of North Texas. Lexicor funded these projects and now the arrangements are such that I can’t disclose more than was published in the abstracts from our talks at ISNR and AAPB. I did at least want to point to these very preliminary findings because theoretically they are in concert with your explanations.
First, we explored 10 participants between the ages of 65 and 85 were recruited at the University of North Texas Health Science Center. Each was diagnosed by the Alzheimer’s Disease Assessment Scale and a medical interview. The aim of the study was to identify current source density markers in AD. EEG recording of the eyes closed condition of an AD group was compared to an age-sex matched control group using within-subject multiple t-test procedures. sLORETA difference maps in nine frequency bands were investigated. Interestingly the results showed that there was a significant increase in current source density in the delta and theta bands in the Brodmann Area (BA) 39 of the right temporal lobe and BA 31, the cingulate gyrus respectively. Additionally there were decreases in alpha in the BA 21 of the right temporal lobe and right inferior parietal lobule (Sherlin, Townsend & Hall, 2006).
This was corroborative previous findings of increased delta and theta and decreased alpha from a single case study of AD I analyzed with Tom Budzynski (Budzyski, Budzynski, & Sherlin, 2002). Results varied from previous studies that showed diffuse differences although the temporal lobe slowing is replicated. We recognized that the proximity of the significant locations to the precuneus and fusiform gyrus which are both important in facial recognition and processing social information. The precuneus is also involved in episodic memory retrieval and imagery of motor functions. A correlation study found similar patterns with sLORETA.
I believe that future investigation for patterns in different types of dementia (vascular vs. alzheimer’s vs. frontal lobe vs. mild cognitive impairment) may increase our ability to differentially diagnose.
The second study we completed was to examine the relationship between memory loss and brain electrical activity that was not AD diagnosable. Eighty-four participants between the ages of 50 and 85 were recruited for the original study. Participants were administered the Alzheimer’s Disease Assessment Scale – Cognitive (ADAS-Cog), a QEEG, and a clinical interview. The cross spectra was averaged and LORETA correlation maps. Correlations were computed for each individual’s ADAS-Cog score compared to each voxel (7x7x7 mm) of their baseline sLORETA.
What we found were significant positive correlations between ADAS-Cog scores and frontal and parietal delta activity, and theta activity in the precuneus. Significant negative correlations were found between ADAS-Cog scores and temporal alpha. This corroborated prior findings and further alluded that as our memory continues to become impaired we expect frontal and parietal delta as well as anterior midline theta to increase. And that alpha will decrease as impairment grows (Townsend, Sherlin & Hall, 2006). This is exactly as you reported as expectations in the EEG.
Budzinski, T., Budzinski, H., & Sherlin, L. (2002). Short and Long Term effects of Audio Visual Stimulation (AVS) on an Alzheimer’s Patient as documented by Quantitative Electroencephalography (QEEG) and Low Resolution Electromagnetic brain Tomography (LORETA) [Abstract]. Journal of Neurotherapy. Vol 6:1.
Sherlin, L. ,Townsend, A., & Hall, J. (2006). LORETA Analysis of Alzheimer’s Disease. [Abstract]. Journal of Neurotherapy. Vol 9:4.
Townsend, A., Sherlin, L., & Hall, J. (2006). LORETA and QEEG Correlations with the Alzheimer’s Disease Assessment Scale. [Abstract]. Journal of Neurotherapy. Vol 9:4.