Quantitative electroencephalographic evaluations of electrophysiological biomarkers and impaired functional networks of older adults diagnosed with dementia
Authors: Williams Kristin S , Berman Marvin H 
Published: December 2021

Background

Alzheimer’s disease (AD) is a neurodegenerative disorder attributable to neurofibrillary tangles, senile neuritic plaques, and a reduction of neurons and synapses. Because the etiopathogenesis of AD is complex and its associated risk factors are not well understood, clinical interventions to effectively treat AD are being developed. Thus, interventional strategies to delay disease progression have been the focus of numerous pharmacologically oriented trials. Recognition of near‐infrared photobiomodulation as having disease modifying properties in the treatment of age‐related dementia has been reported by Paul Chazot PhD, Senior Lecturer in Neuropharmacology at Durham University. The utilization of electrophysiological biomarkers and dysregulated functional networks may allow for neuromodulation applications to curtail symptomatic progression and therefore non‐invasive prophylactic strategies.

Methods

19‐channel electroencephalographic (EEG) assessment was employed across all participants (n=96) to evaluate responsivity to intensive (twice daily), self‐administered, near‐infrared treatment (INIRT) using active or placebo devices that mimicked the photobiomodulation intervention. The EEG recordings were evaluated using a normative database and standardized weight low resonance tomography (swLORETA) analysis software. Participants were administered a comprehensive neuropsychiatric battery before, during and after 60 days to evaluate cognitive performance while undergoing the PBM intervention or sham condition. Specifically, the Alzheimer’s Disease Neuroimaging Initiative (ADNI), which includes 12 inventories such as the Mini Mental State Exam (MMSE), clock drawing test (CDT), auditory verbal learning test‐ immediate (A.V.L.T.‐1), WAIS‐R digit symbol substitution test, the auditory verbal learning test‐ delayed (A.V.L.T.‐2) were employed to evaluate working memory, word recall, visuospatial recall, comprehension, logical memory, and number recall cognitive domains.

Results

Preliminary results indicate subjects in the active PBM condition demonstrated significant improvements in cognitive functioning and activities of daily living and alterations in neural connectivity and phase lag (inter‐electrode signal transmission) in both theta (4‐7hz) and delta (.5‐4hz) frequency bands and a normalization of alpha (8‐12hz) amplitude.

Conclusions

Exposure to PBM interventions indicate subjects in the active PBM condition demonstrated significant alterations in neural connectivity and phase lag (inter‐electrode signal transmission) in both theta (4‐7hz) and delta (.5‐4hz) frequency bands and a normalization of alpha (8‐12hz) amplitude. Normalization of the EEG correlated with symptomatic remission of cognitive impairment, alertness, attention, and improved sleep architecture. Participants exposed to the placebo condition did not report symptomatic remission and continued to exemplify cognitive decline associated with the progression of this neurodegenerative disorder.