Investigation of functional near-infrared spectroscopy as a monitoring tool for measuring the effect of transcranial alternating current stimulation on dementia patients’ cognitive function
Bibliographic record
Abstract
Functional near-infrared spectroscopy (fNIRS) is used as a non-invasive neuroimaging technique for studying the neural dynamics within the human brain. This study uses fNIRS to explore how transcranial alternating current stimulation (tACS) affects cognitive function in people with dementia including Alzheimer’s disease (AD). By measuring changes in blood oxygenation levels, fNIRS provides a valuable means to capture plausible post-treatment alterations in cerebral hemodynamics. Previous studies have shown individuals with dementia exhibit increased oxygen consumption during verbal fluency tasks. This suggested that they might require greater effort to compensate for cognitive deficits. Therefore, it is hypothesized that tACS intervention will potentially alleviate this increased oxygen consumption by enhancing cognitive function, resulting in reduced oxyhemoglobin level post-treatment amongst those who respond positively to tACS treatment. To investigate this hypothesis, this research involved a comprehensive examination of 29 individuals with dementia, who received both real (40 Hz) and sham tACS treatment in a double-blind cross-over randomized trial. Each tACS intervention was paired with cognitive exercises (CE) on a daily basis in two 30-minute sessions for four consecutive weeks (excluding weekends) (tACS+CE). To reduce treatment effects between intervention, each participant had a 2-5 month wash-out period between treatments. Study participants were assigned into two groups using their age and cognitive level as the stratification parameters. One group received real tACS first and sham second (R1S2), and the other group’s real/sham assignment was the opposite (S1R2). An eight-channel fNIRS device was utilized to measure blood oxygenation levels in the prefrontal cortex (PFC) before and after each treatment block, during a mental task (word production and subtraction tasks). The results of this work are in support of our hypothesis that patients with dementia showed a decrease in oxyhemoglobin level after real tACS+CE by a mean difference of 0.06µM for word production task, and a significant decrease of 0.10µM for subtraction task (p=0.04). Notably, real tACS treatment showed a higher decrease in oxyhemoglobin levels compared to the sham treatment, suggesting that real stimulation has a more significant impact on hemodynamic responses than only cognitive exercises. Analyzing changes in blood oxygenation separately for group R1S2 and group S1R2 showed a significant decrease in oxyhemoglobin levels in group R1S2 during real tACS intervention in the subtraction task (p=0.03) but not significant for the word production task. This may be attributed to the fact that dementia participants usually have a ceiling effect in word production task.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".