Investigating the effects of aerobic exercise primed anodal transcranial direct current stimulation on γ‐aminobutyric acid concentrations in mild vascular cognitive impairment
Bibliographic record
Abstract
Abstract Background Mild vascular cognitive impairment (mVCI) is characterized by minor deficits in cognition and memory due to underlying vascular pathology. Anodal transcranial direct current stimulation (atDCS), a non‐invasive neuromodulation technique, has been demonstrated to improve cognition. The effects of atDCS have been suggested to be mediated by γ‐aminobutyric acid (GABA)–a major inhibitory neurotransmitter associated with cerebral perfusion and oxygenation, and cognition and memory. However, previous studies have reported mixed results regarding changes in GABA concentrations following atDCS. Physical activity has been reported to increase cortical GABA levels, and in particular, aerobic exercise (AE) is associated with improved cognition in older adults. Preliminary data from an ongoing trial (EXPRESS‐V) was used to evaluate whether GABA concentration in the motor cortex was altered following AE and/or atDCS and whether this was associated with changes in global cognition in mVCI. Method In this double‐blind, randomized clinical trial, participants received one of four interventions for two weeks: AE and atDCS, AE and sham atDCS, exercise education and atDCS, or exercise education and sham atDCS. mVCI was determined based on a modified Gorelick criteria. At baseline and endpoint, GABA concentration in the motor cortex was measured using magnetic resonance spectroscopy and quantified with the Mescher‐Garwood point resolved spectroscopy pulse sequence, and global cognition was assessed using the Montreal Cognitive Assessment. Wilcoxon signed rank test was used to determine changes in GABA concentrations (ΔGABA). Spearman correlation was used to determine the association between ΔGABA and changes in global cognition (ΔMoCA). Result Ten participants have enrolled so far, with nine participants having completed the study (22.2% female, age = 66.4(9.8), years of education = 8.8(3.4), 55.6% White, baseline MoCA score = 22.8(3.1)). To date, ΔGABA was insignificant between baseline and endpoint (Z = 23.0, p = 0.953). However, a positive trend between ΔGABA and ΔMoCA was observed (ρ = 0.650, p = 0.058). Conclusion Preliminary results from nine participants showed a positive trend between ΔGABA and ΔMoCA. Since the trial is ongoing, with the target of recruiting 80 participants by 2024, analyses on unblinded data upon study completion will determine whether AE and atDCS leads to greater ΔGABA, and whether this is accompanied by greater ΔMoCA in mVCI.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| 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 | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".