Theta‐ and alpha‐band functional connectivity are associated with longitudinal tau accumulation in asymptomatic individuals expressing Aβ pathology
Bibliographic record
Abstract
Abstract Background Recent studies suggest that tau pathology spreads between functionally connected (FC) brain regions. The accumulation of amyloid‐beta (Aß) promotes neural hyper‐activity in asymptomatic older adults, which might enhance tau spreading. We assessed the relationship between band‐specific neurophysiological FC and the rate of tau accumulation over time and tested whether this association is dependent on the presence of Aß pathology. Method We measured cortical Aß deposition using positron emission tomography (PET) and resting‐state neurophysiological activity using magnetoencephalography (MEG) at baseline, as well as longitudinal cortical tau PET deposition (mean time between scans = 4.3 years), in a group of cognitively unimpaired older adults with family history of Alzheimer’s Disease (PREVENT‐AD cohort; N = 84). Region‐specific measures (i.e. Aß, tau, MEG timeseries) were extracted from 68 cortical parcels of the Desikan‐Killiany atlas. Neurophysiological FC between cortical regions was estimated across delta, theta, alpha and beta frequency bands using the corrected amplitude envelope correlation (AEC‐c). A global Aß standardized uptake value ratio (SUVR) was calculated by taking the average across a set of early Aß accumulating regions. Individual‐specific tau epicenters were defined as the six cortical regions with the highest levels of baseline tau‐PET binding. The annual rate of change in tau SUVR between the first and second scan was calculated for each cortical region (Figure 1). Linear mixed‐effects models were designed to test if the neurophysiological FC connectivity of each cortical parcel with tau epicenters was related to increased longitudinal tau accumulation in that region, and whether this association was dependent on baseline levels of Aß pathology. Result Tau epicenters identified across individuals were mainly localized in temporal and medial posterior brain regions. Regional increases in theta‐ and alpha‐band FC with tau epicenters at baseline related to greater longitudinal tau accumulation in individuals expressing higher levels of global Aß pathology (Figure 2). Conclusion Our results suggest that tau spreads across cortical regions that are functionally connected in the theta‐ and alpha‐bands, but only in individuals with high levels of cortical Aß. This finding supports the notion that Aß‐related neural hyper‐activity promotes tau spreading across the cortex following individual‐specific patterns of FC in asymptomatic older adults.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.002 | 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".