1155 LONGITUDINAL CHANGES OF FRACTAL ACTIVITY REGULATION WITH AGING: PRELIMINARY RESULTS FROM THE RUSH MEMORY AND AGING PROJECT
Bibliographic record
Abstract
Human physical activity possesses fractal fluctuations with similar temporal structure at different time scales from minutes to hours. Cross sectional studies suggest that such fractal regulation (FR) is robust in healthy young subjects but is degraded with age and cognitive impairment. Here we aimed to characterize the longitudinal change in FR among community-based older persons and to examine the associations of the change with demographics and cognitive status. We examined physical activity recordings of 991 participants (59–100 years old; Mean=81) in the Rush Memory and Aging Project who had 2–11 assessments (Mean=5). 42 Subjects were diagnosed with AD at baseline. Physical activity was continuously monitored with an actigraph on the wrist (Actical) for up to 10 days. Cognitive function was based on a previously validated summary score for 19 cognitive tests. To assess FR, temporal correlations in activity fluctuations at both smaller (~0.1–1.5h) and larger (2-12h) time scales were quantified and were indicated by two exponents, alpha1 and apha2, respectively. Linear mixed models were used to examine the associations of demographics and baseline cognitive status with annual rate of change in activity correlations. Activity correlations in both time-scale regions decreased over time with an annual decline of 0.003 ± 0.0005(SE) in alpha1 (p<0.0001) and a faster decline in alpha2 (0.010 ± 0.0008[SE], p<0.0001). Faster declines in alpha1 were associated with older age (p<0.0001) and worse baseline cognitive function (p=0.0008). The associations of the decline in alpha2 with age and baseline cognitive function were weaker and didn’t reach statistical significance (age: p=0.076; cognition: p=0.189). Consistently, AD at baseline doubled the decline in alpha1 (p=0.01) and no significant association with alpha2 was observed (p=0.61). These changes/associations were independent of sex and years of education. Fractal regulation of physical activity in old adults declines and is accelerated by poorer cognition and AD. This work was supported by NIH grants R00HL102241, R01AG048108 and P01AG009975 (to K.H.). P.L. was supported by the International Postdoctoral Exchange Fellowship 20150042 from the China Postdoctoral Council.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 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 teacher head, 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".