Geographic bias in hand preference within posterior cortical atrophy
Bibliographic record
Abstract
Abstract Background Posterior cortical atrophy (PCA) is a neurodegenerative disorder of visuospatial and visuoperceptual impairment with high association to underlying Alzheimer’s disease (AD) pathology. In contrast to typical amnestic AD, risk factors for PCA remain largely unknown. Previously, we observed higher rates of neurodevelopmental differences in PCA, including an increased prevalence of non‐right‐handed individuals (left‐handed, ambidextrous, and/or forced‐right‐handed) compared to the general population. Non‐right‐handedness has been associated with many neurologic and psychiatric conditions, and we have found is overrepresented in early and non‐amnestic forms of AD. In this study, we sought to investigate handedness within an international PCA cohort. Method We contacted 55 research centers conducting PCA research identified in a literature review (n = 1353 papers), as well as additional sites recruited through the Alzheimer’s Association International Society to Advance Alzheimer’s Research and Treatment (ISTAART) Atypical AD Professional Interest Group (n = 7 sites) requesting de‐identified, single‐subject data from PCA patients. Single‐subject demographic, clinical, fluid, neuroimaging and neuropathological data were collected from 1121 participants evaluated at 34 sites in 16 countries. In this sub‐project, the sample size was restricted to the 901 PCA participants with reported handedness. Descriptive analyses were performed across the entire cohort and across three different geographic levels: by 1) center, 2) country/region, and 3) continent. Statistical analyses were restricted to the continental view given sample size constraints. Result Within the total consortium PCA cohort, 10.3% (93/901) were non‐right‐handed. Figure 1 shows the distribution of non‐right‐handedness across country/region. Comparisons across continents revealed differences in handedness ( p = 0.04, Yate’s corrected). Sample sizes in Asia, Australia, and South America did not permit comparisons of observed vs. expected rates of non‐right‐handedness, whereas Europe displayed significantly less and North America significantly more non‐right‐handedness than expected ( p = 0.04 and p = 0.02, respectively, employing a 10% non‐right‐handedness rate for the general population). Conclusion Within the international PCA consortium, differences in hand preference presented across centers in a manner that could not be explained by normal variation in the data. Uncovering this global bias in hand preference not only holds relevance towards understanding the etiology of PCA but may have implications for neuroscience research more broadly.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.003 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.001 |
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".