[P3–556]: THE ASSOCIATION BETWEEN TRAUMATIC BRAIN INJURY AND THE RISK AND TIME OF ONSET OF ALZHEIMER's DISEASE AND OTHER DEMENTIAS: AN UPDATED META‐ANALYSIS OF OBSERVATIONAL STUDIES
Bibliographic record
Abstract
Traumatic brain injury (TBI) is known to be associated with an increased risk of Alzheimer's disease (AD) and other dementias. However, it has not yet been conclusively established how TBI affects the age of onset of AD and other dementias. Hence in the present meta-analysis, we aimed to update the literature regarding the overall risk estimate for AD and other dementias with TBI, and quantify any changes in age of onset with TBI. We performed a systematic search of the databases PubMed, MEDLINE, EMBASE, CINAHL, LILACS, CENTRAL and Google Scholar to 31 January 2017, supplemented by a manual search of reference lists. We included studies that were (1) observational studies which (2) examined a relevant outcome related to TBI prior to dementia diagnosis, with (3) a minimum of 50 cases, and which (4) reported an OR with 95% CI, or presented information such that an OR could be calculated. Relevant outcomes were risk of AD or other dementias and differences in age of onset. Subgroup analyses were performed based on gender, study design, geographical region, and APOE genotype. Data were pooled using a random effects model. Quality was assessed using the Newcastle Ottawa Scale, with a preplanned subgroup analysis including only studies of high quality (score of 6 or higher out of a possible 9). Thirty-five observational studies were included in the analysis of the main outcome, the risk of Alzheimer's disease in individuals with a history of any traumatic brain injury. We found a significantly increased risk (OR=1.42, 95% CI 1.17–1.72; p<0.001) that persisted for retrospective (OR=1.57, 95% CI 1.19–2.07; p=0.001) but not prospective (OR=1.22, 95% CI 0.99–1.50; p=0.058) study designs. When analysing by geographical region, the association was significant except for in studies from Europe (OR=1.13, 95% CI 0.79–1.61; p=0.51). There was no publication bias (p=0.83). Results for the remaining analyses will be presented at the conference. Traumatic brain injury is associated with a significantly increased risk of Alzheimer's disease. This is of particular clinical relevance to members of the armed forces and individuals involved in contact sports.
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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 | 0.013 | 0.035 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.011 | 0.053 |
| Bibliometrics | 0.005 | 0.008 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.006 | 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 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".