Association of overt hypothyroidism with risks of cognitive impairment: a meta-analysis and systematic review
Bibliographic record
Abstract
Background: Studies examining the relationship between overt hypothyroidism (oHT) and the risk of cognitive impairment (CI) have yielded mixed results. This study aimed to evaluate the association between oHT and the risk of CI. Methods: We systematically searched relevant studies published up to March 2025. Data were extracted independently by two investigators. Overall odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated using a random-effects model. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of cohort and case-control studies, while the Agency for Healthcare Research and Quality (AHRQ) scale was used for cross-sectional studies. Results were reported following PRISMA guidelines. Results: A total of 11 studies involving 1,190,059 participants were included in the systematic review. Meta-analysis revealed that oHT was associated with an increased risk of CI (OR = 1.18, 95%CI=1.04-1.34). When CI was categorized into mild cognitive impairment (MCI) and severe cognitive impairment (Alzheimer's disease (AD) or all-cause dementia), oHT was associated with an increased risk of MCI (OR = 1.24, 95%CI=1.13-1.36) but not with AD (OR = 1.03, 95%CI=0.77-1.38) or all-cause dementia (OR = 1.20, 95%CI=0.94-1.53). Subgroup analysis based on diagnostic methods for oHT showed that oHT diagnosed solely by TSH levels was associated with a reduced risk of CI (OR = 0.87, 95%CI=0.79-0.95). Conclusion: Available evidence suggests an association between oHT and an increased risk of cognitive impairment, particularly MCI. However, given the observational nature and significant heterogeneity of this study, the strength of this association still requires high-quality prospective studies for final confirmation and precise quantification. Systematic review registration: https://www.crd.york.ac.uk/prospero/, identifier CRD420251012792.
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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 | 0.011 | 0.033 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.017 | 0.032 |
| Bibliometrics | 0.007 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 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".