Thyroid Function and Cognitive Health: Rethinking the Relationship between ‘Suboptimal’ TSH/FT4 Levels and Cognitive Decline
Bibliographic record
Abstract
Abstract Background Emerging hypotheses suggest that 'suboptimal' thyroid function, defined as higher‐normal TSH (2.0–4.5 µIU/ml) or low‐normal FT4, may increase the risk of cognitive decline and dementia. Method This study tested these claims using data from 991 participants in the COMPASS‐ND cohort, aged 50–91, with cognitive statuses ranging from unimpaired to dementia. Thyroid function was classified as “optimal” (TSH<2.0 µIU/ml or FT4≥16.74 pmol/L) or “suboptimal.” Result Chi‐square analysis of 883 participants (523 with FT4 data) found no significant association between “suboptimal” thyroid function and cognitive impairment (TSH: χ 2 =0.1585, p = 0.69; FT4: χ 2 =0.0027, p = 0.96). True hypothyroidism was rare, and 98.6% of participants with elevated TSH had normal FT4 levels. Conclusion These findings refute claims that higher‐normal TSH or low‐normal FT4 increases cognitive decline risk, highlighting the need for caution in redefining TSH cutoffs or pursuing unproven thyroid supplementation as a cognitive health intervention.
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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 | 0.005 | 0.012 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".