Thyroid function and cognitive health: rethinking the relationship between "suboptimal" TSH/FT4 levels and cognitive decline.

ABSTRACT:

Introduction

Controversial hypotheses suggest that "suboptimal" thyroid function - defined as higher-normal thyroid-stimulating hormone (TSH) (2.0 to 4.5 μIU/mL) or low-normal free thyroxine (FT4) - may increase risk of cognitive decline and dementia in older patients.

Methods

We examined this claim using data from the Canadian Comprehensive Assessment of Neurodegeneration and Dementia cohort (ages 50 to 91; cognitive statuses from unimpaired to dementia, rarer subtypes of dementia excluded). Thyroid function was categorized as "optimal" (TSH < 2.0 μIU/mL or FT4 ≥ 16.74 pmol/L) or "suboptimal." Six hundred eighty-eight participants had TSH data, and 476 participants had FT4 data.

Results

Chi-squared analyses showed no significant association between "suboptimal" thyro

SUBMITTER: Dori D 

PROVIDER: S-EPMC12706624 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature