Thyroid Function and Cognitive Health: Rethinking the Relationship between ‘Suboptimal’ TSH/FT4 Levels and Cognitive Decline

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.