Thyroid function and the risk of dementia: The Rotterdam Study

Area of Science:

• Neuroscience
• Endocrinology
• Epidemiology

Background:

• Thyroid dysfunction is increasingly recognized as a potential contributor to cognitive decline and dementia.
• Understanding the relationship between thyroid hormones and brain health is crucial for developing preventative strategies.

Purpose of the Study:

• To investigate the association between thyroid function, cognitive decline, and subclinical vascular brain disease.
• To determine if thyroid hormone levels impact the risk of developing dementia.

Main Methods:

• Prospective, population-based cohort study (Rotterdam Study) with 9,446 participants.
• Cox models and regression analyses assessed thyroid-stimulating hormone (TSH) and free thyroxine in relation to dementia, cognitive scores, and MRI-detected vascular brain disease.
• Analyses were adjusted for relevant risk factors and stratified by sex, including analyses restricted to normal thyroid function.

Main Results:

• Higher TSH levels were associated with a reduced risk of dementia (HR 0.90) and better cognitive scores.
• Elevated free thyroxine levels correlated with an increased dementia risk (HR 1.04).
• No significant association was found between thyroid function and subclinical vascular brain disease on MRI.

Conclusions:

• High and high-normal thyroid function is linked to an increased risk of dementia.
• Thyroid hormone may influence dementia risk through nonvascular pathways, as vascular brain disease was not implicated.
• Further research into thyroid hormone's role in dementia pathogenesis is warranted.