High and high-normal thyroid function is associated with increased risk of dementia, experts say.
Data analysis was done within the Rotterdam Study. A total of 9,446 subjects with a mean age of 65 years were included in the evaluation of the link between thyroid-stimulating hormone (TSH) and free thyroxine with dementia, cognition, and subclinical vascular brain disease by MRI. The subjects were followed-up for a mean duration of 8 years. During this period, 601 subjects developed dementia.
In both full and normal ranges of thyroid function, high TSH function was associated with dementia risk, independent of cardiovascular risk factors.
Subjects with higher free thyroxine were at greater risk of developing dementia. High TSH in older women was associated with decreased absolute 10-year dementia risk.
An association was seen between higher TSH and better global cognitive scores while thyroid function was not linked with to subclinical vascular brain disease.
The authors concluded that high and high-normal thyroid function may increase the risk of developing dementia.