During the monitoring time, certain data was collected, such as smoking history, alcohol use, exercise, diabetes , hypertension and the use of some medications. Thyroid hormone levels were measured at the 2 year visit and the mental status evaluation was performed every couple of years. Dementia was identified based on a specific decline in the Mini Mental State test, prescription of a dementia medication or diagnosis of dementia on a hospital admission. Thyroid function was assessed by measuring a TSH. If the TSH was abnormal, then a free T4 was obtained. People who had a low TSH were divided in two groups with the milder group defined as a TSH between 0.1 and 0.45, and the fully suppressed group, with a TSH of <0.1.
After adjusting for relevant variables, study results showed that dementia risk was higher in those whose TSH was suppressed <0.1 than in people with normal TSH level. Dementia risk was not increased in the group with a slightly low TSH level (0.1-0.45) or in people with a mildly elevated TSH (subclinical hypothyroidism).
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
The strength of this study is the use of a large group of community based subjects, the length of the follow up and the primary outcome (dementia). The limitations were that the number of people with subclinical hyperthyroidism was relatively small (3.2% of participants), and that there was only one TSH measurement at the start of the study. These results are relevant to patients because they show that there is a relationship between what is considered to be a milder form of thyroid disease, specifically subclinical hyperthyroidism, and dementia risk. Many times, physicians are reluctant to treat subclinical thyroid problems. This study suggests that it may be important to treat subclinical hyperthyroidism, especially in the elderly with dementia symptoms.
— Jessie Block-Galarza, MD
ATA THYROID BROCHURE LINKS
Older Patients and Thyroid Disease: https://www.thyroid.org/thyroid-disease-older-patient/
Hyperthyroidism (Overactive): https://www.thyroid.org/hyperthyroidism/
Hypothyroidism (Underactive): https://www.thyroid.org/hypothyroidism/
Thyroid Function Tests: https://www.thyroid.org/thyroid-function-tests/