Hypothyroidism occurs when your thyroid doesn’t create and release enough thyroid hormone into the body. Also known as underactive thyroid disease, hypothyroidism slows down the metabolism, affecting the entire body.
In some cases, thyroid disorders have been associated with dementia symptoms that can be reversible with treatment. There have been limited studies investigating the correlation between thyroid disorder and dementia. A new study sheds light on this correlation- suggesting that older people with hypothyroidism may be at increased risk of developing dementia.
To conduct the study, researchers compared the health records of 7,843 Taiwanese individuals with dementia who had just received their diagnosis with those of a similar number of individuals without dementia. Their average age was 75. Researchers then looked to see who had a history of either hypothyroidism or hyperthyroidism.
A total of 102 people had hypothyroidism, and 133 had hyperthyroidism, also called overactive thyroid disease occurs when the thyroid produces too much hormone.
Researchers didn’t find any link between hyperthyroidism and dementia.
68 people, or 0.9 percent of those with dementia, had hypothyroidism, compared to 34 individuals, or 0.4 percent of those without dementia. Researchers showed that adults over the age of 65 with hypothyroidism were 80% more likely to develop dementia than those of the same age who did not have thyroid issues after adjusting for other factors that could impact the risk of dementia, such as sex, age, high blood pressure, and diabetes.
For people younger than 65, having a history of hypothyroidism was not associated with an increased risk of dementia.
Study author Chien-Hsiang Weng, MD, MPH, of Brown University in Providence, Rhode Island, said, “When we looked only at people who took medication for hypothyroidism, they found they were three times more likely to develop dementia than those who did not take medication. One explanation could be that these people are more likely to experience greater symptoms from hypothyroidism where treatment was needed.”
“The observational study does not prove that hypothyroidism is a cause of dementia; it only shows an association.”
The study has a limitation: scientists could not include information about how severe hypothyroidism was for participants.
- Daniel R Wieland, Julia R Wieland et al. Thyroid Disorders and Dementia Risk: A Nationwide Population-Based Case-Control Study. Neurology Jul 2022; DOI: 10.1212/WNL.0000000000200740