Overview: Older adults who suffer from hypothyroidism have an increased risk of developing dementia. The risk is even greater in those who need thyroid hormone replacement therapy to treat their condition.
Older people with hypothyroidism, also called an underactive thyroid, may be at an increased risk of developing dementia, according to a study published in the July 6, 2022 online issue of Neurology†
The risk of developing dementia was even higher for people whose thyroid disease required thyroid hormone replacement medication.
Hypothyroidism occurs when the thyroid gland does not make enough thyroid hormones. This can slow down the metabolism. Symptoms include fatigue, weight gain, and sensitivity to cold.
“In some cases, thyroid disease has been associated with dementia symptoms that may be reversible with treatment,” said study author Chien-Hsiang Weng, MD, MPH, of Brown University in Providence, Rhode Island.
“While more studies are needed to confirm these findings, people should be aware of thyroid problems as a potential risk factor for dementia and therapies that may prevent or slow irreversible cognitive decline.”
For the study, researchers looked at the health records of 7,843 people newly diagnosed with dementia in Taiwan and compared them with the same number of people who did not have dementia. Their average age was 75 years. Researchers looked at who had a history of hypothyroidism or hyperthyroidism.
Hyperthyroidism, also called an overactive thyroid, is when the thyroid gland produces too much hormone. This can increase the metabolism. Symptoms include unintentional weight loss, fast or irregular heartbeat, and nervousness or anxiety.
A total of 102 people had hypothyroidism and 133 had hyperthyroidism.
The researchers found no association between hyperthyroidism and dementia.
Of the people with dementia, 68 people, or 0.9%, had hypothyroidism, compared with 34 of the people without dementia, or 0.4%.
When researchers adjusted for other factors that can influence dementia risk, such as gender, age, high blood pressure and diabetes, they found that people over 65 with hypothyroidism were 80% more likely to develop dementia than people of the same age who did. . have no thyroid problems.
For people under age 65, a history of hypothyroidism was not associated with an increased risk of dementia.
When researchers looked only at people taking drugs for hypothyroidism, they found that they were three times more likely to develop dementia than those who took no drugs. “One explanation for this could be that these people are more likely to have more symptoms of hypothyroidism where treatment was needed,” Weng said.
Weng noted that the observational study does not prove that hypothyroidism is a cause of dementia; it only shows an association.
One limitation of the study was that researchers were unable to include information about how severe the hypothyroidism was for participants.
About this research news about dementia
Original research: The findings appear in Neurology