Thyroid Condition Linked to Higher Dementia Risk

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Senior woman touching her neck
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Seniors with hypothyroidism may have a higher risk of developing dementia, according to findings published in Neurology, the medical journal of the American Academy of Neurology.

After examining the health records of 7,843 people newly diagnosed with dementia in Taiwan, researchers found that 68 (0.9%) of them had hypothyroidism.

The researchers also looked at the same number of people who did not have dementia and found that just 34 (0.4%) had hypothyroidism.

In both groups, the average age was about 75.

Once the researchers adjusted for several factors that could affect dementia risk — including sex, age, high blood pressure and diabetes — they found that people age 65 and older who had been diagnosed with hypothyroidism were 81% more likely to develop dementia than people the same age who did not have the thyroid condition.

Among those age 65 and older who required medication for their thyroid condition, the likelihood of developing dementia was three times higher than among those who didn’t need medication.

On the other hand, people younger than age 65 with a history of hypothyroidism did not have an increased risk of dementia.

Hypothyroidism is a condition in which the thyroid gland — a butterfly-shaped gland located at the base of the neck — fails to produce adequate levels of thyroid hormones, which can slow the body’s metabolism. It often leads to weight gain and symptoms such as tiredness and sensitivity to cold.

Nearly 5% of Americans age 12 and older have the condition, which is more common among people over age 60 and especially among women, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

In a press release, Dr. Chien-Hsiang Weng of Brown University in Providence, Rhode Island — the study’s lead author — says:

“In some cases, thyroid disorders have been associated with dementia symptoms that can be reversible with treatment. While more studies are needed to confirm these findings, people should be aware of thyroid problems as a possible risk factor for dementia and therapies that could prevent or slow irreversible cognitive decline.”

No link was found between dementia and hyperthyroidism — a condition in which the thyroid gland produces too much thyroid hormone.

Weng also noted that the study was observational, so it simply shows there is an association between hypothyroidism and dementia, rather than showing that hypothyroidism causes the cognitive disorder.

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