Thyroid problems linked to increased risk of dementia?

Older people with hypothyroidism, also called underactive thyroid, may be at increased risk of developing dementia, according to a study published in the, online issue of Neurology, the medical journal of the American Academy of Neurology. The risk of developing dementia was even higher for people whose thyroid condition required thyroid hormone replacement medication.

During the study, researchers looked at the health records of 7,843 people newly diagnosed with dementia in Taiwan and compared them to the same number of people who did not have dementia. Their average age was 75. Researchers looked to see who had a history of either hypothyroidism or hyperthyroidism.

A total of 102 people had hypothyroidism and 133 had hyperthyroidism. The researchers found no link between hyperthyroidism and dementia. Of the people with dementia, 68 people, or 0.9%, had hypothyroidism, compared to 34 of the people without dementia, or 0.4%. When researchers adjusted for other factors that could affect the risk of dementia, such as sex, age, high blood pressure and diabetes, they found that people over age 65 with hypothyroidism were 80% more likely to develop dementia than people the same age who did not have thyroid problems. For people younger than 65, having a history of hypothyroidism was not associated with an increased risk of dementia.

Researchers also 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 for this could be that these people are more likely to experience greater symptoms from hypothyroidism where treatment was needed, said the researchers.

Researchers noted that the observational study does not prove that hypothyroidism is a cause of dementia; it only shows an association.

Reference: "Thyroid problems linked to increased risk of dementia";AMERICAN ACADEMY OF NEUROLOGY;Neurology.