Hypothyroidism linked to an increased risk of Dementia

A new study suggests older people with thyroid problems  may be at increased risk of developing dementia.

The study, published in the online issue of Neurology, has shown an increased risk of developing dementia in older people affected by hypothyroidism. The risk was even higher for people who required thyroid hormone replacement medication.

The research focused on the health records of 7,843 people with an average age of 75, who have newly diagnosed with dementia in Taiwan and it compared them to the same amount of people who did not have dementia. 

Researchers concentrated on the patients who had an history of hypothyroidism or hyperthyroidism. There was no link found between hyperthyroidism ad dementia. 

On the other hand, patients with hypothyroidism were found 80 per cent more likely to develop dementia compared to people the same age who did not have any thyroid problems.

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

A representation of healthy thyroid gland and hyperthyroidism.

When looking at people who took medication for hypothyroidism, the research 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,” Weng added.

The researcher specified that the study does not prove that hypothyroidism is a cause of dementia, but that it only shows an association. The author researcher also noted the limitation of the research in relation to the severity of the hypothyroidism in patients. 

Hypothyroidism, also called under-active thyroid, can slow metabolism as a consequence of a lower production of thyroid hormones than normal. For a patient, this can mean feeling tired, gaining weight and being sensitive to cold.  

This hypo metabolic state can be caused by a primary or a secondary cause. A primary cause is the most common and it directly impacts the thyroid and causes it to create low levels of thyroid hormones. A secondary cause is something that causes the pituitary gland to fail.

Hypothyroidism may be difficult to diagnose as the symptoms can be easily confused with other conditions. The only reliable way to diagnose this state is a blood test called the thyroid stimulating hormones (TSH) test.