Older individuals with hypothyroidism, also known as under-active thyroid, could be at an increased risk of developing dementia, according to a study.
Researchers examined the health records of 7,843 individuals newly diagnosed with dementia in Taiwan and compared them to the same number of individuals who did not suffer with dementia.
The average age of the study same was 75-years-old.
Researchers sought out to find who had a history of either hypothyroidism or hyperthyroidism.
Hypothyroidism occurs when the thyroid gland cannot make a sufficient amount of thyroid hormones. This can result in causing a slower metabolism, which leads to symptoms such as weight gain, feeling tired and sensitivity to cold temperatures.
Hyperthyroidism, also known as overactive thyroid, is where the thyroid is producing too much hormone. This can increase metabolism and symptoms of this include unintended weight loss, nervousness, anxiety and irregular or rapid heartbeat.
102 individuals in the study had hypothyroidism and 133 had hyperthyroidism.
The researchers discovered no link between hyperthyroidism and dementia.
Of those with dementia in the study, 68 individuals, or 0.9 per cent had hypothyroidism, while 34 of the individuals without dementia, or 0.4% had hypothyroidism.
Study author Chien-Hsiang Weng, of Brown University, said: “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.”
Researchers also adjusted for factors that could affect the risk of dementia, such as age, sex, diabetes and high blood pressure. They found that those over the age of 65 with hypothyroidism were 80 per cent more likely to develop dementia than those of the same age who did not have thyroid problems.
For individuals under the age of 65, having a history of hypothyroidism was not associated with an increased risk of dementia.
When researchers looked at only those who took medication for hypothyroidism, they found that they were three times more likely to develop dementia than those who did not take medication.
Weng said that: “One explanation for this could be that these people are more likely to experience greater symptoms from hypothyroidism where treatment was needed.”
Weng also noted that the observational study does not evidentially prove that hypothyroidism is a cause of dementia, and that in fact it only displays an association.
There was a limiting factor in the study, researchers were not able to include information about how severe the hypothyroidism was for the participating individuals.
