A new study from Johns Hopkins Medicine has found that having too much thyroid hormone in the body—called thyrotoxicosis—may increase the risk of memory loss and thinking problems in older adults.
This includes both types of thyrotoxicosis: one that comes from thyroid disorders like hyperthyroidism or Graves’ disease, and one that comes from taking too much thyroid medication.
Thyroid hormone plays a big role in how our body works. It controls metabolism, energy levels, and even how our brain functions. But when there’s too much of it in the body, it can lead to health problems.
In the past, some studies hinted that high levels of thyroid hormone might harm the brain, but they didn’t provide strong evidence. Many of those studies also ignored people who take thyroid medication, which is common in older adults.
To better understand the issue, researchers looked at the health records of nearly 66,000 people aged 65 and older who had been treated at Johns Hopkins between 2014 and 2023. The average age at the start was 71, and each person had at least two visits to a doctor.
The researchers discovered that people with too much thyroid hormone—whether from medication or thyroid disease—were 39% more likely to be diagnosed with cognitive problems, such as memory loss or confusion.
By age 75, about 11% of people with thyrotoxicosis had developed cognitive issues, compared to only 6.4% of those without it. By age 85, the difference was even greater: 34% of those with too much thyroid hormone had memory problems, while only 26% of those without the condition were affected.
The risk was highest in people who had the most thyroid hormone in their system. For those with high levels of hormone from medication, the risk of developing cognitive issues rose by 65%. People with moderate excess levels had a 23% higher risk.
This study suggests that too much thyroid hormone can speed up cognitive decline in older adults, especially when it comes from medication. Because of this, doctors should be cautious when giving thyroid hormone to older people. They should try to avoid giving too much and should adjust treatment based on the patient’s age and needs.
Taking too much thyroid hormone doesn’t help the body and may hurt the brain over time. By carefully managing thyroid treatment, doctors may help older adults stay healthier and protect their thinking abilities.
The findings of this study show how important it is to keep thyroid hormone levels balanced, especially in older people. More research is needed to learn exactly how high thyroid levels affect the brain and to create better ways to treat people who need thyroid hormone.
For those who want to stay heart-healthy, other studies have found that cutting back on coffee may help people with very high blood pressure. Eating more plant-based foods and following early time-restricted eating habits may also help control blood pressure.
If you care about dementia, please read studies about the power of healthy fats for brain health, and wild blueberries can benefit your heart and brain..
For more health information, please see recent studies about how eating nuts can affect your cognitive ability, and brain foods nourish your mind to outsmart dementia.
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