The thyroid is a small gland in the neck, but it plays a very important role in the body. It produces hormones that help control how fast the body uses energy, how the heart beats, and how many systems work together.
When thyroid hormone levels are balanced, the body can function well. However, when there is too much thyroid hormone, a condition called thyrotoxicosis can occur, and this may lead to serious health problems.
New research from Johns Hopkins Medicine has found that thyrotoxicosis may also affect the brain, especially in older adults. The study shows that having too much thyroid hormone could increase the risk of cognitive disorders, which are conditions that affect memory, thinking, and daily functioning.
There are two main types of thyrotoxicosis. One is called endogenous thyrotoxicosis, which happens when the body produces too much hormone on its own. This can occur in conditions such as hyperthyroidism or Graves’ disease. The other type is called exogenous thyrotoxicosis, which happens when a person takes too much thyroid hormone medication.
Thyroid hormone is essential for good health, but too much of it can disrupt the body. In the brain, it may affect how nerve cells work and communicate.
In the past, some studies suggested a possible link between high thyroid hormone levels and cognitive problems, but the evidence was not clear. Many of those studies also did not fully consider the role of thyroid medication.
To better understand this issue, researchers at Johns Hopkins Medicine carried out a large study. They examined the health records of 65,931 people aged 65 and older who received care within the Johns Hopkins Health System between 2014 and 2023.
The average age of the participants was 71 at their first visit, and each person had at least two visits with a gap of at least 30 days.
The results showed a clear pattern. People with thyrotoxicosis were more likely to develop cognitive disorders compared to those without it. Overall, the risk was 39 percent higher.
When the researchers looked at age groups, the difference became even more noticeable. By the age of 75, about 11 percent of people with thyrotoxicosis had been diagnosed with a cognitive disorder. In comparison, only 6.4 percent of people without the condition had such a diagnosis.
By the age of 85, the gap grew wider. About 34 percent of people with thyrotoxicosis had cognitive disorders, compared to 26 percent of those without it. This shows that the effects may become stronger over time.
The study also found that the amount of thyroid hormone mattered. Among people taking thyroid medication, those with the highest levels of excess hormone had a 65 percent higher risk of cognitive problems. Those with moderate excess hormone had a 23 percent higher risk.
These findings suggest that too much thyroid hormone, especially from medication, can increase the risk of cognitive decline in older adults. This is important because many older people take thyroid hormone therapy for conditions like hypothyroidism, where the body does not produce enough hormone.
The study highlights the need for careful treatment. Doctors should monitor thyroid hormone levels closely and adjust medication doses based on each patient’s age and health condition. Avoiding overtreatment is key, as giving too much hormone may do more harm than good.
Managing thyroid health is not just about controlling physical symptoms. It may also play a role in protecting brain health as people age. Early attention to hormone levels could help reduce the risk of memory and thinking problems later in life.
The findings of this study were published in the journal JAMA Internal Medicine. While the results are important, researchers say more studies are needed to fully understand how thyroid hormone affects the brain and how best to prevent these risks.
Other research is also looking at ways to support overall health in older adults. For example, some studies suggest that lifestyle habits can influence blood pressure, and reducing coffee intake may help people with severe high blood pressure.
There is also growing interest in eating patterns, such as early time-restricted eating and plant-based diets, which may improve heart and blood vessel health.
For now, this study offers an important message. Keeping thyroid hormone levels in a healthy range is essential, especially for older adults. With careful monitoring and proper treatment, it may be possible to reduce the risk of cognitive problems and support a healthier brain over time.
If you care about brain health, please read studies about inflammation that may actually slow down cognitive decline in older people, and low vitamin D may speed up cognitive decline.
For more health information, please see recent studies about common exercises that could protect against cognitive decline, and results showing that this MIND diet may protect your cognitive function, prevent dementia.
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