Thyrotoxicosis Linked to Increased Risk of Cognitive Disorders in Older Adults

Thyrotoxicosis, or excess thyroid hormone levels in the body, is associated with an increased risk of cognitive disorders among older adults, according to a study published in JAMA Internal Medicine.

Researchers assessed 65,931 qualified participants aged 65 years and older who received primary care from Johns Hopkins Health System between January 2014 and May 6, 2023, and were included in the system’s electronic health record database. The average patient age during the first recorded primary care visit was 71 years, and all patients had at least two visits that were 30 or more days apart.

According to the study results, all-cause thyrotoxicosis, both endogenous and exogenous, was correlated with a 39% increase in the risk of a cognitive disorder diagnosis across age groups. A total of 11.0% of patients who experienced thyrotoxicosis were diagnosed with a cognitive disorder by age 75 versus 6.4% of patients who did not experience thyrotoxicosis. The researchers observed that by age 85, 34% of patients who had thyrotoxicosis were diagnosed with a cognitive disorder compared with 26% of patients who did not.

Moreover, among patients prescribed a thyroid hormone, the level of exposure to thyroid hormone correlated with the degree of risk for a cognitive disorder. Specifically, patients with a more severe degree of excess thyroid hormone had a 65% increased risk of a cognitive disorder, while those with a more moderate degree of excess thyroid hormone had a 23% increased risk.

“Our results suggest that an increased risk of cognitive disorders is among the potential negative consequences of thyroid hormone excess, a common consequence of thyroid hormone therapy,” said Jennifer Mammen, MD, PhD, the study’s senior author and an assistant professor of medicine at the Johns Hopkins University School of Medicine, via a press release. “Clinicians considering thyroid hormone therapy in older adults should avoid overtreatment by using age-appropriate treatment strategies.”