| Departments — Benchmarks | Autumn 2008 |
Regulatory Concerns A team of researchers followed 1,864 participants in the Framingham Heart Study whose thyroid function—and TSH levels—had been measured between 1977 and 1979. Zaldy Tan, an HMS assistant professor of medicine at Beth Israel Deaconess Medical Center, together with colleagues at HMS and Boston University, monitored the participants for an average of 12.7 years and found that women with TSH values in the lowest and highest third—less than 1 milli-international unit per liter or more than 2.1 milli-international units per liter—were twice as likely to develop Alzheimer’s disease as those with values in the middle third. Men were not at similar risk. The researchers, who published their findings in the July 28 issue of Archives of Internal Medicine, found an elevated risk even in women who, at some point, had undergone hormone supplementation or suppression therapy, suggesting the effects of low and high TSH levels may be irreversible. The finding that puzzles the researchers is that only women were vulnerable to the effects of aberrant hormone production. In fact, women appear to be more vulnerable to other thyroid-associated conditions, such as Graves’ disease. As to how this dysregulation links to Alzheimer’s disease, the investigators pose an intriguing hypothesis. According to Tan, too little or too much thyroid hormone could lead to irregularities in the regulation of the amyloid precursor protein gene, which is controlled by TSH and known to play a role in Alzheimer’s. Abnormal levels may cause aberrant production of plaque-causing amyloid proteins. Misia Landau is the senior science writer for Focus. Photo: ©iStockPhoto.com/Anne de Haas |
debilitating mental conditions. Indeed, physicians will typically check thyroid hormone levels in patients complaining of memory loss or depression. It now appears they may have another reason to check thyroid function in their female patients. A new study suggests that women with low or high levels of thyroid-stimulating hormone (TSH) are more likely to develop Alzheimer’s disease than those with normal levels.
|