Hypothyroidism linked to mood swings

Jun 5 2007

Hypothyroidism is often associated with mood changes like depression lethargy.

Researchers, studying underlying brain processes in search of "why" this happens, reported their results at the 54th Annual Meeting of SNM, the world's largest society for molecular imaging and nuclear medicine professionals.

"The aim of our study was to investigate with positron emission tomography (PET) imaging how physical health and mental health are interrelated," said Waltraud Eichhorn, a nuclear medicine physician at Johannes Gutenberg University in Mainz, Germany. "We found that hypothyroidism is correlated to regional metabolic changes in the thalamus an area of the brain that helps process information from the senses and transmit it to other parts of the brain" she said. "In other words, hypothyroid patients compared to healthy individuals have decreased metabolism in special parts of the brain that are responsible for processing information, " said Eichhorn. "Remarkably, this reduction in metabolism remains detectable after thyroid hormone replacement therapy," she added.

The thyroid, a butterfly-shaped gland in the neck just above the collarbone, is an endocrine gland that makes hormones and helps set a body's metabolism (how the body gets energy from food). Hypothyroidism, a condition in which your body produces too little thyroid hormone, often leads to exhaustion and depression, affecting millions of Americans, many of them women or the elderly. There are 27 million Americans who have underactive or overactive thyroid glands, but more than half remain undiagnosed, according to recent statistics.

Hypothyroidism can be treated by doses of thyroid hormone. Once the blood levels of thyroid hormone reach a normal range called euthyroid lethargy and depression often lift. However, in some patients, the depression persists, which means that successful therapy must address depression directly.

In this study, 10 patients with hypothyroidism underwent a cerebral 18-FDG/PET examination. She indicated that additional research is needed to determine whether special brain regions are responsible for increased depression or anxiety in patients suffering from hypothyroidism.

PET is a safe, highly specialized, noninvasive imaging technique that uses short-lived radioactive substances to produce three-dimensional images of those substances functioning within the body. A special type of camera works with computers to provide precise pictures of the areas of the body being imaged and molecular images of the body's biological functions.