A new study out of Ohio State University suggests that seniors who have more active thyroid glands are at an increased risk of depression.

Previous studies have shown the thyroid gland — a small gland located at the base of the neck that produces hormones that are responsible for hormone and growth — may play another important role in the body by influencing an individual’s mental health. Studies have shown that a thyroid that is overactive or underactive can put an individual at a greater risk of depression.

Researchers note that this most recent study is the first to find a direct link between depression and variations in thyroid activity within the normal range. For the study, researchers measured levels of the thyroid-stimulating hormone to figure out how active each participant’s thyroid was. The study involved a total of 1,503 people, and the average age was 70.

According to the researchers, thyroid-stimulating hormone prompts the thyroid to produce more hormones. When the thyroid levels are low, the thyroid gland is sufficiently active and is producing an adequate amount of thyroid hormones. In addition to measuring participants’ thyroid levels, the researchers also gauged their depression symptoms with a questionnaire. Then, the researchers continually monitored participants for signs of depression symptoms over a span of eight years.

Dr. Marco Medici, the author of the study and member of the Erasmus Medical Center in Rotterdam, said, “We found that older individuals with thyroid activity at the high end of the normal range had a substantially increased risk of developing depression over the course of an eight-year period compared to individuals who had less thyroid activity within the normal range.”

He further explained that the study shows that individuals who have slight changes in their thyroid function “may experience similar mental health effects as those with overt thyroid disorders” such as hypothyroidism, or underactive thyroid, and hyperthyroidism, which is an overactive thyroid.

Medici concluded that the results “provide insight into the powerful effects thyroid activity can have on emotions and mental health.”