When depression starts in the neck

When someone develops depression, the brain usually becomes the focus of attention. But other organs can be the source of the problem. A common example is when the thyroid gland produces too little hormone — a condition known as hypothyroidism.

Nearly 10 million Americans suffer from hypothyroidism. The condition is much more common in women than in men, and becomes more prevalent with age. As many as one in five women will develop hypothyroidism by age 60.

Although researchers aren’t entirely sure why there is a link between hypothyroidism and depression, it is likely that some people are taking antidepressants when they should really be taking thyroid medication. Here is a brief review of when clinicians and patients should consider hypothyroidism as a possible cause of low mood — and what to do next.

The thyroid gland is a small butterfly-shaped structure that sits low in the neck, below the Adam’s apple (a protrusion made of cartilage that both women and men have). Although it weighs less than an ounce, the thyroid exerts a powerful influence throughout the body. It does so by secreting hormones that affect metabolism, a chemical activity that controls how fast and efficiently cells convert nutrients into energy. By regulating metabolism, the thyroid indirectly affects every cell, tissue, and organ in the body — from muscles, bones, and skin to the digestive tract, heart, and brain.

The thyroid, in turn, is regulated by the pituitary or “master” gland. The pituitary gland (a pea-sized gland that sits beneath the brain) constantly monitors blood levels of hormones, including those produced by the thyroid. When blood levels of thyroid hormones fall, the pituitary gland uses a chemical signal known as thyroid-stimulating hormone (TSH) to prompt the thyroid to pump up production. In response, the thyroid uses iodine from food to produce two hormones. Triiodothyronine, known as T3, contains three iodine atoms, while thyroxine, or T4, contains four. A normally functioning thyroid gland, working in conjunction with the pituitary gland, secretes T3 and T4 into the bloodstream at a steady pace.

In a person with hypothyroidism, however, the thyroid gland does not fully respond to TSH, so blood levels of T3 and T4 remain low. Assuming the pituitary is functioning normally, TSH levels rise; physicians often use the TSHlevel to help make a diagnosis of hypothyroidism.

When thyroid hormone levels are low, many organs and internal systems slow down, creating a wide range of symptoms — including depression. People over 60 may have only one symptom — such as mood impairment or difficulty concentrating.