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As thyroid abnormalities can affect a person’s mood, experts speculate that thyroid hormones can treat depression. APRIL CHONG reports
 Feeling depressed for no apparent reason? It might be a good idea to check if your thyroid gland has something to do with it.
Researchers have, for some time, been building evidence that thyroid hormones may have an effect on mood.
If this link can be fully understood, it has the potential to prevent or treat depression.
The thyroid gland, located in the neck, produces hormones that control metabolism, which regulates vital body functions.
Studies over more than two decades have found links between depression and thyroid abnormalities, although the exact mechanism is still being investigated.
“Hypothyroidism is quite definitely associated with depression,” said Dr Soon Puay Cheow, senior consultant endocrinologist at the Soon Diabetes, Thyroid and Endocrinology Clinic.
Hypothyroidism is a condition where the gland produces too little thyroxine hormone. This leads to fatigue, lethargy, poor concentration and excessive sleepiness. These symptoms may translate to feelings of depression or extreme sadness and despair, added Dr Soon.
In 1997, a study published in the journal General Hospital Psychiatry found that up to 40 per cent of hypothyroid patients also showed signs of depression.
Hypothyroidism can arise for various reasons. One cause is autoimmune disease where the body mistakenly takes the thyroid to be foreign tissue and attacks it, causing the gland to become over or underactive.
The gland, in someone with autoimmune thyroid disease, may be producing more of certain antibodies which bind to proteins in the brain, hence altering his mood, said Associate Professor Daphne Khoo, head of endocrinology at Singapore General Hospital (SGH).
A second possible link is that cytokines – proteins involved in inflammation – are produced during autoimmune thyroid disease. This link may cause depression too, she said.
Meanwhile, some depressed patients who did not respond to the usual anti-depressants were found to get better with high doses of orally administered thyroid hormone instead. This is even when they did not have thyroid disease.
“So clearly, thyroid hormones can have an effect on mood,” Dr Khoo said.
Apart from an underactive thyroid causing depression, an overactive gland, or hyperthyroidism, can also be the culprit, although this is more often associated with anxiety.
A hyperthyroid patient usually has palpitations and nervousness.
However, as a patient’s thyroid hormone level may swing during treatment, it can cause reactive depression at times, said Dr Soon.
The inference that some forms of depression may be caused by a thyroid problem can open new doors to depression prevention or treatment.
For now, treatment for depression includes mainly anti-depressant medication and psychotherapy. In some cases, electrical treatment is necessary.
Depression hits about 121 million people worldwide. In Singapore, 8.6 per cent of adults are affected.
SGH is embarking on a study to find out why thyroid patients are prone to mood disorders and what this can mean for treatment. It is looking for volunteers – non-pregnant Chinese women between the ages of 21 and 60 who are depressed, but with no major physical illness.
Those who are interested may contact its clinical research coordinator on 6323-7532.
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