SGH study aims to find missing link between abnormal thyroid function and depression

25 May 2010

Mrs Doris Tan, 35, had just been diagnosed with hypothyroidism, an underactive thyroid disorder. She was feeling low, had trouble sleeping and was losing weight. She was also complaining of lethargy and poor concentration which affected her ability to function as a school teacher. She was easily irritable and frequently lost her temper at her two young children. Slowly, she found herself unable to cope and had fleeting thoughts about ending her life.

During consultation for her thyroid condition, her doctor noticed that she looked depressed and cried frequently in his clinic. Concerned about her mood symptoms, he referred her for a psychiatric assessment. Even though she had no past history of psychiatric illnesses or any family history of mental illness, she was diagnosed to be suffering from depression. Luckily for Mrs Tan, her condition was detected and she responded well to supportive psychotherapy. Her mood began to improve as she continued with her treatment for her thyroid disorder.


Link between Depression and Thyroid

Depression is a condition which affects approximately 121 million people worldwide. Studies show that about 4 to 9 per cent of women and 2 to 3 per cent of men are depressed. In Singapore, 8.6 per cent of adults are found to be in depression.

Left untreated, depression can result in increased risk of suicide, substance abuse or dependence, lower occupational and academic achievements, increased absenteeism from work and school, and impaired social functioning which often results in interpersonal difficulties with family and friends. Depression can also adversely affect treatment outcomes in people with pre-existing conditions such as stroke, heart disease, and diabetes. Yet, the causes of depression are not fully understood.

Untreated underactive or overactive thyroid disorders may be the cause of depression. Although results have not been conclusive, studies have found associations between depression and abnormalities in thyroid antibodies, independent of thyroid hormone levels.

“Higher levels of a specific thyroid antibody and cytokines, which are proteins that serve as messengers between cells, have been found in depressed patients. We are trying to understand the effects of these changes beyond the thyroid gland and how they can contribute to illnesses such as depression. A study on this may lead to new information that will help us understand depression and lead to better treatment in the future,” said Associate Professor Daphne Khoo, Head and Senior Consultant, Department of Endocrinology, SGH.


SGH Study on Depression and Thyroid

To better understand how the thyroid antibodies, cytokines and hormones are linked to each other, researchers at the Singapore General Hospital (SGH) have recently embarked on a study to understand how abnormalities in the above can lead to depression.

Since its launch in February 2010, the study has managed to fully recruit the control group – 80 non-pregnant Chinese females between the ages of 21 and 60, with no major physical illnesses and who are not depressed.

The study will be comparing the control group with a group of symptomatic depressed patients to find out whether there is a difference in terms of thyroid hormones, thyroid antibodies and cytokines.

Depressed individuals with undetected thyroid diseases may benefit from participating in the study so that appropriate treatment can be recommended.

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