Depression, Hormones & The Immune System

Medical Reviewer

Reading Deborah Gray's Sharepost on Depression and Nutritional Health , got me thinking about the ways our hormones can affect mood. Deborah makes the same point and discusses it further in Depression and Thyroid Disease.

Anyone who has ever gone to see their doctor with symptoms of depression will know that one of the first things they do is send a blood sample off for testing. The reason they do this is to rule out any damage that may have resulted from hormone-producing organs that can give rise to symptoms of depression.

There are a number of hormone-producing organs such as the thyroid, adrenal and pineal glands that can affect brain function and cause depression. Neurotransmitter activity is intimately connected with hormonal activity, so any disruption can induce depression in the long term.

One of the culprits is the thyroid gland. Insufficient secretion of thyroxine (hypothyroidism) causes early symptoms that could be confused with depression. The person may complain of feeling the cold more, of feeling fatigue, muscle pain and weakness. They may put on weight and generally feel more sluggish and slow.

Increased activity in the parathyroid gland (small glands in the neck behind the thyroid), which regulate calcium metabolism, may also initially cause depression symptoms.

Many people have heard of cortisol and know it as the stress hormone, although it has more complex functions. Cortisol is secreted by the by the adrenal gland and too much cortisol (Cushing's disease) or too little (Addison's disease) can result in depression.

Viruses affect hormones, and a severe virus, such as influenza, can cause symptoms of depression. Viruses attack the immune system, which affects the hormonal system. Very often, people with a high risk of depression have relative ineffective immune systems. A dose of flu can affect mood-regulating hormones and leave people feeling despondent or depressed after the main flu symptoms have subsided.

People who are already depressed will find their immune system is already down-regulated. This leaves them even more prone to infection and a vicious circle of low moods and infections can follow. This is why it is so very important to eat well, exercise regularly and maintain a healthy lifestyle. It may not prevent all infections or low moods, but it will help speed recovery and quite possibly prevent infections that might otherwise take hold.


Eckman, E. S. (2010, April 19). Pubmed health. Retrieved from