UBC Reports | Vol. 47 | No. 17 | November 1 , 2001

Researcher probes link between flu, depression

The work of a pioneering UBC psychiatrist suggests feeling blue might not be all in your head

Can a bout of flu trigger an episode of depression? UBC Psychiatry Asst. Prof. Cai Song thinks so. She has spent the last 12 years looking at the interactions between the brain and the immune system.

"These are two very complicated systems," she says. "It's very difficult for scientists to link them together. Psychiatrists and immunologists usually don't talk."

Song, a faculty member since 1999, is particularly interested in the relationship between immune disorders and depression.

"Anti-depressants have been used for half a century but they are effective only about 60 per cent of the time and many patients cannot be completely cured," she says. "There must be a better way. We need a revolution."

Her goal is to find drugs or natural nutrition sources that would nourish the immune system without negative side effects and to develop better treatment for depression.

Song has a medical degree in Chinese medicine that informs her holistic approach to health and a PhD in Neuropharmacology with a focus on Neuroimmunology. She examines both the microbiological and behavioural links between the nervous and immune systems.

The discipline, called psychoneuroimmunology, was not well researched until the last decade, she says. She co-authored the first text ever to explore the area.

Her research has shown that depressed patients show abnormalities in their immune system and, conversely, that alterations in the immune system can trigger chemical changes in the brain that result in depression, anxiety and impaired memory.

For example, cancer patients who receive treatments to boost their immune system can experience mental disturbances and develop depression. Traumatic events and illnesses that disturb the immune system may also have a negative effect on the chemical balance needed to keep the brain functioning normally.

In addition, antidepressants may be helpful when the immune system is hyper-activated because of autoimmune disorders. These include multiple sclerosis, lupus, psoriasis and rheumatoid arthritis.

Song emphasizes that not all psychiatric illnesses are related to immune disorders, however, ignoring the links can be dangerous. Many antidepressants have severe side effects and are toxic to the immune system -- the patient's psychiatric health may improve but their overall health may decline as treatment continues.

Also, when patients with painful immune diseases such as lupus report symptoms of depression, physicians often believe the depression is connected to the pain, she says. Song argues that the depression is actually caused by chemical changes in the brain triggered by the distressed immune system.

Her research in Alzheimer's patients shows immune changes that differed from normal aging.

She suspects the disease may be related to an autoimmune disorder caused by aging of the thymus gland which plays an important role in the development of immune responsiveness. The finding could lead to new therapy options for Alzheimer's patients, she says.

In July, Song received a Canadian Institutes of Health Research grant to further her investigations of the brain and immune systems in depression and Alzheimer's disease.