Feeling blue after your flu?
New research shows that there is a link between certain illnesses and depression.
"There is a relationship," said UBC psychiatry assistant professor Cai Song who has been studying the connection for the last 12 years.
She has found that illnesses which affect the immune system cause the release of a small protein which travels to the brain. This protein, released by immune system cells, causes changes in brain chemistry and also changes in hormone levels. These chemical changes cause depression, anxiety and impaired memory.
Scientists have known for some time about the alteration in these chemical levels in depressed patients, said Song.
"This is the same as we see in depressed patients," she said.
But learning that immune disorders can also cause the chemical alterations is an important breakthrough.
Not everyone who gets the flu will get depressed, said Song. Most are healthy enough to fight off the virus and cope with the chemical changes.
But for those few, who have a genetic disposition toward auto immune disorders, a case of the flu can trigger a serious bout of depression.
"I have had several patients with auto immune problems like arthritis, psoriasis, and multiple sclerosis and those kinds of diseases, and when they get a flu their depression can last for half a year and can take a long time for them to go back to normal," said Song.
She hopes this discovery will lead to new ways to treat depressed people.
"Anti-depressants have been used for half a century but they are effective in only about 60 per cent of the time and many patients cannot be completely cured," said Song.
"There must be a better way. We need a revolution."
Song, who has a degree in Chinese medicine and believes in a holistic approach to treating patients, is looking at using Omega 3 fatty acids, found in small quantities in some fish, to treat patients.
"We want to find natural sources to nourish the immune system," said Song.
She is also exploring how to suppress the release of the immune cell protein responsible for the chemical changes.
Song has also found the immune cell protein in cancer patients who have received treatments to boost their immune system. These patients 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.
Song has noted that tissue damage found for example in stroke patients can also be linked to depression through the release of the protein by immune cells.
"Stroke patients can have depression that lasts several months until the tissue damage is repaired," she said.
Chronically stressed people can get caught up in a vicious circle. Their stress makes them depressed, said Song, which affects their immune system, which then releases the protein linked to depression, making their condition worse.
"It can be serious," said Song.
Not all psychiatric illnesses are related to immune disorders, said Song, but ignoring the link can be dangerous.