Cancer and Depression
Reported May 21, 2009
(Ivanhoe Newswire) People who receive a diagnosis of cancer are often depressed about it.
But is that depression just the result of getting the bad news, or is something else at play?
University of Chicago researchers who studied depression in rats with cancer believe theres a biological explanation. They find tumors produce substances associated with depression and then send these substances to the brain, where they cause depressive symptoms.
The researchers note rats are a good model for studies on depression and cancer because the animals have no idea they have the disease and thus cannot be psychologically depressed about it, so any change in their behavior has to have another cause. In the study, rats with tumors did exhibit behavioral changes. For example, they were less motivated to escape during a swimming test and less excited about receiving sugar water, something normal rats highly enjoy.
Blood work and brain studies then revealed these mice had higher levels of cytokines than healthy rats. Cytokines, which are produced by the immune system, have been associated with depression. The stress hormone corticosterone was dampened in mice with tumors as well. Corticosterone is known to help regulate cytokines.
Our research shows that two types of tumor-induced molecules, one secreted by the immune system and another by the stress axis, may be responsible for the depressive symptoms, study author Leah Pyter was quoted as saying.
SOURCE: Proceedings of the National Academy of Sciences, published online May 18, 2009
