We know that there are many biological factors and changes that play into depression, but a recent study has released evidence that inflammation may be a significant cause of depression, driving some depression symptoms such as low mood, loss of appetite and reduced ability to sleep.
Inflammation is the body's biological reaction to an injury in an attempt to protect the injured area. For example, if you sprain your ankle, the muscle and area around the ankle will swell up in order to protect the injured ankle. However, the body can take inflammation too far, resulting in chronic pain when unprovoked or unnecessary inflammation takes place.
Researchers at the Centre for Addiction and Mental Health's (CAMH) Campbell Family Mental Health Research Institute in Toronto, Canada performed a study in which they performed positron emission tomography (PET) scans on 20 patients diagnosed with depression and 20 patients with a clean bill of health. The PET scans showed significant inflammation in the brains of the patients diagnosed with depression. In fact, the inflammation was most severe among participants with severe depression.
This information is critical because it means that brain inflammation that occurs independently of physical illness may be correlated with clinical depression. "This discovery has important implications for developing new treatments for a significant group of people who suffer from depression, says senior author Dr. Jeffrey Meyer, who holds a Canada Research Chair in the neurochemistry of major depression. "It provides a potential new target to either reverse the brain inflammation or shift to a more positive repair role, with the idea that it would alleviate symptoms."