Grant: CIHR Fellowship

According to the World Health Organization, clinical depression is the leading cause of death and disability in moderate to high income nations, affecting up to 5% of Canadians at any one time. While currently available treatments often help, up to 40% of clinical depressions do not adequately respond. It is likely that clinical depression involves several biological mechanisms and that present treatments miss some of these mechanisms. The current study will investigate the possibility that inflammation is one of these overlooked mechanisms that is creating clinical depression. We think that an inflammatory response is part of this illness, as increased markers of inflammation outside the brain have been linked with depressive symptoms and exposures that create inflammation also create depressed mood. Also, a previous study found that substances that stimulate inflammation (called cytokines) are increased in the brain. However, no studies have examined whether markers of inflammation are present in the brain in people who are having clinical depression. We propose to brain scan people with clinical depression using a new kind of brain imaging method that can detect inflammation in the brain. Also, since we think present treatments do not affect brain inflammation, we wish to see if people with treatment resistant clinical depression have brain inflammation. This would be the first study to look at brain inflammation in people suffering from clinical depression. If we see increased brain inflammation in clinical depression and treatment resistant depression, then reducing brain inflammation may become a way to treat clinical depression.