Grant: Doctoral Research Award: Canada Graduate Scholarships

Major depressive disorder (MDD) is a debilitating condition that affects over 300 million individuals worldwide. Approximately 75% of these individuals experience sleep problems. These sleep problems are associated with a greater negative impact. Studies measuring the electrical activity of brain waves and body movements (actigraphy) during sleep have become valuable tools for studying sleep patterns in humans. There is even evidence to suggest that these sleep patterns are, at least partially, regulated by genes. Studies employing this technology have discovered several differences between the sleep patterns in MDD patients and healthy individuals ("sleep signatures"). Our biological target is the mitochondrial system because of prior evidence suggesting its involvement in MDD and sleep. In this proposal, we aim to combine genetics, electrical brain activity measures and actigraphy to identify sleep signatures in MDD individuals. We will also investigate whether any of the sleep signatures or genes studied can be used to predict which MDD individuals will respond to their antidepressant medication. In our approach, we will collect data from 100 MDD patients and 100 healthy individuals. First, we will examine whether there are alterations in the sleep patterns between our MDD patients and healthy individuals to identify which sleep signatures are present in our MDD sample. Next, we will perform association analyses to determine if any genetic markers from our susceptibility genes are associated with these sleep signatures, and whether any of the genetic markers or sleep signatures are associated with antidepressant response. Lastly, we will incorporate these results into a computational model that we can use to classify patient subgroups and predict at-risk populations in larger datasets. Overall, the results from this study will shed light on the genetics of problematic sleep in MDD and could provide evidence for a distinct subtype of MDD.