Psychobiology of Adolescent Depression

Individuals who develop depression in adolescence are more likely to have a severe course with multiple episodes throughout their lives. Also, they have increased risk of academic difficulties, disrupted relationships with family and peers, medical problems, and delinquency. An important force in causing depression early in life is a heightened sensitivity to stress. Individuals who are especially sensitive to stress in their lives will be more likely to get depressed when faced with stressful life events (e.g. a relationship break-up). This project is the first to examine how genetic factors combine with an early environment of abuse and neglect to heighten individuals' sensitivity to stress. We hypothesize that genetic vulnerability (examined by assessing the 5-HTT gene, which has a strong link to depression) and severe childhood adversity (i.e. abuse and neglect) increase vulnerability to a first onset of depression through the mechanism of heightened sensitivity to stress. This project has received funding from the Ontario Mental Health Foundation, the Centre for Addiction and Mental Health, and Bombadier Inc.
 

Blue Sky Project

The transition from adolescence to adulthood can be difficult at the best of times, and, thus, it is not surprising that this is the period of greatest risk for the development of major depressive disorder (MDD). Individuals with a first episode of MDD at this time are at great risk for a recurrent and chronic course of the disorder throughout their lives, and are at risk for significant dysfunction in their academic, occupational, and interpersonal spheres. The goal of the Blue Sky Project is to improve the identification of first-episode depression and to better understand the biological, psychological, and environmental factors that trigger the disorder. This study is recruiting young people (age 18-29) on their first episode of MDD.  We are specifically predicting that particular genetic polymorphisms will interact with a traumatic early life history to increase individuals’ dispositional response to stress through personality and cognitive factors (e.g., Neuroticism, rumination). This project is funded by the Canadian Institutes for Health Research.
 

Theory of Mind

Depression is often associated with profound difficulties in interpersonal functioning and, specifically, a bias to perceive social interactions very negatively. This area of research, in collaboration with Mark Sabbagh and Jill Jacobson, is investigating "theory of mind" as a basic social cognitive skill that might underlie this difficulty. Theory of mind is the everyday ability to make judgments about others' mental states (e.g., emotions, beliefs, desires). We have determined that mildly depressed individuals are significantly better at judging the emotional state portrayed by pictures of eyes when compared to non-depressed individuals. In contrast, clinically depressed patients are significantly worse at judging these emotional states when compared to non-depressed controls. In mood induction studies we have also determined that individuals with a past clinical depression are also significantly better at judging emotional states when compared to never-depressed individuals. Further, making past-depressed individuals happier through mood induction makes them worse at judging others’ mental states. This suggests that mild to moderate depression may be associated with a trait towards hypervigilance to subtle social cues that provide information regarding others' emotional states. In contrast, the state of severe clinical depression may be associated with an impairment in attending to these cues. We are currently following up on this research to determine the mechanism through which mild depression confers an advantage in mental state decoding.