A new understanding of mental illness

"Until recently, it was thought that psychiatric disorders reflected discrete disease entities, each with their own unique causes," says Marco Leyton, the senior author on a recent study published in Neuropsychopharmacologyand a professor in McGill's Department of Psychiatry and Senior Scientist at the Research Institute of the McGill University Health Centre. "The present research upends this idea, suggesting instead that most early onset disorders largely reflect differential expressions of a small number of biological, psychological and social factors."

First study to combine three key factors: temperament, trauma and dopamine

Earlier research has suggested that each of the three factors, in isolation, has at least modest effects on the development of psychiatric disorders. In comparison, the authors of this new study had the first ever opportunity to examine all three factors together. Fifty-two young people, living in the Montreal or Quebec City areas (30 women and 22 men), who have been followed since birth by Jean Séguin (Université de Montréal) and Michel Boivin (Université Laval), had brain imaging scans (PET and MRI) that measured features of their dopamine reward pathway. These brain features were then combined with information about their temperamental traits and histories of early life adversity.

High accuracy & potential predictive value of approach

Strikingly, this combination of just three factors predicted, with over 90% accuracy, which participants had mental health problems either in the past or during the study's three-year follow-up period. Indeed, since the results are so novel and potentially so important, CIHR has provided an additional two million dollars to double the sample size and follow the participants through to their mid-20s. "And the results do need to be replicated, both in larger and ethnically more diverse groups," emphasizes the paper's first author, Maisha Iqbal, a graduate student in McGill's Integrated Program in Neuroscience. "If replicated, our research could transform the way we think about mental illnesses."