Razi Berry

The causes of psychiatric disorders are poorly understood. Now, in work led by researchers at McGill University, there is evidence that a wide range of early onset psychiatric problems (from depression, anxiety and addictions to dyslexia, bulimia, and ADHD) may be largely due to the combination of just three factors. The first is biological — in the form of individual variability in the brain’s dopamine reward pathway. The second is social — and points to the important role of early childhood neglect or abuse. And the third is psychological — and relates to temperament, and particularly to tendencies toward impulsivity and difficulty controlling emotions. These findings have implications for understanding both the causes of a wide range of psychiatric disorders and the features worth targeting in early intervention efforts.

“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 Neuropsychopharmacology and 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.”

1. Maisha Iqbal, Sylvia Maria Leonarda Cox, Natalia Jaworska, Maria Tippler, Natalie Castellanos-Ryan, Sophie Parent, Alain Dagher, Frank Vitaro, Mara R. Brendgen, Michel Boivin, Robert O. Pihl, Sylvana M. Côté, Richard E. Tremblay, Jean R. Séguin, Marco Leyton. A three-factor model of common early onset psychiatric disorders: temperament, adversity, and dopamine. Neuropsychopharmacology, 2021; DOI: 10.1038/s41386-021-01187-z

Razi Berry is the founder and publisher of the journal Naturopathic Doctor News & Review, which has been in print since 2005, and the premier consumer-faced website of naturopathic medicine, NaturalPath. She is the host of The Love is Medicine Project docuseries, The Natural Cancer Prevention Summit, The Heart Revolution-Heal, Empower and Follow Your Heart, and the popular 10-week Sugar Free Summer program. From a near death experience as a young girl that healed her failing heart, to later overcoming infertility and chronic fatigue syndrome and fibromyalgia through naturopathic medicine, Razi has lived the mind/body healing paradigm. Her projects uniquely capture the tradition and philosophy of naturopathy: The healing power of nature, the vital life force in every living thing and the undeniable role that science and mind/body medicine have in creating health and overcoming dis-ease. You can follow Razi on social media: Facebook at Razi Berry, Instagram at Razi.Berry and join the Love is Medicine group to explore the convergence of love and health. Look for more, and listen to more Love is Medicine podcast episodes here.

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