Health factors may offer 90 percent accuracy in predicting mental illness

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New research from McGill University reveals that a wide range of early onset psychiatric problems may be largely due to the combination of three factors, dopamine, trauma, and temperament, according to a study published in the journal, Nature.  

Researchers determined that the first factor 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. The third factor is psychological, relating 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 attributes to target in early intervention, the researchers said.

For the study, to the authors examined all three factors together. Participants included 52 young people, 30 females and 22 males, living in the Montreal or Quebec City areas, who had been followed since birth. The subjects had positron emission tomography (PET) scans and magnetic resonance imaging (MRI) scans 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.

"Until recently, it was thought that psychiatric disorders reflected discrete disease entities, each with their own unique causes," said Marco Leyton, PhD, professor in McGill's Department of Psychiatry and senior scientist at the Research Institute of the McGill University Health Centre, in a statement. "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."

While each of these factors independently had at least modest effects on the development of mental illness, the authors found studying these factors together predicted more than 90 percent accuracy as to which participants had mental health issues either in the past or during the study’s three- year follow-up period. Researchers concluded that a combination of temperamental traits, childhood adversity, and poorly regulated dopamine transmission increases risk for diverse, commonly comorbid, early onset psychiatric problems.

These results have prompted The Canadian Institutes of Health Research (CIHR) to provide an additional $2 million to double the sample size and follow the participants to their mid-20s.

"The results do need to be replicated, both in larger and ethnically more diverse groups," Maisha Iqbal, the paper’s first author and a graduate student at McGill’s Integrated Program in Neuroscience, said in a statement. "If replicated, our research could transform the way we think about mental illnesses."