What’s New in Psychology?

Are We Closer to Understanding What Causes Psychiatric Disorders?

Jim Windell

             What causes psychiatric disorders?

             That’s a very difficult question to answer. In fact, perhaps no one can answer this kind of question in a definitive way while backing up their answer with scientific evidence.

            Of course, many psychological and psychiatric theories attempt to suggest the causes of mental health disorders. And various treatment approaches are built on theories of causation. But, it can certainly be said that there is no consensus in the mental heath field as to the causes of the most common psychiatric disorders – anxiety, depression, bipolar disorders and schizophrenia.

            However, a study from McGill University is proposing a new way of looking at mental illness and the causes of mental disorders.

             In a recently published paper called “A three-factor model of common early onset psychiatric disorders: temperament, adversity, and dopamine,” the authors propose that a wide range of early onset psychiatric problems may be largely due to the combination of just three factors. Those three factors may help explain why people suffer from such disorders as depression, anxiety, dyslexia, bulimia and ADHD, among a variety of typical mental health disorders.

          The three factors identified in this study are 1.) Biological; 2.)  Social and, 3.) Psychological. The McGill researchers suggest that biological factors have to do with the form of individual variability in the brain's dopamine reward pathway. As far as social factors, the study indicates that this factor relates to the important role of early childhood neglect or abuse. The third factor, the psychological factor, relates to temperament, particularly to tendencies toward impulsivity and difficulty controlling emotions. These findings, the researchers suggest, have implications for understanding both the causes of a wide range of psychiatric disorders and the features worth targeting in early intervention efforts.

           Previous research has implicated these three factors and it has been suggested that by themselves each has at least modest effects on the development of psychiatric disorders. However, in this study, the authors had the first ever opportunity to examine all three factors together. To conduct the study, the researchers used research from other investigators who followed from birth 52 people (30 women and 22 men) living in the Montreal or Quebec City areas.  The other researchers, Jean Séguin (Université de Montréal) and Michel Boivin (Université Laval), used brain imaging scans (PET and MRI) that measured features of the participant’s dopamine reward pathway. These brain features were then combined with information about their temperamental traits and histories of early life adversity.

            Taking this information, the McGill team found that 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. Because the initials results are so novel and potentially so important, further research will double the sample size and follow the participants through to their mid-20s.

           Agreeing that the results need to be replicated, the paper's first author, Maisha Iqbal, a graduate student in McGill's Integrated Program in Neuroscience, comments that, “If replicated, our research could transform the way we think about mental illnesses.”

           The senior author of the study, Marco Leyton, a professor in McGill's Department of Psychiatry and Senior Scientist at the Research Institute of the McGill University Health Centre, notes that “Until recently, it was thought that psychiatric disorders reflected discrete disease entities, each with their own unique causes.” Leyton goes on to say that the present research, published in the journal Neuropsychopharmacology, could change the thinking about the causes of mental disorders. He says their study suggests that “most early onset disorders largely reflect differential expressions of a small number of biological, psychological and social factors.”

            If the attempts to replicate the findings of this study are positive, our understanding and treatment of psychiatric disorders would have to change.  

           To read the original article, find it with this reference:

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. (2021). A three-factor model of common early onset psychiatric disorders: temperament, adversity, and dopamine. Neuropsychopharmacology; DOI: 10.1038/s41386-021-01187-z