FEATURE
Exploring the brain-gut connection in mental health An interview with Dr. Margaret Hahn
By Sally Wu
T
rillions of living microorganisms reside in pockets of bustling communities in the human body. An array of bacteria, viruses, fungi, and other microbes collectively form microbiomes—the microbial inhabitants that contribute to human health and well-being. Ongoing efforts by scientists to characterize the functions of microbes, specifically the gut microbiome, have discovered its tremendous impact on metabolism, the immune system, the heart, and other important physiological functions.1 We are only now beginning to understand and acknowledge the importance of having a healthy gut microbiome and its role in health and disease. More recently, studies have suggested that the gut microbiome may also affect mental health.2 Dr. Margaret Hahn (along with Dr. Daniel Mueller), their team at the Centre for Addiction and Mental Health (CAMH), and their collaborators at the Farncombe Institute at McMaster University are leading translational studies to investigate the complex interplay between the gut and the brain. Their research aims to better understand the underlying mechanisms of the metabolic burden observed in patients with schizophrenia. Dr. Hahn completed her undergraduate studies in biochemistry and immunology at McGill University. She has always 10 | IMS MAGAZINE FALL 2021 GI & GUT MICROBIOME
had an interest in metabolic pathways and how these may interact with the immune system. As she completed her MD at the University of Calgary, Dr. Hahn reminisced that “while I enjoyed medical school and seeing patients, I’ve always had the interest to discover novel things and to improve the care of patients. I always felt like the way to do that was through research.” As the “brain was a more undiscovered frontier…that has more potential for discovery and to further the care of patients”, she decided to complete her residency in psychiatry. She later completed her Doctoral degree at the Institute of Medical Science at the University of Toronto. “Thanks to Dr. Gary Remington who managed to convince me that on top of all these years of studies that a PhD was a good idea.” Dr. Hahn laughed and continued, “In the long run, it was a good idea because it gave me the background in not only psychiatry but [also] allowed me to focus on the metabolic comorbidity in schizophrenia.” As the Director of the Mental Health and Metabolism Clinic at CAMH, Dr. Hahn expressed that “working as a clinician in this field has highlighted the lack of ability to improve patient outcomes in so many domains. This includes the huge gaps in physical care and addressing the high cardiovascular mortality rates that represent the leading cause of death in
schizophrenia patients and other severe mental illnesses, [surpassing] suicide.” Even before patients with schizophrenia are prescribed antipsychotics, they present with premorbid metabolic dysregulation, particularly insulin resistance and dysglycemia.3 To make matters worse, antipsychotics additionally induce adverse metabolic side effects, such as insulin resistance, weight gain, and contribute to the very high prevalence of type 2 diabetes in patients.4 A potential culprit of this observed metabolic dysregulation is the gut microbiome. “There is a really complex interplay between the brain and body. We tend to treat each system separately. One of the systems that is linked to mental illness and most certainly a key aspect of metabolism is the gut microbiome,” Dr. Hahn explains. A few years ago, Dr. Hahn and Dr. Daniel Mueller along with other scientists in different areas of research at CAMH had the good fortune to receive a donation from the Farncombe family to ignite a collaboration between CAMH and the Farncombe Family Digestive Health Research Institute at McMaster University (Drs. Elena Verdu and Premysl Bercik) to conduct one of the first pilot projects examining the gut microbiome and mental health in Canada. Their interest and passion in the metabolic health of Graphic design by Amy Assabgui
