Researchers have pinpointed a small region in the genome — the entirety of human hereditary information — as a vital factor in the development of psychiatric disease and obesity.
Brain-derived neurotrophic factor, or BDNF, is a nervous system growth factor that plays a critical role in brain development. To determine the role of BDNF in humans, McGill researchers screened over 35,000 people referred for genetic screening at clinics, as well as over 30,000 control subjects in the U.S., Canada and Europe.
Researchers found five individuals with BDNF deletions, all of whom were obese, had a mild-moderate intellectual impairment, and had a mood disorder.
The children had anxiety disorders, aggressive disorders, or attention deficit-hyperactivity disorder (ADHD), while post-pubescent individuals had anxiety and major depressive disorders. Subjects slowly gained weight with age, suggesting that obesity is a long-term process when BDNF is deleted.
The results of the new study, published in the Archives of General Psychiatry, reveal for the first time the link between BDNF deletion, cognition, and weight gain in humans.
“Scientists have been trying to find a region of the genome which plays a role in human psychopathology, searching for answers anywhere in our DNA that may give us a clue to the genetic causes of these types of disorders,” said Carl Ernst, Ph.D., from McGill’s Department of Psychiatry, Faculty of Medicine.
“Our study conclusively links a single region of the genome to mood and anxiety.”
Based on animal studies, BDNF has been a suspect of several functions in the brain, but no study has proven what happens when BDNF is missing from the human genome. The new study helps provide a better understanding of human behavior and mood by clearly identifying genes associated with mental disorders.
“Mood and anxiety can be seen like a house of cards. In this case, the walls of the house represent the myriad of biological interactions that maintain the structure,” said Ernst, who is also a researcher at the Douglas Mental Health University Institute.
“Studying these moving parts can be tricky, so teasing apart even a single event is important. Linking a deletion in BDNF conclusively to mood and anxiety really tells us that it is possible to dissect the biological pathways involved in determining how we feel and act.”
“We now have a molecular pathway we are confident is involved in psychopathology,” he adds. “Because thousands of genes are involved in mood, anxiety, or obesity, it allows us to root our studies on a solid foundation.”
“All of the participants in our study had mild-moderate intellectual disability, but most people with these cognitive problems do not have psychiatric problems — so what is it about deletion of BDNF that affects mood? My hope now is to test the hypothesis that boosting BDNF in people with anxiety or depression might improve brain health.”
Source: McGill University