Elevated Opioid Neurotransmitter Activity Found in Anorexia Patients

A recent investigation conducted at the Turku PET Center in Finland has unveiled significant insights into the neurobiological underpinnings of anorexia nervosa, a serious psychiatric condition marked by extreme dietary restrictions, an intense fear of weight gain, and disturbed body image. The findings were introduced in the journal Molecular Psychiatry on January 12, 2025.

This study highlights the role of opioid neurotransmitters in appetite regulation and pleasure perception within the brain. Researchers discovered that individuals suffering from anorexia nervosa exhibited heightened activity of opioidergic neurotransmission when compared to healthy counterparts. Interestingly, previous research indicated that this system's activity is diminished in individuals with obesity, suggesting a complex interplay between appetite regulation and body weight.

Professor Pirjo Nuutila, a prominent figure at the University of Turku, emphasized the dual nature of these neurotransmitters, suggesting that they may influence both appetite suppression and stimulation. Additionally, the study assessed glucose uptake in the brain, as the organ accounts for approximately 20% of the body's overall energy use. Understanding the brain's energy balance is crucial, particularly in contexts of reduced caloric intake.

Despite the physical toll of anorexia, including significant weight loss, findings indicate that the brains of these patients utilize glucose at levels comparable to those of healthy individuals. Professor Lauri Nummenmaa, also from the Turku PET Center, commented on the brain's resilience, noting that it strives to maintain its functionality even under severe nutritional deficits.

The research indicates that alterations in brain function related to appetite and feeding behavior are not only associated with obesity but also with low body weight conditions like anorexia. Furthermore, the connection between altered opioid activity and emotional disturbances, such as anxiety and depression, could provide valuable insights into the psychological symptoms often seen in anorexia nervosa.

This study was a collaborative effort involving the Turku University Hospital and Pusan National University in South Korea. The imaging of brain activity in both anorexia patients and healthy controls was conducted using positron emission tomography (PET) technology at the Turku PET Center, enabling researchers to visualize the differences in neurotransmitter activity.

The implications of this research could be profound, potentially guiding future therapeutic approaches for individuals struggling with anorexia nervosa by targeting the underlying neurobiological mechanisms.