Recently, two patients in my practice illustrated the diverse psychiatric and medical effects of a single medication.
A 35-year-old woman taking semaglutide noticed within a week that her desire for alcohol diminished and the persistent "food noise" in her mind nearly disappeared. At five feet five inches tall, her weight decreased from 210 pounds to 145 pounds. She started her own business, teaching infants and mothers in a swimming pool, and now wears a swimsuit with confidence.
A 60-year-old businessman, after receiving a low dose of tirzepatide, observed improvements in his arthritis and chronic inflammatory bowel disease. He now is able to enjoy foods that previously caused him significant discomfort.
Semaglutide (Wegovy) and tirzepatide (Zepbound) were originally developed to treat diabetes and obesity. How could these medications positively influence alcohol consumption, food cravings, arthritis, and bowel disease?
Semaglutide and tirzepatide mimic a class of molecules known as incretins. Molecules are the building blocks of all chemical structures in your body. Incretins function as hormones, which your body utilizes for internal communication. These incretins are produced in your gastrointestinal tract, often called the second brain, and in your brainstem, also referred to as the reptilian brain.
Incretins interact with and control your gastrointestinal tract, cardiovascular system, kidneys, and immune system, influencing at least six distinct areas in your brain.
How can one type of signal result in such a wide range of effects? Evolution provides a framework for grasping this phenomenon. In his exceptional book Life Ascending, Nick Lane, a biochemist and Professor of Evolutionary Biochemistry at University College London, remarks, "The deepest question of all is why complex life emerged just once in the entire history of life on our planet." His book is my favorite among those I surveyed to understand evolution.
When complex life emerged billions of years ago, evolution followed intricate paths with numerous diversions. However, simplicity offered advantages in conserving energy, adapting quickly, and maintaining structural stability. Evolution consistently employs efficient signaling systems for diverse functions.
Roger McIntyre, a psychiatrist and Professor of Psychiatry and Pharmacology at the University of Toronto, is a leading brain researcher and a trailblazer in incretin studies, and as I have come to appreciate, an outstanding educator. In an article published this year in Psychiatry and Clinical Psychopharmacology, he notes:
"...preclinical, neuroimaging, observational, and emergent contr0lled trial data evidence suggests that incretin receptor agonists may exert direct central nervous effects - augmenting neurogenesis, neuroplasticity, and functional connectivity..."
Dr. McIntyre suggests that incretins could promote the development of new neurons in the human brain and improve the connections among the brain's eighty-six billion neurons. Neurons provide the matrix for communication within the brain.
Your body is made up of around thirty trillion cells that form dozens of organs, all in constant and immediate communication. Despite this intricate system, there is a fundamental simplicity. Ancient biological systems, maintained over millennia, use the same molecules to transmit signals throughout your body. Incretins are involved in a sequence that influences other bodily signals. In the brain, they manage dopamine, serotonin, and other neurotransmitters. Simplicity gives rise to complexity.
Semaglutide and tirzepatide represent the beginning. Many new incretin analogues or molecular mimics are actively being researched. The next decade will provide a much deeper understanding of incretins.
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