Why do people engage in compulsive behaviors? It’s a question Bryan Cruz, PhD, has been turning over since his undergraduate days, and one that became impossible to set aside as he watched people close to him struggle with compulsive and addictive behaviors that didn’t fit neatly into simple explanations. What others might attribute to personality or circumstance, Dr. Cruz saw as something deeper. He saw biology. A question worth spending a career answering.
“Most of us have everyday habits we consider ‘addictive.’ But how does severe trauma turn a habit into a devastating, long-term cycle of addiction? That is exactly what my lab is trying to figure out,” he said about his work as a new faculty member at the University of Tennessee Health Sciences.
That curiosity, equal parts personal and scientific, has led Dr. Cruz to research one of the most stubborn and devastating problems in American medicine: the cycle of trauma and alcohol that traps so many veterans long after they’ve returned home.
Dr. Cruz joined UT Health Sciences as an assistant professor in the College of Medicine’s Department of Pharmacology, Addiction Science, and Toxicology in January 2026 after completing his postdoctoral training in San Diego. He recently received a prestigious federal grant that will give him the resources and runway to pursue his research in earnest: $749,000 from the National Institute on Alcohol Abuse and Alcoholism through a MOSAIC K99/R00 award. This competitive career development grant is specifically designed to support early-career scientists as they transition from mentored training into fully independent research. The two-phase structure of the award first provides protected time for advanced skill-building under expert guidance, then funds the launch of the recipient’s own research program. It is, in effect, an investment not just in a single study, but in a scientific career.
When Stress Gets Stuck
To help contextualize what he’s working on, Dr. Cruz explains what happens in the brain when trauma doesn’t heal on its own.
Deep inside the brain is a region called the central amygdala, a hub for processing fear, stress, and emotional memory. Under normal circumstances, the brain releases stress chemicals when danger is present, then dials them back when the threat passes. In people with PTSD, that dial gets stuck. A chemical called corticotropin-releasing factor, or CRF, keeps flooding the system long after the traumatic event is over.
“When these stress peptides are released in the brain, they directly drive an individual’s vulnerability to alcohol addiction,” Dr. Cruz explained. “This stress mechanism becomes constantly active. What we are seeing in both our models and in humans is that chronic alcohol exposure combined with PTSD creates an almost permanent rewiring of the brain.”
In other words, the brain is running its emergency stress response around the clock. For many veterans, alcohol becomes the only thing that quiets it.
Dr. Cruz doesn’t see this as a moral failing. He sees it as a biological trap. “Many individuals living with PTSD develop a profound vulnerability to addiction,” he said. “They turn to alcohol and other substances simply as a way to numb their intense physical and emotional pain.”
A Natural Brake on the Brain’s Alarm System
What makes Dr. Cruz’s research distinctive is what he’s found on the other side of that equation: a naturally occurring brain chemical that may be able to pump the brakes on the runaway stress response.
It’s called somatostatin, and Dr. Cruz describes it as an “anti-stress” counterpart to CRF. While CRF revs the system up, somatostatin appears capable of calming it down. When Dr. Cruz’s team infused somatostatin directly into the central amygdala of stressed rats that were drinking heavily, the animals drank less.
There is, however, a scientifically intriguing catch. The effect appears to be specific to males. In animals that experienced both PTSD and alcohol exposure, somatostatin levels dropped significantly in males but not in females.
“We’ve validated that in multiple ways,” Dr. Cruz said, describing gene expression analyses conducted across multiple approaches. “Consistently, SST is only decreased in the males and not the females. We’re still trying to identify why that’s happening.” Given that the overwhelming majority of combat veterans are male, this finding could have significant implications for how future treatments are designed and targeted.
A Faster Path to the Clinic
Perhaps the most immediately hopeful aspect of Dr. Cruz’s research is how far somatostatin has already traveled through the medical pipeline, though not yet for this particular purpose.
Synthetic versions of this peptide are already established treatments for certain neuroendocrine disorders. Major pharmaceutical companies have compounds in clinical trials that target the somatostatin system, and those drugs have already cleared many of the safety and regulatory hurdles that can bog down drug development for decades.
“One challenge for our team is finding a compound that can easily cross into the brain,” Dr. Cruz said. “If we can collaborate with a pharmaceutical company or a research team that already has a viable, systemically administered compound for this target, we will reach our long-term goal of developing a new therapy much sooner.”
The goal, in other words, is repurposing. If a compound already proven safe for neuroendocrine disorders can be shown to reduce alcohol craving and PTSD symptoms in veterans, the road to a prescription could be measured in years rather than decades.
“This research has real potential to reach real people.”
Vice Chancellor for Research Jessica Snowden, MD
That possibility is inseparable from what success means to Dr. Cruz, and it isn’t a Nobel Prize or a landmark publication. “I would really love to see this end up in a clinical trial,” he said. “It doesn’t have to alleviate the whole disease. If a compound that targets this mechanism can alleviate some of the symptoms — the hyperarousal, the irritability, the disrupted sleep — that is success to me.”
“What excites me about Dr. Cruz’s work is that it doesn’t start from scratch but builds on an existing body of knowledge in a smart, targeted way, ” said Jessica Snowden, MD, vice chancellor for Research at UT Health Sciences. “That kind of translational thinking, finding new solutions by connecting the dots between different areas of science, is how we get treatments to patients faster. This research has real potential to reach real people.”
What the Public Gets Wrong
Dr. Cruz is also candid about what he thinks most people misunderstand about veterans living with PTSD and alcohol use disorder.
“It is highly context-dependent,” he said. “There is a deep-seated memory component to trauma that directly drives the drinking behavior. I wish the public understood that this is not an easy disorder to overcome; it is an incredibly complex neurobiological disease.”
He pointed to growing public interest in psychedelics like ibogaine as evidence that people are beginning to grasp the role of traumatic memory in addiction. But he worries that the complexity of the underlying biology gets lost in the conversation. “Understanding the specific neurobiological mechanisms I am studying is a critical piece of the puzzle,” he said. “It will get us closer to understanding the complete etiology of the disease.”
Dr. Cruz has family in the military. He has met and presented his research to patients living with PTSD, and he has seen the way their eyes light up when they recognize themselves in the science. He came to this work through curiosity, stayed through fascination, and is now propelled by purpose.
The $749,000 NIAAA award will support three years of research — the beginning, as Dr. Cruz sees it, of building something lasting. If somatostatin bears out as a target, if the biology holds, if a compound can be tested in humans, if even some of the symptoms ease, then for veterans who have spent years trying to outrun their own nervous systems, that beginning could matter enormously.