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Q&A: The neural switch sparking relapse in addicts

Currently, 24 million Americans struggle with addiction, one of the most common culprits being prescription painkillers. Unfortunately, 80 to 90% of those who overcome this disease face the reality of relapse within the first year of recovery.

The University of Minnesota is driven to fight addiction and improve the lives of those affected by the epidemic.

HealthTalk spoke with Mark Thomas, Ph.D., Associate Professor in the Departments of Neuroscience and Psychology, who is researching the neural switch responsible for sparking intense cravings and causing relapse in recovering addicts.

HealthTalk: What drove you to specialize in this area?

Mark Thomas: My primary area of research is in what we call experience-dependent neuroplasticity; essentially, how does the brain change with experience?

I first specialized in this because of my fascination with how we learn information and how learning experiences change the human brain. As I delved deeper, it seemed like an opportunity to apply this field of study to help others overcome addiction. We know the brain is changing in maladaptive ways because of drug exposure. If we could understand those changes, we can potentially disrupt them to reduce problematic drug use.

HT:  Could you describe the goals and procedures involved in your cutting edge research?

MT: Our research is largely in a mouse model, where we are able to measure changes in the brain related to exposure to addictive substances. After measuring behavior, we introduce a drug free period and then them to stimuli that could provoke a relapse. These stimuli include exposing them to the drugs or similar situations associated with drugs, or creating a moderately stressful experience. In humans, that’s akin to going back to a neighborhood where a person used or seeing drug paraphernalia. These events can provoke intense cravings in addicts. We’re looking at how the brain and the addict’s behavior change with these stimuli, by studying the communication between nerve cells at synapses. The most recent approach we’ve been taking uses light pulse technologies to activate or inhibit highly sensitive neurons in ways that could disrupt relapse behavior.

HT:  How might your work shed light on similarities in drug responses between rodents and humans?

Rodents have a surprising degree of similarity to humans in terms of their neuroanatomy, including the neurotransmitters that communicate between groups of neurons. This is especially true for “reward circuits” that control our natural response to stimuli like food, sex, and building social networks. With resources available here at the U, we’re starting to do brain imaging in rodents that has been done in people for some time. This will help us draw the links between mice and humans for brain changes that contribute to addiction.

HT: What advancements in addiction research do you envision happening within the next 10 years? How do you think the multidisciplinary approach taken by the U of M will contribute to these advancements?

MT: I think there will be advancements in pain medications reducing reliance on these addictive substances. Nonetheless, there will still be plenty of patients who become addicted. For these patients there are some new biology based treatments, like vaccines, destroying drugs in the bloodstream before they reach the brain. Researchers are also working on ways of fine tuning brain circuits to disrupt craving, promoting longer periods free from problematic drug use. My lab collaborates with psychiatry, radiology, pharmacology and medicinal chemistry to work toward making these discoveries. With the Medical Discovery Team on Addiction now forming at the University of Minnesota, we have an opportunity to produce even stronger links between efforts in different departments across the health sciences.

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