Neuroscientist to investigate how meth abuse weakens brain’s protective barrier

October 30, 2013 | Research, UToday, Medicine and Life Sciences
By Meghan Cunningham

The combination of meth abuse and chronic stress compromises the brain’s protective barrier, leaving it more susceptible to dangerous viruses and bacteria, according to research by UT neuroscientist Dr. Bryan Yamamato.



A natural barrier comprised of tightly formed capillaries and other cells separates the brain from large potentially harmful molecules such as bacteria present in a person’s blood, but the abuse of methamphetamine combined with chronic stress causes that barrier to be more permeable, said Yamamoto, professor and chair of the UT Department of Neurosciences.

“Most drug addicts suffer from chronic stress and the combination of that and meth abuse causes the capillaries in the brain to leak,” Yamamoto said. “That situation puts the brain at risk for viruses and bacteria that previously wouldn’t have been able to enter the brain.”

It’s a specific concern for the gingivitis bacteria, also known as “meth mouth,” that many meth abusers suffer from, which could enter the brain and wreak havoc, Yamamoto said.

A new $2.2 million grant from the National Institutes of Health will allow Yamamoto and his collaborators, Dr. Nicolas Chiaia and Dr. Nicole Northrop, both faculty members in the Department of Neurosciences, to study this process using animal models and investigate what causes the opening in the blood-brain barrier and how long it persists.

Yamamoto proposes to use animals trained to self-administer meth by pressing a bar inside their cages to get a dose of the drug, and exposing them to unpredictable stressors in a manner that reflects how humans experience common stressors. The team will examine whether anti-inflammatory drugs help reduce the effects of the opening of the blood-brain barrier in these animals.

“The implications of this research go beyond individuals who are addicted to methamphetamine to understand how chronic stress impacts the brain and renders our brain more vulnerable,” Yamamoto said. “In contrast, the basic mechanisms revealed by our studies may provide insight for other scientists who are researching ways to temporarily and safely bypass the blood-brain barrier so drugs used to treat brain cancer that ordinarily do not cross the barrier can have greater access to the brain and be more effective.”

Meth abuse and manufacturing is increasing not only in the United States, but also around the world because of how easily and inexpensively it can be “cooked,” despite efforts to control the drugs and chemicals used to manufacture it, Yamamoto said. The drug is most commonly smoked or injected, causing a euphoric feeling when the brain releases the chemical dopamine, which is a neurotransmitter that controls pleasure.

The drug also became more widely known with the popularity of the AMC “Breaking Bad” television program that recently celebrated its series finale to much fanfare. In the show, chemistry teacher Walter White is diagnosed with lung cancer and turns to manufacturing meth to earn extra money to leave to his family.

“Meth abuse continues to grow worldwide and ‘Breaking Bad,’ I think, has opened a lot of people’s eyes to what is going on by depicting its damaging effects,” Yamamoto said. “I would hope the show does not glamorize methamphetamine and therefore would not increase the popularity of the drug.”

Yamamoto has been studying the impact of drugs such as methamphetamine and ecstasy on the brain for more than 20 years. He continues active research on how meth use affects the liver in a way that contributes to brain damage. Read more at

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