A new study of lab rats who were given cocaine is shedding new light on the cognition of addiction.
Identifying populations vulnerable to substance use disorder is an increasing focus for prevention strategies, yet scientists have long struggled to understand why certain people develop disorders while others do not.
The focus of this latest round of research was aversive cues, the unpleasant experiences that often accompany the consumption of addictive substances. These include but are not limited to bitter taste, smoke inhalation, and needle use.
Researchers say the initial reaction to these experiences can help determine individual susceptibility to addiction.
“Aversive cues matter from the very first exposure,” study author and University of Texas at El Paso biologist Travis Moschak, Ph.D said. He explained that while previous studies have explored the relationship between aversive cues and drug use, this is the first to study them as a paired experience from the very first instance of drug use.
In the new study, published on Wednesday in the journal Drug and Alcohol Dependence, nearly 30 lab rats had the opportunity to self-administer small doses of cocaine by placing their noses in a specified hole. Each hit of cocaine was preceded by a bitter-tasting dose of quinine.
Moshak and his team measured the response of the rats to this mixed positive-negative experience to gauge whether their distaste for quinine outweighed the joy of a coke high.
Three distinct patterns emerged among the cocaine rats — and the third was not what they expected.
One group expressed a strong aversion to the quinine and stopped taking the cocaine entirely. Moshak likens this response to a person who tries a drug, has a negative experience, and never does it again.
A second group began with low doses of blow before gradually increasing their intake, suggesting that the bitterness of the quinine was not enough of a deterrent to make them stop. The sweet high was worth the bad bitter, so to speak.
A third unexpected group began with heavy cocaine consumption that gradually tapered off.
“The third group surprised us,” Moschak said. “They seemed to have over-indulged, and the combination of too much cocaine and too much aversive stimulus took over.”
Moschak said that these findings can help explain why some individuals develop addictive patterns.
He added that future research will focus on the brain regions activated during the paired experience of drugs and aversive cues. He is hopeful this information will help his team and others better understand the genetic and biological differences that inform substance use and abuse.
Deaths involving cocaine spiked in 2022 — rising more than 12% in just one year.
“This is a fascinating study with great potential to help us better understand and address drug abuse in people,” said Robert Kirken, Ph.D., dean of the College of Science. “With further study, this research could lead to better ways to prevent and treat addiction.”
If you’re curious about where the rodents got their nose candy, it was procured through the National Institute on Drug Abuse’s Drug Supply Program, which supplies restricted substances for research purposes. At the conclusion of the study, the revved-up rats were taken off of the cocaine and were, according to the team, unharmed by the experience.
