Theravive Home

A new study published in the Journal of Neuropharmacology looked at whether a sensation-seeking trait confers a dormant susceptibility to addiction through intermittent cocaine self-administration in rats. The advantage of studying this phenomenon in rats is that researchers can examine what is different about the brains of high- versus low- sensation-seeking rats. This will help identify new targets for medications designed to treat cocaine use disorder.

“Many people experiment with illicit drugs such as cocaine or heroin during their lifetime,” study author Dr. Morgan James told us. “The majority of people who experiment with drugs do not go on to abuse drugs in a manner that interferes with their daily functioning. However, a small proportion of the population are susceptible to developing problematic patterns of drug use that become debilitating. Here, we studied whether a behavioral trait known as sensation-seeking can predict a person’s addiction vulnerability before they have any drug experience.”

Over 35 million people in the United States over the age of 12 have tried cocaine. Previous studies have indicated that sensation-seekers, or people with a desire for intense and novel experiences and who are more willing to take risks, have a greater likelihood of developing drug dependence problems. Similar to humans, some rats have stronger sensation-seeking tendencies.

“We can test this by measuring their willingness to explore a novel environment,” Dr. James told us. “We predicted that those rats who exhibited higher sensation seeking would be more susceptible to developing problematic drug use patterns when allowed to press a lever for cocaine infusions.”

Substance use disorders inflict significant suffering on the afflicted individual, their family, and society more generally. By identifying personality traits that predict an individual’s propensity to develop substance abuse problems, Dr. James explained to us, we can better tailor interventions – both pharmacological and societal – to prevent the development of addictions in at-risk persons.

Rats were tested for the sensation-seeking trait and then trained to press a lever for cocaine.
Following initial training, rats were allowed to ‘binge’ on cocaine repeatedly throughout the day, similar to how humans use cocaine. Researchers then tested the rat’s motivation for cocaine by asking how hard they were willing to ‘work’ to earn their cocaine. To do this, they increased the number of times the rat needed to press the lever to maintain a steady level of cocaine intake.

“Prior to being allowed to binge on cocaine, there was no difference in drug taking behaviors between high- and low- sensation-seeking rats,” Dr. James told us. “Interestingly, when rats were allowed to binge on cocaine, stark differences began to emerge between the two groups.”

Rats that scored high on sensation-seeking test were more likely to show human-like addiction behaviors, compared to rats that scored low on the sensation-seeking test. High sensation-seeking rats progressively increased their cocaine intake across the cocaine binge sessions, whereas low sensation-seeking rats maintained a relatively stable level of intake.

While all rats had higher motivation for cocaine following the cocaine binge sessions, the biggest increases in drug motivation were observed in the high sensation-seeking rats.

“Previous studies indicate that high sensation-seeking individuals are inherently more ‘at risk’ of developing an addiction,” Dr. James told us. “Our data point to an important gene x environment interaction in the development of addiction, whereby high sensation-seeking individuals are more at risk of developing problematic drug use only following repeated cocaine binges.”

Dr. James believes it will be important for future studies to examine whether the sensation-seeking trait can also predict vulnerability to developing problematic behaviors following binge consumption of opioids such as heroin and fentanyl, both of which are contributing to the ongoing opioid crisis in the United States.