New study reveals distinct differences in how different drugs relate to criminal behavior

A study published in the Journal of Psychopharmacology suggests that different substances have vastly different associations with criminal behavior and police arrests. The research indicates that while some psychedelics like psilocybin tend to be associated with lower rates of arrest, other substances like PCP and GHB show strong links to violent and non-violent crimes. These findings provide evidence that the influence of drugs on society is not uniform and depends heavily on the specific substance being used.

Jesse J. Norris, an associate professor of criminal justice at the State University of New York at Fredonia, conducted this research to examine the role of substances that scientists do not often study in relation to crime. He noticed that much research focuses on common drugs like alcohol or cannabis but rarely looks at chemicals like phencyclidine, which is also known as PCP. He wanted to explore how these less common substances relate to both police arrests and crimes that people report themselves.

Norris explained that two specific motivations led him to explore this topic. “First, PCP is stereotypically associated with extreme violence, and there are certainly some anecdotes to support that, in which people under the influence of PCP committed cannibalism or beheaded someone, for example,” Norris said. He realized there was very little systematic research on PCP and no broad agreement about its association with violence.

Since the National Survey on Drug Use and Health collects data on criminal activity and PCP use, he decided to test for associations between the two. This survey is a nationally representative study, which means it is a survey of tens of thousands of Americans designed to reflect the demographics of the whole country. Norris intended to see if the violent stories associated with PCP were reflected in a large group of people.

The second reason for the study involved recent evidence suggesting that psilocybin use is associated with a lower chance of being arrested for various offenses. While these findings are interesting, Norris thought the logical next step was to conduct a broader analysis. This analysis would incorporate all psychedelic drugs and all available measures of criminal activity.

Free daily newsletter

“Therefore, in this study, which is based on the responses of over 500,000 US residents from 10 years of NSDUH data, I examined associations between each psychedelic drug and various outcomes, including arrest for several different offenses, and self-reported criminal activity like attacking other people and repeated thefts,” Norris explained.

He noted that this kind of research is important because psychedelics are becoming more popular among researchers and the public. He believes we need to have a good evidence base for understanding the potential impacts of psychedelics on people’s behavior.

The researcher used data from the National Survey on Drug Use and Health collected between 2014 and 2023. This resulted in a total sample size of 544,740 people. The survey asks participants about their drug use at different times, such as within the last month, the last year, or at any point in their lives. It also asks if they have been arrested for various crimes, including assault, theft, or driving under the influence.

Additionally, the survey includes questions where people admit to committing crimes, such as selling drugs or attacking someone, even if they were never caught. To analyze this information, Norris used a method called multivariable logistic regression. This is a statistical tool used to predict the likelihood of an event, like an arrest, based on many different factors.

In this study, the results are often presented as adjusted odds ratios. An odds ratio is a way to compare whether the probability of a certain event is higher or lower for one group than another. If the odds ratio is above one, it suggests an increased likelihood. If it is below one, it suggests a decreased likelihood. The word “adjusted” means the researchers accounted for factors like age, gender, income, and education level to ensure those variables did not distort the results.

The findings provides evidence that PCP was strongly associated with violence. “This study found that people who have used PCP in the last month have over 10 times the odds of having been arrested for a serious violence offense in the last year,” Norris said. Serious violent offenses include major crimes like murder, rape, or aggravated assault.

“Recent PCP users are also much more likely to be arrested for a sex offense or admit attacking several people in the last year,” Norris told PsyPost. While the researchers do not know whether PCP is causing these behaviors, these findings suggest a close association between PCP use and violent offending. Although PCP use is fairly rare, and most violent crime has nothing to do with PCP, the author suggests it is worth exploring whether interventions with PCP users might prevent some violence.

Another rarely used substance, GHB, also showed a strong link to criminal activity. GHB is a central nervous system depressant that is sometimes used as a club drug. The study suggests that GHB users were much more likely to be arrested for crimes like arson, robbery, burglary, and fraud.

One result regarding GHB was particularly unexpected for the researcher. “I didn’t expect the associations between certain drugs and certain crimes to be so strong,” Norris admitted. “For example, women who have used GHB in the last year have more than 100 times the odds of being arrested for a sex offense, compared to non-GHB users.” However, he noted that some of these effect sizes may be misleadingly large due to the small numbers of users in the study.

When looking at psychedelics, the findings were more varied than in previous research. Psilocybin was associated with a lower likelihood of several different types of arrests. People who had used psilocybin at some point in their lives had reduced odds of being arrested for assault, robbery, theft, and fraud.

“Many people today are optimistic about the ability of psychedelic drugs like psilocybin to have positive effects on people’s emotions and behaviors,” Norris observed. “But my study’s mixed results on psychedelics suggest that this optimism may be premature, at least when it comes to psychedelics’ impact on criminal behavior.” While psilocybin showed protective associations, other psychedelics with very similar effects on the brain had very different results.

For example, a group of drugs called tryptamines, which includes DMT and a synthetic drug nicknamed “Foxy” (5-MeO-DiPT), were associated with an increased risk of arrest. Users of these drugs were much more likely to be arrested for arson or burglary. Other drugs, like LSD and a plant called Salvia divinorum, showed mixed results, where they were linked to higher odds of some crimes but lower odds of others.

“Like previous studies, my study found that psilocybin was often associated with a lower odds of arrest,” Norris explained. “However, other psychedelics with very similar effects on the brain had very different results, either increasing the odds of arrest across the board or increasing the odds of some offenses while reducing the odds of others.” He suggested that factors like the type of people who use these drugs and the social context in which they are used might be driving these results, rather than the effects of the substances themselves.

Social context refers to the environment, the people, and the culture surrounding drug use. This is often called the “setting.” Norris pointed out that even though the study accounts for variables like education and income, residual socioeconomic confounding might be present. Socioeconomic confounding refers to differences in economic status and social position that the study did not measure.

“For example, it is possible that psilocybin causes psychological changes that reduce criminal behavior,” Norris stated. “But it is also possible that psilocybin does not have such an effect, and psilocybin users simply tend to be the type of people who were unlikely to get arrested to begin with.” This means the drug might not be the cause of the lower arrest rate; instead, the people who choose to use it might already be less likely to commit crimes.

The study also looked at how these patterns changed for younger people under the age of 18. For these youth, the protective effects of psychedelics were almost entirely absent. Instead of being associated with fewer arrests, psychedelic use among minors was often linked to a higher risk of being arrested or committing violence.

“In addition, the fact that psilocybin is associated with a reduced odds of arrest for adults but not for juveniles, and for whites but not for African-Americans, suggests that it may not be psilocybin itself that is influencing people’s behavior,” Norris said. This finding regarding race is consistent with prior research suggesting that minorities are less likely to benefit from psychedelics. This is often attributed to structural racism and different social pressures rather than biological differences.

One of the most notable results involved cannabis. “While cannabis was not the focus of the study, I was surprised by how consistently cannabis use was associated with a higher odds of arrest and self-reported criminal behavior,” Norris noted. Cannabis use measures had some of the highest odds ratios for many types of crime, which provides evidence against the idea that cannabis use is unrelated to criminal activity.

There are some important caveats readers should keep in mind to avoid misinterpretation. “It’s important to point out that statistically-significant associations between a certain drug and a certain crime, and even large associations like a tenfold increase in odds, do not necessarily imply that the drug is causing the criminal behavior,” Norris cautioned. “More research is needed whether that is the case.”

The study relies on surveys, which have limits because people may not always remember or report their behavior accurately. It is also difficult to know if the drug use happened before or after the crime. Norris noted that the next logical step for this research is to conduct similar analyses with more fine-grained variables about psychedelic use. This would include looking at how recently or frequently the participants have used each psychedelic.

“I’m working on one such project now involving a single psychedelic drug,” Norris shared regarding his future plans. This future work may help scientists understand if the timing and frequency of drug use change how they relate to crime. For now, the current study highlights that the relationship between substances and the law is highly complex and depends on many social and chemical factors.

The study, “Substance use predictors of arrest and self-reported criminal behavior in the United States: The role of psychedelics and rarely used drugs,” was authored by Jesse J. Norris.