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Twins Study Busts Cannabis Gateway Theory

February 13, 2023 Published by

Legal access to recreational cannabis has no effect on increasing the probability of disorders using alcohol or illicit drugs, according to a recent study of twins.

In a recent report published by the journal Psychological Medicine, researchers observed data gathered from observing twins living in Colorado and Minnesota. They found no link to legal access to marijuana with the likelihood of developing substance abuse problems. 

“Cannabis legalization was associated with no other adverse outcome in the co-twin design, including cannabis use disorder,” researchers found. “No risk factor significantly interacted with legalization status to predict any outcome.”

“We found mostly a lot of nothing, which I think is personally interesting,” lead researcher Stephanie Zellers added. “I think this is a case where we don’t find much is actually more interesting maybe than finding a bunch of results.”

The study also noted that residents living in legal cannabis states didn’t appear to show an increase in problems associated with mental health, relationships, work and finances.

“Recreational legalization was associated with increased cannabis use and decreased alcohol use disorder symptoms but wasn’t associated with other maladaptations,” researchers wrote. “These effects were maintained within twin pairs discordant for residence. “Moreover, vulnerabilities to cannabis use were not exacerbated by the legal cannabis environment.”

Access to Legal Market

Zellers and her research team observed 240 pairs of twins where one lives in the legal state of Colorado while the other lives in Minnesota, where cannabis remains prohibited. Now aged 24 to 49, the participants have provided data on their personal use of alcohol, tobacco, cannabis and several illicit drugs, as well as measures of “psychosocial health” since adolescence.

“This co-twin design automatically controls for a wide range of variables, including age, social background, early home life and even genetic inheritance” that can influence health outcomes, said co-researcher John Hewitt, professor of psychology and neuroscience at CU Boulder. “If the association holds up, it provides strong evidence that the environment, in this case legalization, is having an impact.”

“There’s lots of things that could explain why one person is behaving one way or why people of one state behave one way compared to another,” Zellers said. “But with twins, we were able to rule out so many of those alternatives—not everything, but a lot of them.”

The recent study acted as a follow-up to prior research that found an increase in adult cannabis use where states have allowed recreational use. Despite the rise in use, however, the team found no relationship to a spike in cannabis abuse or addiction.

“Obviously the cannabis use increases, but we didn’t see an increase in cannabis-use disorder, which is a little surprising,” Zellers said. “We didn’t really see changes in how much people were drinking or using tobacco. No large personality or workplace or IQ differences or anything like that.”

But while cannabis use increased in legal situations, twins living in such areas were also less likely to drive drunk or develop alcohol use disorders.

“You’re combining drinking with something that could be physically unsafe,” Zellers said. “The residents of legal states do that less, which is interesting and maybe something a little unexpected.”

Disproving the Cannabis Gateway Theory

The findings also reject the gateway drug theory that using marijuana only leads to using stronger substances.

“We asked in the last 12 months have you tried or used heroin, prescription opiates, cocaine, methamphetamine, hallucinogens—kind of the whole 11 or 12 categories of illicit drugs,” Zellers said. “And there’s no difference there. People living in a state with legal cannabis, they’re not necessarily transitioning on to more illicit drugs.”

The results are quite promising but are far from an absolute conclusion. The study does have several limitations, as it focuses on adults, and few of whom consider themselves as heavy users.

“Our sample is an adult community sample broadly characterized by low levels of substance use and psychosocial dysfunction,” the researchers wrote. “This limits our ability to generalize relationships between legalization, outcomes and risk factors for the individuals at greatest risk.”

The post Twins Study Busts Cannabis Gateway Theory appeared first on Cannabis Now.

Long-Term Study of Twins Finds No Link Between Legalization, Drug Abuse

February 1, 2023 Published by

Once again the gateway theory—the belief that cannabis use leads to other drugs, popularized about 40 years ago—is being crushed by new evidence, this time finding no evidence of worsened drug abuse in legal states, using twins as controls. 

A new long-term study examined sets of twins, over 4,000 individuals, and found that state legalization status wasn’t associated with a rise in substance-use disorders of other drugs, and other psychological problems and vulnerabilities. Researchers also noted that legalization led to an increase in cannabis use but decrease in alcohol use disorder (AUD). 

The study, “Recreational cannabis legalization has had limited effects on a wide range of adult psychiatric and psychosocial outcomes,” was published online by Cambridge University Press on Jan. 5. In it, researchers sought to “quantify possible causal effects of recreational cannabis legalization on substance use, substance use disorder, and psychosocial functioning, and whether vulnerable individuals are more susceptible to the effects of cannabis legalization than others.”

Addiction usually goes well beyond the substances involved: The Colorado Sun reports that researchers measured general psychological dysfunction, going beyond substance-use disorders but also measuring financial problems, mental health, community disengagement, and relationship issues that are sometimes believed to be linked to pot use.

After noting that twins consumed cannabis about 20% more in legal states than non-green states in a previous study, the same team of researchers set out again to see if this impacts addiction of other substances, and other psychiatric disorders.

Researchers gathered data from longitudinal studies of twins in two opposing states, one with legal pot and one without: Colorado or Minnesota. The states provided near-perfect controls to examine the full effects of legalization versus a state that prohibits most forms of cannabis. Researchers in both states observed the twins over long periods of time. By using twins there are more automatic controls over socioeconomic status or genetic differences.

Researchers gathered data from 4,078 individuals, first assessed in adolescence and now ages 24-49, and currently residing in states with different cannabis policies (Colorado or Minnesota). Study participants were recruited as teens via birth records from the years 1972–1994, beginning before 2014, when adult-use cannabis stores opened in Colorado. Parents provided informed consent when the study participants were minors.

Living in a legal state was “not associated” with substance abuse disorders, although they found it led to higher pot use but lower alcohol use. Living in a legal state was associated, in fact, with lower AUD rates.

“In the co-twin control design accounting for earlier cannabis frequency and alcohol use disorder (AUD) symptoms respectively, the twin living in a recreational state used cannabis on average more often, and had fewer AUD symptoms than their co-twin living in an non-recreational state. Cannabis legalization was associated with no other adverse outcome in the co-twin design, including cannabis use disorder. No risk factor significantly interacted with legalization status to predict any outcome.”

This led researchers to come to several conclusions.

“Recreational legalization was associated with increased cannabis use and decreased AUD symptoms but was not associated with other maladaptations,” wrote researchers. “These effects were maintained within twin pairs discordant for residence. Moreover, vulnerabilities to cannabis use were not exacerbated by the legal cannabis environment. Future research may investigate causal links between cannabis consumption and outcomes.”

While living in a legal state was associated with higher pot use, it didn’t impact drug abuse and other psychological problems. “At least from the psychological point of view,” Stephanie Zellers, one of the researchers, told The Colorado Sun. “We really didn’t find that the policies (on cannabis legalization) have a lot of negative influence, which I think is important.”

“That twin component really allows us to rule out a lot of possible alternatives—maybe there were just cultural differences, family differences, things like that,” Zellers said, explaining the need to observe twins.

Zellers also led the earlier study looking at the impact of legalization. The team has funded much of the research based on grants from the National Institutes of Health. 

Researchers stipulate that more data is needed to determine the effects of cannabis legalization regarding psychiatric disorders and addiction. 

The post Long-Term Study of Twins Finds No Link Between Legalization, Drug Abuse appeared first on High Times.

Study Shows 20% Increase in Frequency of Cannabis Consumption in Recreational States

August 25, 2022 Published by

A new study published in the journal Addiction on Aug. 24 analyzed cannabis consumption data across the nation, with a specific focus on adult identical twins. Called “Impacts of recreational cannabis legalization on cannabis use: a longitudinal discordant twin study,” the study used twins to explore the frequency of cannabis across two different states.

“In this study, we evaluated the effects of recreational cannabis legalization in a large sample of prospectively assessed adult twins from similar cohorts of individuals born in Colorado and Minnesota, demographically similar states with different cannabis policies,” the researchers presented in their introduction. “While many participants still reside in their birth states, some participants have migrated to other states resulting in pairs discordant for exposure to recreational legalization.”

Researchers reviewed data from either the Minnesota Center for Twin Family Research or the University of Colorado, Boulder Center for Antisocial Drug Dependence, with a total of 3,452 individuals (split between 1,700 individuals from Minnesota and 1,752 from Colorado). All individuals had previously been asked about their cannabis use before and after 2014, when the state of Colorado legalized recreational cannabis, and Minnesota legalized medical cannabis. Of this number, there was a split among different types of twins: monozygotic (363 pairs), same-sex dizygotic (208) pairs and opposite-sex dizygotic (129 pairs).

The researchers concluded that in 111 pairs of twins, there were no genetic influences that led to cannabis consumption frequency, however they did confirm that “Existing genetic influences were moderated by the legal environment, as the genetic correlation between marijuana use before and after legalization was lower in states that legalized compared with states that did not.”

“Using a longitudinal design accounting for age, sex and earlier cannabis use, we found a ~24% increase in mean cannabis use frequency attributable to legalization,” researchers explained. “Furthermore, co-twin control results indicate that within monozygotic pairs, the twin living in a legal state uses cannabis ~20% more frequently than their illegally residing co-twin.”

However, the researchers also noted that nearly 92% of participants were white and projected how the inclusion of more non-white participants could alter the results. “An important extension of our work would be to investigate individual differences in the context of cannabis policy with respect to sex or racial background. Prior to recreational legalization, black Americans disproportionately bore the consequences of cannabis law enforcement,” researchers wrote. “Racial disparities in pre-legalization enforcement could mean that the legalization-related environmental changes experienced by black Americans were more dramatic than those experienced by their white counterparts, but we are not able to address this issue effectively in these samples.”

In their conclusion, researchers stated that this particular topic could use more elaboration to further understand how cannabis may have affected people in other states. “Through the use of zygosity-stratified co-twin control analyses, we found a ~20% increase in cannabis use frequency, consistent with a causal effect of recreational legalization,” they wrote. “These results do not, by themselves, demonstrate how more frequent use in legal states translates to changes in health or behavioral consequences, therefore future work is necessary to further address complex questions around the public health impacts of legalization and vulnerability to widely available marijuana.”

On Aug. 24, a new study from the National Institutes of Health found that consumption of cannabis and hallucinogens is at an all-time high for individuals between the ages of 19-30. Researchers said that consumption in this age group has “increased significantly in 2021 compared to five and 10 years ago,” and is the highest level of consumption since 1988.

National Institute on Drug Abuse Director Nora Volkow said in an accompanying statement that this research is crucial to understanding the long-term effects of cannabis on youth. “As the drug landscape shifts over time, this data provides a window into the substances and patterns of use favored by young adults. We need to know more about how young adults are using drugs like marijuana and hallucinogens, and the health effects that result from consuming different potencies and forms of these substances,” Volkow said. “Young adults are in a critical life stage and honing their ability to make informed choices. Understanding how substance use can impact the formative choices in young adulthood is critical to help position the new generations for success.”

The post Study Shows 20% Increase in Frequency of Cannabis Consumption in Recreational States appeared first on High Times.

Study Finds Weekly Cannabis Use Has Minimal Impairment on Physical Health

June 13, 2022 Published by

Research on the influence of cannabis use on cardiovascular functions, pulmonary functions, and other indicators is still growing, but one new study has shed new light on the topic. “The effects of cannabis use on physical health: A co-twin control study,” published in the journal Drug and Alcohol Dependence explored the relationship between cannabis use and physical health among 308 sets of twins, with the results suggesting that cannabis use is not associated with detrimental physical effects.

Cannabis research is still catching up to studies surrounding tobacco and alcohol’s effect on physical health, though studies so far have indicated cannabis has an impact on respiratory health, cardiovascular health, and body mass index.

The data is from an ongoing study called “Colorado Adoption/Twin Study of Lifespan Behavioral Development and Cognitive Aging,” through the University of Colorado Boulder. It is the first prospective study of cognitive aging from infancy through adulthood, with a purpose of studying “how early and current influences accumulate over one’s life to impact how well individuals build and maintain cognitive functioning,” according to the CU Boulder website.

As part of the study, researchers are tracing factors associated with decreases, maintenance or boosts in cognitive abilities. Through in-depth behavioral and health measurements, analysis of environmental settings, biomarker and genotype data, researchers are looking to assess the association of cognitive changes with possible physical and behavioral health precursors, “to trace the emergence of these associations,” researchers say on the CU Boulder site.

As part of the study, researchers are tracing factors associated with decreases, maintenance, or boosts in cognitive abilities. Through in-depth behavioral and health measurements, analysis of environmental settings, biomarker and genotype data, researchers are looking to assess the association of cognitive changes with possible physical and behavioral health precursors, “to trace the emergence of these associations,” researchers say on the CU Boulder site.

Study author Jessica Megan Ross worked with her team to better understand these effects, specifically focusing on monozygotic twins (or twins sharing 100% of their genetic makeup) and dizygotic twins (or twins sharing 50% of their genetic makeup.

Researchers are also using siblings and twins for the larger study, assessing them on a wide array of measures almost yearly from birth into their 20s. With this model, researchers were able to control shared genetic and environmental factors as they analyzed the results for the cannabis study and others.

“Understanding the impact of cannabis use on physical health is an important public health concern because the extant literature has reported mixed results,” Ross told PsyPost. “The changes in legalization of cannabis use throughout the United States has been associated with increases in adult cannabis use. However, we still do not have a clear picture of how cannabis use impacts physical health.”

Respondents were asked to self-report how often they used cannabis, tobacco, alcohol, or other drugs during adolescence. Researchers then calculated each person’s average lifetime frequency of cannabis, calculating individuals’ average number of days in the past month they had used cannabis across the study assessments.

So, increased cannabis use in adolescence isn’t necessarily the cause of less exercise in adulthood, just as frequent cannabis use in adulthood isn’t necessarily related to more frequent appetite loss.

Researchers also looked at between-family and within-family effects; between-family effects looked at average cannabis use frequency within each twin pair and compared the averages across all the pairs, while within-family effects were measured by a twin’s deviations from the average cannabis frequency within their pair.

They found that, at the between-family level, more cannabis use in adolescence was associated with infrequent exercise as an adult; these effects weren’t present at the within-family level, suggesting that the effects were partially because of shared family factors, not cannabis use. At the within-twin level, more frequent cannabis use in adulthood was correlated with a lower resting heart rate for monozygotic twin pairs. The observation held true after controlling for family factors and other substance use, providing some evidence that cannabis use can affect the resting heart rate.

The study conclusions note, “The associations between cannabis use with exercise engagement and frequency of appetite loss are explained by familial confounding while the association between cannabis use and resting HR was not. These results do not support a causal association between cannabis use once a week and poorer physical health effects among adults aged 25–35.”

The researchers noted the study was limited in a number of ways, namely that the findings may not generalize to the greater U.S. population. Ross said that these results apply to adults using cannabis once a week on average and do not apply to adolescents and adults using cannabis more frequently.

“Although we did not find that cannabis use (once a week) is associated with detrimental physical health effects, people can still develop other negative outcomes from use like a cannabis use disorder,” Ross said.

The post Study Finds Weekly Cannabis Use Has Minimal Impairment on Physical Health appeared first on High Times.