Differences between combined, isolated use of cannabis, nicotine on brain networks
August 28, 2018
Science Daily/Center for BrainHealth
Researchers at the Center for BrainHealth® at the University of Texas at Dallas investigated the effects on the brain of concurrent cannabis and nicotine use, versus the use of solely cannabis and solely nicotine.
The results, recently published in the journal Brain Structure and Function, show that not only were the effects in these three categories different, but also that the group using both nicotine and cannabis more closely resembled the control (non-user) group in brain connectivity. The isolated nicotine and isolated cannabis users showed equally less connectivity in general.
Previous research in rats has suggested that nicotine may be a "gateway drug" leading to cannabis and other drug use. Studies performed with rats exposed to THC -- the main psychoactive compound found in marijuana -- demonstrated an increased likelihood to self-administer nicotine that was not observed with rats exposed to heroin or cocaine, suggesting that there is something unique about the cannabis-nicotine interaction.
"Most of the literature to date has focused on associations of isolated cannabis and nicotine use, even though concurrent cannabis and nicotine use is more prevalent in society than cannabis use alone," said the study's lead author, Dr. Francesca M. Filbey, the Bert Moore Chair in BrainHealth at UT Dallas. "Our findings confirm the limitations of existing research."
While the outcome of the study could be, in part, due to the opposing effects nicotine and cannabis have on the brain, the difference in the brains of concurrent users versus isolated users of each product begs for further research in functional connectivity metrics in these populations, Filbey said.
MRI scans were used to evaluate resting state functions in 12 different regions of the brain among four groups of participants: 28 nicotine users, 53 cannabis users, 26 nicotine and cannabis users, and 30 non-users in a control group. These scans revealed that the control group displayed greater connectivity in almost all of the networks compared to the nicotine and cannabis groups, while the combined nicotine plus cannabis group had greater connectivity than the only-nicotine and only-cannabis groups. Notably, this study did not demonstrate a correlation between substance use severity and functional connectivity.
Differences in brain network connectivity suggest alterations in the underlying neural architecture of the brain that support brain function. Overall, Filbey said the study suggests unique and combined contributions of cannabis and nicotine on brain network connectivity, which could be helpful knowledge for intervention programs.
https://www.sciencedaily.com/releases/2018/08/180828133934.htm
'Yes' to one drug could become 'yes' for other drugs
October 8, 2013
Science Daily/Springer Science+Business Media
High school seniors who frown upon the use of drugs are most likely to be female, nonsmokers or hold strong religious beliefs, according to a study¹ by Joseph Palamar of New York University. Palamar examines how teenagers' attitudes toward marijuana influenced their thoughts on the further use of other illicit drugs. The work appears online in the journal Prevention Science², published by Springer.
The study was conducted as marijuana use continues to be on the upswing in the United States, along with more lenient legislation and diminishing public disapproval toward its use. Although previous research has shown that people who disapprove of a particular drug will in all likelihood not use it, little is known about how the use of one drug affects people's attitudes toward using other drugs.
Palamar therefore examined how demographics and a lifetime use of various drugs -- marijuana use in particular -- can predict if a person will become partial to using "harder" and more dangerous drugs, such as powder cocaine, crack, LSD, heroin, amphetamine and ecstasy, also known as "Molly." Data was obtained from 29,054 high school seniors who took part in the Monitoring the Future annual cross-sectional survey of approximately 130 public and private schools in 48 states between 2007 and 2011.
Palamar found that youths who smoked cigarettes or used more than one "hard" drug were consistently less critical of other drug use. The lifetime use of alcohol had no impact on people's attitudes. Those who used only marijuana tended to be less judgmental of further using such so-called "socially acceptable" drugs as LSD, amphetamine and ecstasy. They did not approve of cocaine, crack or heroin, however, most likely because of their perceived dangers and addictive qualities.
Unsurprisingly, female high school seniors consistently disapproved of using cocaine, crack, LSD and ecstasy. Compared to their male counterparts, females are generally less likely to use most drugs. Palamar was also not surprised by the finding that religiosity robustly increased attitudes against drug use, as it is a major force in societal values.
Youths from more advantaged socio-economic backgrounds with highly educated parents as well as those living in urban areas were much less disapproving of the use of the so-called "less dangerous" drugs. Palamar believes that the higher prevalence of illicit drug use in urban areas may be helping to normalize drug use in cities.
The finding that Black students are less disapproving of powder cocaine, crack and ecstasy is somewhat paradoxical as members of this group generally use such drugs less than White students do. This could, in part, be explained by their strong religious beliefs and the higher rates of arrests and incarceration among Blacks that may serve as a deterrent. The normalization of ecstasy, specifically in rap and hip-hop music, may explain why Black youths are less disapproving of it.
"Public health and policy experts need to ensure that the use of other drugs does not increase in light of the growing prevalence of marijuana use and more lenient policies surrounding it," Palamar explains. "Although it may be difficult to prevent an adolescent or a young adult from using alcohol, tobacco or marijuana, we need to prevent individuals from becoming users of multiple drugs."
https://www.sciencedaily.com/releases/2013/10/131008112434.htm
Perception of marijuana as a 'safe drug' is scientifically inaccurate, finds review of teen brain studies
August 27, 2013
Science Daily/Universite de Montreal
The nature of the teenage brain makes users of cannabis amongst this population particularly at risk of developing addictive behaviors and suffering other long-term negative effects, according to researchers at the University of Montreal and New York's Icahn School of Medicine at Mount Sinai.
"Of the illicit drugs, cannabis is most used by teenagers since it is perceived by many to be of little harm. This perception has led to a growing number of states approving its legalization and increased accessibility. Most of the debates and ensuing policies regarding cannabis were done without consideration of its impact on one of the most vulnerable population, namely teens, or without consideration of scientific data," wrote Professor Didier Jutras-Aswad of the University of Montreal and Yasmin Hurd, MD, PhD, of Mount Sinai. "While it is clear that more systematic scientific studies are needed to understand the long-term impact of adolescent cannabis exposure on brain and behavior, the current evidence suggests that it has a far-reaching influence on adult addictive behaviors particularly for certain subsets of vulnerable individuals."
The researchers reviewed over 120 studies that looked at different aspects of the relationship between cannabis and the adolescent brain, including the biology of the brain, chemical reaction that occurs in the brain when the drug is used, the influence of genetics and environmental factors, in addition to studies into the "gateway drug" phenomenon. "Data from epidemiological studies have repeatedly shown an association between cannabis use and subsequent addiction to heavy drugs and psychosis (i.e. schizophrenia). Interestingly, the risk to develop such disorders after cannabis exposure is not the same for all individuals and is correlated with genetic factors, the intensity of cannabis use and the age at which it occurs. When the first exposure occurs in younger versus older adolescents, the impact of cannabis seems to be worse in regard to many outcomes such as mental health, education attainment, delinquency and ability to conform to adult role," Dr Jutras-Aswad said.
Although it is difficult to confirm in all certainty a causal link between drug consumption and the resulting behavior, the researchers note that rat models enable scientists to explore and directly observe the same chemical reactions that happen in human brains. Cannabis interacts with our brain through chemical receptors (namely cannabinoid receptors such as CB1 and CB2.) These receptors are situated in the areas of our brain that govern our learning and management of rewards, motivated behavior, decision-making, habit formation and motor function. As the structure of the brain changes rapidly during adolescence (before settling in adulthood), scientists believe that the cannabis consumption at this time greatly influences the way these parts of the user's personality develop. In adolescent rat models, scientists have been able to observe differences in the chemical pathways that govern addiction and vulnerability -- a receptor in the brain known as the dopamine D2 receptor is well known to be less present in cases of substance abuse.
Only a minority (approximately one in four) of teenage users of cannabis will develop an abusive or dependent relationship with the drug. This suggests to the researchers that specific genetic and behavioral factors influence the likelihood that the drug use will continue. Studies have also shown that cannabis dependence can be inherited through the genes that produce the cannabinoid receptors and an enzyme involved in the processing of THC. Other psychological factors are also likely involved. "Individuals who will develop cannabis dependence generally report a temperament characterized by negative affect, aggressivity and impulsivity, from an early age. Some of these traits are often exacerbated with years of cannabis use, which suggests that users become trapped in a vicious cycle of self-medication, which in turn becomes a dependence," Jutras-Aswad said.
The researchers stress that while a lot remains unknown about the mechanics of cannabis abuse, the body of existing research has clear implications for society. "It is now clear from the scientific data that cannabis is not harmless to the adolescent brain, specifically those who are most vulnerable from a genetic or psychological standpoint. Identifying these vulnerable adolescents, including through genetic or psychological screening, may be critical for prevention and early intervention of addiction and psychiatric disorders related to cannabis use. The objective is not to fuel the debate about whether cannabis is good or bad, but instead to identify those individuals who might most suffer from its deleterious effects and provide adequate measures to prevent this risk" Jutras-Aswad said. "Continuing research should be performed to inform public policy in this area. Without such systematic, evidenced-based research to understand the long-term effects of cannabis on the developing brain, not only the legal status of cannabis will be determined on uncertain ground, but we will not be able to innovate effective treatments such as the medicinal use of cannabis plant components that might be beneficial for treating specific disorders," Dr Hurd said.
https://www.sciencedaily.com/releases/2013/08/130827091401.htm