Early-and-regular cannabis use by youth is associated with alteration in brain circuits that support cognitive control
June 20, 2019
Science Daily/Elsevier
The development of neural circuits in youth, at a particularly important time in their lives, can be heavily influenced by external factors -- specifically the frequent and regular use of cannabis. A new study in the Journal of the American Academy of Child and Adolescent Psychiatry (JAACAP), published by Elsevier, reports that alterations in cognitive control -- an ensemble of processes by which the mind governs, regulates and guides behaviors, impulses, and decision-making based on goals are directly affected.
The researchers found that these brain alterations were less intense in individuals who recently stopped using cannabis, which may suggest that the effects of cannabis are more robust in recent users. Additional findings from the study also suggest greater and more persistent alterations in individuals who initiated cannabis use earlier, while the brain is still developing.
"Most adults with problematic substance use now were most likely having problems with drugs and alcohol in adolescence, a developmental period during which the neural circuits underlying cognitive control processes continue to mature," said lead author Marilyn Cyr, PhD. "As such, the adolescent brain may be particularly vulnerable to the effects of substance use, particularly cannabis -- the most commonly used recreational drug by teenagers worldwide," added the postdoctoral scientist in the Division of Child and Adolescent Psychiatry at the New York State Psychiatric Institute, Vagelos College of Physicians & Surgeons, Columbia University, New York.
The findings are based on functional magnetic resonance imaging (fMRI) data acquired from 28 adolescents and young adults (aged 14-23 years) with significant cannabis use and 32 age and sex-matched non-using healthy controls. Participants were scanned during their performance of a Simon Spatial Incompatibility Task, a cognitive control task that requires resolving cognitive conflict to respond accurately.
Compared to their healthy counterparts, the adolescents and young adults with significant cannabis use showed reduced activation in the frontostriatal circuits that support cognitive control and conflict resolution.
The authors also examined the degree to which fluctuations in activity in relation to conflict resolution is synchronized across the different regions comprised in this frontostriatal circuit (that is, to what extent are regions functionally connected with each other). Although circuit connectivity did not differ between cannabis-using and non-using youth, the research team found an association between how early individuals began regularly using cannabis and the extent to which frontostriatal regions were disrupted, suggesting that earlier chronic use may have a larger impact on circuit development than use of later onset.
"The present findings support the mission of the Adolescent Brain and Cognitive Development study, a longitudinal study aimed at understanding the developmental trajectory of brain circuits in relation to cannabis use," said Dr. Cyr. "In addition, these findings are a first step towards identifying brain-based targets for early interventions that reduce addiction behaviors by enhancing self-regulatory capacity.
"Given that substance use and relapse rates are associated with control processes, interventions based on neural stimulation, such as transcranial magnetic stimulation (TMS), and behavioral interventions, such as cognitive training, that specifically target the brain circuits underlying these control processes may be helpful as adjunct intervention strategies to complement standard treatment programs for cannabis use disorder."
https://www.sciencedaily.com/releases/2019/06/190620104858.htm
Cannabis withdrawal symptoms common among adolescents treated for substance use disorder
September 2, 2014
Science Daily/Massachusetts General Hospital
Although cannabis -- commonly known as marijuana -- is broadly believed to be nonaddictive, a study by Massachusetts General Hospital (MGH) investigators found that 40 percent of cannabis-using adolescents receiving outpatient treatment for substance use disorder reported experiencing symptoms of withdrawal, which are considered a hallmark of drug dependence. Study participants reporting withdrawal were more likely to meet criteria for severe substance use and for mood disorders, although the presence or absence of withdrawal did not appear to change long-term treatment outcomes. The report will be published in the Journal of Addiction Medicine and has been released online.
"Our results are timely given the changing attitudes and perceptions of risk related to cannabis use in the U.S.," says John Kelly, PhD, of the Center for Addiction Medicine in the MGH Department of Psychiatry, senior author of the study. "As more people are able to obtain and consume cannabis legally for medical and, in some states, recreational use, people are less likely to perceive it as addictive or harmful. But research shows that cannabis use can have significant consequences, and we know that among adolescents it is second only to alcohol in rates of misuse."
While several previous studies have looked at the incidence of cannabis withdrawal in adolescents and its relationship to treatment outcomes, few have included follow-up periods longer than 30 days or examined the relationship of withdrawal to factors such as the severity and consequence of cannabis use and the presence of other psychiatric symptoms. The current study enrolled 127 adolescents between ages 14 and 19 being treated at an outpatient substance use disorder clinic, 90 of whom indicated that cannabis was the substance they used most frequently.
Upon entering the study and at follow-up visits 3, 6 and 12 months later, participants received comprehensive assessments including interviews by study staff and completion of survey instruments analyzing factors related to substance use -- including whether or not they thought they might have a problem with drug use -- withdrawal symptoms, consequences in their lives attributable to substance use, and other psychiatric symptoms and diagnoses. Based on their answers, participants were divided into two groups -- those who reported cannabis withdrawal symptoms such as anxiety, irritability, depression and difficulty sleeping and those who did not.
Of the 90 cannabis-using participants, 76 (84 percent) met criteria for cannabis dependence -- which include increased tolerance and use of cannabis, unsuccessful efforts to reduce or stop using, and persistent use in spite of medical and psychological problems made worse by cannabis. Withdrawal symptoms were reported by 36 participants (40 percent of the overall group), all of whom also met criteria for dependence. At the study's outset, substance use was likely to be more severe and consequences -- such as missing work or school, financial and relationship problems -- tended to be greater in participants reporting withdrawal symptoms, who also were more likely to have mood disorders.
While the presence of withdrawal symptoms is a strong indicator of cannabis dependence, the authors note, it did not significantly impact the ability of participants to reduce their use of cannabis during the 12-month follow-up period. The factor that did appear to make a difference was whether or not an individual recognized having a problem with substance use upon entering the study. Participants who both reported withdrawal symptoms and recognized having a problem had a small but steady improvement in abstinence through the entire study period. Those who reported withdrawal symptoms but did not recognize a substance use problem had a slight increase in abstinence in the first 3 months, but then had some increase in cannabis use during the subsequent 9 months, a pattern that was also seen in participants not experiencing withdrawal.
"We hypothesize that participants who experience withdrawal symptoms but do not recognize having a substance use problem may not attribute those symptoms to cannabis withdrawal," says Claire Greene, MPH, corresponding author of the report. "Those who do acknowledge a substance-use problem may correctly attribute those symptoms to cannabis withdrawal, giving them even more motivation to change their substance use behavior." Formerly with the MGH Center for Addiction Medicine, Greene is now a doctoral candidate at the Johns Hopkins Bloomberg School of Public Health.
Kelly, the Spallin Associate Professor of Psychiatry in Addiction Medicine at Harvard Medical School, adds, "The importance of understanding the addictiveness, risks and harms associated with cannabis use is a major theme of this study's findings. Recognizing those risks is known to reduce the likelihood that someone will start to use drugs, and better understanding of the role of substances in the problems experienced by patients may help them cut down on future use.
"Unfortunately, the general trend in attitudes in the U.S. is to minimize the risks and not recognize the addictiveness of cannabis," he continues. "Further research is needed determine the impact of these changing public attitudes and investigate the benefits of programs that reduce these misconceptions, which could allow us to predict whether increased education and awareness could help reduce the onset of, and harm caused by, cannabis use disorders." The study was supported by National Institute of Alcohol Abuse and Alcoholism grant R01AA015526.
https://www.sciencedaily.com/releases/2014/09/140902094103.htm