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
Brain growth inhibited by heavy alcohol use
April 1, 2019
Science Daily/Oregon Health & Science University
New research in nonhuman primates shows that heavy use of alcohol can actually slow the rate of growth in developing brains. The study, to be published April 1, in the journal eNeuro, shows that heavy alcohol use reduced the rate of brain growth by 0.25 milliliters per year for every gram of alcohol consumed per kilogram of body weight. In human terms, that's the equivalent of four beers per day.
Heavy use of alcohol among adolescents and young adults is not only dangerous in its own right, but new research in nonhuman primates shows that it can actually slow the rate of growth in developing brains.
The study, published today in the journal eNeuro, shows that heavy alcohol use reduced the rate of brain growth by 0.25 milliliters per year for every gram of alcohol consumed per kilogram of body weight. In human terms, that's the equivalent of four beers per day. The research involved rhesus macaque monkeys at the Oregon National Primate Research Center.
"Chronic alcohol self-intoxication reduced the growth rate of brain, cerebral white matter and subcortical thalamus," the researchers write.
Researchers measured brain growth through magnetic resonance imaging of 71 rhesus macaques that voluntarily consumed ethanol or beverage alcohol. Scientists precisely measured intake, diet, daily schedules and health care, thus ruling out other factors that tend to confound results in observational studies involving people. The findings in the study help validate previous research examining the effect of alcohol use on brain development in people.
"Human studies are based on self-reporting of underage drinkers," said co-author Christopher Kroenke, Ph.D., an associate professor in the Division of Neuroscience at the primate center. "Our measures pinpoint alcohol drinking with the impaired brain growth."
The new study is the first to characterize normal brain growth of 1 milliliter per 1.87 years in rhesus macaques in late adolescence and early adulthood. And it further reveals a decrease in the volume of distinct brain areas due to voluntary consumption of ethanol.
Lead author Tatiana Shnitko, Ph.D., a research assistant professor in the Division of Neuroscience at the primate center, said previous research has shown the brain has a capacity to recover at least in part following the cessation of alcohol intake. However, it's not clear whether there would be long-term effects on mental functions as the adolescent and young adult brain ends its growth phase. The next stage of research will explore that question.
"This is the age range when the brain is being fine-tuned to fit adult responsibilities," Shnitko said. "The question is, does alcohol exposure during this age range alter the lifetime learning ability of individuals?"
https://www.sciencedaily.com/releases/2019/04/190401133019.htm
Overdose risk factors in youth with substance use disorders
More than a quarter of young people seeking treatment had history of at least one overdose
April 24, 2018
Science Daily/Massachusetts General Hospital
A team of Massachusetts General Hospital (MGH) investigators has identified factors that may increase the risk of drug overdose in adolescents and young adults. In their report published online in the Journal of Clinical Psychiatry, the researchers describe finding that more than a quarter of those seeking treatment at Addiction Recovery Management Service, an MGH-based outpatient substance-use-disorder treatment program for youth ages 14 to 26, had a history of at least one overdose. Factors associated with increased overdose risk were disorders involving the use of alcohol, cocaine or amphetamines and histories of depression, anxiety or eating disorders.
"Very little research exists on risk factors associated with overdose in young people presenting for substance use disorder treatment," says lead and corresponding author Amy Yule, MD, of Addiction Recovery Management Service and the MGH Division of Child Psychiatry. "In addition to screening for substance-specific risk factors, it is important that providers systematically screen young patients for overdose histories and for psychiatric factors that may increase overdose risk."
Most studies of overdose risk among individuals with substance use disorders have focused on adults, and the few that specifically studied young people only assessed substance-related risk factors and not psychiatric symptoms. Yule notes that, since substance use patterns are known to differ between youth and adults, and since brain regions important to decision making do not fully mature until the 20s, it is important to investigate whether risk factors differ between the two age groups.
The research team conducted a retrospective analysis of deidentified data from intake assessments conducted at Addiction Recovery Management Service from January 2012 through June 2013. These comprehensive assessments include details of both substance use and psychiatric histories and are conducted by social workers, psychologists and psychiatrists with additional training in addiction medicine.
Of the 200 patients whose data were collected, 58 had a history of at least one overdose -- defined as substance use associated with significant impairment in the level of consciousness or an ingestion of any substance with the intent of self-harm that was reported as a suicide attempt. Among those with an overdose history, 62 percent (36 patients) had unintentional overdoses only, 31 percent (18 patients) had intentional overdose only, and 7 percent (4 patients) had a history of both intentional and unintentional overdose; 24 patients had histories of more than one overdose.
Patients with two or more substance use disorders were more than three times as likely to have a history of overdose, compared to patients with a single substance use disorder. The best substance-associated predictors of an overdose were alcohol use disorder, cocaine use disorder and amphetamine use disorder; psychiatric conditions associated with overdose history were eating disorders, depression and anxiety disorders. Patients with a history of intentional overdose were more likely than those with unintentional overdose to have a history of self-harming behavior and inpatient psychiatric treatment.
Yule notes that, since the association of eating disorders with overdose risk has never been reported previously, it needs to be replicated in future studies, but assessing for eating disorders and other psychiatric risk factors in youth with substance use disorders is essential. The lack of an association between opioid use and overdose history in this study could reflect the fact that opioid use usually begins at later ages than does use of substances such as cannabis and alcohol, which are more common among adolescents. In addition, she adds, the presence of fentanyl, which significantly increases overdose risk, was much lower in Massachusetts at the time this study's data were collected.
"It's going to be helpful to assess overdose risk among young people with substance use disorders over a longer period of time and to examine whether treatment mitigates the risk for subsequent overdose," says Yule, an instructor in Psychiatry at Harvard Medical School (HMS). "While the opioid epidemic has raised public awareness of the importance of increased access to evidence-based treatment for substance use disorders, our findings support the importance of considering all substances of misuse -- both opioids and non-opioids -- when assessing overdose risk."
Study senior author Timothy Wilens, MD, chief of Child and Adolescent Psychiatry at MGH and associate professor of Psychiatry at HMS adds, "The striking prevalence of overdose history in treatment-seeking young people reflects how common overdose unfortunately is among those with substance use disorders, no matter the age."
https://www.sciencedaily.com/releases/2018/04/180424141140.htm