Subregional Hippocampal Thickness Abnormalities in Older Adults with a History of Heavy Cannabis Use

The association between cannabis use and neuroimaging measures in older adults: findings from the UK biobank

BACKGROUND

Cannabis use has increased in recent years. However, the long-term implications of cannabis use on brain health remain unknown. We explored the associations of cannabis use with volumetric brain magnetic resonance imaging (MRI) measures in dementia-free older adults.

METHODS

This cross-sectional and longitudinal study included dementia-free participants of the UK Biobank aged ≥60 years. Linear regression models were used to evaluate the association of cannabis use and patterns of use with volumetric brain MRI measures. The association between cannabis use and change in brain MRI measures over time was also tested. All models were adjusted for potential confounders.

RESULTS

The sample included 19,932 participants (mean age 68 ± 5 years, 48% men), 3,800 (19%) reported lifetime use of cannabis. Cannabis use was associated with smaller total, white, grey and peripheral cortical grey matter volumes (B = -6,690 ± 1,157; P < 0.001, B = -4,396 ± 766; P < 0.001, B = -2,140 ± 690; P = 0.002 and B = -2,451 ± 606; P < 0.001, respectively). Among cannabis users, longer duration of use was associated with smaller total brain, grey and cortical grey matter volumes (B = -7,878 ± 2,396; P = 0.001, B = -5,411 ± 1,430; P < 0.001, B = -5,396 ± 1,254; P < 0.001, respectively), and with increased white matter hyperintensity volume (B = 0.09 ± 0.03; P = 0.008). Additionally, current vs. former users (B = -10,432 ± 4,395; P = 0.020) and frequent versus non-frequent users (B = -2,274 ± 1,125; P = 0.043) had smaller grey and cortical grey matter volumes, respectively. No significant associations were observed between cannabis use and change in brain MRI measures.

DISCUSSION

Our findings suggest that cannabis use, particularly longer duration and frequent use, may be related to smaller grey and white matter volumes in older ages, but not to late-life changes in these measures over time.

Adolescent substance use initiation and long-term neurobiological outcomes: insights, challenges and opportunities

The increased frequency of risk taking behavior combined with marked neuromaturation has positioned adolescence as a focal point of research into the neural causes and consequences of substance use. However, little work has provided a summary of the links between adolescent initiated substance use and longer-term brain outcomes. Here we review studies exploring the long-term effects of adolescent-initiated substance use with structural and microstructural neuroimaging. A quarter of all studies reviewed conducted repeated neuroimaging assessments. Long-term alcohol use, as well as tobacco use were consistently associated with smaller frontal cortices and altered white matter microstructure. This association was mostly observed in the ACC, insula and subcortical regions in alcohol users, and for the OFC in tobacco users. Long-term cannabis use was mostly related to altered frontal cortices and hippocampal volumes. Interestingly, cannabis users scanned more years after use initiation tended to show smaller measures of these regions, whereas those with fewer years since initiation showed larger measures. Long-term stimulant use tended to show a similar trend as cannabis in terms of years since initiation in measures of the putamen, insula and frontal cortex. Long-term opioid use was mostly associated with smaller subcortical and insular volumes. Of note, null findings were reported in all substance use categories, most often in cannabis use studies. In the context of the large variety in study designs, substance use assessment, methods, and sample characteristics, we provide recommendations on how to interpret these findings, and considerations for future studies.

A longitudinal study of cannabis use and risk for cognitive and functional decline among older adults with HIV

Cannabis use is rapidly increasing among older adults in the United States, in part to treat symptoms of common health conditions (e.g., chronic pain, sleep problems). Longitudinal studies of cannabis use and cognitive decline in aging populations living with chronic disease are lacking. We examined different levels of cannabis use and cognitive and everyday function over time among 297 older adults with HIV (ages 50-84 at baseline). Participants were classified based on average cannabis use: frequent (> weekly) (n = 23), occasional (≤ weekly) (n = 83), and non-cannabis users (n=191) and were followed longitudinally for up to 10 years (average years of follow-up = 3.9). Multi-level models examined the effects of average and recent cannabis use on global cognition, global cognitive decline, and functional independence. Occasional cannabis users showed better global cognitive performance overall compared to non-cannabis users. Rates of cognitive decline and functional problems did not vary by average cannabis use. Recent cannabis use was linked to worse cognition at study visits when participants had THC+ urine toxicology-this short-term decrement in cognition was driven by worse memory and did not extend to reports of functional declines. Occasional (≤ weekly) cannabis use was associated with better global cognition over time in older adults with HIV, a group vulnerable to chronic inflammation and cognitive impairment. Recent THC exposure may have a temporary adverse impact on memory. To inform safe and efficacious medical cannabis use, the effects of specific cannabinoid doses on cognition and biological mechanisms must be investigated in older adults.

Effects of inhaled cannabis high in Δ9-THC or CBD on the aging brain: A translational MRI and behavioral study

With the recent legalization of inhaled cannabis for medicinal and recreational use, the elderly represents one of the newest, rapidly growing cohorts of cannabis users. To understand the neurobiological effects of cannabis on the aging brain, 19-20 months old mice were divided into three groups exposed to vaporized cannabis containing ~10% Δ9-THC, ~10% CBD, or placebo for 30 min each day. Voxel based morphometry, diffusion weighted imaging, and resting state functional connectivity data were gathered after 28 days of exposure and following a two-week washout period. Tail-flick, open field, and novel object preference tests were conducted to explore analgesic, anxiolytic, and cognitive effects of cannabis, respectively. Vaporized cannabis high in Δ9-THC and CBD achieved blood levels reported in human users. Mice showed antinociceptive effects to chronic Δ9-THC without tolerance while the anxiolytic and cognitive effects of Δ9-THC waned with treatment. CBD had no effect on any of the behavioral measures. Voxel based morphometry showed a decrease in midbrain dopaminergic volume to chronic Δ9-THC followed but an increase after a two-week washout. Fractional anisotropy values were reduced in the same area by chronic Δ9-THC, suggesting a reduction in gray matter volume. Cannabis high in CBD but not THC increased network strength and efficiency, an effect that persisted after washout. These data would indicate chronic use of inhaled cannabis high in Δ9-THC can be an effective analgesic but not for treatment of anxiety or cognitive decline. The dopaminergic midbrain system was sensitive to chronic Δ9-THC but not CBD showing robust plasticity in volume and water diffusivity prior to and following drug cessation an effect possibly related to the abuse liability of Δ9-THC. Chronic inhaled CBD resulted in enhanced global network connectivity that persisted after drug cessation. The behavioral consequences of this sustained change in brain connectivity remain to be determined.

Consensus paper of the WFSBP task force on cannabis, cannabinoids and psychosis

OBJECTIVES

The liberalisation of cannabis laws, the increasing availability and potency of cannabis has renewed concern about the risk of psychosis with cannabis.

METHODS

The objective of the WFSBP task force was to review the literature about this relationship.

RESULTS

Converging lines of evidence suggest that exposure to cannabis increases the risk for psychoses ranging from transient psychotic states to chronic recurrent psychosis. The greater the dose, and the earlier the age of exposure, the greater the risk. For some psychosis outcomes, the evidence supports some of the criteria of causality. However, alternate explanations including reverse causality and confounders cannot be conclusively excluded. Furthermore, cannabis is neither necessary nor sufficient to cause psychosis. More likely it is one of the multiple causal components. In those with established psychosis, cannabis has a negative impact on the course and expression of the illness. Emerging evidence also suggests alterations in the endocannabinoid system in psychotic disorders.

CONCLUSIONS

Given that exposure to cannabis and cannabinoids is modifiable, delaying or eliminating exposure to cannabis or cannabinoids, could potentially impact the rates of psychosis related to cannabis, especially in those who are at high risk for developing the disorder.

Detection of vaping, cannabis use, and hazardous prescription opioid use among adolescents

There has been a global surge in adolescents' use of electronic nicotine delivery systems (vaping), cannabis (vaped and edible), and prescription opioids, collectively termed ECPO. The nature of ECPO use can make it difficult to detect due to few obvious immediate physical and behavioural signs, as well as subtle long-term effects that allow adolescents to transition from initial exploration into hazardous ECPO use without easy detection by care providers. Here, we address the nature of the presentation of ECPO use in adolescents (roughly age 13-18 years), including challenges in detecting use and related complications, which affect screening, prevention, and intervention. We begin by reviewing empirical data on these difficult to detect effects in adolescents, including acute effects at cellular and neural levels and long-term neurocognitive and developmental changes that precede outwardly detectable physical signs. We then provide concrete approaches for providers to screen for ECPO use in adolescents even in the absence of overt physical and behavioural symptoms. Finally, we conclude with direct practice recommendations for prevention and intervention.

Strukturelle Gehirnveränderungen und Läsionen durch den Konsum illegaler Drogen und Psychedelika

Drogen können sowohl die Funktion wie auch die Struktur des Gehirns verändern. Gelegentlicher oder regelmäßiger Drogenkonsum ist in der Bevölkerung weit verbreitet. Daher ist die Kenntnis möglicher Nebenwirkungen und charakteristischer Bildbefunde bei Untersuchungen des Gehirns für den klinischen Alltag wichtig. Dieser Artikel beschreibt die für die am weitesten verbreiteten Substanzen typischen Komplikationen und morphologisch-radiologischen Veränderungen. Zu den möglichen Pathomechnismen gehören neurotoxische Effekte, die zu Leukenzephalopathie oder Hirnatrophie führen können, und vaskuläre Komplikationen wie Vasokonstriktion, Vaskulitis oder Hypertonus, durch die es zu intrazerebralen Blutungen oder Infarkten kommen kann. Da die klinische Präsentation oft unspezifisch ist, und die betroffenen Patienten ihren Drogenkonsum häufig verschweigen, ist das Erkennen typischer Bildbefunde essentiell für eine zuverlässige Diagnosestellung und zielgerichtete Therapie.

Differences in Inhibitory Control and Resting Brain Metabolism between Older Chronic Users of Tetrahydrocannabinol (THC) or Cannabidiol (CBD)—A Pilot Study

Δ9-Tetrahydrocannabinol is the main psychoactive component of cannabis and cannabidiol is purportedly responsible for many of the medicinal benefits. The effects of Δ9-tetrahydrocannabinol and cannabidiol in younger populations have been well studied; however, motor function, cognitive function, and cerebral glucose metabolism in older adults have not been extensively researched. The purpose of this study was to assess differences in cognitive function, motor function, and cerebral glucose metabolism (assessed via [¹⁸F]-fluorodeoxyglucose positron emission tomography) in older adults chronically using Δ9-tetrahydrocannabinol, cannabidiol, and non-using controls. Eight Δ9-tetrahydrocannabinol users (59.3 ± 5.7 years), five cannabidiol users (54.6 ± 2.1 years), and 16 non-users (58.2 ± 16.9 years) participated. Subjects underwent resting scans and performed cognitive testing (reaction time, Flanker Inhibitory Control and Attention Test), motor testing (hand/arm function, gait), and balance testing. Δ9-tetrahydrocannabinol users performed worse than both cannabidiol users and non-users on the Flanker Test but were similar on all other cognitive and motor tasks. Δ9-tetrahydrocannabinol users also had lower global metabolism and relative hypermetabolism in the bilateral amygdala, cerebellum, and brainstem. Chronic use of Δ9-tetrahydrocannabinol in older adults might negatively influence inhibitory control and alter brain activity. Future longitudinal studies with larger sample sizes investigating multiple Δ9-tetrahydrocannabinol:cannabidiol ratios on functional outcomes and cerebral glucose metabolism in older adults are necessary.

Long-Term Cannabis Use and Cognitive Reserves and Hippocampal Volume in Midlife

OBJECTIVE

Cannabis use is increasing among midlife and older adults. This study tested the hypotheses that long-term cannabis use is associated with cognitive deficits and smaller hippocampal volume in midlife, which is important because midlife cognitive deficits and smaller hippocampal volume are risk factors for dementia.

METHODS

Participants are members of a representative cohort of 1,037 individuals born in Dunedin, New Zealand, in 1972-1973 and followed to age 45, with 94% retention. Cannabis use and dependence were assessed at ages 18, 21, 26, 32, 38, and 45. IQ was assessed at ages 7, 9, 11, and 45. Specific neuropsychological functions and hippocampal volume were assessed at age 45.

RESULTS

Long-term cannabis users showed IQ decline from childhood to midlife (mean=-5.5 IQ points), poorer learning and processing speed relative to their childhood IQ, and informant-reported memory and attention problems. These deficits were specific to long-term cannabis users because they were either not present or were smaller among long-term tobacco users, long-term alcohol users, midlife recreational cannabis users, and cannabis quitters. Cognitive deficits among long-term cannabis users could not be explained by persistent tobacco, alcohol, or other illicit drug use, childhood socioeconomic status, low childhood self-control, or family history of substance dependence. Long-term cannabis users showed smaller hippocampal volume, but smaller hippocampal volume did not statistically mediate cannabis-related cognitive deficits.

CONCLUSIONS

Long-term cannabis users showed cognitive deficits and smaller hippocampal volume in midlife. Research is needed to ascertain whether long-term cannabis users show elevated rates of dementia in later life.

Neurocognitive and substance use disorders in older adults: challenges and evidence

Purpose

This study aims to review the presentation of substance use disorders in older adults, how addiction intertwines with neurocognitive disorders and how to approach this vulnerable population.

Design/methodology/approach

Electronic data searches of PubMed, Medline and the Cochrane Library (years 2000–2021) were performed using the keywords “neurocognitive,” “dementia,” “substance use,” “addiction,” “older adults” and “elderly.” The authors, in consensus, selected pivotal studies and conducted a narrative synthesis of the findings.

Findings

Research about substance use disorders in older adults is limited, especially in those with superimposed neurocognitive disorders. Having dual diagnoses can make the identification and treatment of either condition challenging. Management should use a holistic multidisciplinary approach that involves medical professionals and caregivers.

Originality/value

This review highlights some of the intertwining aspects between substance use disorders and neurocognitive disorders in older adults. It provides a comprehensive summary of the available evidence on treatment in this population.

The Effects of Cannabis Use on Cognitive Function in Healthy Aging: A Systematic Scoping Review

BACKGROUND

Older adults (≥50 years) represent the fastest-growing population of people who use cannabis, potentially due to the increasing promotion of cannabis as medicine by dispensaries and cannabis websites. Given healthy aging and cannabis use are both associated with cognitive decline, it is important to establish the effects of cannabis on cognition in healthy aging.

OBJECTIVE

This systematic scoping review used preferred reporting items for systematic reviews and meta-analyses guidelines to critically examine the extent of literature on this topic and highlight areas for future research.

METHOD

A search of six databases (PubMed, EMBASE, PsycINFO, Web of Science, Family and Society Studies Worldwide, and CINAHL) for articles published by September 2019, yielded 1,014 unique results.

RESULTS

Six articles reported findings for older populations (three human and three rodent studies), highlighting the paucity of research in this area. Human studies revealed largely null results, likely due to several methodological limitations. Better-controlled rodent studies indicate that the relationship between ∆9-tetrahydrocannabinol (THC) and cognitive function in healthy aging depends on age and level of THC exposure. Extremely low doses of THC improved cognition in very old rodents. Somewhat higher chronic doses improved cognition in moderately aged rodents. No studies examined the effects of cannabidiol (CBD) or high-CBD cannabis on cognition.

CONCLUSIONS

This systematic scoping review provides crucial, timely direction for future research on this emerging issue. Future research that combines neuroimaging and cognitive assessment would serve to advance understanding of the effects of age and quantity of THC and CBD on cognition in healthy aging.

Marijuana: A systems-based primer of adverse effects associated with use and an overview of its therapeutic utility

Marijuana use is on the rise in the United States. By the end of 2019, 33 states have legalized marijuana use and marijuana byproduct use for medical purposes. However, marijuana use does not come without side effects. This manuscript reviews the increasing usage of marijuana and the different forms (natural and synthetic) that patients may use when presenting to clinicians. It also addresses the biochemical and behavioral changes observed with marijuana use, including the location and changes associated with cannabinoid receptors (abbreviated CB1 and CB2). These two topics lead into an extensive review of the side effects of marijuana use. This manuscript discusses gastrointestinal side-effects, such as Cannabinoid Hyperemesis Syndrome, pancreatitis, and hepatotoxicity. It also briefly reviews cardiovascular, neurologic, and pulmonary side effects. This article provides an overview of therapeutic effects of marijuana including the antiemetic effect, its medical utility as an appetite stimulant, and usefulness in cancer patients post-chemotherapy. A thorough social history pertaining to marijuana use is an important consideration for clinicians in patients presenting with a variety of symptoms, including those effecting the gastrointestinal, cardiovascular, pulmonary, or neurologic systems.

Increased Likelihood of Falling in Older Cannabis Users vs. Non-Users

Cannabis is one of the most common drugs in the United States and is the third most prevalent substance consumed by adults aged 50 years and older. Normal aging is associated with physiological changes that make older adults vulnerable to impaired function and geriatric conditions (e.g., falls, cognitive impairment). However, the impact of medical cannabis use on fall risk in older adults remains unexplored. The purpose of this study was to investigate if cannabis use in older adults influences fall risk, cognitive function, and motor function. It was hypothesized that older chronic cannabis users would perform worse than non-users on gait, balance, and cognitive tests. Sixteen older adults, split into cannabis Users and age- and sex-matched Non-Users groups (n = 8/group), participated in the study. The results indicate a higher fall risk, worse one leg standing balance performance, and slower gait speed in Users vs. Non-Users. No significant differences in cognitive function were found. Thus, chronic cannabis use was purported to exacerbate the poorer balance control and slower gait velocity associated with normal aging. Future mechanistic (e.g., neuroimaging) investigations of the short- and long-term effects of using a variety of cannabis products (e.g., THC/CBD ratios, routes of administration) on cognitive function, motor function, and fall incidence in older adults are suggested.

The Behavioral Sequelae of Cannabis Use in Healthy People: A Systematic Review

Background: Cannabis is known to have a broad range of effects on behavior, including experiencing a "high" and tranquility/relaxation. However, there are several adverse behavioral sequalae that can arise from cannabis use, depending on frequency of use, potency (e.g., THC content), age of onset, and cumulative exposure. This systematic review examined evidence for cannabis-related adverse behavioral sequalae in otherwise healthy human subjects. Methods: Following PRISMA guidelines, we conducted a systematic review of cross-sectional and longitudinal studies from 1990 to 2020 that identified cannabis-related adverse behavioral outcomes in subjects without psychiatric and medical co-morbidities from PubMed and PsychInfo searches. Key search terms included "cannabis" OR "tetrahydrocannabinol" OR "cannabidiol" OR "marijuana" AND "anxiety" OR "depression" OR "psychosis" OR "schizophrenia" "OR "IQ" OR "memory" OR "attention" OR "impulsivity" OR "cognition" OR "education" OR "occupation". Results: Our search detected a total of 2,870 studies, from which we extracted 124 relevant studies from the literature on cannabis effects in the non-clinical population. Effects of cannabis on several behavioral sequelae including cognition, motivation, impulsivity, mood, anxiety, psychosis intelligence, and psychosocial functioning were identified. The preponderance of the evidence suggests that frequency of cannabis use, THC (but not CBD) content, age of onset, and cumulative cannabis exposure can all contribute to these adverse outcomes in individuals without a pre-existing medical condition or psychiatric disorder. The strongest evidence for the negative effects of cannabis are for psychosis and psychosocial functioning. Conclusions: Although more research is needed to determine risk factors for development of adverse behavioral sequelae of cannabis use, these findings underline the importance of understanding vulnerability to the adverse effects of cannabis, which has implications for prevention and treatment of problematic cannabis use.

Self-reported cognition and marijuana use in older adults: Results from the national epidemiologic survey on alcohol and related conditions-III

Marijuana use among older adults is on an unprecedented rise, yet little is known about its effects on cognition in this population where, due to advanced age, risk for cognitive decline is high. Thus, we investigated whether marijuana use and use characteristics were associated with self-reported cognition among older adults ages ≥ 50 years using the National Epidemiologic Survey on Alcohol and Related Conditions-III. Respondents either had never used marijuana ("never": n = 10,976), used but not in the past 12 months ("former": n = 2990), or used in the past 12 months ("current": n = 712). Self-reported cognition was measured using the Executive Function Index. Marijuana and substance use characteristics were obtained using the Alcohol Use Disorder and Associated Disabilities Interview Schedule-5. Covariates included demographics, mental health and disability, and comorbid mental and substance use disorder. Using general linear models of cross-sectional data, we found that current users, particularly those with cannabis use disorder, reported worse cognition than never or former users, but these effects were small in magnitude. Among both former and current users, greater duration of past use was associated with worse cognition. Frequent use within the past 12 months was associated with worse cognition among current users, but daily users reported better cognition compared to monthly or weekly users. Thus, marijuana use may impact self-reported cognition in older adulthood, although these effects may be subtle, specific to particular use characteristics, and possibly affected by self-awareness of deficits. Future work using objective measures such as neuropsychological testing or neuroimaging may better elucidate these effects.

Interaction of Cannabis Use and Aging: From Molecule to Mind

Given the aging Baby Boomer generation, changes in cannabis legislation, and the growing acknowledgment of cannabis for its therapeutic potential, it is predicted that cannabis use in the older population will escalate. It is, therefore, important to determine the interaction between the effects of cannabis and aging. The aim of this report is to describe the link between cannabis use and the aging brain. Our review of the literature found few and inconsistent empirical studies that directly address the impact of cannabis use on the aging brain. However, research focused on long-term cannabis use points toward cumulative effects on multimodal systems in the brain that are similarly affected during aging. Specifically, the effects of cannabis and aging converge on overlapping networks in the endocannabinoid, opioid, and dopamine systems that may affect functional decline particularly in the hippocampus and prefrontal cortex, which are critical areas for memory and executive functioning. To conclude, despite the limited current knowledge on the potential interactive effects between cannabis and aging, evidence from the literature suggests that cannabis and aging effects are concurrently present across several neurotransmitter systems. There is a great need for future research to directly test the interactions between cannabis and aging.

Cannabis Use in Adolescence: A Review of Neuroimaging Findings

Objective: Shifting policies and widespread acceptance of cannabis for medical and/or recreational purposes have fueled worries of increased cannabis initiation and use in adolescents. In particular, the adolescent period is thought to be associated with an increased susceptibility to the potential harms of repeated cannabis use, due to being a critical period for neuromaturational events in the brain. This review investigates the neuroimaging evidence of brain harms attributable to adolescent cannabis use. Methods: PubMed and Scopus searches were conducted for empirical articles that examined neuroimaging effects in both adolescent cannabis users and adult user studies that explored the effect of age at cannabis use onset on the brain. Results: We found 43 studies that examined brain effect (structural and functional magnetic resonance imaging) in adolescent cannabis users and 20 that examined the link between onset age of cannabis use and brain effects in adult users. Studies on adolescent cannabis users relative to nonusers mainly implicate frontal and parietal regions and associated brain activation in relation to inhibitory control, reward, and memory. However, studies in adults are more mixed, many of which did not observe an effect of onset age of cannabis use on brain imaging metrics. Conclusions: While there is some evidence of compromised frontoparietal structure and function in adolescent cannabis use, it remains unclear whether the observed effects are specifically attributable to adolescent onset of use or general cannabis use-related factors such as depressive symptoms. The relative contribution of adolescent onset of cannabis use and use chronicity will have to be more comprehensively examined in prospective, longitudinal studies with more rigorous measures of cannabis use (dosage, exposure, dependence, constituent compounds such as the relative cannabinoid levels).

A Systematic Review of the Neurocognitive Effects of Cannabis Use in Older Adults

Purpose of Review

Older adults currently represent the fastest growing demographic of cannabis users, yet few studies have investigated the effects of cannabis use on cognitive functioning in aging. We conducted a systematic review of the recent literature examining cognitive outcomes associated with cannabis use in older adults, with and without neurocognitive disorders, to clarify the potential neuroprotective benefits and risks of cognitive decline in this population.

Recent Findings

We identified 26 studies examining cognitive outcomes associated with medical and recreational use of cannabis in healthy aging, dementia, Parkinson's disease, multiple sclerosis, HIV, and pain populations. Although variability in the cannabis products used, outcomes assessed, and study quality limits the conclusions that can be made, modest reductions in cognitive performance were generally detected with higher doses and heavier lifetime use.

Summary

This review highlights the need for additional high-quality research using standardized, validated assessments of cannabis exposure and cognitive outcomes. Reliable measures and longitudinal data are necessary to better characterize the effects of cannabis use on cognitive aging, as well as differential effects of recreational and medical cannabis.

Cannabis effects on brain structure, function, and cognition: considerations for medical uses of cannabis and its derivatives

Background: Cannabis is the most widely used illicit substance worldwide, and legalization for recreational and medical purposes has substantially increased its availability and use in the United States.Objectives: Decades of research have suggested that recreational cannabis use confers risk for cognitive impairment across various domains, and structural and functional differences in the brain have been linked to early and heavy cannabis use.Methods: With substantial evidence for the role of the endocannabinoid system in neural development and understanding that brain development continues into early adulthood, the rising use of cannabis in adolescents and young adults raises major concerns. Yet some formulations of cannabinoid compounds are FDA-approved for medical uses, including applications in children.Results: Potential effects on the trajectory of brain morphology and cognition, therefore, should be considered. The goal of this review is to update and consolidate relevant findings in order to inform attitudes and public policy regarding the recreational and medical use of cannabis and cannabinoid compounds.Conclusions: The findings point to considerations for age limits and guidelines for use.