One of the first research groups to look at cannabinoid exposure found poorer performance on cognitive tasks, such as maze learning, in immature rats compared to mature rats treated with THC. Schneider and Koch have reported alterations in pubertal rats treated with the receptor agonist WIN, discrepancies in performance range from sensorimotor functioning, object recognition memory, and social behavior. A more recent study by Schneider and colleagues found that chronic WIN treated pubertal rats demonstrated object/social recognition deficits, which the authors suggest is consistent with impairment in short-term information processing. Particularly, immature animals demonstrated more pronounced behavioral alterations as compared to mature animals after acute exposure to WIN, and more lasting deficits in social play and grooming behaviors. Deficits in object recognition have also been reported in male and female pubertal rats treated with a cannabinoid receptor agonist as well as THC, and there is some support that findings are consistent across age groups. Spatial functioning in adolescent rats has also shown affected by acute THC treatment. In a recent investigation by Abush and colleagues , chronic WIN treatment was found to result in both acute and longer term effects not only in spatial memory and object recognition, but interestingly, long term potentiation in areas such as nucleus accumbens pathways. Studies are actively evaluating emotional functioning and neurochemical transmission in adolescent animals after exposure to cannabinoid agonists, as well as how cannabinoids moderate state-dependent learning based on brain regions. While this is not an exhaustive review of the preclinical findings, in general, the data suggest differential and often negative impact on adolescent animals compared to adult animals exposed to THC or other cannabinoid agonists in behavioral, emotional, and social outcomes.

The animal work is particularly important to highlight, given the consistency in many adolescent neurocognitive and neuroimaging studies conducted with human subjects reporting regular use of marijuana,plant bench indoor as the findings often point to the deleterious effects on brain functioning compared to non-using controls. When California voters approved Proposition 64 in 2016, legalizing recreational cannabis for adults, they fundamentally altered the state’s cannabis landscape. They also, albeit unintentionally, furnished UC researchers with intriguing new avenues of potential inquiry — many of which are blocked by federal law and pursuant UC policy. For example, researchers interested in the cannabis-derived sprays and beverages readily available at California’s retail cannabis establishments cannot obtain those products for research purposes by any permissible means. Licensed cannabis businesses dot the state today, but cannabis research still operates within the same strict constraints that have hindered it since legalization was a futile sentiment on a bumper sticker. Because state law is subordinate to federal law, Proposition 64 is subordinate to the 1970 Controlled Substances Act. Associated with that act is a “scheduling” apparatus, overseen by the Drug Enforcement Administration , that identifies cannabis as ripe for abuse and devoid of medical merit. Thus, along with heroin and other Schedule I substances, the psychoactive variety of cannabis cannot under federal law be cultivated, processed, sold, consumed — or, for the most part, researched. The University of California, as a law-abiding institution, complies with the Controlled Substances Act and its nearly total cannabis prohibition. As an institution that receives federal funding, UC complies with the Drug-Free Workplace Act and the Safe and Drug Free Schools and Communities Act — which require universities, if they wish to receive federal funding, to implement policies prohibiting on-campus activities such as possession or use of controlled substances.

UC personnel, including staff, faculty and UC Cooperative Extension specialists and advisors, are therefore prohibited, in their professional capacities, from direct contact with the cannabis plant or its extracts, and also from certain types of indirect contact. They cannot, for example, visit cannabis cultivation sites or advise cannabis growers on topics such as yield increases. Researchers can’t even use cannabis or cannabis-derived products in medical studies — unless they fulfill a rather daunting set of federal requirements. Those requirements for medical studies include obtaining a Schedule I license from the DEA; submitting research protocols for Food and Drug Administration approval; submitting to the FDA an investigational new drug application ; and, as a non-federal matter, gaining the approval of a state entity, the Research Advisory Panel of California . If all goes well, researchers can then obtain cannabis or cannabis-derived substances from a DEA-licensed cultivator, a DEA registered bulk manufacturer or, with a DEA import license, a foreign exporter. The only DEA-licensed cannabis cultivator is the University of Mississippi, which grows the plant under a contract funded by the National Institute on Drug Abuse . Bulk manufacturers of cannabis products such as tetrahydrocannabinol — the psychoactive component in cannabis — include, for example, the Massachusetts based life science company MilliporeSigma . Providers of imported cannabis products — such as Tilray, a Canadian firm — must be based in jurisdictions where such products are legal. No matter which path researchers choose, the process isn’t fast or easy. “You need a patient, dedicated team willing to jump through extra hoops at the institutional, state and federal levels,” says Jeffrey Chen, Executive Director of UCLA’s Cannabis Research Initiative. Even so, Chen reports, federal restrictions on types and sources of cannabis products can prevent researchers from conducting cannabis studies at all. And again, only medical researchers are eligible to obtain cannabis for research. Those who wish to perform agronomic studies, for example, are simply out of luck. For all that, opportunities to research cannabis are not scarce around the UC system. Observational studies of cannabis users are permissible, though the cannabis in question cannot be provided by the university and must be consumed off campus. Researchers interested in the legal or economic dimensions of cannabis, or in cannabis policy, will discover few obstacles in the Controlled Substances Act. Several UC researchers are vigorously investigating the environmental consequences of cannabis cultivation — and in fact Proposition 64 has effectively expanded the scope for such research. According to Ted Grantham, a UCCE specialist at UC Berkeley and co-director of the UCB Cannabis Research Center, researchers can now interact with cannabis growers — to learn, for example, about their cultivation practices — in a way that grower reluctance previously precluded. Today, Grantham reports, “a subset of growers is very interested in day lighting the cannabis industry to establish its legitimacy as an agricultural crop rather than an illicit substance.” In years to come, UC investigators will likely perform extensive research on industrial hemp.

This form of cannabis, which contains extremely small amounts of THC, is useless for producing a “high” — but very useful for making fabrics, insulation, paper and more. Until recently, however, federal law did not distinguish between low-THC hemp and high-THC cannabis — nor between THC and cannabidiol , a nonpsychoactive cannabis compound purported to relieve medical conditions ranging from arthritis to anxiety. The legal landscape for hemp and CBD began to change on the federal level in 2014, when that year’s Farm Bill allowed universities to cultivate industrial hemp for research purposes . In June of last year, the FDA approved a CBD-based medicine for treatment of epilepsy-related seizures. With last December’s passage of the 2018 Farm Bill, industrial hemp became a legal crop — pending establishment of a regulatory framework to govern it. Hemp-derived CBD now appears on course for complete de-scheduling by the DEA, and the FDA is wrestling with how to regulate the CBD-based consumer products already hitting the market in many states. Amid this liberalization of federal law on hemp and CBD, it becomes easy to envision UC academics and UCCE personnel performing agronomic studies with hemp — and providing California hemp growers with the same sort of research-based knowledge that has long been available to cultivators of almonds, grapes and lettuce.EF includes processes such as planning, organization, decision-making, set shifting and maintenance, working memory, and the like . Individuals with poor EF have difficulty engaging in future goal oriented behavior and incorporating experience to modify behavior. A defining characteristic of SUD is intense desire to use substance regardless of short and long term consequences. Significant substance use can dramatically affect how an individual handles the reinforcing properties of substances as well as influence control mechanisms and quality of responses to decisions . It is not surprising both that regular substance use is associated with deficits in EF and etiological models include cognitive dysfunction as a risk factor for developing SUD . A population with inherent EF difficulties includes individuals with attention-deficit/ hyperactivity disorder . Patients with ADHD have particular deficits in the domains of attention and response inhibition , working memory , risky decision-making , and planning and shifting . Not surprisingly, childhood ADHD is associated with increased risk of later substance use, abuse, or dependence in adolescence and adulthood . In addition, individuals with SUD frequently have comorbid ADHD . It is not clear whether individuals with ADHD are at risk for more adverse cognitive consequences of substance use than individuals without ADHD. The minimal research on this topic is mixed. Some studies do not find a relationship between substance use and EF in individuals with ADHD.Others suggest substance use uniquely predicts EF deficits even after controlling for Diagnostic and Statistical Manual disorders, including ADHD . In the current study,greenhouse rolling racks we evaluated EF performance for young adults with and without ADHD histories crossed with cannabis use.

We aimed to ascertain whether any aspects of EF deficits are specific to ADHD or to cannabis use, and whether co-occurring ADHD and cannabis use have an additive effect on EF deficits. Our focus on cannabis is relevant because it is the most commonly used illicit drug in individuals with ADHD and cannabinoids significantly impact on EF . We anticipated individuals with a history of ADHD would perform more poorly than demographically similar age-mates without ADHD histories on response inhibition, decision-making, working memory, verbal memory including acquisition, recall, and recognition, and processing speed. The cognitive functioning literature is mixed for cannabis use, but we predicted that cannabis users would perform more poorly than non-users on decision-making , verbal memory , and cognitive interference . Although no studies to our knowledge have specifically examined the interaction of ADHD and cannabis use, we anticipated the most severe cognitive deficits for cannabis users with ADHD. It is also possible that early onset of cannabis use may disrupt healthy neuro development, which is of concern in cases of ADHD given reports of developmental lags in brain maturation among individuals with this disorder . Adolescence is a dynamic time when brain regions associated with EF undergo gray matter synaptic pruning which continues into the mid-20s . Maturation of white matter tracts, yielding more efficient neural conductivity, also continues into the early-30s . During adolescence, the limbic system develops earlier than the prefrontal cortex ; development of top-down control of the limbic system is therefore a gradual process . Adolescence may be a sensitive period associated with increased neurocognitive deficits resulting from substance use. Indeed, research has shown an association between initiation of cannabis use prior to the age of 16 and enduring deficits on attention and short-term memory even after 28 days of monitored abstinence . Therefore, we also conducted exploratory analyses investigating whether regular cannabis use prior to age 16 was a stronger predictor of EF deficits than contemporaneous use. We anticipated that cannabis users who engaged earlier in cannabis use would demonstrate poorer EF performance. Participants were recruited from the longitudinal follow-up of the Multi-modal Treatment Study of ADHD to participate in the current study. Recruitment took place at either the 14- or 16-year follow-up assessments . Original MTA participants included 579 children aged 7.0 to 9.9 years diagnosed in childhood with ADHD Combined Type. The MTA procedures for diagnosis, treatment specifics, and sample demographics have been described elsewhere . A local normative comparison group was recruited 24 months after baseline assessment to reflect the local populations from which the ADHD sample was drawn. ADHD and LNCG participants have been followed longitudinally with visits at 36-months, and 6, 8, 10, 12, 14, and 16 years after baseline assessment of the ADHD group. Participants in the current study included 87 ADHD and 41 LNCG based on their self-report of cannabis in the past year.