More research is needed to understand the socioeconomic impacts of legalization, which likely extend beyond those accounted for in the state’s economic impact analysis, which primarily focuses on economic contributions that a legalized market will bring to the state.Bodwitch et al.report that surveyed growers characterized legalization as a process that has excluded small farmers, altered local economies and given rise to illicit markets.The environmental impacts of cannabis production have received attention because of expansion into remote areas near sensitive natural habitats.The negative impacts are likely not because cannabis production is inherently detrimental to the environment, but rather due to siting decisions and cultivation practices.In the absence of regulation and best management practices based on research, it is no surprise that there have been instances of negative impacts on the environment.At the same time, many growers appear to have adopted an environmentally proactive approach to production and created networks to share and promote best management practices.Organizations that we approached to recruit survey participants had a fairly large base membership , which is on a par with other major commodity groups, like the Almond Board of California and California Association of Wine grape Growers.Membership included cannabis growers, distributors and processors as well as interested members of the public, and some people were members of more than one organization, suggesting a large, engaged community.Most of the organizations we contacted enthusiastically agreed to help us recruit growers for our survey, and we received excellent feedback on our initial survey questions.Growers who completed the survey were also clearly knowledgeable about cannabis cultivation.Some potential future research topics include the development of pest and disease monitoring programs; quantifying economic treatment thresholds; evaluating the efficacy of different biological, cultural and chemical controls; developing strategies to improve water use and irrigation efficiency; understanding grower motivations for regulatory compliance; understanding the impacts of regulation; and characterizing the competition between labor in cannabis and other agricultural crops — to name just a few.
As cannabis research and extension programs are developed, it will be critical to ensure that future surveys capture a representative sample of cannabis growers operating inside and outside the legal market, to identify additional areas for research and develop best practices for the various cultivation settings in which California cannabis grow equipment is grown.Approximately, 35% of high school seniors and young adults ages 19–28 reported using cannabis in the past year.Cannabis use during youth has been a recent focus in public health research, as it may influence one’s risk for reporting symptoms of anxiety and depression.A potential mechanism underlying cannabis’ influence on mood and affective symptoms may involve frontolimbic functioning [see ].Understanding differences in frontolimbic connectivity among young adults with frequent cannabis use may provide insight into the etiology of associated mood or affective risk.Cannabinoids in cannabis, such as 1 9-tetrahydrocanabidiol and cannabidiol , are chemicals that mimic endogenous neurotransmitters anandamide and 2AG by binding to endocannabinoid receptors CB1 and CB2.THC is the main psychoactive component of cannabis and is responsible for the subjective “high” individuals experience [see ].CB1 activity modulates the release of the neurotransmitters GABA and glutatmate [see ].The eCB system modulates several functions related to physical and mental health, including regulation of emotional and stress responses [see ].More specifically, the eCB system plays a role in mood and affect , integrating reward feedback , and threat related signals.Brain regions primarily involved in the affective processing system include several interacting cortical and subcortical regions.This system is highly innervated with CB1 receptors and animal models demonstrate developmental changes in CB1 expression within the mPFC, ACC and insula , suggesting the system demonstrates plasticity during adolescence.Therefore, repeated THC exposure during development may impact naturally occurring changes in eCB functioning within mesocorticolimbic regions.Indeed, daily cannabis users have shown decreased CB1 receptor density within frontolimbic regions , ACC, and insula compared to non-users which recovered after a month of abstinence.Further, acute THC administration has resulted in abnormal performance on behavioral measures of emotional processing , amygdala reactivity , and altered functional connectivity and signaling in PFC regions.
However, additional research is needed to confirm the influence of repeated THC exposure on affective outcomes in adolescents and young adults.Due to the neuromodulatory role of the eCB system, examining brain functional connectivity is an important outcome to study in regular cannabis users.These relationships can be examined during tasks and also at rest, when individuals are not actively engaging in any specific cognitive tasks, called resting state, or intrinsic functional connectivity.Connectivity patterns in frontolimbic regions continue to develop into late adolescence and emerging adulthood; prefrontal maturation purports enhanced emotion regulation and behavior inhibition capabilities [see ], giving rise to a functional coupling between frontal and limbic regions.Collectively, the developmental changes in frontolimbic connectivity are thought to enhance socioemotional regulation [see ], specifically via functioning within the amygdala, medial PFC, vmPFC, ACC, insula, and inferior frontal gyrus.A particular region within the PFC, the ACC, also undergoes significant age-related changes in intrinsic functional connectivity, particularly in rostral ACC subregions involved in social cognition and emotion regulation.Therefore, this system may be particularly vulnerable to repeated THC exposure during development.Thus far, studies have found slower response times in users when identifying emotional faces and more liberal criterion for selecting sadness , poorer facial recognition and emotion matching , and emotion identification and discrimination impairments compared to non-users; though accuracy in emotion identification may not display a dosedependent relationship.fMRI studies have found aberrant amygdala and ACC activity in young cannabis users during affective processing tasks, including blunted ACC and amygdala activation during sub-conscious facial viewing , blunted amygdala response among youth with comorbid cannabis dependence and depression , and greater amygdala reactivity to angry faces in young adolescents.However, to date very few studies have examined intrinsic functional connectivity in adolescents and emerging adults.Studies to date in adolescent and young adult cannabis users have demonstrated increased intrinsic connectivity in frontal -temporal gyrus-cerebellar regions , frontal-parietalcerebellar network , increased middle-frontal and cingulate gyrus connectivity , and increased frontal gyrus activity along with reduced middle temporal activity.Increased connectivity patterns were linked with increased symptoms of cannabis dependence and recent cannabis use frequency.In young adult males, cannabis use was linked with increased connectivity in insula and decreased connectivity in the anterior cingulate and midbrain, even after a month of abstinence.
Thus, overall, young cannabis users appear to demonstrate increased intrinsic connectivity patterns, especially in frontal-limbic regions.Still, these studies were primarily in men , thus findings may not generalize to female users.Further, two studies did not control for comorbid alcohol use and despite the aforementioned link between cannabis use and affective processing, no studies to date have specifically examined affective processing networks in cannabis users.Therefore, additional research is needed to examine intrinsic connectivity in affective processing networks in larger samples that include both males and females, controlling for comorbid alcohol use.The purpose of the current study was to explore whether regular cannabis use in adolescents and young adults was associated with aberrant ifcMRI frontolimbic connectivity at rest.We employed a priori region of interest analysis focusing on regions with reported cortical differences between young cannabis users and controls, including: vmPFC , ACC , insula , and amygdala.This project utilized ifcMRI data from three collection sites from the Imaging Data in Emerging Adults with Addiction Consortium.The strength of utilizing multi-site data sets include excellent reliability and validity when combining multi-site ifcMRI data , increased generalizability of more heterogenous groups , and larger sample sizes.It was hypothesized that cannabis users would demonstrate increased intrinsic connectivity patterns in regions subserving emotional expression [amygdala, insula, and caudal and rostral ACC ].Lastly, in order to interpret the findings, a secondary aim examined if group differences in connectivity were associated with cannabis users’ self-reported anxiety and depressive symptoms.The current study examined whether cannabis use was associated with frontolimbic intrinsic connectivity using a cross-sectional design in a sample devoid of independent Axis I anxiety FIGURE 2 | Scatter plot between total depression symptoms and bilateral rAcc connectivity in cannabis users.or mood disorders.After controlling for MRI collection site, recent alcohol, and nicotine use, and abstinence from cannabis use, cannabis users demonstrated increased intrinsic connectivity between the left rACC and the following: left insula, left amygdala, and right rACC in comparison to controls, though only group differences between bilateral rACC survived after correcting for multiple comparisons.Further, we found that increased bilateral rACC connectivity was associated with greater sub-clinical depressive symptoms in cannabis users.Current findings parallel previous intrinsic functional studies indicating frequent cannabis use among youth is associated with greater connectivity between frontal and temporal regions , and increased ACC connectivity in males.Resting state connectivity increases in comparison to controls was also reported within the medial frontal gyrus among a high-risk mostly male adolescent group.The present study adds to existing literature by including more females, controlling for other substance use and cannabis abstinence period, and relating the observed connectivity differences to mood-related symptoms.
Task-based studies also report altered medial PFC activity associated with cannabis use among emerging adults ,vertical grow system suggesting chronic cannabis use is associated with region-specific changes in brain activity and connectivity among regions implicated in emotion regulation, identification, and modulation.The current findings of abnormal functional connectivity in the rACC and limbic regions, which is consistent with our previous structural findings.Our team recently reported that greater cannabis use was related to reduced left rACC volume among young cannabis users, and smaller rACC volumes were also significantly associated with lower performance in an emotional discrimination task.Further, we also found reduced right ACC cortical thickness in a sample of young cannabis users, including a subset of cannabis users with a history of childhood attention deficit hyperactivity disorder, compared to non-using controls.The ACC undergoes significant developmental shifts in functional connectivity during young adulthood , has been implicated in ones’ ability to detect and monitor self-produced errors whether one is conscious/aware of the error or not.The ACC may be less engaged in cannabis users compared to controls during tasks requiring inhibitory control and error monitoring.The rostral subdivision of the ACC is functionally connected with the amygdala , forming a network for processing affective facets of behavior.In concert with the insula, the ACC also serves to incorporate perceptual information with autonomic and emotional information.More specifically, the rACC has been posited to have top down control influence, serving as a gatekeeper, between regions processing negative affective information and those integrating environmental stimuli [see ], and demonstrates protracted development during young adulthood.The rACC is involved in implicit or automatic emotion regulation that occurs at a subconscious level.Indeed, lesions in the rACC are posited to impair ones’ sensitivity to adjustments in personal performance during a cognitive control task.For example, cannabis users have demonstrated reduced P300 during implicit and empathic emotional processing paradigms, particularly for the highest using cannabis users that also demonstrated deficits in explicit processing of negative emotions.Thus, abnormalities in rACC structure and function may impact various behavioral aspects, including cognitive control and emotional regulation.The current study suggests that chronic cannabis use may increase intrinsic connectivity between emotion regulation regions, which was opposite of our original hypothesis.A potential interpretation may include the inefficiency of prefrontal top-down regulation, as hypothesized by Behan et al., suggesting reduced intrinsic amygdala responsiveness.Further, Pujol et al.found reduced ACC and insula connectivity; however, the study did not examine sub-components of the ACC and used seed-based rather than region of interest approaches.Thus, disruptions in rACC function may lead to challenges in modulating ones’ mood, consistent with the current study findings, or adjusting to emotionally salient internal and external information.Indeed, we also found that increased depressive symptoms among cannabis users were associated with greater connectivity between the bilateral rACC.Alterations in rACC structure and function [see ] have been previously linked with depressive and affective symptoms and antidepressant response.Though the current sample did not meet criteria for an Axis I mood or anxiety disorder, cannabis use may impact regions implicated in symptom manifestation.Although cannabis users reported significantly greater sub-clinical levels of depression, we are unable to determine whether the endorsed symptoms predated the initiation of cannabis use or whether the endorsed symptoms occurred during the course of regular cannabis use among users.Indeed, cross-sectional and longitudinal studies among cannabis using youth have found increased risk of mood and affective symptoms.Even casual cannabis using young adults report greater depressive symptomatology.Thus, structural and functional abnormalities within the rACC observed in cannabis users may result in mood dysregulation.