Browsing by Subject "Cannabis"

Now showing 1 - 5 of 5
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    Cannabis Cessation to Address Cannabis Hyperemesis Syndrome: a Plain Language Summary
    (2020) Newcome, Elle Maureen
    Cannabis Hyperemesis Syndrome (CHS) is a condition that involves repeated and severe bouts of nausea and vomiting in individuals with daily, long-term cannabis use. This Plain Language Summary introduces readers to CHS and answers common questions about the condition.
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    Cannabis use and cognition from adolescence to young adulthood: exploring cause, consequence, and influencing factors
    (2021-08) Bair, Jessica
    There are two overarching themes of this dissertation. The first is to evaluate the robustness of unique relationships between nonacute cannabis use occurring across adolescence and young adulthood and young adult cognitive outcomes. The second is to explore possible alternative explanations for associations found and separate potential causal influences of cannabis on cognition from shared familial or environmental factors. Research in this area has predominantly relied upon cross-sectional studies, and critics have raised concerns regarding the impact of extraneous factors insufficiently addressed within research, leaving the true relationship between cannabis and cognition uncertain. To address this and other limitations in the literature, this dissertation was designed to examine the relationship between cannabis use across adolescence and young adulthood and young adult cognitive outcomes. We used a large population-based twin sample with longitudinal tracking of cannabis use along with extensive neuropsychological assessment and interviewing and a quasi-experimental research design to draw stronger causal inferences. Across the two studies, nonacute cannabis use was associated with deficits in neurocognitive outcomes. Study 1 highlighted the importance of controlling for confounding as many of the associations did not survive covariate analyses, such that cannabis did not uniquely predict cognitive outcomes. However, beyond other factors, heavier and early cannabis use was related to deficits in domains, such as decision-making, processing speed, visuospatial attention, and general cognitive abilities. A pattern of sex-specific effects emerged such that males performed more poorly than females on decision-making and processing speed tasks with cannabis use. Converging on Study 1 conclusions to explore the etiology of the most robust relationships, Study 2 found evidence that deficits in neurocognitive performance indexed pre-existing familial or environmental liability but may also in turn be adversely impacted by heavy and early cannabis use, specifically for IQ and, in males, decision-making performance. Collectively, this work suggests a complex relationship between nonacute cannabis use and cognition, with differences in cognition reflecting a mixture of premorbid familial risk factors and possible adverse consequences of cannabis exposure. This information has implications for shaping policy decisions and targeting prevention and intervention efforts to reduce negative consequences of cannabis exposure in youth.
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    The Effects of Alcohol and Cannabis Use on Inhibitory Control Brain Networks In Emerging Adulthood: Causal Inferences From A Cotwin Control Study
    (2020-06) Harper, Jeremy
    The overarching theme of this dissertation was to separate the causal influences of familial risk toward substance misuse (e.g., genetic liability) from the potential effects of alcohol and cannabis exposure on multi-method indicators of the (pre)frontal inhibitory control brain network in a sample of 24-year-old twins. Deficits in inhibitory control and measures of its underlying brain circuitry have been implicated as core phenotypes of substance misuse. Research often assumes an exposure effect of alcohol or cannabis misuse on the still-developing emerging adult (ages 18-25) brain, but these individual differences may reflect the familial (e.g., genetic) risk toward both substance use and brain deviations. This remains largely unknown as the vast majority of prior work used research designs that could not disentangle exposure from risk. To address this and other limitations in the literature at large, this dissertation was designed to study how alcohol and cannabis use during emerging adulthood affect the structure and function of the inhibitory control network. We used a large (N = 673) genetically informative population-based twin sample, careful phenotyping of alcohol and cannabis use, multi-method brain assessment (EEG; structural MRI; resting-state fMRI connectivity), and a quasi-experimental research design (cotwin control analysis) to draw causal inferences regarding the effect of alcohol/cannabis use on the brain in a field where true experimentation is often unfeasible. Across the three studies in this dissertation, we found evidence that alcohol and/or cannabis use were associated with deviations in EEG theta-band rhythms, cortical thickness, and resting-state functional connectivity measures of the (pre)frontal inhibitory control network. The cotwin control analyses offered evidence that some of the anomalies can be attributed to consequences of alcohol and cannabis exposure, while others primarily reflect the liability to misuse alcohol or cannabis. Interestingly, deviations in the frontal medial cortex, a key hub of the control-related circuit, were implicated across all three studies, suggesting that it may play a crucial role in substance-related disinhibition. The work collectively suggests that substance-related variations in the inhibitory control brain network reflect a mixture of premorbid brain-based characteristics of familial risk and the deleterious effects of alcohol/cannabis exposure. Findings have implications for informing and shaping policy, public messaging, and prevention efforts to curb the alarmingly high rates of alcohol and cannabis use in emerging adults.
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    Evaluating Cannabis Cessation Treatment to Address Cannabis Hyperemesis Syndrome: Critically Appraised Topic
    (2020) Newcome, Elle Maureen
    In individuals with Cannabinoid Hyperemesis Syndrome (CHS), cognitive behavioural therapy (CBT) in addition to Cannabis cessation motivational interviewing (MI) leads to reduction of cannabis use at short-term follow up visits (median follow up visit: 4 months) resulting in lower recurrent cycles of vomiting and nausea when compared with no intervention or CBT or MI alone. The information provided does not necessarily reflect the views of the University of Minnesota Medical School physicians and faculty and is not intended to take the place of the advice and recommendations of your personal health care provider.
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    Longitudinal Change in Cognition and White Matter Integrity in Young Adult Cannabis Users
    (2015-09) Becker, Mary
    Cross-sectional research indicates that cannabis use is associated with cognitive and neuroanatomical damage, particularly when used regularly during development. The timing of use-related impacts on cognition and brain structure remains unclear. This dissertation includes two studies to characterize the longitudinal (1) neurocognitive profile and (2) white matter microstructure of young adult cannabis users who initiated use during adolescence. Cannabis users were assessed on a comprehensive neurocognitive battery and Diffusion Tensor Imaging (DTI) protocol at baseline and at a 2-year follow-up. In Study 1, cannabis users had stable deficits in verbal learning and memory as well as planning ability, and a stable relative strength in processing speed at baseline and follow-up. Deficits in spatial working memory and motivated decision-making observed at baseline recovered to control-level performance at follow-up. Heavier and earlier use of cannabis during adolescence was associated with decline in verbal learning and memory performance over time. In Study 2, change in white matter microstructure between time points was observed. Cannabis users exhibited reduced white matter microstructure organization in the central and parietal regions of the superior longitudinal fasciculus, left superior frontal gyrus, corticospinal tract, right anterior thalamic radiation, and in the posterior cingulum; cannabis users demonstrated increased white matter microstructure in the left anterior corpus callosum and left thalamic white matter. The findings suggest that continued heavy cannabis use during adolescence and young adulthood disrupts ongoing development of white matter microstructure. White matter microstructure changes were generally unrelated to cognitive performance, and future research is needed to clarify their functional significance. Potential mechanisms and implications of the findings are discussed.