Browsing by Author "Chambers, Robert Andrew"

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    Assessment of Risk Behaviors in Patients With Opioid Prescriptions: A Study of Indiana’s Inspect Data
    (Wiley, 2017-12) Greene, Marion S.; Chambers, Robert Andrew; Yiannoutsos, Constantin T.; Wright, Eric R.; Steele, Gregory K.; Zollinger, Terrell W.; Health Policy and Management, School of Public Health
    Background and Objectives Prescription Drug Monitoring Programs (PDMPs) can serve as screening tools and support the clinical decision‐making process in patients receiving opioids. The objective of the study was to utilize 2014 INSPECT (Indiana's PDMP) data to identify factors that increase patients’ likelihood to engage in opioid‐related risk behaviors. Methods Based on a literature review, four risk behaviors were identified: Receiving >90 morphine milligram equivalents (MME), having >4 opioid prescribers, obtaining opioids from >4 pharmacies, and concurrent use of opioids and benzodiazepines. Two binary logistic regression analyses (engaging in at least one risk behaviors; engaging in all four risk behaviors) and an ordinal regression analysis (engaging in 0–4 risk behaviors) were conducted to identify factors associated with these opioid‐related risk behaviors. Results Of the 1,538,120 unique opioid patients included in the study, 18.4% engaged in one, 5.3% in two, 1.6% in three, and .4% in all four risk behaviors. Depending on the model, prescribing a second monthly opioid increased patients’ odds to engage in risk behaviors by a factor of 10 or more and prescribing two or more benzodiazepines annually increased the odds at least 13‐fold. Conclusions and Scientific Significance About one‐fourth of all patients consuming opioids engaged in one or more risk behaviors; higher number of opioid prescriptions and addition of even a small number of benzodiazepine prescriptions dramatically increased these odds. PDMPs can be helpful in identifying opioid users at high‐risk for misuse. This information could be used to target efforts to reduce the prescription drug epidemic.
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    Integrated Effects of Neonatal Ventral Hippocampal Lesions and Impoverished Social-Environmental Rearing on Endophenotypes of Mental Illness and Addiction Vulnerability
    (Karger, 2019) Chambers, Robert Andrew; Sentir, Alena M.; Psychiatry, School of Medicine
    A wide range of mental illnesses show high rates of addiction comorbidities regardless of their genetic, neurodevelopmental, and/or adverse-environmental etiologies. Understanding how the spectrum of mental illnesses produce addiction vulnerability will be key to discovering more effective preventions and integrated treatments for adults with addiction and dual diagnosis comorbidities. A population of 131 rats containing a spectrum of etiological mental illness models and degrees of severity was experimentally generated by crossing neonatal ventral hippocampal lesions (NVHL; n = 68) or controls (SHAM-operated; n = 63) with adolescent rearing in environmentally/socially enriched (ENR; n = 66) or impoverished (IMP; n = 65) conditions. This population was divided into 2 experiments: first, examining NVHL and IMP effects on novelty and mild stress-induced locomotion across 3 adolescent ages; second, looking at initial cocaine reactivity and long-term cocaine behavioral sensitization in adulthood. NVHL and IMP-environmental conditions independently produced remarkably similar and robustly significant abnormalities of hyperreactivity to novelty, mild stress, and long-term cocaine sensitization. The combined NVHL-IMP groups showed the most severe phenotypes across the board, so that the mental illness and addiction vulnerability phenotypes increased together in severity in a consistent stepwise progression from the healthiest rats to those with the greatest loading of etiological models. These findings add weight to our understanding of mental illness and addiction vulnerability as brain disorders that are biologically and developmentally unified in ways that transcend etiological causes, and yet co-intensify with increased loading of etiological conditions. Combining neurodevelopmental and adverse-environmental models of mental illness may provide an approach to identifying and therapeutically targeting cortical-striatal-limbic network mechanisms that generate addiction and dual diagnosis diseases.
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    Ventral and dorsal striatal dopamine efflux and behavior in rats with simple vs. co-morbid histories of cocaine sensitization and neonatal ventral hippocampal lesions
    (Springer Verlag, 2010-07-15) Chambers, Robert Andrew; Sentir, Alena M.; Engleman, Eric A.; Psychiatry, School of Medicine
    xposing animal models of mental illness to addictive drugs provides an approach to understanding the neural etiology of dual diagnosis disorders. Previous studies have shown that neonatal ventral hippocampal lesions (NVHL) in rats produce features of both schizophrenia and addiction vulnerability. Objective This study investigated ventral and dorsal striatal dopamine (DA) efflux in NVHL rats combined with behavioral sensitization to cocaine. Methods Adult NVHL vs. SHAM-operated rats underwent a 5-day injection series of cocaine (15 mg/kg/day) vs. saline. One week later, rats were cannulated in nucleus accumbens SHELL, CORE, or caudate–putamen. Another week later, in vivo microdialysis sampled DA during locomotor testing in which a single cocaine injection (15 mg/kg) was delivered. Results NVHLs and cocaine history significantly increased behavioral activation approximately 2-fold over SHAM-saline history rats. DA efflux curves corresponded time dependently with the cocaine injection and locomotor curves and varied significantly by striatal region: Baseline DA levels increased 5-fold while cocaine-stimulated DA efflux decreased by half across a ventral to dorsal striatal gradient. However, NVHLs, prior cocaine history, and individual differences in behavior were not underpinned by differential DA efflux overall or within any striatal region.Conclusion Differences in ventral/dorsal striatal DA efflux are not present in and are not required for producing differential levels of acute cocaine-induced behavioral activation in NVHLs with and without a behaviorally sensitizing cocaine history. These findings suggest other neurotransmitter systems, and alterations in striatal network function post-synaptic to DA transmission are more important to understanding the interactive effects of addictive drugs and mental illness.