Cognitive function during early abstinence from opioid dependence: a comparison to age, gender, and verbal intelligence matched controls

Revive and Refuse: Capacity, Autonomy, and Refusal of Care After Opioid Overdose

Physicians generally recommend that patients resuscitated with naloxone after opioid overdose stay in the emergency department for a period of observation in order to prevent harm from delayed sequelae of opioid toxicity. Patients frequently refuse this period of observation despiteenefit to risk. Healthcare providers are thus confronted with the challenge of how best to protect the patient's interests while also respecting autonomy, including assessing whether the patient is making an autonomous choice to refuse care. Previous studies have shown that physicians have widely divergent approaches to navigating these conflicts. This paper reviews what is known about the effects of opioid use disorder on decision-making, and argues that some subset of these refusals are non-autonomous choices, even when patients appear to have decision making capacity. This conclusion has several implications for how physicians assess and respond to patients refusing medical recommendations after naloxone resuscitation.

Neurocognitive Functions After 6-Month Buprenorphine (Naloxone)-Based Opioid Agonist Maintenance Treatment: A Controlled Prospective Study

BACKGROUND

Medications for opioid use disorder (OUD) may influence neurocognitive functions. Inadequate power, confounders, and practice effects limit the validity of the existing research. We examined the change in cognitive functions in patients with OUD at 6-month buprenorphine (naloxone) posttreatment and compared the cognitive performance of the buprenorphine-treated group with control subjects.

METHODS

We recruited 498 patients with OUD within a week of initiating buprenorphine. Assessments were done twice-at baseline and 6 months. Those abstinent from illicit opioids and adherent to treatment (n = 199) underwent follow-up assessments. Ninety-eight non-substance-using control subjects were recruited from the community. The neurocognitive assessments comprised the Wisconsin Card Sorting Test, Iowa Gambling Task, Trail-Making Tests A and B (TMT-A and TMT-B), and verbal and visual N-Back Test. We controlled for potential effect modifiers.

RESULTS

Twenty-five of the 32 test parameters significantly improved with 6 months of buprenorphine treatment; 20 parameters withstood corrections for multiple comparisons (P < 0.001). The improved test domains spread across cognitive tests: Wisconsin Card Sorting Test (perseverative errors and response, categories completed, conceptual responses), TMTs (time to complete), verbal and visual N-Back Tests (hits, omission, and total errors). After treatment, OUD (vs control subjects) had less perseverative response and error (P < 0.001) and higher conceptual response (P = 0.004) and took lesser time to complete TMT-A (P < 0.001) and TMT-B (P = 0.005). The baseline neurocognitive functions did not differ between those who retained and those who discontinued the treatment.

CONCLUSION

Cognitive functions improve in patients with OUD on buprenorphine. This improvement is unlikely to be accounted for by the practice effect, selective attrition, and potential confounders.

Neurocognitive Dysfunctions in People with Concurrent Cannabis Use and Opioid Dependence: A Cross-Sectional, Controlled Study

Cannabis and opioid co-dependence is independently associated with cognitive impairments. We examined neurocognitive dysfunctions in people with concurrent opioid dependence with cannabis dependence (OD+CD) or cannabis use (OD+CU) compared to those with only opioid dependence (OD) and healthy controls (HC). We selected adult participants, any sex, who met the diagnosis of OD (N = 268), OD+CU (N = 58), and OD + CD (N = 115). We recruited 68 education-matched HC. We administeredStandard progressive matrices (SPM), Wisconsin card sorting test (WCST), Iowa gambling task (IGT), Trail making tests A and B (TMT), and verbal and visual working memory 1-, 2-backtests. 496 (97.5%) were men, and 13 (2.5%) were women. In WCST, OD and OD+CD had significantly higher non-perseverative errors than HC. OD+CD group completed significantly lesser categories than HC. In verbal working memory 2-back, HC scored significantly fewer errors than OD and OD +CD. All patient groups, OD, OD+CU, and OD+CD, scored higher commission errors than HC in visual working memory 1-back. OD and OD+CD scored higher commission and total errors than the controls. OD+CU showed lesser error score than HC in TMT B. Cannabis and opioid co-dependence contribute to cognitive impairments, especially in working memory and executive functions.

Chronic Voluntary Morphine Intake Is Associated with Changes in Brain Structures Involved in Drug Dependence in a Rat Model of Polydrug Use

Chronic opioid intake leads to several brain changes involved in the development of dependence, whereby an early hedonistic effect (liking) extends to the need to self-administer the drug (wanting), the latter being mostly a prefrontal-striatal function. The development of animal models for voluntary oral opioid intake represents an important tool for identifying the cellular and molecular alterations induced by chronic opioid use. Studies mainly in humans have shown that polydrug use and drug dependence are shared across various substances. We hypothesize that an animal bred for its alcohol preference would develop opioid dependence and further that this would be associated with the overt cortical abnormalities clinically described for opioid addicts. We show that Wistar-derived outbred UChB rats selected for their high alcohol preference additionally develop: (i) a preference for oral ingestion of morphine over water, resulting in morphine intake of 15 mg/kg/day; (ii) marked opioid dependence, as evidenced by the generation of strong withdrawal signs upon naloxone administration; (iii) prefrontal cortex alterations known to be associated with the loss of control over drug intake, namely, demyelination, axonal degeneration, and a reduction in glutamate transporter GLT-1 levels; and (iv) glial striatal neuroinflammation and brain oxidative stress, as previously reported for chronic alcohol and chronic nicotine use. These findings underline the relevance of polydrug animal models and their potential in the study of the wide spectrum of brain alterations induced by chronic morphine intake. This study should be valuable for future evaluations of therapeutic approaches for this devastating condition.

Opioid relapse and its predictors among methadone maintenance patients: a multicenter, cross-sectional study in Vietnam

BACKGROUND

Opioid relapse, one of the common and severe problems during methadone maintenance treatment, can give rise to poor treatment outcomes. This study measured the opioid relapse rate and its associated factors among methadone maintenance patients in Vietnam.

METHODS

Information about the demographic characteristics and social support of 655 patients was collected through direct interviews. Medical records were used to gather data on treatment characteristics. Relapse was determined via urine opioid test results.

RESULTS

The overall relapse rate of patients during treatment was 13.1%. According to the multivariate logistic regression model, living in mountainous areas (adjusted odds ratio (aOR) = 3.63, 95% CI 1.90-7.46) and long duration of drug use in the past (aOR = 1.06, 95% CI 1.03-1.09) were associated with an increase in the odds of opioid relapse. By contrast, living with many family members (aOR = 0.69, 95% CI 0.55-0.85), having longer treatment time (aOR = 0.80, 95% CI 0.73-0.87), and completely adhering to treatment (aOR = 0.38, 95% CI 0.23-0.64) were protective for opioid relapse. As per the univariate analyses, the odds of opioid relapse declined by 25% for each increase of one close friend or relative (OR = 0.75, 95% CI 0.66-0.86). Regarding social support (range score: 0-100), each additional increase of one score was associated with a 1% decrease in the odds of opioid relapse (OR = 0.99, 95% CI 0.98-0.99). Patient sex, education level, occupation type, patient's monthly income, family's monthly income, the number of previous treatments, daily methadone dose, comorbidity, and received antiretroviral therapy were not associated with opioid relapse among patients (p > 0.05).

CONCLUSIONS

Residence, the role of family and social support, and treatment adherence should be paid more attention to guarantee and enhance the success of methadone maintenance treatment.

Differential effects of acute and prolonged morphine withdrawal on motivational and goal-directed control over reward-seeking behavior

Opioid addiction is a relapsing disorder marked by uncontrolled drug use and reduced interest in normally rewarding activities. The current study investigated the impact of spontaneous withdrawal from chronic morphine exposure on emotional, motivational, and cognitive processes involved in regulating the pursuit and consumption of natural food rewards in male rats. In Experiment 1, rats experiencing acute morphine withdrawal lost weight and displayed somatic signs of drug dependence. However, hedonically-driven sucrose consumption was significantly elevated, suggesting intact and potentially heightened emotional reward processing. In Experiment 2, rats undergoing acute morphine withdrawal displayed reduced motivation when performing an effortful response for palatable food reward. Subsequent reward devaluation testing revealed that acute withdrawal also disrupted their ability to exert flexible goal-directed control over their reward-seeking behavior. Specifically, morphine-withdrawn rats displayed insensitivity to reward devaluation both when relying on prior action-outcome learning and when given direct feedback about the consequences of their actions. In Experiment 3, rats tested after prolonged morphine withdrawal displayed heightened rather than diminished motivation for food rewards and retained their ability to engage in flexible goal-directed action selection. However, brief re-exposure to morphine was sufficient to impair motivation and disrupt goal-directed action selection, though in this case insensitivity to reward devaluation was only observed in the presence of morphine-paired context cues and in the absence of response-contingent feedback. We suggest that these opioid-withdrawal induced deficits in motivation and goal-directed control may contribute to addiction by interfering with the pursuit of adaptive alternatives to drug use.

Cognitive impairment in opioid use disorders: Is there a case for use of nootropics?

Opioid Use Disorders (OUDs) are often associated with cognitive impairments, which may lead to an increased risk of relapse. These cognitive deficits do not resolve with abstinence or medication-assisted treatment and may require targeted management. While psychotherapies and neuromodulation techniques have been studied for their effectiveness, they have certain limitations and challenges. Cognition enhancing prescription drugs like donepezil and memantine, which are used in dementias, have shown promise in a small number of studies examining their role in the reversal of opioid-induced cognitive deficits. The authors explore the potential role of nootropics in improvement of cognitive decline associated with OUDs.

Latent profile analysis of data from the brief inventory of neurocognitive impairment (BINI) to develop neuro-cognitive profiles among opioid-dependent patients in drug treatment

BACKGROUND

Neurocognitive dysfunction is common among individuals with opioid use disorders (OUD) and can impede a range of treatment outcomes. We developed the 57-item Brief Inventory of Neuro-cognitive Impairment (BINI) to help detect and monitor neurocognitive dysfunction in the context of drug treatment settings. To date, no study has examined the possible presence of BINI subgroups among OUD patients, which could enhance our ability to tailor intervention strategies to meet individual treatment needs. The purpose of this study was to conduct a latent profile analysis to identify BINI subgroups that differ in terms of their reported and objective neurocognitive dysfunction. We hypothesized that subgroups would emerge, suggesting the potential benefit of implementing tailored strategies for optimal treatment outcomes.

METHODS

Latent profile analyses included data from opioid-dependent patients (N = 177) enrolled in a methadone maintenance treatment program between July 2018 and October 2019.

RESULTS

We found three profiles of self-reported neurocognitive symptoms, including those with 1) minimal concerns 2) moderate concerns, and 3) many concerns across multiple domains.

CONCLUSIONS

If these results are confirmed, the BINI may be used to rapidly identify persons who require specific accommodation strategies to improve their drug treatment outcomes.

Neurocognitive Functions in Patients with Comorbid Hepatitis C and Opioid Dependence: A Comparative Study

Background

Hepatitis C virus (HCV) infection is commonly comorbid with opioid dependence (OD). We wanted to compare the neurocognitive functions of OD subjects with or without HCV [HCV (+), HCV (-)] and healthy controls (HC).

Methods

We recruited 40 adult subjects (age 18-55 years) in each group. HCV(+) group had a detectable viral load. Subjects with HIV or hepatitis B infection, head injury, epilepsy, or comorbid mental illness were excluded. We administered Standard Progressive Matrices (SPM), Wisconsin Card Sorting Test, Iowa Gambling Task (IGT), trail-making tests A and B, and verbal and visual N-back tests (NBT) one week after opioid abstinence. The group differences in cognitive performance were adjusted for age and years of education. Effect size (ES) is expressed as Cohen's D.

Results

The HCV(+) and HCV(-) groups did not differ in potential effect modifiers (age and years of education) or confounders (age of opioid initiation, duration of use, dependence severity, tobacco use, and cannabis use) of neuropsychological functioning. HCV(+) showed significantly poorer performance than HCV(-) in SPM (P = 0.006; ES = 0.72). Both HCV(+) and HCV(-) performed worse than controls in IGT(P < 0.001; ES = 0.8) and visual NBT[P < 0.01 and ES > 1 for total errors]; HCV(+) had a larger ES of group difference than HCV(-). HCV(+) had higher error scores in verbal NBT than control.

Conclusion

HCV(+) has poorer general intellectual ability and reasoning than HCV(-) persons and controls. Chronic HCV infection causes a higher magnitude of dysfunction in decision-making and visual working memory in opioid-dependent individuals.

A role for the circadian transcription factor NPAS2 in the progressive loss of non-rapid eye movement sleep and increased arousal during fentanyl withdrawal in male mice

RATIONALE

Synthetic opioids like fentanyl are contributing to the rise in rates of opioid use disorder and drug overdose deaths. Sleep dysfunction and circadian rhythm disruption may worsen during opioid withdrawal and persist during abstinence. Severe and persistent sleep and circadian alterations are putative factors in opioid craving and relapse. However, very little is known about the impact of fentanyl on sleep architecture and sleep-wake cycles, particularly opioid withdrawal. Further, circadian rhythms regulate sleep-wake cycles, and the circadian transcription factor, neuronal PAS domain 2 (NPAS2) is involved in the modulation of sleep architecture and drug reward. Here, we investigate the role of NPAS2 in fentanyl-induced sleep alterations.

OBJECTIVES

To determine the effect of fentanyl administration and withdrawal on sleep architecture, and the role of NPAS2 as a factor in fentanyl-induced sleep changes.

METHODS

Electroencephalography (EEG) and electromyography (EMG) was used to measure non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS) at baseline and following acute and chronic fentanyl administration in wild-type and NPAS2-deficient male mice.

RESULTS

Acute and chronic administration of fentanyl led to increased wake and arousal in both wild-type and NPAS2-deficient mice, an effect that was more pronounced in NPAS2-deficient mice. Chronic fentanyl administration led to decreased NREMS, which persisted during withdrawal, progressively decreasing from day 1 to 4 of withdrawal. The impact of fentanyl on NREMS and arousal was more pronounced in NPAS2-deficient mice.

CONCLUSIONS

Chronic fentanyl disrupts NREMS, leading to a progressive loss of NREMS during subsequent days of withdrawal. Loss of NPAS2 exacerbates the impact of fentanyl on sleep and wake, revealing a potential role for the circadian transcription factor in opioid-induced sleep changes.

Electroacupuncture attenuates surgical pain-induced delirium-like behavior in mice via remodeling gut microbiota and dendritic spine

Surgical pain is associated with delirium in patients, and acupuncture can treat pain. However, whether electroacupuncture can attenuate the surgical pain-associated delirium via the gut-brain axis remains unknown. Leveraging a mouse model of foot incision-induced surgical pain and delirium-like behavior, we found that electroacupuncture stimulation at specific acupoints (e.g., DU20+KI1) attenuated both surgical pain and delirium-like behavior in mice. Mechanistically, mice with incision-induced surgical pain and delirium-like behavior showed gut microbiota imbalance, microglia activation in the spinal cord, somatosensory cortex, and hippocampus, as well as an enhanced dendritic spine elimination in cortex revealed by two-photon imaging. The electroacupuncture regimen that alleviated surgical pain and delirium-like behavior in mice also effectively restored the gut microbiota balance, prevented the microglia activation, and reversed the dendritic spine elimination. These data demonstrated a potentially important gut-brain interactive mechanism underlying the surgical pain-induced delirium in mice. Pending further studies, these findings revealed a possible therapeutic approach in preventing and/or treating postoperative delirium by using perioperative electroacupuncture stimulation in patients.

Effect of tramadol on apoptosis and synaptogenesis in hippocampal neurons: The possible role of µ-opioid receptor

Tramadol is a synthetic opioid with centrally acting analgesic activity that alleviates moderate to severe pain and treats withdrawal symptoms of the other opioids. Like other opioid drugs, tramadol abuse has adverse effects on central nervous system components. Chronic administration of tramadol induces maladaptive plasticity in brain structures responsible for cognitive function, such as the hippocampus. However, the mechanisms by which tramadol induces these alternations are not entirely understood. Here, we examine the effect of tramadol on apoptosis and synaptogenesis of hippocampal neuronal in vitro. First, the primary culture of hippocampal neurons from neonatal rats was established, and the purity of the neuronal cells was verified by immunofluorescent staining. To evaluate the effect of tramadol on neuronal cell viability MTT assay was carried out. The western blot analysis technique was performed for the assessment of apoptosis and synaptogenesis markers. Results show that chronic exposure to tramadol reduces cell viability of neuronal cells and naloxone reverses this effect. Also, the level of caspase-3 significantly increased in tramadol-exposed hippocampal neurons. Moreover, tramadol downregulates protein levels of synaptophysin and stathmin as synaptogenesis markers. Interestingly, the effects of tramadol were abrogated by naloxone treatment. These findings suggest that tramadol can induce neurotoxicity in hippocampal neuronal cells, and this effect was partly mediated through opioid receptors.

Inflammatory, oxidative stress and cognitive functions in patients under maintenance treatment with methadone or buprenorphine and healthy subjects

BACKGROUND

Methadone and buprenorphine which are widely used for opioid maintenance treatment can affect redox status and also brain functions. The present study aimed to compare inflammation, oxidative stress, and cognitive function in methadone maintenance patients (MMP), buprenorphine maintenance patients (BMP), and healthy participants.

METHOD

Oxidative- antioxidant markers, inflammatory factors were investigated in MMP (n = 30), BMP (n = 30), and healthy participants (n = 30) by evaluating the ferritin, malondialdehyde (MDA), total antioxidant capacity (TAC), and also High-sensitivity C-reactive protein (hs-CRP). Also, executive function was evaluated using Wisconsin Card Sorting Test (WCST).

FINDINGS

MMP and BMP showed impairment in executive function compared to the healthy participants. Both buprenorphine and methadone treatments induced oxidative stress. The ferritin level in BMP was significantly lower compared to MMP and healthy participants (P = 0.01). There was a significant difference between control and MMP and BMP (P > 0.0001) in terms of hs-CRP level. BMP had the highest and healthy participant's lowest MDA level (P < 0.001). The TAC levels in BMP were lower than in MMP (p = 0.002) and healthy participants (p = 0.001). Finally, executive function was significantly correlated with oxidative-antioxidant status.

DISCUSSION

Both methadone and buprenorphine induced severe oxidative activity (especially buprenorphine) and cognitive deficits compared to healthy participants. Stress oxidative can affect normal brain activity and consequently cognitive functions. It's suggested that concomitant antioxidant administration with buprenorphine or methadone can potentially enhance their beneficial action by regulating blood redox status.

Goofballing of Opioid and Methamphetamine: The Science Behind the Deadly Cocktail

Globally, millions of people suffer from various substance use disorders (SUD), including mono-and polydrug use of opioids and methamphetamine. Brain regions such as the cingulate cortex, infralimbic cortex, dorsal striatum, nucleus accumbens, basolateral and central amygdala have been shown to play important roles in addiction-related behavioral changes. Clinical and pre-clinical studies have characterized these brain regions and their corresponding neurochemical changes in numerous phases of drug dependence such as acute drug use, intoxication, craving, withdrawal, and relapse. At present, many studies have reported the individual effects of opioids and methamphetamine. However, little is known about their combined effects. Co-use of these drugs produces effects greater than either drug alone, where one decreases the side effects of the other, and the combination produces a prolonged intoxication period or a more desirable intoxication effect. An increasing number of studies have associated polydrug abuse with poorer treatment outcomes, drug-related deaths, and more severe psychopathologies. To date, the pharmacological treatment efficacy for polydrug abuse is vague, and still at the experimental stage. This present review discusses the human and animal behavioral, neuroanatomical, and neurochemical changes underlying both morphine and methamphetamine dependence separately, as well as its combination. This narrative review also delineates the recent advances in the pharmacotherapy of mono- and poly drug-use of opioids and methamphetamine at clinical and preclinical stages.

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.

Integrating Cognitive Dysfunction Accommodation Strategies Into Behavioral Interventions for Persons on Medication for Opioid Use Disorder

Background

Cognitive dysfunction is disproportionately prevalent among persons with opioid use disorder (OUD). Specific domains of cognitive dysfunction (attention, executive functioning, memory, and information processing) may significantly impede treatment outcomes among patients on medication for OUD (MOUD). This limits patient's ability to learn, retain, and apply information conveyed in behavioral intervention sessions. Evidence-based accommodation strategies have been integrated into behavioral interventions for other patient populations with similar cognitive profiles as persons with OUD; however, the feasibility and efficacy of these strategies have not yet been tested among patients on MOUD in a drug treatment setting.

Methods

We conducted a series of focus groups with 25 key informants (10 drug treatment providers and 15 patients on MOUD) in a drug treatment program in New Haven, CT. Using an inductive approach, we examined how cognitive dysfunction impedes participant's ability to retain, recall, and utilize HIV prevention information in the context of drug treatment.

Results

Two main themes capture the overall responses of the key informants: (1) cognitive dysfunction issues and (2) accommodation strategy suggestions. Subthemes of accommodation strategies involved suggestions about particular evidence-based strategies that should be integrated into behavioral interventions for persons on MOUD. Specific accommodation strategies included: use of a written agenda, mindfulness meditation, multi-modal presentation of information, hands-on demonstrations, and a formal closure/summary of sessions.

Conclusions

Accommodation strategies to compensate for cognitive dysfunction were endorsed by both treatment providers and patients on MOUD. These accommodation strategies have the potential to enhance the efficacy of behavioral interventions to reduce HIV transmission among persons on MOUD as well as addiction severity, and overdose.

CpH methylome analysis in human cortical neurons identifies novel gene pathways and drug targets for opioid use disorder

INTRODUCTION

DNA methylation (DNAm), an epigenetic mechanism, has been associated with opioid use disorder (OUD) in preclinical and human studies. However, most of the studies have focused on DNAm at CpG sites. DNAm at non-CpG sites (mCpHs, where H indicates A, T, or C) has been recently shown to have a role in gene regulation and to be highly abundant in neurons. However, its role in OUD is unknown. This work aims to evaluate mCpHs in the human postmortem orbital frontal cortex (OFC) in the context of OUD.

METHODS

A total of 38 Postmortem OFC samples were obtained from the VA Brain Bank (OUD = 12; Control = 26). mCpHs were assessed using reduced representation oxidative bisulfite sequencing in neuronal nuclei. Differential analysis was performed using the "methylkit" R package. Age, ancestry, postmortem interval, PTSD, and smoking status were included as covariates. Significant mCpHs were set at q-value < 0.05. Gene Ontology (GO) and KEGG enrichment analyses were performed for the annotated genes of all differential mCpH loci using String, ShinyGO, and amiGO software. Further, all annotated genes were analyzed using the Drug gene interaction database (DGIdb).

RESULTS

A total of 2,352 differentially methylated genome-wide significant mCpHs were identified in OUD, mapping to 2,081 genes. GO analysis of genes with differential mCpH loci showed enrichment for nervous system development (p-value = 2.32E-19). KEGG enrichment analysis identified axon guidance and glutamatergic synapse (FDR 9E-4-2.1E-2). Drug interaction analysis found 3,420 interactions between the annotated genes and drugs, identifying interactions with 15 opioid-related drugs, including lofexidine and tizanidine, both previously used for the treatment of OUD-related symptoms.

CONCLUSION

Our findings suggest a role of mCpHs for OUD in cortical neurons and reveal important biological pathways and drug targets associated with the disorder.

Release of endogenous dynorphin opioids in the prefrontal cortex disrupts cognition

Following repeated opioid use, some dependent individuals experience persistent cognitive deficits that contribute to relapse of drug-taking behaviors, and one component of this response may be mediated by the endogenous dynorphin/kappa opioid system in neocortex. In C57BL/6 male mice, we find that acute morphine withdrawal evokes dynorphin release in the medial prefrontal cortex (PFC) and disrupts cognitive function by activation of local kappa opioid receptors (KORs). Immunohistochemical analyses using a phospho-KOR antibody confirmed that both withdrawal-induced and optically evoked dynorphin release activated KOR in PFC. Using a genetically encoded sensor based on inert KOR (kLight1.2a), we revealed the in vivo dynamics of endogenous dynorphin release in the PFC. Local activation of KOR in PFC produced multi-phasic disruptions of memory processing in an operant-delayed alternation behavioral task, which manifest as reductions in response number and accuracy during early and late phases of an operant session. Local pretreatment in PFC with the selective KOR antagonist norbinaltorphimine (norBNI) blocked the disruptive effect of systemic KOR activation during both early and late phases of the session. The early, but not late phase disruption was blocked by viral excision of PFC KORs, suggesting an anatomically dissociable contribution of pre- and postsynaptic KORs. Naloxone-precipitated withdrawal in morphine-dependent mice or optical stimulation of pdyn^Cre neurons using Channelrhodopsin-2 disrupted delayed alternation performance, and the dynorphin-induced effect was blocked by local norBNI. Our findings describe a mechanism for control of cortical function during opioid dependence and suggest that KOR antagonism could promote abstinence.

Drugs of Abuse Differentially Alter the Neuronal Excitability of Prefrontal Layer V Pyramidal Cell Subtypes

The medial prefrontal cortex (mPFC) plays an important role in regulating executive functions including reward seeking, task flexibility, and compulsivity. Studies in humans have demonstrated that drugs of abuse, including heroin, cocaine, methamphetamine, and alcohol, alter prefrontal function resulting in the consequential loss of inhibitory control and increased compulsive behaviors, including drug seeking. Within the mPFC, layer V pyramidal cells, which are delineated into two major subtypes (type I and type II, which project to subcortical or commissurally to other cortical regions, respectively), serve as the major output cells which integrate information from other cortical and subcortical regions and mediate executive control. Preclinical studies examining changes in cellular physiology in the mPFC in response to drugs of abuse, especially in regard to layer V pyramidal subtypes, are relatively sparse. In the present study, we aimed to explore how heroin, cocaine, methamphetamine, ethanol, and 3,4-methylenedioxypyrovalerone (MDPV) alter the baseline cellular physiology and excitability properties of layer V pyramidal cell subtypes. Specifically, animals were exposed to experimenter delivered [intraperitoneal (i.p.)] heroin, cocaine, the cocaine-like synthetic cathinone MDPV, methamphetamine, ethanol, or saline as a control once daily for five consecutive days. On the fifth day, whole-cell physiology recordings were conducted from type I and type II layer V pyramidal cells in the mPFC. Changes in cellular excitability, including rheobase (i.e., the amount of injected current required to elicit action potentials), changes in input/output curves, as well as spiking characteristics induced by each substance, were assessed. We found that heroin, cocaine, methamphetamine, and MDPV decreased the excitability of type II cells, whereas ethanol increased the excitability of type I pyramidal cells. Together, these results suggest that heroin, cocaine, MDPV, and methamphetamine reduce mPFC commissural output by reducing type II excitability, while ethanol increases the excitability of type I cells targeting subcortical structures. Thus, separate classes of abused drugs differentially affect layer V pyramidal subtypes in the mPFC, which may ultimately give rise to compulsivity and inappropriate synaptic plasticity underlying substance use disorders.

Adapting behavioural interventions to compensate for cognitive dysfunction in persons with opioid use disorder

Treatment for opioid use disorder (OUD) is often in the context of biobehavioural interventions, consisting of medication for OUD (for example, methadone and buprenorphine), which is accompanied by psychoeducation and/or behavioural therapies. Patients with OUD often display weaknesses in cognitive function that may impact the efficacy of such behavioural interventions. A review of the literature was conducted to: (1) describe common cognitive dysfunction profiles among patients with OUD, (2) outline intervention approaches for patients with OUD, (3) consider the cognitive demands that interventions place on patients with OUD and (4) identify potential accommodation strategies that may be used to optimise treatment outcomes. Cognitive profiles of patients with OUD often include weaknesses in executive function, attention, memory and information processing. Behavioural interventions require the patients' ability to learn, understand and remember information (placing specific cognitive demands on patients). Accommodation strategies are, therefore, needed for patients with challenges in one or more of these areas. Research on accommodation strategies for patients with OUD is very limited. We applied research from populations with similar cognitive profiles to form a comprehensive collection of potential strategies to compensate for cognitive dysfunction among patients with OUD. The cognitive profiles and accommodation strategies included in this review are intended to inform future intervention research aimed at improving outcomes among patients with OUD.

Maternal opioid use disorder: Placental transcriptome analysis for neonatal opioid withdrawal syndrome

Excessive prenatal opioid exposure may lead to the development of Neonatal Opioid Withdrawal Syndrome (NOWS). RNA-seq was done on 64 formalin-fixed paraffin-embedded placental tissue samples from 32 mothers with opioid use disorder, with newborns with NOWS that required treatment, and 32 prenatally unexposed controls. We identified 93 differentially expressed genes in the placentas of infants with NOWS compared to unexposed controls. There were 4 up- and 89 downregulated genes. Among these, 7 genes CYP1A1, APOB, RPH3A, NRXN1, LINC01206, AL157396.1, UNC80 achieved an FDR p-value of <0.01. The remaining 87 genes were significant with FDR p-value <0.05. The 4 upregulated, CYP1A1, FP671120.3, RAD1, RN7SL856P, and the 10 most significantly downregulated genes were RNA5SP364, GRIN2A, UNC5D, DMBT1P1, MIR3976HG, LINC02199, LINC02822, PANTR1, AC012178.1, CTNNA2. Ingenuity Pathway Analysis identified the 7 most likely to play an important role in the etiology of NOWS. Our study expands insights into the genetic mechanisms of NOWS development.

Neuronal apoptosis induced by morphine withdrawal is mediated by the p75 neurotrophin receptor

Morphine withdrawal evokes neuronal apoptosis through mechanisms that are still under investigation. We have previously shown that morphine withdrawal increases the levels of pro-brain-derived neurotrophic factor (BDNF), a proneurotrophin that promotes neuronal apoptosis through the binding and activation of the pan-neurotrophin receptor p75 (p75NTR). In this work, we sought to examine whether morphine withdrawal increases p75NTR-driven signaling events. We employed a repeated morphine treatment-withdrawal paradigm in order to investigate biochemical and histological indicators of p75NTR-mediated neuronal apoptosis in mice. We found that repeated cycles of spontaneous morphine withdrawal promote an accumulation of p75NTR in hippocampal synapses. At the same time, TrkB, the receptor that is crucial for BDNF-mediated synaptic plasticity in the hippocampus, was decreased, suggesting that withdrawal alters the neurotrophin receptor environment to favor synaptic remodeling and apoptosis. Indeed, we observed evidence of neuronal apoptosis in the hippocampus, including activation of c-Jun N-terminal kinase (JNK) and increased active caspase-3. These effects were not seen in saline or morphine-treated mice which had not undergone withdrawal. To determine whether p75NTR was necessary in promoting these outcomes, we repeated these experiments in p75NTR heterozygous mice. The lack of one p75NTR allele was sufficient to prevent the increases in phosphorylated JNK and active caspase-3. Our results suggest that p75NTR participates in the neurotoxic and proinflammatory state evoked by morphine withdrawal. Because p75NTR activation negatively influences synaptic repair and promotes cell death, preventing opioid withdrawal is crucial for reducing neurotoxic mechanisms accompanying opioid use disorders.

Cognitive functioning in patients maintained on buprenorphine at peak and trough buprenorphine levels: An experimental study

OBJECTIVES

To assess the cognitive functions in participants maintained on buprenorphine for opioid dependence at peak and trough buprenorphine levels.

METHODS

This was a double-blind, randomized, experimental study. Sixty participants maintained on buprenorphine were matched for age and education and randomly allocated to "peak" group or "trough" group. The "peak" group received buprenorphine two hours before assessment, whereas the trough group received placebo. The cognitive domains of attention, learning and memory, and executive function including fluency, working memory, response inhibition and set shifting were tested.

RESULTS

The two groups were comparable on socio-demographic, substance use profile and opioid agonist treatment-related characteristics. Significant differences in performance of peak and trough group were observed on Wisconsin Card Sorting Test parameters of number of correct responses (U = 289.00, p = 0.03), number of errors (t = 02.26, df = 58, p = 0.03), and perseverative errors (U = 301.50, p = 0.04).

CONCLUSIONS

The time since buprenorphine dose has significant relation on specific cognitive tasks in patients maintained on buprenorphine for opioid dependence.

Developing a cognitive dysfunction risk score for use with opioid-dependent persons in drug treatment

BACKGROUND

Cognitive dysfunction is common in persons seeking medication for opioid use disorder (MOUD) and may hinder many addiction-related services. Brief but accurate screening measures are needed to efficiently assess cognitive dysfunction in these resource-limited settings. The study aimed to develop a brief predictive risk score tailored for use among patients in drug treatment.

METHODS

The present study examined predictors of mild cognitive impairment (MCI), objectively assessed via the NIH Toolbox, among 173 patients receiving methadone as MOUD at an urban New England drug treatment facility. Predictors of MCI were identified in one subsample using demographic characteristics, medical chart data, and selected items from the Brief Inventory of Neuro-Cognitive Impairment (BINI). Predictors were cross-validated in a second subsample using logistic regression. Receiver operating curve (ROC) analyses determined an optimal cut-off score for detecting MCI.

RESULTS

A cognitive dysfunction risk score (CDRS) was calculated from patient demographics (age 50+, non-White ethnicity, less than high school education), medical and substance use chart data (history of head injury, overdose, psychiatric diagnosis, past year polysubstance use), and selected self-report items (BINI). The CDRS discriminated acceptably well, with a ROC curve area of 70.6 %, and correctly identified 78 % of MCI cases (sensitivity = 87.5 %; specificity = 55.6 %).

CONCLUSIONS

The CDRS identified patients with cognitive challenges at a level likely to impede treatment engagement and/or key outcomes. The CDRS may assist in efficiently identifying patients with cognitive dysfunction while requiring minimal training and resources. Larger validation studies are needed in other clinical settings.

The Clinical and Financial Burden of Spinal Infections in People who Inject Drugs

BACKGROUND

People who inject drugs (PWID) are known to be at increased risk of infectious diseases including bacterial and blood-borne viral infections. However, there is limited literature surrounding the burden of spinal infections as a complication of injecting drug use (IDU).

AIMS

To quantify the clinical and financial burden of IDU-related spinal infections.

METHODS

Retrospective chart review of adult PWID with spinal infections requiring hospital admission to a tertiary health service in Melbourne, Australia between 2011 and 2019.

RESULTS

Fifty-seven PWID with 63 episodes of spinal infections were identified with a median hospital stay of 47 days (IQR 16, range 4-243). One-third of episodes required neurosurgical intervention and 11 episodes (17%) required intensive care unit (ICU) admission (range 2-17 days). Staphylococcus aureus was the most common causative pathogen, present in three-quarters of all episodes (n = 47). The median duration of antibiotic regime was 59 days (IQR 42) and longer courses were associated with known bacteraemia (p = 0.048), polymicrobial infections (p = 0.001) and active IDU (p = 0.066). Predictors of surgery include neurological symptoms at presentation (RR 2.6; p = 0.010), inactive IDU status (RR 3.0; p = 0.002), a diagnosis of epidural abscess (RR 4.1; p = 0.001) and spinal abscess (RR ∞; p < 0.001). Completion of planned antimicrobial therapy was reported in 51 episodes (82%). Average expenditure per episode was AUD $61 577.

CONCLUSIONS

Spinal infections in PWID are an underreported serious medical complication of IDU. Though mortality is low, there is significant morbidity with prolonged admissions, large antimicrobial requirements and surgical interventions generating a substantial cost to the health system. This article is protected by copyright. All rights reserved.

Differences in cue-induced brain activation between long-term methadone maintenance treatment and protracted abstinence in heroin use disorder patients: a functional magnetic resonance imaging study

Background

Heroin use disorder (HUD) remains one of the gravest public health issues in China. Methadone maintenance treatment (MMT) and protracted abstinence (PA) are the most commonly used treatments for HUD. Although both treatment approaches can alleviate heroin cravings, a previous study found that MMT patients had stronger cue-induced brain activation than patients undergoing PA; however, the changes associated with long-term treatment are unclear.

Methods

Male patients with HUD who had been undergoing either PA (n=24) or MTT (n=21) for approximately 12 months, together with 20 demographically matched healthy controls, completed an event-related functional magnetic resonance imaging (fMRI) task. The subjective craving for heroin was evaluated using a visual analog scale.

Results

Compared to the healthy controls, the MMT and PA groups demonstrated significantly higher brain activation in the left pallidum, middle occipital gyrus, postcentral gyrus, anterior cingulate cortex, middle cingulate cortex, inferior parietal lobule, superior parietal lobule, amygdala, hippocampus, right inferior temporal gyrus, inferior frontal gyrus triangularis, and caudate during exposure to heroin-related cues. Compared to those undergoing PA, patients in the MMT group demonstrated significantly higher brain activation in all of these regions. Except for the left inferior parietal lobule and left superior parietal lobule, there were no statistically significant differences between the PA and healthy control groups. The MMT patients showed significantly higher subjective cravings before and after exposure to heroin cues than the PA group, but there was no significant difference in the change in subjective cravings between the 2 groups.

Conclusions

The results suggested that although the HUD patients receiving long-term MMT complied with the treatment, they still had higher subjective cravings and cue-induced brain activation than those undergoing PA. Therefore, long-term PA appears to be more beneficial than MMT in reducing the salience value of drug cues in patients with HUD.

Cognitive Impairment among People Who Use Heroin and Fentanyl: Findings from the Miami Adult Studies on HIV (MASH) Cohort

Background: Cognitive impairment is common in people living with HIV (PLWH). Opioid drugs exert direct and indirect effects on cognitive processes, which may contribute to cognitive dysfunction among PLWH. This study was designed to determine if opioid use is associated with cognitive impairment and whether the effect differs between PLWH and HIV-uninfected adults. Other neuropsychiatric symptoms, such as depression and apathy, were also examined. We conducted a cross-sectional analysis of 265 PLWH and 284 HIV-uninfected participants from the Miami Adult Studies on HIV (MASH) cohort. The Mini-Mental State Examination (MMSE) was used to assess cognitive impairment. Substance use was self-reported. Overall, 26.8% of PLWH and 15.1% of HIV-uninfected used opioids. Cognitive impairment was more frequent among people who used heroin and/or fentanyl than those who misused prescription opioids (31.6% vs. 10.5%, p = .005). The use of heroin/fentanyl was associated with increased odds for cognitive impairment (adjusted OR: 2.21, 95% CI 1.05-4.64, p = .036). Among PLWH only, the misuse of opioids was associated with a higher frequency of neuropsychiatric symptoms such as depression and apathy. A higher risk for cognitive impairment was seen among people who used heroin and fentanyl. PLWH who misuse opioids may be at an increased risk for neuropathology, but elucidation of mechanisms for opioid-induced cognitive deficits is needed.

Acute Aerobic Exercise Ameliorates Cravings and Inhibitory Control in Heroin Addicts: Evidence From Event-Related Potentials and Frequency Bands

Objective

Aerobic exercise is considered a potential adjunctive treatment for heroin addicts, but little is known about its mechanisms. Less severe cravings and greater inhibitory control have been associated with reduced substance use. The aim of the current study was to determine the effects, as measured by behavioral and neuroelectric measurements, of acute aerobic exercise on heroin cravings and inhibitory control induced by heroin-related conditions among heroin addicts.

Design

The present study used a randomized controlled design.

Methods

Sixty male heroin addicts who met the DSM-V criteria were recruited from the Isolated Detoxification Center in China and randomly assigned to one of two groups; one group completed a 20-min bout of acute stationary cycle exercise with vigorous intensity (70-80% of maximum heart rate, exercise group), and the other group rested (control group). The self-reported heroin craving levels and inhibitory control outcomes (measured by a heroin-related Go/No-Go task) were assessed pre- and post-exercise.

Results

The heroin craving levels in the exercise group were significantly attenuated during, immediately following, and 40 min after vigorous exercise compared with before exercise; moreover, during exercise, a smaller craving was observed in the exercise group than in the control group. Acute exercise also facilitated inhibition performance in the No-Go task. After exercise, the participants' accuracy, the N2d amplitudes, and the theta two band spectral power during the No-Go conditions were higher in the exercise group than in the control group. Interestingly, significant correlations between the changes in these sensitive measurements and the changes in cravings were observed.

Conclusions

This is the first empirical study to demonstrate that aerobic exercise may be efficacious for reducing heroin cravings and promoting inhibitory control among heroin addicts.

Association between the brief inventory of neurocognitive impairment (BINI) and objective cognitive testing among persons with opioid use disorders in drug treatment

The current study examined the association between subjective cognitive dysfunction and objective test performance in persons enrolled in drug treatment and stabilized on methadone maintenance therapy (MMT). A total of 177 participants completed the self-reported brief inventory of neurocognitive impairment (BINI) and NIH Toolbox test battery. In participants with neurocognitive dysfunction, scores on all BINI subscales were negatively associated with objective performance on the NIH Toolbox (BINI Global r = -0.26, p = 0.01; BINI Subscales ranging -0.22 to -0.32, all p's < 0.03). Using cutoff scores, results showed participants who scored above the cutoff on the BINI Learning subscale demonstrated significant evidence of objective neurocognitive dysfunction on the NIH Toolbox (65% vs. 35%; χ² = 6.57, p = 0.02), suggesting possible clinical utility. Future studies are needed to determine the feasibility of using the BINI to inform the accommodation of patients with specific neurocognitive profiles to optimize treatment outcomes.

Onset Age of Substance Use and Neuropsychological Performance in Hospital Patients

OBJECTIVE

Several studies have found neurocognitive deficits in adolescents following substance abuse. Predisposing risk factors may further impact vulnerability to neurocognitive deficits. Little is known about the cognitive performance of adult onset substance users compared to earlier onset users. This study aims to explore differences in neuropsychological functioning between early (EOAs) and late onset substance abusers (LOAs) when the effects of confounding factors are controlled.

METHOD

Data for this cross-sectional study was collected from hospital patients. A total of 164 patients with substance use disorder (SUD) aged 19 to 65, 76 with single-drug diagnosis and 88 with multidrug diagnosis, underwent neuropsychological tests for verbal capacity, attention, speed of processing, perceptual reasoning, memory and learning, executive functioning, and inhibitory capacity. Associations between regular onset age and neuropsychological measures were analysed using in multi-way ANCOVA, and the effect of age, multiple substance abuse, education level and learning difficulties were controlled.

RESULTS

Compared with LOAs, EOAs had weaker performance in the Digit Symbol test for mono-substance users. Meanwhile, compared with EOAs, LOAs had weaker performance in the Delayed Visual Memory test and the Raven test for mono-substance users, and the Block Design test for poly-substance users. From the confounding factors, early onset age of substance use is heightened among individuals with learning disabilities.

CONCLUSIONS

Onset age of substance use is related to the deterioration of performance in neuropsychological tests. Premorbid poor learning and inhibitory capacity may be important predisposing risk factors of SUD. Conversely, high level of education may be a protective factor for cognitive performance in patients with SUD.

Feasibility and acceptability of safety screening among patients receiving addiction treatment

INTRODUCTION

Premature mortality associated with opioid-related overdose and suicide is a significant public health problem in the United States. Approximately 20-30% of individuals with opioid use disorder (OUD) have a history of both suicide attempt and unintentional opioid overdose. The objective of this study is to evaluate the feasibility of a standardized screen for suicide and overdose among patients receiving addiction treatment.

METHODS

We conducted a cross-sectional study using a convenience sample of patients (n = 113) recruited from two inpatient treatment programs. We used a modified version of the Patient Safety Screener (mPSS) to screen for suicidal ideation, suicide attempt, and overdose. Study staff administered the screen in-person during treatment, and we linked results to administrative clinical data. Subjects (n = 108) and members of their clinical care team (n = 20) completed a screening acceptability survey. We recorded a positive mPSS if a patient reported suicidal ideation in the past two weeks, a suicide attempt, and/or an overdose in the past six months.

RESULTS

Fifty-eight percent of subjects had a positive mPSS screen, and 30.3% reported suicidal ideation, suicide attempt, and overdose. Subjects and clinical staff reported that it was acceptable to screen for suicide attempt(s) and overdose(s). About a third of the clinical staff reported concerns about administration time (n = 7) and impact on workflow (n = 6).

CONCLUSIONS

Both suicide and overdose are important patient safety factors that should be incorporated into addiction treatment and discharge planning. This study's findings support simultaneously screening for suicide and overdose in OUD inpatient treatment settings. Future research needs to determine whether screening improves provision of services and reduces self-injurious behavior.

Neurocognitive functions in patients on buprenorphine maintenance for opioid dependence: A comparative study with three matched control groups

BACKGROUND

Neurocognitive dysfunction with buprenorphine has mixed evidence, with many confounding factors. We compared the neurocognitive functions in patients with opioid dependence on buprenorphine maintenance (Index Group; IG) with those on naltrexone (NG), opioid-dependent in early detoxification (OD), and healthy control (CG).

MATERIALS & METHODS

The four groups were matched for age, sex, and years of education. Except for the healthy control group (CG; n = 30), the two other comparison groups had twenty participants each. Subjects with other substance use disorders, HIV infection, head injury, epilepsy, and severe mental illness were excluded. Cognitive tests consisted of Trail Making Tests (TMT-A & B), Digit Vigilance test (DVT), verbal and visual N-Back Test (NBT), Rey's Auditory Verbal Learning Test (RAVLT), Wisconsin Card Sorting Test (WCST), Controlled Oral Word Association Test (COWA), and Wechsler Adult Intelligence Scale (WAIS).

RESULTS

IG performed significantly worse in TMT-B, DVT, verbal NBT, and WCST (non-perseverative error) than CG. When IQ was controlled for, significance persisted in TMT-B, a marker of poor cognitive flexibility. The OD showed significantly poorer performance than NG and CG in the TMT-A & B, visual and verbal NBT, DVT, and RAVLT. When compared to the IG, the performance of the OD was significantly poor in the TMT-A & B. IG performed worse than NG in TMT-B, and NG performed poorer (than CG) in RAVLT.

CONCLUSION

Patients on medication-assisted treatment had significant cognitive impairment limited to fewer cognitive domains, however, the extent and severity were highest in the group with active opioid dependence.

Behavioral strategies to reduce stress reactivity in opioid use disorder: Study design

OBJECTIVES

More than 2 million people in the United States had an opioid use disorder in 2017. Treatment for opioid use disorder-particularly medication combined with psychosocial support-is effective for reducing opioid use and decreasing overdose risk. However, approximately 50% of people who receive treatment will relapse or drop out. Stress reactivity, defined as the subjective and physiological response to stress, is heightened in people with opioid use disorder and higher stress reactivity is associated with poorer outcomes. Preliminary studies suggest that stress reactivity may be a key mechanistic target for improving outcomes. This article describes the design of an ongoing study examining behavioral strategies for reducing stress reactivity in adults with opioid use disorder. Our objective is to test the efficacy of two behavioral strategies for reducing stress reactivity and enhancing behavioral persistence in the context of stress (distress tolerance).

METHOD

We will recruit 120 adults with opioid use disorder and randomly assign them to brief training in (a) cognitive reappraisal, (b) affect labeling, or (c) a psychoeducational control. Participants will receive the training intervention followed by a laboratory stressor during which they will be instructed to apply the trained skill.

RESULTS

Subjective and physiological responses to stress will be measured as indices of stress reactivity and the stressor task will include a behavioral persistence component as a measure of distress tolerance.

CONCLUSIONS

The ultimate goal of this study is to inform the development of behavioral interventions that can be used as an adjunct to medication-based treatment for opioid use disorder. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Reduced response inhibition after exposure to drug-related cues in male heroin abstainers

RATIONALE

Deficits in response inhibition associated with heroin use could last several months after abstinence in heroin users, and their response inhibition can also be interfered with task-irrelevant drug-related cues. However, it is unclear whether exposure to drug-related cues affects subsequent response inhibition in heroin users following abstinence.

OBJECTIVES

The present study aimed to investigate how drug-related cues with different durations between stimulus presentations, referred to as stimulus onset asynchronies (SOAs), affect subsequent response inhibition in heroin abstainers (HAs) with different length of abstinence.

METHODS

Sixty-seven male HAs performed a modified Go/NoGo task in which a motor response to frequent Go targets and no response to rare NoGo targets were required and a Go or NoGo target was displayed after either a heroin-related or a neutral picture presented for the 200 ms and 600 ms SOAs.

RESULTS

The HAs responded significantly faster to Go targets following the neutral pictures for the 600 ms SOA compared to other conditions. They also made more commission errors following heroin-related pictures compared to neutral pictures regardless of the SOAs. The shorter-term HAs made more commission errors compared to the longer-term HAs following the 200 ms SOA, and it was only a trend when the SOA was 600 ms. Additionally, negative correlations between the duration of current abstinence and commission errors were observed following cues with the 200 ms SOA.

CONCLUSIONS

Impaired response inhibition in HAs can be improved through protracted drug abstinence. However, that effect can be reduced by exposure to drug-related cues, which may increase the risk of relapse.

Discrimination learning in oxycodone-treated nonhuman primates

BACKGROUND

Prescription opioid abuse continues to be a public health concern of epidemic proportions. Notwithstanding the extensive literature regarding opioid action, there has been little systematic research regarding the effects of opioid dependence and withdrawal on aspects of cognition-related behavior in laboratory animals. The present studies examined the effects of the prescription opioid oxycodone on learning processes in nonhuman primates.

METHODS

The ability of subjects to repeatedly learn novel touchscreen-based visual discriminations was examined during three conditions of opioid exposure. Discrimination learning was examined, first, during oxycodone self-administration (3-hr sessions, 0.1 mg/kg/injection) and, next, during non-contingent chronic treatment with oxycodone (10 mg/kg/day). Finally, discrimination learning was re-examined during antagonist-precipitated opioid withdrawal (0.001-0.1 mg/kg naltrexone) and, subsequently, following abrupt discontinuation of oxycodone treatment.

RESULTS

Although motoric behavior was disrupted by oxycodone, neither the development of discrimination learning nor steady-state performance were impaired following oxycodone self-administration or during non-contingent chronic oxycodone treatment. However, discrimination learning was substantially impaired during oxycodone withdrawal, whether elicited by naltrexone or by abrupt oxycodone discontinuation. Moreover, these learning impairments were concordant with autonomic signs of opioid withdrawal.

CONCLUSIONS

Taken together, the present studies indicate that impairment of learning processes can accompany the unconditioned signs of opioid withdrawal.

Indices of dentate gyrus neurogenesis are unaffected immediately after or following withdrawal from morphine self-administration compared to saline self-administering control male rats

Opiates - including morphine - are powerful analgesics with high abuse potential. In rodents, chronic opiate exposure or self-administration negatively impacts hippocampal-dependent function, an effect perhaps due in part to the well-documented opiate-induced inhibition of dentate gyrus (DG) precursor proliferation and neurogenesis. Recently, however, intravenous (i.v.) morphine self-administration (MSA) was reported to enhance the survival of new rat DG neurons. To reconcile these disparate results, we used rat i.v. MSA to assess 1) whether a slightly-higher dose MSA paradigm also increases new DG neuron survival; 2) how MSA influences cells in different stages of DG neurogenesis, particularly maturation and survival; and 3) if MSA-induced changes in DG neurogenesis persist through a period of abstinence. To label basal levels of proliferation, rats received the S-phase marker bromodeoxyuridine (BrdU, i.p.) 24 -h prior to 21 days (D) of i.v. MSA or saline self-administration (SSA). Either immediately after SA (0-D) or after 4 weeks in the home cage (28-D withdrawal), stereology was used to quantify DG proliferating precursors (or cells in cell cycle; Ki67+ cells), neuroblast/immature neurons (DCX+ cells), and surviving DG granule cells (BrdU+ cells). Analysis revealed the number of DG cells immunopositive for these neurogenesis-relevant markers was similar between MSA and SSA rats at the 0-D or 28-D timepoints. These negative data highlight the impact experimental parameters, timepoint selection, and quantification approach have on neurogenesis results, and are discussed in the context of the large literature showing the negative impact of opiates on DG neurogenesis.

Non-nociceptive roles of opioids in the CNS: opioids' effects on neurogenesis, learning, memory and affect

Mortality due to opioid use has grown to the point where, for the first time in history, opioid-related deaths exceed those caused by car accidents in many states in the United States. Changes in the prescribing of opioids for pain and the illicit use of fentanyl (and derivatives) have contributed to the current epidemic. Less known is the impact of opioids on hippocampal neurogenesis, the functional manipulation of which may improve the deleterious effects of opioid use. We provide new insights into how the dysregulation of neurogenesis by opioids can modify learning and affect, mood and emotions, processes that have been well accepted to motivate addictive behaviours.

The neurobiology of addiction

Substance and alcohol use disorders impose large health and economic burdens on individuals, families, communities, and society. Neither prevention nor treatment efforts are effective in all individuals. Results are often modest. Advances in neuroscience and addiction research have helped to describe the neurobiological changes that occur when a person transitions from recreational substance use to a substance use disorder or addiction. Understanding both the drivers and consequences of substance use in vulnerable populations, including those whose brains are still maturing, has revealed behavioral and biological characteristics that can increase risks of addiction. These findings are particularly timely, as law- and policymakers are tasked to reverse the ongoing opioid epidemic, as more states legalize marijuana, as new products including electronic cigarettes and newly designed abused substances enter the legal and illegal markets, and as "deaths of despair" from alcohol and drug misuse continue.

Impact of Substance Use Disorder Pharmacotherapy on Executive Function: A Narrative Review

Substance use disorders are chronic, relapsing, and harmful conditions characterized by executive dysfunction. While there are currently no approved pharmacotherapy options for stimulant and cannabis use disorders, there are several evidence-based options available to help reduce symptoms during detoxification and aid long-term cessation for those with tobacco, alcohol and opioid use disorders. While these medication options have shown clinical efficacy, less is known regarding their potential to enhance executive function. This narrative review aims to provide a brief overview of research that has investigated whether commonly used pharmacotherapies for these substance use disorders (nicotine, bupropion, varenicline, disulfiram, acamprosate, nalmefene, naltrexone, methadone, buprenorphine, and lofexidine) effect three core executive function components (working memory, inhibitory control and cognitive flexibility). While pharmacotherapy-induced enhancement of executive function may improve cessation outcomes in dependent populations, there are limited and inconsistent findings regarding the effects of these medications on executive function. We discuss possible reasons for the mixed findings and suggest some future avenues of work that may enhance the understanding of addiction pharmacotherapy and cognitive training interventions and lead to improved patient outcomes.

It is time for an ethical, evidence-based approach to youth presenting to the ED with an opioid overdose

Currently, there is a dangerous inconsistency between our current understanding of adolescent development and the effects of drugs on cognition when compared to our collective approach to youth who present in the emergency department with an opioid overdose. We call upon practitioners to embrace a new paradigm and we ask the Canadian Pediatric Society (CPS) to spearhead the development of guidelines to advise on best practices to manage youth who present to the emergency department with an illicit drug overdose.

Acute effects of methadone on EEG power spectrum and event-related potentials among heroin dependents

Methadone as the most prevalent opioid substitution medication has been shown to influence the neurophysiological functions among heroin addicts. However, there is no firm conclusion on acute neuroelectrophysiological changes among methadone-treated subjects as well as the effectiveness of methadone in restoring brain electrical abnormalities among heroin addicts. This study aims to investigate the acute and short-term effects of methadone administration on the brain's electrophysiological properties before and after daily methadone intake over 10 weeks of treatment among heroin addicts. EEG spectral analysis and single-trial event-related potential (ERP) measurements were used to investigate possible alterations in the brain's electrical activities, as well as the cognitive attributes associated with MMN and P3. The results confirmed abnormal brain activities predominantly in the beta band and diminished information processing ability including lower amplitude and prolonged latency of cognitive responses among heroin addicts compared to healthy controls. In addition, the alteration of EEG activities in the frontal and central regions was found to be associated with the withdrawal symptoms of drug users. Certain brain regions were found to be influenced significantly by methadone intake; acute effects of methadone induction appeared to be associative to its dosage. The findings suggest that methadone administration affects cognitive performance and activates the cortical neuronal networks, resulting in cognitive responses enhancement which may be influential in reorganizing cognitive dysfunctions among heroin addicts. This study also supports the notion that the brain's oscillation powers and ERPs can be utilized as neurophysiological indices for assessing the addiction treatment traits.

Neuropsychological functioning in opioid use disorder: A research synthesis and meta-analysis

BACKGROUND

Research has demonstrated that patients with opioid use disorders (OUD; including both opioid abuse and/or dependence) have poorer neuropsychological functioning compared to healthy controls; however, the pattern and robustness of the findings remain unknown.

OBJECTIVES

This study meta-analyzed the results from previous research examining the neuropsychological deficits associated with opioids across 14 neurocognitive domains.

METHOD

Articles comparing patients with OUD to healthy controls were selected based on detailed inclusion/exclusion criteria and variables of interest were coded. In total, 61 studies were selected for the analyses. These consisted of 2580 patients with OUD and 2102 healthy control participants (15.9% female). Drug-related variables were analyzed as potential moderators.

RESULTS

The largest effect size difference in neuropsychological performance was observed in complex psychomotor ability. With the exception of the motor and processing speed domains, which showed no group differences, small-to-medium effect sizes were associated with all neurocognitive domains examined. Meta-regression revealed that increases in the length of abstinence were associated with decreases in effect sizes of the complex psychomotor domain. Additionally, attentional ability predicted effect size differences in executive functioning as well as verbal memory ability. Although the majority of meta-analyzed studies demonstrated significant differences between patients with OUD and controls, the average raw scores for patients with OUD in these studies typically fell within the normal range.

CONCLUSION

The pattern of neuropsychological performance among patients with OUD appears to reflect mild generalized cognitive dysfunction, with a large effect in complex psychomotor abilities.

Safety and tolerability of sauna detoxification for the protracted withdrawal symptoms of substance abuse

Objective

Protracted drug withdrawal symptoms can last months or years after drug cessation, often precipitating a return to substance misuse. We evaluated the safety and preliminary health benefits of a unique chemical exposure regimen based on exercise, sauna and therapeutic nutrients.

Methods

This was a prospective evaluation of 109 individuals sequentially enrolled into a sauna detoxification component of a multi-modal, long-term residential substance abuse treatment centre.

Results

Data from medical charts, client self-reports and Short Form Health Survey (SF-36) responses indicated that the Hubbard sauna detoxification method was well tolerated, with a 99% completion rate, including one human immunodeficiency virus and nine hepatitis C positive clients. There were no cases of dehydration, overhydration or heat illness. Statistically significant improvements were seen in both mental and physical SF-36 scores at regimen completion, as well as in Addiction Severity Index and Global Appraisal of Individual Needs Short Screener change scores at rehabilitation program discharge, compared with enrolment.

Conclusions

The regimen lacked serious adverse events, had a very low discontinuation rate and high client-reported satisfaction. The SF-36 data indicated improved physical and emotional symptoms. Therefore, broader investigation of this sauna-based treatment regimen is warranted.

The impact of drugs of abuse on executive function: characterizing long-term changes in neural correlates following chronic drug exposure and withdrawal in rats

Addiction has long been characterized by diminished executive function, control, and impulsivity management. In particular, these deficits often manifest themselves as impairments in reversal learning, delay discounting, and response inhibition. Understanding the neurobiological substrates of these behavioral deficits is of paramount importance to our understanding of addiction. Within the cycle of addiction, periods during and after withdrawal represent a particularly difficult point of intervention in that the negative physical symptoms associated with drug removal and drug craving increase the likelihood that the patient will relapse and return to drug use in order to abate these symptoms. Moreover, it is often during this time that drug induced deficits in executive function hinder the ability of the patient to refrain from drug use. Thus, it is necessary to understand the physiological and behavioral changes associated with withdrawal and drug craving-largely manifesting as deficits in executive control-to develop more effective treatment strategies. In this review, we address the long-term impact that drugs of abuse have on the behavioral and neural correlates that give rise to executive control as measured by reversal learning, delay discounting, and stop-signal tasks, focusing particularly on our work using rats as a model system.

Verbal and spatial working memory among drug-using HIV-infected men and women

Working memory (WM) is a critical component of many neurocognitive functions. The literature has demonstrated consistently that WM impairment is more frequent and severe among substance-dependent individuals (SDIs) infected with HIV compared with uninfected SDIs; however, the SDIs who participated in these previous studies were primarily male. There are few published data on WM performance among HIV+ women with or without substance use disorders, and essentially no direct comparisons of WM performance between HIV+ men and women, regardless of substance use. We investigated potential sex and serostatus effects on WM among a sample of 360 SDIs (114 with HIV; 66% female) verified abstinent from alcohol and drugs of abuse at testing and generally comparable on substance use and comorbid characteristics. Participants were tested with the n-back task, a well-established WM measure that is sensitive to HIV-associated cognitive impairment. HIV+ men and women performed spatial and verbal versions of the n-back significantly less accurately compared with HIV- participants. Women showed slower response times compared with men on both versions, regardless of HIV serostatus. Individuals dependent on cocaine showed faster RTs compared with non-dependent users, but this effect was not apparent among opioid- or alcohol-dependent groups. Findings on n-back accuracy are consistent with our previous proposal that WM impairment represents a signature deficit among HIV+ SDIs; however, WM impairment appears less common among HIV+ women without a substance use history. The pattern of sex differences in response speed but serostatus effects on response accuracy is comparable to a recent report by our group of sex differences in learning speed but serostatus effects on delayed recall.

Remifentanil maintains lower initial delayed nonmatching-to-sample accuracy compared to food pellets in male rhesus monkeys

Emerging human laboratory and preclinical drug self-administration data suggest that a history of contingent abused drug exposure impairs performance in operant discrimination procedures, such as delayed nonmatching-to-sample (DNMTS), that are hypothesized to assess components of executive function. However, these preclinical discrimination studies have exclusively used food as the reinforcer and the effects of drugs as reinforcers in these operant procedures are unknown. The present study determined effects of contingent intravenous remifentanil injections on DNMTS performance hypothesized to assess 1 aspect of executive function, working memory. Daily behavioral sessions consisted of 2 components with sequential intravenous remifentanil (0, 0.01-1.0 μg/kg/injection) or food (0, 1-10 pellets) availability in nonopioid dependent male rhesus monkeys (n = 3). Remifentanil functioned as a reinforcer in the DNMTS procedure. Similar delay-dependent DNMTS accuracy was observed under both remifentanil- and food-maintained components, such that higher accuracies were maintained at shorter (0.1-1.0 s) delays and lower accuracies approaching chance performance were maintained at longer (10-32 s) delays. Remifentanil maintained significantly lower initial DNMTS accuracy compared to food. Reinforcer magnitude was not an important determinant of DNMTS accuracy for either remifentanil or food. These results extend the range of experimental procedures under which drugs function as reinforcers. Furthermore, the selective remifentanil-induced decrease in initial DNMTS accuracy is consistent with a selective impairment of attentional, but not memorial, processes. (PsycINFO Database Record

Reduction in N2 amplitude in response to deviant drug-related stimuli during a two-choice oddball task in long-term heroin abstainers

RATIONALE

Chronic heroin use can cause deficits in response inhibition, leading to a loss of control over drug use, particularly in the context of drug-related cues. Unfortunately, heightened incentive salience and motivational bias in response to drug-related cues may exist following abstinence from heroin use.

OBJECTIVES

The present study aimed to examine the effect of drug-related cues on response inhibition in long-term heroin abstainers.

METHODS

Sixteen long-term (8-24 months) male heroin abstainers and 16 male healthy controls completed a modified two-choice oddball paradigm, in which a neutral "chair" picture served as frequent standard stimuli; the neutral and drug-related pictures served as infrequent deviant stimuli of different conditions respectively. Event-related potentials were compared across groups and conditions.

RESULTS

Our results showed that heroin abstainers exhibited smaller N2d amplitude (deviant minus standard) in the drug cue condition compared to the neutral condition, due to smaller drug-cue deviant-N2 amplitude compared to neutral deviant-N2. Moreover, heroin abstainers had smaller N2d amplitude compared with the healthy controls in the drug cue condition, due to the heroin abstainers having reduced deviant-N2 amplitude compared to standard-N2 in the drug cue condition, which reversed in the healthy controls.

CONCLUSIONS

Our findings suggested that heroin addicts still show response inhibition deficits specifically for drug-related cues after longer-term abstinence. The inhibition-related N2 modulation for drug-related could be used as a novel electrophysiological index with clinical implications for assessing the risk of relapse and treatment outcome for heroin users.