Alterations in brain structure and functional connectivity in prescription opioid-dependent patients

Effects of chronic naltrexone treatment on relapse-related behavior and neural responses to fentanyl in awake nonhuman primates

Naltrexone, an opioid antagonist that blocks the reinforcing properties of opioid agonists, is often prescribed to preclude relapse to opioid use disorder (OUD) following detoxification. However, few laboratory studies have directly investigated the ability of naltrexone to alter relapse-inducing effects of opioid agonists, including their priming strength in reinstatement studies and their impact in brain regions known to be involved in drug-induced reinforcement in MRI studies. Here we directly address this issue by investigating the effects of continuous exposure to naltrexone on 1) fentanyl-induced reinstatement of drug-seeking behavior, 2) fentanyl-induced patterns of blood oxygenation level dependent (BOLD) activation in the nucleus accumbens (NAcc), and 3) fentanyl-induced changes in NAcc functional connectivity (FC) in awake non-human primates that are engaged in ongoing opioid self-administration studies. We found that naltrexone antagonizes the priming strength of fentanyl as shown by a rightward shift in its reinstatement dose-effect curve and that naltrexone surmountably antagonizes the BOLD response induced by fentanyl. However, while naltrexone also countered fentanyl's effects on NAcc FC, the effects were not surmounted by a higher dose of fentanyl. Together, these data suggest that, in contrast to naltrexone's modulation of fentanyl's effects on behavior and BOLD responses, their interactive effects on FC between multiple brain regions do not reflect their receptor-mediated activity. Additionally, we demonstrated opposing effects in the absence and presence of naltrexone on NAcc FC at baseline (i.e., in the absence of any fentanyl prime) suggesting that naltrexone alters FC at baseline, even though naltrexone appears behaviorally silent in the absence of an agonist prime. Together these data provide additional insight into ways in which naltrexone interacts with opioid agonists, both behaviorally and in the brain. Further understanding the effects of opioid agonists on patterns of FC could help elucidate our understanding of the neural processes that contribute to the initiation of and relapse to opioid-seeking behavior in OUD.

Ibogaine administration following repeated morphine administration upregulates myelination markers 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNP) and myelin basic protein (MBP) mRNA and protein expression in the internal capsule of Sprague Dawley rats

Ibogaine is a psychedelic alkaloid being investigated as a possible treatment for opioid use disorder. Ibogaine has a multi-receptor profile with affinities for mu and kappa opioid as well as NMDA receptors amongst others. Due to the sparsity of research into ibogaine's effects on white matter integrity and given the growing evidence that opioid use disorder is characterized by white matter pathology, we set out to investigate ibogaine's effects on two markers of myelination, 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNP) and myelin basic protein (MBP). Fifty Sprague Dawley rats were randomly assigned to five experimental groups of n = 10; (1) a saline control group received daily saline injections for 10 days, (2) a morphine control group received escalating morphine doses from 5 to 15 mg/kg over 10 days, (3) an ibogaine control group that received 10 days of saline followed by 50 mg/kg ibogaine hydrochloride, (4) a combination morphine and ibogaine group 1 that received the escalating morphine regime followed by 50 mg/kg ibogaine hydrochloride and (5) a second combination morphine and ibogaine group 2 which followed the same morphine and ibogaine regimen yet was terminated 72 h after administration compared to 24 h in the other groups. White matter from the internal capsule was dissected and qPCR and western blotting determined protein and gene expression of CNP and MBP. Morphine upregulated CNPase whereas ibogaine alone had no effect on CNP mRNA or protein expression. However, ibogaine administration following repeated morphine administration had an immediate effect by increasing CNP mRNA expression. This effect diminished after 72 h and resulted in a highly significant upregulation of CNPase protein at 72 h post administration. Ibogaine administration alone significantly upregulated protein expression yet downregulated MBP mRNA expression. Ibogaine administration following repeated morphine administration significantly upregulated MBP mRNA expression which increased at 72 h post administration resulting in a highly significant upregulation of MBP protein expression at 72 h post administration. These findings indicate that ibogaine is able to upregulate genes and proteins involved in the process of remyelination following opioid use and highlights an important mechanism of action of ibogaine's ability to treat substance use disorders.

Pivotal role of orexin signaling in the posterior paraventricular nucleus of the thalamus during the stress-induced reinstatement of oxycodone-seeking behavior

BACKGROUND

The orexin (OX) system has received increasing interest as a potential target for treating substance use disorder. OX transmission in the posterior paraventricular nucleus of the thalamus (pPVT), an area activated by highly salient stimuli that are both reinforcing and aversive, mediates cue- and stress-induced reinstatement of reward-seeking behavior. Oral administration of suvorexant (SUV), a dual OX receptor (OXR) antagonist (DORA), selectively reduced conditioned reinstatement of oxycodone-seeking behavior and stress-induced reinstatement of alcohol-seeking behavior in dependent rats.

AIMS

This study tested whether OXR blockade in the pPVT with SUV reduces oxycodone or sweetened condensed milk (SCM) seeking elicited by conditioned cues or stress.

METHODS

Male Wistar rats were trained to self-administer oxycodone (0.15 mg/kg, i.v., 8 h/day) or SCM (0.1 ml, 2:1 dilution [v/v], 30 min/day). After extinction, we tested the ability of intra-pPVT SUV (15 µg/0.5 µl) to prevent reinstatement of oxycodone or SCM seeking elicited by conditioned cues or footshock stress.

RESULTS

The rats acquired oxycodone and SCM self-administration, and oxycodone intake correlated with signs of physical opioid withdrawal, confirming dependence. Following extinction, the presentation of conditioned cues or footshock elicited reinstatement of oxycodone- and SCM-seeking behavior. Intra-pPVT SUV blocked stress-induced reinstatement of oxycodone seeking but not conditioned reinstatement of oxycodone or SCM seeking or stress-induced reinstatement of SCM seeking.

CONCLUSIONS

The results indicate that OXR signaling in the pPVT is critical for stress-induced reinstatement of oxycodone seeking, further corroborating OXRs as treatment targets for opioid use disorder.

Association of prenatal substance exposure and the development of the amygdala, hippocampus, and parahippocampus

CONTEXT

Prenatal substance exposure (PSE) can lead to various harmful outcomes for the developing fetus and is linked to many emotional, behavioral, and cognitive difficulties later in life. Therefore, examination of the relationship between the development of associated brain structures and PSE is important for the development of more specific or new preventative methods.

OBJECTIVES

Our study's primary objective was to examine the relationship between the physical development of the amygdala, hippocampus, and parahippocampus following prenatal alcohol, tobacco, and prescription opioid exposure.

METHODS

We conducted a cross-sectional analysis of the Adolescent Brain and Cognitive Development (ABCD) Study, a longitudinal neuroimaging study that measures brain morphometry from childhood throughout adolescence. Data were collected from approximately 12,000 children (ages 9 and 10) and parents across 22 sites within the United States. Prenatal opioid, tobacco, and alcohol use was determined through parent self-report of use during pregnancy. We extracted variables assessing the volumetric size (mm3) of the amygdala, hippocampus, and parahippocampal gyrus as well as brain volume, poverty level, age, sex, and race/ethnicity for controls within our adjusted models. We reported sociodemographic characteristics of the sample overall and by children who had PSE. We calculated and reported the means of each of the specific brain regions by substance exposure. Finally, we constructed multivariable regression models to measure the associations between different PSE and the demographic characteristics, total brain volume, and volume of each brain structure.

RESULTS

Among the total sample, 24.6% had prenatal alcohol exposure, 13.6% had prenatal tobacco exposure, and 1.2% had prenatal opioid exposure. On average, those with prenatal tobacco exposure were found to have a statistically significant smaller parahippocampus.

CONCLUSIONS

We found a significant association between prenatal tobacco exposure and smaller parahippocampal volume, which may have profound impacts on the livelihood of individuals including motor delays, poor cognitive and behavioral outcomes, and long-term health consequences. Given the cumulative neurodevelopmental effects associated with PSE, we recommend that healthcare providers increase screening rates, detection, and referrals for cessation. Additionally, we recommend that medical associations lobby policymakers to address upstream barriers to the effective identification of at-risk pregnant individuals, specifically, eliminating or significantly reducing punitive legal consequences stemming from state laws concerning prenatal substance use.

Neuroimaging of opioid effects in humans across conditions of acute administration, chronic pain therapy, and opioid use disorder

Evidence of central nervous system (CNS) exogenous opioid effects in humans has been primarily gained through neuroimaging of three participant populations: individuals after acute opioid administration, those with opioid use disorder (OUD), and those with chronic pain receiving opioid therapy. In both the brain and spinal cord, opioids alter processes of pain, cognition, and reward. Opioid-related CNS effects may persist and accumulate with longer opioid use duration. Meanwhile, opioid-induced benefits versus risks to brain health remain unclear. This review article highlights recent accumulating evidence for how exogenous opioids impact the CNS in humans. While investigation of CNS opioid effects has remained largely disparate across contexts of opioid acute administration, OUD, and chronic pain opioid therapy, integration across these contexts may enable advancement toward effective interventions.

Prescription Opioids and Brain Structure in Community-Dwelling Older Adults

OBJECTIVE

To evaluate the associations between prescription opioid exposures in community-dwelling older adults and gray and white matter structure by magnetic resonance imaging.

METHODS

Secondary analysis was conducted of a prospective, longitudinal population-based cohort study employing cross-sectional imaging of older adult (≥65 years) enrollees between November 1, 2004, and December 31, 2017. Gray matter outcomes included cortical thickness in 41 structures and subcortical volumes in 6 structures. White matter outcomes included fractional anisotropy in 40 tracts and global white matter hyperintensity volumes. The primary exposure was prescription opioid availability expressed as the per-year rate of opioid days preceding magnetic resonance imaging, with a secondary exposure of per-year total morphine milligram equivalents (MME). Multivariable models assessed associations between opioid exposures and brain structures.

RESULTS

The study included 2185 participants; median (interquartile range) age was 80 (75 to 85) years, 47% were women, and 1246 (57%) received opioids. No significant associations were found between opioids and gray matter. Increased opioid days and MME were associated with decreased white matter fractional anisotropy in 15 (38%) and 16 (40%) regions, respectively, including the corpus callosum, posterior thalamic radiation, and anterior limb of the internal capsule, among others. Opioid days and MME were also associated with greater white matter hyperintensity volume (1.02 [95% CI, 1.002 to 1.036; P=.029] and 1.01 [1.001 to 1.024; P=.032] increase in the geometric mean, respectively).

CONCLUSION

The duration and dose of prescription opioids were associated with decreased white matter integrity but not with gray matter structure. Future studies with longitudinal imaging and clinical correlation are warranted to further evaluate these relationships.

Baseline Characteristics From a New Longitudinal Cohort of Patients With Noncancer Pain and Chronic Opioid Use in the United States

Retrospective cohort studies have consistently observed that long-term prescription opioid use is a risk factor for new major depressive episodes. However, prospective studies are needed to confirm these findings and establish evidence for causation. The Prescription Opioids and Depression Pathways cohort study is designed for this purpose. The present report describes the baseline sample and associations between participant characteristics and odds of daily versus nondaily opioid use. Second, we report associations between participant characteristics and odds of depression, dysthymia, anhedonia, and vital exhaustion. Patients with noncancer pain were eligible if they started a new period of prescription opioid use lasting 30 to 90 days. Participants were 54.8 (standard deviation ± 11.3) years of age, 57.3% female and 73% White race. Less than college education was more common among daily versus nondaily opioid users (32.4% vs 27.3%; P = .0008), as was back pain (64.2% vs 51.3%; P < .0001), any nonopioid substance use disorder (12.8% vs 4.8%; P < .0001), and current smoking (30.7% vs 18.4% P < .0001). High pain interference (50.9% vs 28.4%; P < .0001) was significantly associated with depression, as was having more pain sites (6.9 ± 3.6 vs 5.7 ± 3.6; P < .0001), and benzodiazepine comedication (38.2% vs 23.4%; P < .0001). High pain interference was significantly more common among those with anhedonia (46.8% vs 27.4%; P < .0001), and more pain sites (7.0 ± 3.7 vs 5.6 ± 3.6; P < .0001) were associated with anhedonia. Having more pain sites (7.9 ± 3.6 vs 5.5 ± 3.50; P < .0001) was associated with vital exhaustion, as was back pain (71.9% vs 56.8%; P = .0001) and benzodiazepine comedication (42.8% vs 22.8%; P < .0001). Patients using prescription opioids for noncancer pain have complex pain, psychiatric, and substance use disorder comorbidities. Longitudinal data will reveal whether long-term opioid therapy leads to depression or other mood disturbances such as anhedonia and vital exhaustion. PERSPECTIVE: This study reports baseline characteristics of a new prospective, noncancer pain cohort study. Risk factors for adverse opioid outcomes were most common in those with depression and vital exhaustion and less common in dysthymia and anhedonia. Baseline data highlight the complexity of patients receiving long-term opioid therapy for noncancer pain.

Mapping Brain Structure Variability in Chronic Pain: The Role of Widespreadness and Pain Type and Its Mediating Relationship With Suicide Attempt

BACKGROUND

Chronic pain affects nearly 20% of the U.S.

POPULATION

It is a leading cause of disability globally and is associated with a heightened risk for suicide. The role of the central nervous system in the perception and maintenance of chronic pain has recently been accepted, but specific brain circuitries involved have yet to be mapped across pain types in a large-scale study.

METHODS

We used data from the UK Biobank (N = 21,968) to investigate brain structural alterations in individuals reporting chronic pain compared with pain-free control participants and their mediating effect on history of suicide attempt.

RESULTS

Chronic pain and, more notably, chronic multisite pain was associated with, on average, lower surface area throughout the cortex after adjusting for demographic, clinical, and neuropsychiatric confounds. Only participants with abdominal pain showed lower subcortical volumes, including the amygdala and brainstem, and lower cerebellum volumes. Participants with chronic headaches showed a widespread thicker cortex compared with control participants. Mediation analyses revealed that precuneus thickness mediated the relationship of chronic multisite pain and history of suicide attempt. Mediating effects were also identified specific to localized pain, with the strongest effect being amygdala volume in individuals with chronic abdominal pain.

CONCLUSIONS

Results support a widespread effect of chronic pain on brain structure and distinct brain structures underlying chronic musculoskeletal pain, visceral pain, and headaches. Mediation effects of regions in the extended ventromedial prefrontal cortex subsystem suggest that exacerbated negative internal states, negative self-referencing, and impairments in future planning may underlie suicidal behaviors in individuals with chronic pain.

Investigating brain dynamics and their association with cognitive control in opioid use disorder using naturalistic and drug cue paradigms

Objectives

Opioid use disorder (OUD) impacts millions of people worldwide. The prevalence and debilitating effects of OUD present a pressing need to understand its neural mechanisms to provide more targeted interventions. Prior studies have linked altered functioning in large-scale brain networks with clinical symptoms and outcomes in OUD. However, these investigations often do not consider how brain responses change over time. Time-varying brain network engagement can convey clinically relevant information not captured by static brain measures.

Methods

We investigated brain dynamic alterations in individuals with OUD by applying a new multivariate computational framework to movie-watching (i.e., naturalistic; N=76) and task-based (N=70) fMRI. We further probed the associations between cognitive control and brain dynamics during a separate drug cue paradigm in individuals with OUD.

Results

Compared to healthy controls (N=97), individuals with OUD showed decreased variability in the engagement of recurring brain states during movie-watching. We also found that worse cognitive control was linked to decreased variability during the rest period when no opioid-related stimuli were present.

Conclusions

These findings suggest that individuals with OUD may experience greater difficulty in effectively engaging brain networks in response to evolving internal or external demands. Such inflexibility may contribute to aberrant response inhibition and biased attention toward opioid-related stimuli, two hallmark characteristics of OUD. By incorporating temporal information, the current study introduces novel information about how brain dynamics are altered in individuals with OUD and their behavioral implications.

The perception of Mandarin speech conveying communicative functions in Chinese heroin addicts

Drug addiction can cause severe damage to the human brain, leading to significant problems in cognitive processing, such as irritability, speech distortions, and exaggeration of negative stimuli. Speech plays a fundamental role in social interaction, including both the production and perception. The ability to perceive communicative functions conveyed through speech is crucial for successful interpersonal communication and the maintaining good social relationships. However, due to the limited number of previous studies, it remains unclear whether the cognitive disorder caused by drug addiction affects the perception of communicative function conveyed in Mandarin speech. To address this question, we conducted a perception experiment involving sixty male participants, including 25 heroin addicts and 35 healthy controls. The experiment aimed to examine the perception of three communicative functions (i.e., statement, interrogative, and imperative) under three background noise conditions (i.e., no noise, SNR [Signal to Noise Ratio] = 10, and SNR = 0). Eight target sentences were first recorded by two native Mandarin speakers for each of the three communicative functions. Each half was then combined with Gaussian White Noise under two background noise conditions (i.e., SNR = 10 and SNR = 0). Finally, 48 speech stimuli were included in the experiment with four options provided for perceptual judgment. The results showed that, under the three noise conditions, the average perceptual accuracies of the three communicative functions were 80.66% and 38% for the control group and the heroin addicts, respectively. Significant differences were found in the perception of the three communicative functions between the control group and the heroin addicts under the three noise conditions, except for the recognition of imperative under strong noise condition (i.e., SNR = 0). Moreover, heroin addicts showed good accuracy (around 50%) in recognizing imperative and poor accuracy (i.e., lower than the chance level) in recognizing interrogative. This paper not only fills the research gap in the perception of communicative functions in Mandarin speech among drug addicts but also enhances the understanding of the effects of drugs on speech perception and provides a foundation for the speech rehabilitation of drug addicts.

Neuropsychology of chronic back pain managed with long-term opioid use

Chronic pain is commonly treated with long-term opioids, but the neuropsychological outcomes associated with stable long-duration opioid use remain unclear. Here, we contrasted the psychological profiles, brain activity, and brain structure of 70 chronic back pain patients on opioids (CBP+O, average opioid exposure 6.2 years) with 70 patients managing their pain without opioids. CBP+O exhibited moderately worse psychological profiles and small differences in brain morphology. However, CBP+O had starkly different spontaneous brain activity, dominated by increased mesocorticolimbic and decreased dorsolateral-prefrontal activity, even after controlling for pain intensity and duration. These differences strongly reflected cortical opioid and serotonin receptor densities and mapped to two antagonistic resting-state circuits. The circuits' dynamics were explained by mesocorticolimbic activity and reflected negative affect. We reassessed a sub-group of CBP+O after they briefly abstained from taking opioids. Network dynamics, but not spontaneous activity, reflected exacerbated signs of withdrawal. Our results have implications for the management and tapering of opioids in chronic pain.

The dynamics of heroin and illicit opioid use disorder, casual use, treatment, and recovery: A mathematical modeling analysis

A leading crisis in the United States is the opioid use disorder (OUD) epidemic. Opioid overdose deaths have been increasing, with over 100,000 deaths due to overdose from April 2020 to April 2021. This paper presents a mathematical model to address illicit OUD (IOUD), initiation, casual use, treatment, relapse, recovery, and opioid overdose deaths within an epidemiological framework. Within this model, individuals remain in the recovery class unless they relapse back to use and due to the limited availability of specialty treatment facilities for individuals with OUD, a saturation treatment function was incorporated. Additionally, a casual user class and its corresponding specialty treatment class were incorporated. We use both heroin and all-illicit opioids datasets to find parameter estimates for our models. Bistability of equilibrium solutions was found for realistic parameter values for the heroin-only dataset. This result implies that it would be beneficial to increase the availability of treatment. An alarming effect was discovered about the high overdose death rate: by 2046, the disorder-free equilibrium would be the only stable equilibrium. This consequence is concerning because it means the epidemic would end due to high overdose death rates. The IOUD model with a casual user class, its sensitivity results, and the comparison of parameters for both datasets, showed the importance of not overlooking the influence that casual users have in driving the all-illicit opioid epidemic. Casual users stay in the casual user class longer and are not going to treatment as quickly as the users of the heroin epidemic. Another result was that the users of the all-illicit opioids were going to the recovered class by means other than specialty treatment. However, the change in the relapse rate has more of an influence for those individuals than in the heroin-only epidemic. The results above from analyzing this model may inform health and policy officials, leading to more effective treatment options and prevention efforts.

Patient Motivation to Reduce or Discontinue Opioids for Chronic Pain: Self-efficacy, Barriers, and Readiness to Change

OBJECTIVES

This study aimed to assess levels and predictors of self-efficacy and motivation to change opioid use among a community sample of patients using opioids for chronic pain, as well as patient-reported barriers to pursuing opioid discontinuation.

METHODS

Participants with a variety of chronic pain conditions, recruited from ResearchMatch.org , completed a battery of electronic, self-report questionnaires assessing demographic and medical characteristics, pain treatment history, and levels of readiness, self-efficacy, and other attitudes toward reducing or discontinuing opioid use. Multiple regression analyses and analyses of variance were conducted to examine predictors of readiness and self-efficacy to change opioid use. A modified version of rapid qualitative analysis was utilized to analyze themes in participant responses to an open-ended item about "what it would take" to consider opioid discontinuation.

RESULTS

The final sample included N=119 participants, the majority of whom were female (78.2%), Caucasian (77.3%), and well-educated. Readiness and self-efficacy to decrease or stop opioid use were fairly low on a 0 to 10 Visual Analog Scale (2.6 to 3.8) and significantly higher to decrease than stop ( P <0.01). Higher readiness to change was predicted by lower pain severity and higher concern about opioids, whereas higher self-efficacy was predicted by shorter pain duration. Results from the qualitative analyses revealed that the availability of an alternative treatment option was the most commonly cited requirement to consider opioid discontinuation.

DISCUSSION

Patients with lower pain severity, shorter duration of pain, and higher concerns about opioids may be a prime target from a motivation standpoint for interventions addressing opioid tapering and discontinuation.

Traumatic Brain Injury and Opioids: Twin Plagues of the Twenty-First Century

Traumatic brain injury (TBI) and opioid use disorder (OUD) comprise twin plagues causing considerable morbidity and mortality worldwide. As interactions between TBI and OUD are to our knowledge uncharted, we review the possible mechanisms by which TBI may stimulate the development of OUD and discuss the interaction or crosstalk between these two processes. Central nervous system damage due to TBI appears to drive adverse effects of subsequent OUD and opioid use/misuse affecting several molecular pathways. Pain, a neurological consequence of TBI, is a risk factor that increases the likelihood of opioid use/misuse after TBI. Other comorbidities including depression, anxiety, posttraumatic stress disorder, and sleep disturbances are also associated with deleterious outcomes. We examine the hypothesis that a TBI "first hit" induces a neuroinflammatory process involving microglial priming, which, on a second hit related to opioid exposure, exacerbates neuroinflammation, modifies synaptic plasticity, and spreads tau aggregates to promote neurodegeneration. As TBI also impairs myelin repair by oligodendrocytes, it may reduce or degrade white matter integrity in the reward circuit resulting in behavioral changes. Along with approaches focused on specific patient symptoms, understanding the CNS effects following TBI offers a promise of improved management for individuals with OUD.

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.

Effects of fentanyl self-administration on risk-taking behavior in male rats

RATIONALE

Individuals with opioid use disorder (OUD) exhibit impaired decision making and elevated risk-taking behavior. In contrast to the effects of natural and semi-synthetic opioids, however, the impact of synthetic opioids on decision making is still unknown.

OBJECTIVES

The objective of the current study was to determine how chronic exposure to the synthetic opioid fentanyl alters risk-based decision making in adult male rats.

METHODS

Male rats underwent 14 days of intravenous fentanyl or oral sucrose self-administration. After 3 weeks of abstinence, rats were tested in a decision-making task in which they chose between a small, safe food reward and a large food reward accompanied by variable risk of footshock punishment. Following testing in the decision-making task, rats were tested in control assays that assessed willingness to work for food and shock reactivity. Lastly, rats were tested on a probabilistic reversal learning task to evaluate enduring effects of fentanyl on behavioral flexibility.

RESULTS

Relative to rats in the sucrose group, rats in the fentanyl group displayed greater choice of the large, risky reward (risk taking), an effect that was present as long as 7 weeks into abstinence. This increased risk taking was driven by enhanced sensitivity to the large rewards and diminished sensitivity to punishment. The fentanyl-induced elevation in risk taking was not accompanied by alterations in food motivation or shock reactivity or impairments in behavioral flexibility.

CONCLUSIONS

Results from the current study reveal that the synthetic opioid fentanyl leads to long-lasting increases in risk taking in male rats. Future experiments will extend this work to females and identify neural mechanisms that underlie these drug-induced changes in risk taking.

Peripherally acting anti-CGRP monoclonal antibodies alter cortical gray matter thickness in migraine patients: A prospective cohort study

Migraine is underpinned by central nervous system neuroplastic alterations thought to be caused by the repetitive peripheral afferent barrage the brain receives during the headache phase (cortical hyperexcitability). Calcitonin gene-related peptide monoclonal antibodies (anti-CGRP-mAbs) are highly effective migraine preventative treatments. Their ability to alter brain morphometry in treatment-responders vs. non-responders is not well understood. Our aim was to determine the effects of the anti-CGRP-mAb galcanezumab on cortical thickness after 3-month treatment of patients with high-frequency episodic or chronic migraine. High-resolution magnetic resonance imaging was performed pre- and post-treatment in 36 migraine patients. In this group, 19 patients were classified responders (≥50 % reduction in monthly migraine days) and 17 were considered non-responders (<50 % reduction in monthly migraine days). Following cross-sectional processing to analyze the baseline differences in cortical thickness, two-stage longitudinal processing and symmetrized percent change were conducted to investigate treatment-related brain changes. At baseline, no significant differences were found between the responders and non-responders. After 3-month treatment, decreased cortical thickness (compared to baseline) was observed in the responders in regions of the somatosensory cortex, anterior cingulate cortex, medial frontal cortex, superior frontal gyrus, and supramarginal gyrus. Non-responders demonstrated decreased cortical thickness in the left dorsomedial cortex and superior frontal gyrus. We interpret the cortical thinning seen in the responder group as suggesting that reduction in head pain could lead to changes in neural swelling and dendritic complexity and that such changes reflect the recovery process from maladaptive neural activity. This conclusion is further supported by our recent study showing that 3 months after treatment initiation, the incidence of premonitory symptoms and prodromes that are followed by headache decreases but not the incidence of the premonitory symptoms or prodromes themselves (that is, cortical thinning relates to reductions in the nociceptive signals in the responders). We speculate that a much longer recovery period is required to allow the brain to return to a more 'normal' functioning state whereby prodromes and premonitory symptoms no longer occur.

A neuropsychiatric case of delayed post-hypoxic leukoencephalopathy from opioid intoxication resulting in Anton-Babinski syndrome and quadriplegia

This is the case of a 26-year-old male who developed Anton Babinski syndrome (ABS), quadriplegia, and delayed post-hypoxic leukoencephalopathy (DPHL) after an opioid overdose. He exhibited cortical blindness, visual anosognosia, and confabulation upon awakening. Several days later, he experienced acute psychosis and agitation. T2-FSE MRI revealed extensive supratentorial leukoencephalopathy involving both cerebral hemispheres, extending to the posterior corpus callosum due to cerebral anoxia. This case report will discuss different types of encephalopathy from opioid abuse, ABS, visual anosognosia, and confabulation's pathogenic mechanisms. It underscores the necessity of researching substance-induced neuropsychiatric disorders and their pathogenic mechanisms for effective treatments.

Reduced anterior insular cortex volume in male heroin addicts: a postmortem study

We and others have observed reduced volumes of brain regions, including the nucleus accumbens, globus pallidus, hypothalamus, and habenula in opioid addiction. Notably, the insular cortex has been under increasing study in addiction, and a smaller anterior insula has been found in alcohol-addicted cases. Here, we have investigated whether similar effects occur in heroin addicts compared to healthy controls. Volumes of the anterior and posterior insula in heroin addicts (n = 14) and controls (n = 13) were assessed by morphometry of Nissl-myelin-stained serial whole-brain coronal sections. The mean relative volume of the anterior insular cortex was smaller than in non-addicted controls (3010 ± 614 *10-6 versus 3970 ± 1306 *10-6; p = 0.021). However, no significant differences in neuronal cell counts were observed. Therefore, the observed volume reduction appears to be a consequence of damaged connecting structures such as neuropil and glial cells. The findings were not confounded by age or duration of autolysis. Our results provide further evidence of structural deficits in key hubs of the addiction circuitry in heroin-dependent individuals and warrant further research in this area.

Reduced Spinal Cord Gray Matter in Patients with Fibromyalgia Using Opioids Long-term

Objective

Chronic pain involves alterations in brain gray matter volume (GMV). Moreover, opioid medications are known to reduce GMV in numerous brain regions involved in pain processing. However, no research has evaluated (1) chronic pain-related GMV alterations in the spinal cord or (2) the effect of opioids on spinal cord GMV. Accordingly, this study evaluated spinal cord GMV in health controls and patients with fibromyalgia who were using and not using opioids long-term.

Methods

We analyzed average C5 - C7 GMV of the spinal cord dorsal and ventral horns in separate female cohorts of healthy controls (HC, n = 30), fibromyalgia patients not using opioids (FMN, n = 31), and fibromyalgia patients using opioids long-term (FMO, n = 27). To assess the effect of group on average dorsal and ventral horn GMV, we conducted a one-way multivariate analysis of covariance.

Results

After controlling for age, we observed a significant effect of group on ventral horn GMV (p = 0.03, η2 = 0.09), and on dorsal horn GMV (p = 0.05, η2 = 0.08). Tukey's posthoc comparisons showed that, compared to HC participants, FMOs had significantly lower ventral (p = 0.01) and dorsal (p = 0.02) GMVs. Among FMOs only, ventral horn GMV was significantly positively associated with pain severity and interference, and both dorsal and ventral GMVs were significantly positively associated with cold pain tolerance.

Conclusion

Long-term opioid use may impact sensory processing in fibromyalgia via gray matter changes within the cervical spinal cord.

An fMRI analysis of verbal and non-verbal working memory in people with a past history of opioid dependence

Introduction

Working memory describes the ability to maintain and manipulate information held in mind, and it is a fundamental aspect of executive function. Within drug addiction, impairments of executive control over behavior are thought to lead to poor decision making and risky behaviors. Previous research has demonstrated working memory (WM) and executive function difficulties in opioid-dependent individuals, but the neural underpinnings of such impairments in this population are not well understood.

Methods

This study used functional magnetic resonance imaging to examine the neural mechanisms involved in WM in 13 opioid-dependent, methadone-maintained participants (OP) and 13 matched, healthy controls (HC). A Sternberg item-recognition task was administered with three conditions: (1) a "verbal" condition in which participants determined whether any six visually presented target letters matched a probe item that was presented 4-6 s later, (2) a "non-verbal" condition in which participants were presented with a Chinese character and, following a 4-6 s delay, determined whether the character matched the probe item, and (3) a "control" condition in which participants were presented with three horizontal lines and following the same delay, determined whether the lines matched a probe item (always the same three lines). Functional magnetic resonance imaging (fMRI) contrasts focused on the delay (or "maintenance") phase for verbal and non-verbal conditions relative to the control condition.

Results

Accuracy on the WM task did not differ between groups, but the OP group was significantly slower to respond. The fMRI imaging results indicated differences in brain activity between the OP and HC groups. fMRI-guided regions of interest correlated with age of first alcohol and THC use, suggesting that early substance use, in addition to years of opioid-abuse, may have played a role in the OP group's WM performance.

Discussion

A deeper understanding of these neural differences between opioid-dependent individuals and their healthy control counterparts helps shed light on fundamental ways in which substance use impacts the brain and cognition, potentially opening up novel avenues for therapeutic targets to treat substance use disorder.

Heroin use and neuropsychological impairments: comparison of intravenous and inhalational use

BACKGROUND AND OBJECTIVES

Injection and inhalational heroin use are associated with different levels of brain exposure to heroin and its metabolites and differences in the severity of dependence, which might lead to differential impacts on neuropsychological functions. We examined the difference and the magnitude of difference in the neuropsychological functions between inhalational and injection heroin-dependent subjects and also compared them with healthy controls.

METHODS

The study sample comprised three groups: 73 subjects with injection heroin dependence, 74 with inhalational heroin dependence, and 75 healthy controls (HC). We excluded patients with HIV, head injury, epilepsy, and severe mental illness. Neuropsychological assessments were done by Standard Progressive Matrices, Wisconsin Card Sorting Test (WCST), Iowa Gambling Task, Trail-Making Tests A and B (TMT), and Verbal and Visual Memory 1 and 2 Backtests (NBT). We estimated independent effects of the groups on various neuropsychological test parameters, adjusted for age and duration of dependence.

RESULTS

In the WCST, the inhalational heroin-dependent group took more trials to complete the first category and had higher scores in the failure to maintain set than controls. The intravenous group had higher total errors than controls in verbal working memory tests and Visual Working Memory 2 Backtest. This group scored higher commission errors in the Verbal 2 Backtest than the controls. The two groups of heroin users differed in failure to maintain set and Verbal Working Memory 2 Backtests. The effect sizes of the group differences were modest.

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

Either route of heroin use is associated with cognitive impairments; inhalational and injection use involve different cognitive domains.

Effects of current smoking severity on brain gray matter volume in opioid use disorder - a voxel-based morphometry study

Background: Cigarette smoking (CS) and opioid use disorder (OUD) significantly alter brain structure. Although OUD and cigarette smoking are highly comorbid, most prior neuroimaging research in OUD did not control for smoking severity. Specifically, the combined effect of smoking and OUD on the brain gray matter volume (GMV) remains unknown.Objectives: We used structural magnetic resonance imaging (sMRI) to examine: (1) the GMV differences between OUD and non-OUD individuals with comparable smoking severity; and (2) the differential effect of smoking severity on the brain GMV between individuals with and without OUD.Methods: We performed a secondary analysis of existing sMRI datasets of 116 individuals who smoked cigarettes daily, among whom 60 had OUD (CS-OUD; 37 male, 23 female) and 56 did not (CS; 31 male, 25 female). Brain GMV was estimated by voxel-based morphometry analysis.Results: Compared to the CS group, the CS-OUD group had a higher GMV in the occipital cortex and lower GMV in the prefrontal and temporal cortex, striatum, and pre/postcentral gyrus (whole-brain corrected-p < .05). There was a significant interaction between group and smoking severity on GMV in the medial orbitofrontal cortex (whole-brain corrected-p < .05), such that heavier smoking was associated with lower medial orbitofrontal GMV in the CS-OUD but not CS participants (r=-0.32 vs. 0.12).Conclusions: Our findings suggest a combination of independent and interactive effects of cigarette smoking and OUD on the brain gray matter. Elucidating the neuroanatomical correlates of comorbid opioid and tobacco use may shed the light on the development of novel interventions for affected individuals.

Comparative efficacy of psychosocial interventions for opioid-dependent people receiving methadone maintenance treatment: A network meta-analysis

AIMS

To estimate the efficacy of multiple psychosocial interventions for opioid-dependent people receiving methadone maintenance treatment (MMT).

METHODS

Systematic review and network meta-analysis of randomized controlled trials (RCTs) reporting the effect of psychosocial intervention for opioid-dependent people receiving MMT in outpatient clinics. We searched multiple data sources (Medline, Embase, Web of Science, PsycINFO and Cochrane Library) from inception to January 2022, finding 21 RCTs evaluating a total of 2862 people with opioid dependence receiving MMT. The primary outcome was the opioid-positive rate (assessed by urinalysis) and the secondary outcome was treatment discontinuation (the number of patients who terminated the study for any reason). We performed random-effects Bayesian meta-analysis. We used relative ranking using surface under the cumulative ranking method and certainty of evidence using grading of recommendations, assessment, development and evaluations.

RESULTS

Cognitive-behavioral therapy (CBT) [odds ratio (OR) = 0.66, 95% credible interval (CI) = 0.66-0.96; low certainty] and educational and behavioral counseling (EBC) (OR = 0.28, 95% CI = 0.12-0.25; high certainty) were more effective than treatment as usual (TAU) in efficacy. In terms of treatment discontinuation, at the end of the follow-up period there was no statistical significance among psychosocial interventions. According to the ranking probabilities, EBC might be the most effective treatment and behavioral couples' therapy (BCT) might be the best discontinuation treatment.

CONCLUSIONS

Educational and behavioral counseling and cognitive-behavioral therapy appear to be the most effective psychosocial interventions for opioid-dependent people receiving methadone maintenance treatment.

Accelerated brain aging with opioid misuse and HIV: New insights on the role of glially derived pro-inflammation mediators and neuronal chloride homeostasis

Opioid use disorder (OUD) has become a national crisis and contributes to the spread of human immunodeficiency virus (HIV) infection. Emerging evidence and advances in experimental models, methodology, and our understanding of disease processes at the molecular and cellular levels reveal that opioids per se can directly exacerbate the pathophysiology of neuroHIV. Despite substantial inroads, the impact of OUD on the severity, development, and prognosis of neuroHIV and HIV-associated neurocognitive disorders is not fully understood. In this review, we explore current evidence that OUD and neuroHIV interact to accelerate cognitive deficits and enhance the neurodegenerative changes typically seen with aging, through their effects on neuroinflammation. We suggest new thoughts on the processes that may underlie accelerated brain aging, including dysregulation of neuronal inhibition, and highlight findings suggesting that opioids, through actions at the μ-opioid receptor, interact with HIV in the central nervous system to promote unique structural and functional comorbid deficits not seen in either OUD or neuroHIV alone.

Nucleus accumbens: a systematic review of neural circuitry and clinical studies in healthy and pathological states

OBJECTIVE

The nucleus accumbens (NAcc) of the ventral striatum is critically involved in goal- and reward-based behavior. Structural and functional abnormalities of the NAcc or its associated neural systems are involved in neurological and psychiatric disorders. Studies of neural circuitry have shed light on the subtleties of the structural and functional derangements of the NAcc across various diseases. In this systematic review, the authors sought to identify human studies involving the NAcc and provide a synthesis of the literature on the known circuity of the NAcc in healthy and diseased states, as well as the clinical outcomes following neuromodulation.

METHODS

A systematic review was conducted using the PubMed, Embase, and Scopus databases. Neuroimaging studies that reported on neural circuitry related to the human NAcc with sample sizes greater than 5 patients were included. Demographic data, aim, design and duration, participants, and clinical and neurocircuitry details and outcomes of the studies were extracted.

RESULTS

Of 3591 resultant articles, 123 were included. The NAcc and its corticolimbic connections to other brain regions, such as the prefrontal cortex, are largely involved in reward and pain processes, with distinct functional circuitry between the shell and core in healthy patients. There is heterogeneity between clinical studies with regard to the NAcc indirect targeting coordinates, methods for postoperative confirmation, and blinded trial design. Neuromodulation studies provided promising clinical results in the context of addiction and substance misuse, obsessive-compulsive disorder, and mood disorders. The most common complications were impaired memory or concentration, and a notable serious complication was hypomania.

CONCLUSIONS

The functional diversity of the NAcc highlights the importance of studying the NAcc in healthy and pathological states. The results of this review suggest that NAcc neuromodulation has been attempted in the management of diverse psychiatric indications. There is promising, emerging evidence that the NAcc may be an effective target for specific reward- or pain-based pathologies with a reasonable risk profile.

Cognitive network reconstruction in individuals who use opioids compared to those who do not: Topological analysis of cognitive function through graph model and centrality measures

Introduction

Cognitive dysfunction related to opioid use disorder (OUD) requires investigation of the interconnected network of cognitive domains through behavioral experiments and graph data modeling.

Methods

We conducted n-back, selective and divided attention, and Wisconsin card sorting tests and reconstructed the interactive cognitive network of subscales or domains for individuals who use opioids and controls to identify the most central cognitive functions and their connections using graph model analysis. Each two subscales with significant correlations were connected by an edge that incorporated in formation of interactive networks. Each network was analyzed topologically based on the betweenness and closeness centrality measures.

Results

Results from the network reconstructed for individuals who use opioids show that in the divided attention module, reaction time and number of commission errors were the most central subscales of cognitive function. Whereas in controls, the number of correct responses and commission errors were the most central cognitive measure. We found that the subscale measures of divided attention module are significantly correlated with those of other tests. These findings corroborate that persons who use opioids show impaired divided attention as higher reaction time and errors in performing tasks. Divided attention is the most central cognitive function in both OUD subjects and controls, although differences were observed between the two groups in various subscales.

Discussion

Although equal proportions of males and females may be used in future studies, divided attention and its subscales may be the most promising target for cognitive therapies, treatments and rehabilitation as their improvement can enhance overall cognitive domain performance.

α2δ-1 protein drives opioid-induced conditioned reward and synaptic NMDA receptor hyperactivity in the nucleus accumbens

Glutamate NMDA receptors (NMDARs) in the nucleus accumbens (NAc) are critically involved in drug dependence and reward. α2δ-1 is a newly discovered NMDAR-interacting protein that promotes synaptic trafficking of NMDARs independently of its conventional role as a calcium channel subunit. However, it remains unclear how repeated opioid exposure affects synaptic NMDAR activity and α2δ-1-NMDAR interaction in the NAc. In this study, whole-cell patch-clamp recordings showed that repeated treatment with morphine in mice markedly increased the NMDAR-mediated frequency of miniature excitatory postsynaptic currents (mEPSCs) and amplitude of puff NMDAR currents in medium spiny neurons in the NAc core region. Morphine treatment significantly increased the physical interaction of α2δ-1 with GluN1 and their synaptic trafficking in the NAc. In Cacna2d1 knockout mice, repeated treatment with morphine failed to increase the frequency of mEPSCs and amplitude of puff NMDAR currents in the NAc core. Furthermore, inhibition of α2δ-1 with gabapentin or disruption of the α2δ-1-NMDAR interaction with the α2δ-1 C terminus-interfering peptide blocked the morphine-elevated frequency of mEPSCs and amplitude of puff NMDAR currents in the NAc core. Correspondingly, systemically administered gabapentin, Cacna2d1 ablation, or microinjection of the α2δ-1 C terminus-interfering peptide into the NAc core attenuated morphine-induced conditioned place preference and locomotor sensitization. Our study reveals that repeated opioid exposure strengthens presynaptic and postsynaptic NMDAR activity in the NAc via α2δ-1. The α2δ-1-bound NMDARs in the NAc have a key function in the rewarding effect of opioids and could be targeted for treating opioid use disorder and addiction.

Striatal resting-state connectivity after long-term diacetylmorphine treatment in opioid-dependent patients

New treatment approaches for opioid-dependent patients include injectable opioid agonist treatment with diacetylmorphine. While evidence has shown beneficial clinical effects of diacetylmorphine, it is still not clear how long-term diacetylmorphine treatment affects the brain and whether functional brain changes are accompanied by clinical improvements. Therefore, this prospective case-control study focuses on long-term effects of diacetylmorphine on resting-state functional connectivity. We included opioid-dependent patients (N = 22, age range 33-58, 16 males) treated with diacetylmorphine and healthy controls (N = 9, age range 27-55, 5 males) that underwent two MRI assessments approximately nine years apart. For the patients, the assessments took part shortly after the diacetylmorphine intake to be able to explore changes in resting-state functional connectivity in brain regions related to the stage of binge and intoxication (caudate, putamen, nucleus accumbens). A cluster in the right superior frontal gyrus was detected, showing over nine years an increase in functional connectivity originating from the left caudate and the left accumbens in patients but not in healthy controls. These connectivity changes in patients were related to the duration of the diacetylmorphine treatment at the follow-up, indicating smaller increases in functional connectivity with longer treatment duration (r = 0.63, P < 0.01). These results suggest that long-term diacetylmorphine treatment in opioid-dependent patients increases fronto-striatal connections, an effect that is linked to the duration of the treatment duration. Future research needs to further address the wide-ranging effects of diacetylmorphine on brain functioning and deepen the understanding of their clinical relevance.

The effect of long-term methadone maintenance treatment on coupling among three large-scale brain networks in male heroin-dependent individuals: A resting-state fMRI study

PURPOSE

Methadone maintenance treatment (MMT) is considered as an effective and mainstream therapy for heroin dependence. However, whether long-term MMT would improve the coupling among the three core large-scale brain networks (salience, default mode, and executive control) and its relationship with the craving for heroin is unknown.

METHODS

Forty-four male heroin-dependent individuals during long-term MMT, 27 male heroin-dependent individuals after short-term detoxification/abstinence (SA), and 26 demographically matched healthy controls (HC) underwent resting-state functional magnetic resonance imaging. We analyzed the difference in coupling among the salience, default mode, and executive control networks among the three groups and examined how the coupling among these large-scale networks was associated with craving before and after drug-cue exposure.

RESULTS

Compared with the SA group, the MMT group showed lower craving before and after cue exposure and stronger connectivity between the dorsal anterior cingulate cortex (a key node of the salience network) and key regions of the bilateral executive control network, including the bilateral dorsolateral prefrontal cortex, posterior parietal cortex, and dorsomedial prefrontal cortex. Among the heroin-dependent individuals, the functional connectivity was negatively correlated with the craving before and after heroin-cue exposure.

CONCLUSION

Our findings suggest that long-term MMT could increase the coupling between the salience and bilateral executive control networks and decrease craving for heroin. These findings contribute to the understanding of the neural mechanism of MMT, from the perspective of large-scale brain networks.

Combined fractional anisotropy and subcortical volumetric deficits in patients with mild-to-moderate depression: Evidence from the treatment of antidepressant traditional Chinese medicine

Numerous neuroimaging studies have demonstrated that diverse brain structural plasticity could occur in a human brain during a depressive episode. However, there is a lack of knowledge regarding the underlying mechanisms of mild-to-moderate depression (MMD), especially the changes of brain structural characteristics after treatment with the Shuganjieyu capsule (SG), a kind of traditional Chinese medicine that has been recommended for the specialized treatment of MMD. In this study, we investigated the structural brain plasticity in MMD that have been undergoing 8 weeks of SG treatment compared with age- and sex-matched healthy controls (HCs) and assessed the relationship between these brain structural alternations and clinical symptoms in MMD. At the baseline, we found that: (1) fractional anisotropy (FA) values in patients with MMD were found to be significantly increased in the regions of anterior limb of internal capsule (ALIC) [MNI coordinates: Peak (x/y/z) = 102, 126, 77; MMD FA_peak (Mean ± SD) = 0.621 ± 0.043; HCs FA_peak (Mean ± SD) = 0.524 ± 0.052; MMD > HCs, t = 9.625, p < 0.001] and posterior limb of internal capsule (PLIC) [MNI coordinates: Peak (x/y/z) = 109, 117, 87; MMD FA_peak (Mean ± SD) = 0.694 ± 0.042; HCs FA_peak (Mean ± SD) = 0.581 ± 0.041; MMD > HCs, t = 12.90, p < 0.001], and FA values were significantly positively correlated with HAMD scores in patients with MMD. (2) Patients with MMD showed smaller gray matter volume (GMV) of the dorsolateral prefrontal cortex (DLPFC), frontal cortex, occipital cortex, and precuneus, and the GMV of DLPFC was negatively correlated with HAMD scores. After SG treatment, we found that (1) the HAMD scores decreased; (2) FA values were significantly decreased in the regions of the ALIC and PLIC compared to those at baseline and TBSS revealed no significant differences in FA values between patients with MMD and HCs. (3) The structural characteristics of DLPFC in patients with MMD obtained at the 8th week were improved, e.g., no significant differences in GMV of DLPFC between the two groups. Taken together, our results provided neuroimaging evidence suggesting that SG is an effective treatment for patients with MMD. Moreover, alterations of GMV after 8 weeks of SG treatment indicated a potential modulation mechanism in brain structural plasticity within the DLPFC in patients with MMD.

Pain, Opioid Analgesics, and Cognition: A Conceptual Framework in Older Adults

Chronic pain is highly prevalent in older adults and is associated with poor functional outcomes. Furthermore, opioid analgesics are commonly utilized for the treatment of pain in older adults despite well-described adverse effects. Importantly, both chronic pain and opioid analgesics have been linked with impairments in cognitive function, though data are limited. In this manuscript we summarize the evidence and critical knowledge gaps regarding the relationships between pain, opioid analgesics, and cognition in older adults. Furthermore, we provide a conceptual framework to guide future research in the development, implementation, and evaluation of strategies to optimize analgesic outcomes in older adults while minimizing deleterious effects on cognition.

Long-term prescription opioid users' risk for new-onset depression increases with frequency of use

ABSTRACT

Long-term opioid therapy (LTOT) is associated with increased risk for depression. It is not known if the frequency of opioid use during LTOT is associated with new-onset depression. We used Optum's de-identified Integrated Claims-Clinical dataset (2010-2018) to create a cohort of 5146 patients, 18 to 80 years of age, with an encounter or claims in the year before new LTOT. New LTOT was defined by >90-day opioid use after remaining opioid free for 6 months. Opioid use frequency during the first 90 days of LTOT was categorized into occasional use (<50% days covered), intermittent use (50% to <80% days covered), frequent use (80% to <90% days covered), and daily use (≥90% days covered). Propensity scores and inverse probability of exposure weighting controlled for confounding in models estimating risk for new-onset depression. Patients were on average 54.5 (SD ± 13.6) years of age, 55.7% were female, 72.5% were White, and 9.5% were African American. After controlling for confounding, daily users (hazard ratio = 1.40; 95% confidence interval: 1.14-1.73) and frequent users (hazard ratio = 1.34; 95% confidence interval: 1.05-1.71) were significantly more likely to develop new-onset depression compared with occasional users. This association remained after accounting for the contribution of post-index pain diagnoses and opioid use disorder. In LTOT, risk for new depression episodes is up to 40% greater in near-daily users compared with occasional users. Patients could reduce depression risk by avoiding opioid use on as many low pain days as possible. Repeated screening for depression during LTOT is warranted.

Altered resting-state functional connectivity within corticostriatal and subcortical-striatal circuits in chronic pain

Brain corticostriatal circuits are important for understanding chronic pain and highly relevant to motivation and cognitive processes. It has been demonstrated that in patients with chronic back pain, altered nucleus accumbens (NAcc)-medial prefrontal cortex (MPFC) circuit fMRI-based activity is predictive of patient outcome. We evaluated the NAcc-MPFC circuit in patients with another chronic pain condition, fibromyalgia, to extend these important findings. First, we compared fMRI-based NAcc-MPFC resting-state functional connectivity in patients with fibromyalgia (N = 32) vs. healthy controls (N = 37). Compared to controls, the NAcc-MPFC circuit's connectivity was significantly reduced in fibromyalgia. In addition, within the fibromyalgia group, NAcc-MPFC connectivity was significantly correlated with trait anxiety. Our expanded connectivity analysis of the NAcc to subcortical brain regions showed reduced connectivity of the right NAcc with mesolimbic circuit regions (putamen, thalamus, and ventral pallidum) in fibromyalgia. Lastly, in an exploratory analysis comparing our fibromyalgia and healthy control cohorts to a separate publicly available dataset from patients with chronic back pain, we identified reduced NAcc-MPFC connectivity across both the patient groups with unique alterations in NAcc-mesolimbic connectivity. Together, expanding upon prior observed alterations in brain corticostriatal circuits, our results provide novel evidence of altered corticostriatal and mesolimbic circuits in chronic pain.

Neural alterations in opioid-exposed infants revealed by edge-centric brain functional networks

Prenatal opioid exposure has been linked to adverse effects spanning multiple neurodevelopmental domains, including cognition, motor development, attention, and vision. However, the neural basis of these abnormalities is largely unknown. A total of 49 infants, including 21 opioid-exposed and 28 controls, were enrolled and underwent MRI (43 ± 6 days old) after birth, including resting state functional MRI. Edge-centric functional networks based on dynamic functional connections were constructed, and machine-learning methods were employed to identify neural features distinguishing opioid-exposed infants from unexposed controls. An accuracy of 73.6% (sensitivity 76.25% and specificity 69.33%) was achieved using 10 times 10-fold cross-validation, which substantially outperformed those obtained using conventional static functional connections (accuracy 56.9%). More importantly, we identified that prenatal opioid exposure preferentially affects inter- rather than intra-network dynamic functional connections, particularly with the visual, subcortical, and default mode networks. Consistent results at the brain regional and connection levels were also observed, where the brain regions and connections associated with visual and higher order cognitive functions played pivotal roles in distinguishing opioid-exposed infants from controls. Our findings support the clinical phenotype of infants exposed to opioids in utero and may potentially explain the higher rates of visual and emotional problems observed in this population. Finally, our findings suggested that edge-centric networks could better capture the neural differences between opioid-exposed infants and controls by abstracting the intrinsic co-fluctuation along edges, which may provide a promising tool for future studies focusing on investigating the effects of prenatal opioid exposure on neurodevelopment.

Neurodegeneration Within the Amygdala Is Differentially Induced by Opioid and HIV-1 Tat Exposure

Opioid use disorder (OUD) is a critical problem that contributes to the spread of HIV and may intrinsically worsen neuroHIV. Despite the advent of combined antiretroviral therapies (cART), about half of persons infected with HIV (PWH) experience cognitive and emotional deficits that can be exacerbated by opioid abuse. HIV-1 Tat is expressed in the central nervous system (CNS) of PWH on cART and is thought to contribute to neuroHIV. The amygdala regulates emotion and memories associated with fear and stress and is important in addiction behavior. Notwithstanding its importance in emotional saliency, the effects of HIV and opioids in the amygdala are underexplored. To assess Tat- and morphine-induced neuropathology within the amygdala, male Tat transgenic mice were exposed to Tat for 8 weeks and administered saline and/or escalating doses of morphine twice daily (s.c.) during the last 2 weeks of Tat exposure. Eight weeks of Tat exposure decreased the acoustic startle response and the dendritic spine density in the basolateral amygdala, but not the central nucleus of the amygdala. In contrast, repeated exposure to morphine alone, but not Tat, increased the acoustic startle response and whole amygdalar levels of amyloid-β (Aβ) monomers and oligomers and tau phosphorylation at Ser396, but not neurofilament light chain levels. Co-exposure to Tat and morphine decreased habituation and prepulse inhibition to the acoustic startle response and potentiated the morphine-induced increase in Aβ monomers. Together, our findings indicate that sustained Tat and morphine exposure differentially promote synaptodendritic degeneration within the amygdala and alter sensorimotor processing.

Corticosteroid sensitization drives opioid addiction

The global crisis of opioid overdose fatalities has led to an urgent search to discover the neurobiological mechanisms of opioid use disorder (OUD). A driving force for OUD is the dysphoric and emotionally painful state (hyperkatifeia) that is produced during acute and protracted opioid withdrawal. Here, we explored a mechanistic role for extrahypothalamic stress systems in driving opioid addiction. We found that glucocorticoid receptor (GR) antagonism with mifepristone reduced opioid addiction-like behaviors in rats and zebrafish of both sexes and decreased the firing of corticotropin-releasing factor neurons in the rat amygdala (i.e., a marker of brain stress system activation). In support of the hypothesized role of glucocorticoid transcriptional regulation of extrahypothalamic GRs in addiction-like behavior, an intra-amygdala infusion of an antisense oligonucleotide that blocked GR transcriptional activity reduced addiction-like behaviors. Finally, we identified transcriptional adaptations of GR signaling in the amygdala of humans with OUD. Thus, GRs, their coregulators, and downstream systems may represent viable therapeutic targets to treat the "stress side" of OUD.

Opioid analgesia alters corticospinal coupling along the descending pain system in healthy participants

Opioids are potent analgesic drugs with widespread cortical, subcortical, and spinal targets. In particular, the central pain system comprising ascending and descending pain pathways has high opioid receptor densities and is thus crucial for opioid analgesia. Here, we investigated the effects of the opioid remifentanil in a large sample (n = 78) of healthy male participants using combined corticospinal functional MRI. This approach offers the possibility to measure BOLD responses simultaneously in the brain and spinal cord, allowing us to investigate the role of corticospinal coupling in opioid analgesia. Our data show that opioids altered activity in regions involved in pain processing such as somatosensory regions, including the spinal cord and pain modulation such as prefrontal regions. Moreover, coupling strength along the descending pain system, that is, between the anterior cingulate cortex, periaqueductal gray, and spinal cord, was stronger in participants who reported stronger analgesia during opioid treatment while participants that received saline showed reduced coupling when experiencing less pain. These results indicate that coupling along the descending pain pathway is a potential mechanism of opioid analgesia and can differentiate between opioid analgesia and unspecific reductions in pain such as habituation.

Association of pre-admission opioid abuse and/or dependence on major complications in traumatic brain injury (TBI) patients

SETTING

In the last few decades, an opioid related health crisis has been a challenging problem in many countries around the world, especially the United States. Better understanding of the association of pre-admission opioid abuse and/or dependence (POAD) on specific major complications in traumatic brain injury (TBI) patients can aid the medical team in improving patient care management and outcomes.

STUDY OBJECTIVE

Our goal is to assess and quantify the risk of POAD on in-hospital mortality and major complications in TBI patients.

DESIGN

We conducted a retrospective study and used the National Inpatient Sample (NIS) database from 2004 to 2015 to investigate the impact of POAD on in-hospital mortality and major complications in TBI patients. We utilized propensity score matching and conditional logistic regression models, adjusted with injury severity score (ISS) and comorbidities, to obtain the adjusted odds ratios (OR).

MAIN RESULTS

POAD TBI patients had lower risks of in-hospital mortality (OR 0.58; p < 0.001) and acute myocardial infarction (OR 0.53; p = 0.045), while a higher risk of respiratory (OR 1.59; p < 0.001) and neurologic complications (OR 2.54; p < 0.001), compared to non-POAD TBI patients. Additionally, POAD patients were significantly more likely to have sepsis (OR 2.16, p < 0.001), malnutrition (OR 1.56, p < 0.001), delirium (OR 2.81, p < 0.001), respiratory failure (OR 1.79, p < 0.001), and acute renal failure (OR 1.83, p < 0.001). POAD TBI patients had shorter length of hospital stay compared to non-POAD TBI patients (mean 8.0 vs 9.2 days, p < 0.001).

CONCLUSIONS

POAD TBI patients have a lower in-hospital mortality, shorter duration of hospitalization and a lower risk of acute myocardial infarction, while they are more likely to have respiratory failure, delirium, sepsis, malnutrition, and acute renal failure compared to TBI patients without POAD. Prospective study is warranted to further confirm these findings.

Extended amygdala, conditioned withdrawal and memory consolidation

Opioid withdrawal can be associated to environmental cues through classical conditioning. Exposure to these cues can precipitate a state of conditioned withdrawal in abstinent subjects, and there are suggestions that conditioned withdrawal can perpetuate the addiction cycle in part by promoting the storage of memories. This review discusses evidence supporting the hypothesis that conditioned withdrawal facilitates memory consolidation by activating a neurocircuitry that involves the extended amygdala. Specifically, the central amygdala, the bed nucleus of the stria terminalis, and the nucleus accumbens shell interact functionally during withdrawal, mediate expression of conditioned responses, and are implicated in memory consolidation. From this perspective, the extended amygdala could be a neural pathway by which drug-seeking behaviour performed during a state of conditioned withdrawal is more likely to become habitual and persistent.

Right arcuate fasciculus and left uncinate fasciculus abnormalities in young smoker

Previous diffusion tensor imaging (DTI) studies had investigated the white matter (WM) integrity abnormalities in smokers. Exposure to nicotine disrupts neurodevelopment during adolescence, possibly by disrupting the trophic effects of acetylcholine. However, little is known about the diffusion parameters of specific fibre bundles at multiple locations in young smokers. Thirty-seven young smokers and 29 age-, education- and gender-matched healthy non-smokers participated in this study. Automated Fibre Quantification (AFQ) was employed to investigate the WM microstructure in young smokers by integrating multiple indices. Diffusion parameters, that is, fractional anisotropy (FA), axial diffusion (AD), radial diffusion (RD) and mean diffusion (MD), were calculated at 100 points along the length of 18 major brain tracts. The relationships between neuroimaging differences and smoking behaviours were explored, including Fagerström Test of Nicotine Dependence (FTND) and pack-years. Compared with non-smokers, young smokers showed significantly increased FA, AD and decreased RD in the left uncinate fasciculus (UF) and right thalamic radiation (TR), increased AD, RD and decreased FA in the right arcuate fasciculus (Arc). Correlation analyses revealed that FA values of the left UF and RD values of the right Arc were negatively correlated with FTND score in smokers and FA values of the right Arc were positively correlated with FTND scores. Positive correlation was observed between AD values of the left UF and pack-years in smokers. The findings enhanced our understanding of the potential effect of adolescent smoking on WM microstructure.

Cingulate circuits are associated with escalation of heroin use and naloxone-induced increases in heroin self-administration

Opioid use disorder (OUD) is defined as a compulsion to seek and take opioids, loss of control over intake and the development of a negative emotional state when access to opioids is denied. Using functional magnetic resonance imaging (fMRI) data in a rat model of OUD, we demonstrate that the escalation of heroin self-administration (SA) and the increased heroin SA following an injection of an opioid receptor antagonist (naloxone) are associated with changes in distinct brain circuits, centered on the cingulate cortex (Cg). Here, SA escalation score was negatively associated with changes in resting state functional connectivity (rsFC) between the Cg and the dorsal striatum. Conversely, increased heroin SA following naloxone injection, was associated with increased connectivity between the Cg and the extended amygdala and hypothalamus. Naloxone-induced increased SA was also positively associated with changes in the amplitude of low frequency fluctuations within the Cg, a measure of spontaneous neuronal activity. Characterizing the distinct brain circuit and behavior changes associated with different facets of addiction increases our understanding of OUD and may provide insight into addiction prevention and treatment.

Distinct networks of periaqueductal gray columns in pain and threat processing

Noxious events that can cause physical damage to the body are perceived as threats. In the brainstem, the periaqueductal gray (PAG) ensures survival by generating an appropriate response to these threats. Hence, the experience of pain is coupled with threat signaling and interfaces in the dl/l and vlPAG columns. In this study, we triangulate the functional circuits of the dl/l and vlPAG by using static and time-varying functional connectivity (FC) in multiple fMRI scans in healthy participants (n=37, 21 female). The dl/l and vlPAG were activated during cue, heat, and rating periods when the cue signaled a high threat of experiencing heat pain and the incoming intensity of heat pain was low; responses were significantly lower after low threat cues. The two regions responded similarly to the cued conditions but showed prominent distinctions in the extent of FC with other brain regions. Thus, both static and time-varying FC showed significant differences in the functional circuits of dl/l and vlPAG in rest and task scans. The dl/lPAG consistently synchronized with the salience network, suggesting a role in threat detection, while the vlPAG exhibited more widespread synchronization and frequently connected with memory/language and sensory regions. Hence, these two PAG regions process heat pain when stronger pain is expected or when it is uncertain, and preferentially synchronize with distinct brain circuits in a reproducible manner. The dl/lPAG seems more directly involved in salience detection, while the vlPAG seems engaged in contextualizing threats.

Altered Spontaneous Brain Activity in Betel Quid Dependence Chewers: A Resting-State Functional MRI Study With Percent Amplitude of Fluctuation

OBJECTIVE

This study aimed to investigate brain spontaneous neural activity changes in betel quid dependence (BQD) chewers using the percent amplitude of fluctuation (PerAF) method.

METHODS

This study included 48 BQD chewers. The healthy control (HC) group comprised 35 volunteers who were matched with BQD chewers in age, gender, and educational status. All subjects underwent resting-state functional magnetic resonance imaging (rs-fMRI) and neuropsychological tests. The PerAF method was used to identify BQD-related regional brain activity changes. An independent samples t-test was used to evaluate the PerAF difference across two groups. The association between PerAF changes and clinical features such as BQD scores, duration of BQD, Hamilton Depression Rating Scale-24 item (HAMD-24), and Hamilton Anxiety Rating Scale-14 item (HAMA-14) was evaluated by using Spearman's correlation analysis. It assessed the ability of the PerAF method to distinguish between BQD chewers and HCs using a receiver operating characteristic (ROC) curve.

RESULTS

Compared to the control group, BQD chewers showed decreased PerAF in right anterior cingulate cortex (ACC), right middle frontal gyrus (MFG), right insula, right precuneus, left putamen, left supramarginal gyrus (SMG), and left cerebellum and increased PerAF in right orbitofrontal and left superior temporal gyrus (STG) [P < 0.05, Gaussian random field (GRF) corrected]. PerAF values of the right MFG and right ACC had a significant negative relationship with the duration of BQD (P < 0.05). The average values of PerAF in the left putamen, left cerebellum, and left STG showed significant discriminatory power in distinguishing BQD chewers from HCs, with relatively prime area under the curve (AUC) values.

CONCLUSION

Our findings suggested that betel quid chewing is associated with spontaneous neural activity alterations in the impulsivity areas (MFG and ACC), cognitive (MFG, ACC, precuneus, and the cerebellum), and reward (orbitofrontal, putamen, and insula) systems, which may be correlated with neuropathological mechanisms of BQD. Also, PerAF may be useful as a potential sensitive biomarker for identifying spontaneous brain activity changes in BQD chewers.

Neurocircuitry basis of the opioid use disorder-post-traumatic stress disorder comorbid state: conceptual analyses using a dimensional framework

Understanding the interface between opioid use disorder (OUD) and post-traumatic stress disorder (PTSD) is challenging. By use of a dimensional framework, such as research domain criteria, convergent and targetable neurobiological processes in OUD-PTSD comorbidity can be identified. We hypothesise that, in OUD-PTSD, circuitry that is implicated in two research domain criteria systems (ie, negative valence and cognitive control) underpins dysregulation of incentive salience, negative emotionality, and executive function. We also propose that the OUD-PTSD state might be systematically investigated with approaches outlined within a neuroclinical assessment framework for addictions and PTSD. Our dimensional analysis of the OUD-PTSD state shows how first-line therapeutic approaches (ie, partial μ-type opioid receptor [MOR1] agonism) modulate overlapping neurobiological and clinical features and also provides mechanistic rationale for evaluating polytherapeutic strategies (ie, partial MOR1 agonism, κ-type opioid receptor [KOR1] antagonism, and α-2A adrenergic receptor [ADRA2A] agonism). A combination of these therapeutic mechanisms is projected to facilitate recovery in patients with OUD-PTSD by mitigating negative valence states and enhancing executive control.

Brain opioid segments and striatal patterns of dopamine release induced by naloxone and morphine

Opioid receptors are expressed throughout the brain and play a major role in regulating striatal dopamine (DA) release. Clinical studies have shown that naloxone (NAL, a nonspecific opioid antagonist) in individuals with opioid use disorder and morphine (MRP, a nonspecific opioid agonist) in healthy controls, resulted in DA release in the dorsal and ventral striatum, respectively. It is not known whether the underlying patterns of striatal DA release are associated with the striatal distribution of opioid receptors. We leveraged previously published PET datasets (collected in independent cohorts) to study the brain‐wide distribution of opioid receptors and to compare striatal opioid receptor availability with striatal DA release patterns. We identified three major gray matter segments based on availability maps of DA and opioid receptors: striatum, and primary and secondary opioid segments with high and intermediate opioid receptor availability, respectively. Patterns of DA release induced by NAL and MRP were inversely associated and correlated with kappa (NAL: r(68) = −0.81, MRP: r(68) = 0.54), and mu (NAL: r(68) = −0.62, MRP: r(68) = 0.46) opioid receptor availability. Kappa opioid receptor availability accounted for a unique part of variance in NAL‐ and MRP‐DA release patterns (ΔR² >0.14, p <.0001). In sum, distributions of opioid receptors distinguished major cortical and subcortical regions. Patterns of NAL‐ and MRP‐induced DA release had inverse associations with striatal opioid receptor availability. Our approach provides a pattern‐based characterization of drug‐induced DA targets and is relevant for modeling the role of opioid receptors in modulating striatal DA release.

Reward Deficiency Syndrome (RDS): A Cytoarchitectural Common Neurobiological Trait of All Addictions

Alcohol and other substance use disorders share comorbidity with other RDS disorders, i.e., a reduction in dopamine signaling within the reward pathway. RDS is a term that connects addictive, obsessive, compulsive, and impulsive behavioral disorders. An estimated 2 million individuals in the United States have opioid use disorder related to prescription opioids. It is estimated that the overall cost of the illegal and legally prescribed opioid crisis exceeds one trillion dollars. Opioid Replacement Therapy is the most common treatment for addictions and other RDS disorders. Even after repeated relapses, patients are repeatedly prescribed the same opioid replacement treatments. A recent JAMA report indicates that non-opioid treatments fare better than chronic opioid treatments. Research demonstrates that over 50 percent of all suicides are related to alcohol or other drug use. In addition to effective fellowship programs and spirituality acceptance, nutrigenomic therapies (e.g., KB220Z) optimize gene expression, rebalance neurotransmitters, and restore neurotransmitter functional connectivity. KB220Z was shown to increase functional connectivity across specific brain regions involved in dopaminergic function. KB220/Z significantly reduces RDS behavioral disorders and relapse in human DUI offenders. Taking a Genetic Addiction Risk Severity (GARS) test combined with a the KB220Z semi-customized nutrigenomic supplement effectively restores dopamine homeostasis (WC 199).

Genetics and prescription opioid use (GaPO): study design for consenting a cohort from an existing biobank to identify clinical and genetic factors influencing prescription opioid use and abuse

BACKGROUND

Prescription opioids (POs) are commonly used to treat moderate to severe chronic pain in the health system setting. Although they improve quality of life for many patients, more work is needed to identify both the clinical and genetic factors that put certain individuals at high risk for developing opioid use disorder (OUD) following use of POs for pain relief. With a greater understanding of important risk factors, physicians will be better able to identify patients at highest risk for developing OUD for whom non-opioid alternative therapies and treatments should be considered.

METHODS

We are conducting a prospective observational study that aims to identify the clinical and genetic factors most stongly associated with OUD. The study design leverages an existing biobank that includes whole exome sequencing and array genotyping. The biobank is maintained within an integrated health system, allowing for the large-scale capture and integration of genetic and non-genetic data. Participants are enrolled into the health system biobank via informed consent and then into a second study that focuses on opioid medication use. Data capture includes validated self-report surveys measuring addiction severity, depression, anxiety, and nicotine use, as well as additional clinical, prescription, and brain imaging data extracted from electronic health records.

DISCUSSION

We will harness this multimodal data capture to establish meaningful patient phenotypes in order to understand the genetic and non-genetic contributions to OUD.