Impaired frontostriatal functional connectivity among chronic opioid using pain patients is associated with dysregulated affect

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.

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.

Chronic pain, chronic stress and substance use: overlapping mechanisms and implications

Chronic pain is among the most common reasons adults in the U.S. seek medical care. Despite chronic pain's substantial impact on individuals' physical, emotional, and financial wellness, the biologic underpinnings of chronic pain remain incompletely understood. Such deleterious impact on an individuals' wellness is also manifested in the substantial co-occurrence of chronic stress with chronic pain. However, whether chronic stress and adversity and related alcohol and substance misuse increases risk of developing chronic pain, and, if so, what the overlapping psychobiological processes are, is not well understood. Individuals suffering with chronic pain find alleviation through prescription opioids as well as non-prescribed cannabis, alcohol, and other drugs to control pain, and use of these substances have grown significantly. Substance misuse also increases experience of chronic stress. Thus, given the evidence showing a strong correlation between chronic stress and chronic pain, we aim to review and identify overlapping factors and processes. We first explore the predisposing factors and psychologic features common to both conditions. This is followed by examining the overlapping neural circuitry of pain and stress in order to trace a common pathophysiologic processes for the development of chronic pain and its link to substance use. Based on the previous literature and our own findings, we propose a critical role for ventromedial prefrontal cortex dysfunction, an overlapping brain area associated with the regulation of both pain and stress that is also affected by substance use, as key in the risk of developing chronic pain. Finally, we identify the need for future research in exploring the role of medial prefrontal circuits in chronic pain pathology. Critically, in order to alleviate the enormous burden of chronic pain without exacerbating the co-occurring substance misuse crisis, we emphasize the need to find better approaches to treat and prevent chronic pain.

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.

Potential brain recovery of frontostriatal circuits in heroin users after prolonged abstinence: A preliminary study

Neuroscientists have devoted efforts to explore potential brain recovery after prolonged abstinence in heroin users (HU). However, not much is known about whether frontostriatal circuits can recover after prolonged abstinence in HU. An eight-month longitudinal study was carried out for HU. Two MRI scans were obtained at baseline (HU1) and 8-month follow-up (HU2). The functional and structural connectivities of dorsal and ventral frontostriatal pathways were measured by resting-state functional connectivity (RSFC) and diffusion tensor imaging (DTI). Correlation analyses were employed to reveal the associations between neuroimaging and behavioral changes. Results suggested that relative to healthy controls (HCs), HU1 showed lower fractional anisotropy (FA) in the right dorsolateral prefrontal cortex (DLPFC)-to-caudate tracts and medial orbitofrontal cortex (mOFC)-to-nucleus accumbens (NAc) tracts as well as decreased RSFC in the left mOFC-NAc circuits. Longitudinal results revealed reduced craving and enhanced cognitive control in HU2 compared with HU1. After prolonged abstinence, HU2 showed increased FA values in the right DLPFC-caudate and mOFC-NAc tracts as well as increased RSFC strength in the bilateral mOFC-NAc circuits compared with HU1. In addition, changes in RSFC and FA values in the right mOFC-NAc circuit were negatively correlated with craving score changes. Similarly, negative correlations were also found between changes of RSFC in the bilateral DLPFC-caudate circuits and TMT-A scores. We provided scientific evidence for brain recovery of the dorsal and ventral frontostriatal circuits in HU after prolonged abstinence, and these circuits may be potential neuroimaging biomarkers for cognition and craving changes.

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.

Altered Reward Processing and Sex Differences in Chronic Pain

Chronic pain and reward processing are understood to be reciprocally related to one another. Previous studies of reward processing in chronic pain patients have reported incongruent findings. While several factors likely contribute to these disparate findings, these previous studies did not stratify their analyses by sex-a factor previously shown to robustly impact reward-related responses. Thus, we examined sex as a factor of interest in level of striatal activation during anticipation of monetary incentives among patients with chronic non-specific back pain and healthy controls (HC). This study utilized functional magnetic resonance imaging during a monetary incentive delay task to evaluate reward and loss responsivity in the striatum among males and females with and without chronic pain (N = 90). Group, sex, and group-by-sex interactions were analyzed via repeated measures analysis of variance. Among HC, males exhibited significantly greater blood oxygen level dependent (BOLD) signal in the striatum during reward anticipation, particularly during large reward trials. By contrast, no significant sex differences were observed among patients. A significant group-by-sex interaction was also observed, revealing diminished BOLD responses among males with chronic pain relative to control males. These results provide novel evidence of sex-specific reductions in anticipatory responses to reward in patients with chronic pain. Altered striatal reward responsivity among males, but not females, suggests that the reward systems of males and females are uniquely disrupted by chronic pain, and highlights the value of including sex as a factor of interest in future studies of reward responsivity in the context of persistent pain.

Altered prefrontal-striatal theta-band oscillatory dynamics underlie working memory deficits in neuropathic pain rats

BACKGROUND

Prelimbic medial prefrontal cortex (PL-mPFC) and nucleus accumbens core region (NAcc) play an important role in supporting several executive cognitive mechanisms, such as spatial working-memory (WM). Recently, this circuit has been also associated with both sensory and affective components of pain. However, it is still unclear whether this circuit is endogenously engaged in neuropathic pain-related cognitive dysfunctions.

METHODS

To answer this question, we induced the expression of halorhodopsin in local PL-mPFC neurons projecting to NAcc, and then selectively inhibited the terminals of these neurons in the NAcc while recording neural activity during the performance of a delayed non-match to sample (DNMS) spatial WM task. Within-subject behavioral performance and PL-mPFC to NAcc circuit neural activity was assessed after the onset of a persistent rodent neuropathic pain model - spared nerve injury (SNI).

RESULTS

Our results revealed that the induction of the neuropathy reduced WM performance, and altered the interplay between PL-mPFC and NAcc neurons namely in increasing the functional connectivity from NAcc to PL-mPFC, particularly in the theta-band spontaneous oscillations; in addition, these behavioral and functional perturbations were partially reversed by selective optogenetic inhibition of PL-mPFC neuron terminals into the NAcc during the DNMS task delay-period, without significant antinociceptive effects.

CONCLUSIONS

Altogether, these results strongly suggest that the PL-mPFC excitatory output into the NAcc plays an important role in the deregulation of WM under pain conditions.

SIGNIFICANCE

Selective optogenetic inhibition of prefrontal-striatal microcircuit reverses pain-related working memory deficits, but has no significant impact on pain responses. Neuropathic pain underlies an increase of functional connectivity between the nucleus accumbens core area and the prelimbic medial prefrontal cortex mediated by theta-band activity.

Prioritization of personally relevant stimuli in male abstinent heroin users

The prioritization of the processing of highly relevant personal stimuli pervades various cognitive domains and is vital to our survival and normal functioning. However, the extent to which this process is altered by drug addiction remains to be elucidated. The present study examined the self-prioritization effect in abstinent heroin users (AHUs) using the perceptual matching task, which controls for the confounding effect of familiarity, and further modified it to revalidate the drug-prioritization effect (DPE). Eighty male AHUs and forty healthy control (HC) participants were recruited for this study. Participants filled in the questionnaire and completed two perceptual matching tasks. The questionnaire included demographic information (e.g., age, education) and characteristics of drug use, whereas the HC participants only completed the demographic information. AHUs exhibited a robust self-advantage in the self-perceptual matching task, and that the magnitude of the self-prioritization effect (MSPE) was comparable to that in HCs. Only AHUs prioritized the processing of drug-related stimuli in the drug-perceptual matching task, and showed similar prioritization effects during self- and drug-related processing. The MSPE and magnitude of the drug-prioritization effect (MDPE) were correlated with the heroin consumption behavior in AHUs. The process of self-prioritization is intact in drug users, and they uniquely prioritize the processing of drug cues. The similar pattern between the self- and drug-related processing provided behavioral evidence to support that drug cues are likely to be associated with heightened personal relevance in drug users. These prioritization processes may play critical roles in addiction and provide a promising route for intervention.

Spinal Cord Resting State Activity in Individuals With Fibromyalgia Who Take Opioids

Chronic pain coincides with myriad functional alterations throughout the brain and spinal cord. While spinal cord mechanisms of chronic pain have been extensively characterized in animal models and in vitro, to date, research in patients with chronic pain has focused only very minimally on the spinal cord. Previously, spinal cord functional magnetic resonance imaging (fMRI) identified regional alterations in spinal cord activity in patients (who were not taking opioids) with fibromyalgia, a chronic pain condition. Here, in patients with fibromyalgia who take opioids (N = 15), we compared spinal cord resting-state fMRI data vs. patients with fibromyalgia not taking opioids (N = 15) and healthy controls (N = 14). We hypothesized that the opioid (vs. non-opioid) patient group would show greater regional alterations in spinal cord activity (i.e., the amplitude of low frequency fluctuations or ALFF, a measure of regional spinal cord activity). However, we found that regional spinal cord activity in the opioid group was more similar to healthy controls, while regional spinal cord activity in the non-opioid group showed more pronounced differences (i.e., ventral increases and dorsal decreases in regional ALFF) vs. healthy controls. Across patient groups, self-reported fatigue correlated with regional differences in spinal cord activity. Additionally, spinal cord functional connectivity and graph metrics did not differ among groups. Our findings suggest that, contrary to our main hypothesis, patients with fibromyalgia who take opioids do not have greater alterations in regional spinal cord activity. Thus, regional spinal cord activity may be less imbalanced in patients taking opioids compared to patients not taking opioids.

Mind-body approaches targeting the psychological aspects of opioid use problems in patients with chronic pain: evidence and opportunities

Opioids are commonly prescribed for the management of patients with chronic noncancer pain. Despite the potential analgesic benefits of opioids, long-term opioid therapy (LTOT) may be accompanied by problems such as opioid misuse and opioid use disorder (OUD). In this review, we begin with a description of opioid misuse and OUD and the patient-specific factors associated with these problems among patients with chronic pain. We will focus primarily on highlighting the predominant role played by psychological factors in the occurrence of opioid misuse and OUD in these patients. Several psychological factors have been found to be associated with opioid use problems in patients with chronic pain, and evidence indicates that patients presenting with psychological disturbances are particularly at risk of transitioning to long-term opioid use, engaging in opioid misuse behaviors, and developing OUD. The biological factors that might underlie the association between psychological disturbances and opioid use problems in patients with chronic pain have yet to be fully elucidated, but a growing number of studies suggest that dysfunctions in reward, appetitive, autonomic, and neurocognitive systems might be involved. We end with an overview of specific types of psychological interventions that have been put forward to prevent or reduce the occurrence of opioid misuse and OUD in patients with chronic pain who are prescribed LTOT.

Structural MRI and functional connectivity features predict current clinical status and persistence behavior in prescription opioid users

Prescription opioid use disorder (POUD) has reached epidemic proportions in the United States, raising an urgent need for diagnostic biological tools that can improve predictions of disease characteristics. The use of neuroimaging methods to develop such biomarkers have yielded promising results when applied to neurodegenerative and psychiatric disorders, yet have not been extended to prescription opioid addiction. With this long-term goal in mind, we conducted a preliminary study in this understudied clinical group. Univariate and multivariate approaches to distinguishing between POUD (n = 26) and healthy controls (n = 21) were investigated, on the basis of structural MRI (sMRI) and resting-state functional connectivity (restFC) features. Univariate approaches revealed reduced structural integrity in the subcortical extent of a previously reported addiction-related network in POUD subjects. No reliable univariate between-group differences in cortical structure or edgewise restFC were observed. Contrasting these mixed univariate results, multivariate machine learning classification approaches recovered more statistically reliable group differences, especially when sMRI and restFC features were combined in a multi-modal model (classification accuracy = 66.7%, p < .001). The same multivariate multi-modal approach also yielded reliable prediction of individual differences in a clinically relevant behavioral measure (persistence behavior; predicted-to-actual overlap r = 0.42, p = .009). Our findings suggest that sMRI and restFC measures can be used to reliably distinguish the neural effects of long-term opioid use, and that this endeavor numerically benefits from multivariate predictive approaches and multi-modal feature sets. This can serve as theoretical proof-of-concept for future longitudinal modeling of prognostic POUD characteristics from neuroimaging features, which would have clearer clinical utility.

Factors mediating pain-related risk for opioid use disorder

Pain is a complex experience with far-reaching organismal influences ranging from biological factors to those that are psychological and social. Such influences can serve as pain-related risk factors that represent susceptibilities to opioid use disorder. This review evaluates various pain-related risk factors to form a consensus on those that facilitate opioid abuse. Epidemiological findings represent a high degree of co-occurrence between chronic pain and opioid use disorder that is, in part, driven by an increase in the availability of opioid analgesics and the diversion of their use in a non-medical context. Brain imaging studies in individuals with chronic pain that use/abuse opioids suggest abuse-related mechanisms that are rooted within mesocorticolimbic processing. Preclinical studies suggest that pain states have a limited impact on increasing the rewarding effects of opioids. Indeed, many findings indicate a reduction in the rewarding and reinforcing effects of opioids during pain states. An increase in opioid use may be facilitated by an increase in the availability of opioids and a decrease in access to non-opioid reinforcers that require mobility or social interaction. Moreover, chronic pain and substance abuse conditions are known to impair cognitive function, resulting in deficits in attention and decision making that may promote opioid abuse. A better understanding of pain-related risk factors can improve our knowledge in the development of OUD in persons with pain conditions and can help identify appropriate treatment strategies. This article is part of the special issue on 'Vulnerabilities to Substance Abuse.'.

Hopes and fears before opioid tapering: a quantitative and qualitative study of patients with chronic pain and long-term opioids

Background

It is clear that the risks of opioids in chronic pain outweigh the benefits, creating a drive for clinicians to support patients taper and stop long-term opioids. However, it is not known how patients who have been taking these medicines for months or years feel about reducing them. Using quantitative and qualitative data, this study describes the psychological complexity of these patients and examines their hopes and fears before opioid reduction.

Methods

Sixty patients attending the opioid clinic completed psychological and pain questionnaires, providing quantitative data, just before they commenced opioid tapering. They scored the severity of opioid side effects and completed a free text framework to express their beliefs about stopping or continuing opioids. A phenomenological approach was used to identify common qualitative themes.

Results

Most patients were taking opioid doses above the UK recommended maximum dose and reported severe pain with high pain interference. Over 80% of patients described significant depression and 60% significant anxiety. Negative themes around stopping opioids were more common than positive ones, with 63% patients fearing increased pain. A quarter of patients referred to addiction and 16% feared withdrawal. Five patients hoped for a better quality of life; seven feared a worse one. Opioid side effects were common and severe.

Conclusion

Patients with chronic pain taking long-term opioids demonstrate high psychological distress and low self-efficacy. Their concerns around opioid tapering relate to pain, quality of life and withdrawal. Identifying and addressing patients' individual concerns should increase the likelihood of successful opioid tapering.

Chronic Opioid Therapy: A Scoping Literature Review on Evolving Clinical and Scientific Definitions

The management of chronic noncancer pain (CNCP) with chronic opioid therapy (COT) is controversial. There is a lack of consensus on how COT is defined resulting in unclear clinical guidance. This scoping review identifies and evaluates evolving COT definitions throughout the published clinical and scientific literature. Databases searched included PubMed, Embase, and Web of Science. A total of 227 studies were identified from 8,866 studies published between January 2000 and July 2019. COT definitions were classified by pain population of application and specific dosage/duration definition parameters, with results reported according to PRISMA-ScR. Approximately half of studies defined COT as "days' supply duration >90 days" and 9.3% defined as ">120 days' supply," with other days' supply cut-off points (>30, >60, or >70) each appearing in <5% of total studies. COT was defined by number of prescriptions in 63 studies, with 16.3% and 11.0% using number of initiations or refills, respectively. Few studies explicitly distinguished acute treatment and COT. Episode duration/dosage criteria was used in 90 studies, with 7.5% by Morphine Milligram Equivalents + days' supply and 32.2% by other "episode" combination definitions. COT definitions were applied in musculoskeletal CNCP (60.8%) most often, and typically in adults aged 18 to 64 (69.6%). The usage of ">90 days' supply" COT definitions increased from 3.2 publications/year before 2016 to 20.7 publications/year after 2016. An increasing proportion of studies define COT as ">90 days' supply." The most recent literature trends toward shorter duration criteria, suggesting that contemporary COT definitions are increasingly conservative. PERSPECTIVE: This study summarized the most common, current definition criteria for chronic opioid therapy (COT) and recommends adoption of consistent definition criteria to be utilized in practice and research. The most recent literature trends toward shorter duration criteria overall, suggesting that COT definition criteria are increasingly stringent.