Systematic Review and Meta‐Analysis on Neuropsychological Effects of Long‐Term Use of Opioids in Patients With Chronic Noncancer Pain

Fentanyl Overdose Causes Prolonged Cardiopulmonary Dysregulation in Male SKH1 Mice

Fentanyl overdose is a survivable condition that commonly resolves without chronic overt changes in phenotype. While the acute physiological effects of fentanyl overdose, such as opioid-induced respiratory depression (OIRD) and Wooden Chest Syndrome, represent immediate risks of lethality, little is known about longer-term systemic or organ-level impacts for survivors. In this study, we investigated the effects of a single, bolus fentanyl overdose on components of the cardiopulmonary system up to one week post. SKH1 mice were administered subcutaneous fentanyl at the highest non-lethal dose (62 mg/kg), LD10 (110 mg/kg), or LD50 (135 mg/kg), before euthanasia at 40 min, 6 h, 24 h, or 7 d post-exposure. The cerebral cortex, heart, lungs, and plasma were assayed using an immune monitoring 48-plex panel. The results showed significantly dysregulated cytokine, chemokine, and growth factor concentrations compared to time-matched controls, principally in hearts, then lungs and plasma to a lesser extent, for the length of the study, with the cortex largely unaffected. Major significant analytes contributing to variance included eotaxin-1, IL-33, and betacellulin, which were generally downregulated across time. The results of this study suggest that cardiopulmonary toxicity may persist from a single fentanyl overdose and have wide implications for the endurance of the expanding population of survivors.

Chronic Non-cancer Pain and Associated Risks of Incident Mild Cognitive Impairment and Alzheimer's Disease and Related Dementias in Middle-Aged and Older Adults

The goal of this study is to investigate the association between chronic non-cancer pain (CNCP) and mild cognitive impairment (MCI)/Alzheimer's disease and related dementias (ADRDs) development among adults aged ≥50 using administrative claims data from a national commercial health insurance company during 2007-2017. To reduce selection bias, propensity-score matching was applied to select comparable CNCP and non-CNCP patients. Time-dependent Cox proportional-hazards regressions were conducted to estimate the hazard ratios (HRs) of incident MCI/ADRDs. Of 170,900 patients with/without CNCP, 0.61% developed MCI and 2.33% had been diagnosed with ADRDs during the follow-up period. Controlling for potential confounders, CNCP patients had a 123% increase in MCI risk (HR = 2.23; 95% CI = 1.92-2.58) and a 44% increase in ADRDs risk (HR = 1.44; 95% CI = 1.34-1.54) relative to non-CNCP patients. CNCP is a risk factor for MCI/ADRDs. Promoting awareness and improving early CNCP diagnosis in middle-aged and older adults should be incorporated into cognitive impairment and dementia prevention.

Problems with opioids beyond misuse

The U.S. is grappling with an opioid epidemic, with millions of adults on long-term opioid therapy (LTOT). Although patients often report pain relief and improved daily function with opioids, research shows no significant differences in short-term outcomes between opioid and non-opioid users, as well as no long-term opioid benefits. This scoping review aims to identify lesser-known side effects of long-term opioid use and increase awareness of them, allowing healthcare providers and patients to better assess the risks and benefits of opioid use. Our data search from PubMed and Google Scholar used keywords related to opioids, chronic pain, hypogonadism, endocrinopathies, cancer progression, cardiovascular events, renovascular events, sleep disturbances, mood disorders and others, narrowing down to English-language full articles published from January 2018 to April 2023. This review emphasizes the probable serious adverse consequences of long-term opioid use on various body systems in patients with chronic pain. Given the lack of long-term benefits and significant adverse effects, our review underscores the critical need for healthcare providers to include these risks in discussions with patients when considering the long-term use of opioid therapy.

Neuropathic Pain in Aged People: An Unresolved Issue Open to Novel Drug Approaches, Focusing on Painful Diabetic Neuropathy

A majority of older patients suffer from neuropathic pain (NP) that significantly alters their daily activities and imposes a significant burden on health care. Multiple comorbidities and the risk of polypharmacy in the elderly make it challenging to determine the appropriate drug, dosage, and maintenance of therapy. Age-dependent processes play a contributing role in neuropathy given that diabetic neuropathy (DN) is the most common form of neuropathy. This narrative review is mainly focused on the drug treatment approach for neuropathy-associated pain in aged people including both drugs and dietary supplements, considering the latter as add-on mechanism-based treatments to increase the effectiveness of usual treatments by implementing their activity or activating other analgesic pathways. On one hand, the limited clinical studies assessing the effectiveness and the adverse effects of existing pain management options in this age segment of the population (> 65), on the other hand, the expanding global demographics of the elderly contribute to building up an unresolved pain management problem that needs the attention of healthcare providers, researchers, and health authorities as well as the expansion of the current therapeutic options.

New Psychoactive Substances: Major Groups, Laboratory Testing Challenges, Public Health Concerns, and Community-Based Solutions

Across communities worldwide, various new psychoactive substances (NPSs) continue to emerge, which worsens the challenges to global mental health, drug rules, and public health risks, as well as combats their usage. Specifically, the vast number of NPSs that are currently available, coupled with the rate at which new ones emerge worldwide, increasingly challenges both forensic and clinical testing strategies. The well-established NPS detection techniques include immunoassays, colorimetric tests, mass spectrometric techniques, chromatographic techniques, and hyphenated types. Nonetheless, mitigating drug abuse and NPS usage is achievable through extensive community-based initiatives, with increased focus on harm reduction. Clinically validated and reliable testing of NPS from human samples, along with community-driven solution, such as harm reduction, will be of great importance, especially in combating their prevalence and the use of other illicit synthetic substances. There is a need for continued literature synthesis to reiterate the importance of NPS, given the continuous emergence of illicit substances in the recent years. All these are discussed in this overview, as we performed another look into NPS, from differentiating the major groups and identifying with laboratory testing challenges to community-based initiatives.

Incident Functional Limitations Among Community-Dwelling Adults Using Opioids: A Retrospective Cohort Study Using a Propensity Analysis with the Health and Retirement Study

BACKGROUND

Opioid analgesics are commonly used to manage pain; however, it is unclear how they affect patient function. This study examines the association between opioid analgesics and incident limitations in activities of daily living (ADL), instrumental activities of daily living (IADL), and cognitive functioning among community-dwelling older adults.

METHODS

Data included 10,003 participants of the 2016 and 2018 waves of the Health and Retirement Study, which sampled US adults aged 51-98 years. The primary exposure was self-reported opioid pain medication use in 2016. Outcomes included incident limitations in ADL, IADL, and cognitive functioning in 2018. Statistical methods adjusted for confounding using multivariable logistic regressions, inverse probability of treatment weighting, and propensity scores.

RESULTS

Opioid use (adjusted odds ratio [aOR]: 1.34, 95% confidence interval [CI] 1.07-1.68) was associated with a statistically significant higher odds of incident ADL limitation in multivariable regression and in propensity score adjustment (aOR: 1.41, 95% CI 1.13-1.76). The association between opioid use and ADL and IADL limitations was modified by age. Adults aged < 65 years had a higher odds of incident ADL (aOR: 1.83, 95% CI 1.38-2.42) and IADL (aOR: 1.42, 95% CI 1.06-1.90) limitations compared with those aged ≥ 65 years.

CONCLUSIONS

Community-dwelling adults using opioid analgesics to manage pain may be at risk for incident ADL limitations. Middle-aged adults, compared with those older than 65 years of age, experienced the greatest odds for incident ADL and IADL limitations following opioid use. According to sensitivity analyses, our findings were robust to unmeasured confounding.

Comparison of the Impacts of Under-Treated Pain and Opioid Pain Medication on Cognitive Impairment

Purpose: To guide clinicians in balancing the risks and benefits of opioids when treating pain, we conducted two systematic reviews: 1) the impact of pain on cognitive function, and 2) the impact of opioids on cognitive function.

Methods: Part one addressed the impact of pain on cognitive impairment; Part two considered the impact of opioids on cognitive impairment. PubMed was used to search for eligible articles. For part one, 1786 articles were identified, of which 23 met our eligibility criteria. For part two, among 584 articles, 18 were found eligible.

Results: For part one, 16 studies concluded that patients with chronic pain showed impaired cognitive function; six studies found that chronic pain does not worsen cognitive function; one study concluded that the impact of pain on cognitive function differs based on the underlying cognitive status. For part two, 15 studies found that using opioids to control pain did not cause significant cognitive impairment, while three studies concluded the opposite. Studies evaluating older subjects did not observe different results from those in the whole population for both reviews.

Conclusion: The published literature indicates that moderate to severe pain can impair cognitive function, and that careful use of opioid analgesics in such subjects does not necessarily worsen cognition. Although our results are insufficient to support clear guidance due to heterogeneity of cohorts and outcomes, this study may assist primary care providers by rendering explicitly the factors to be considered by providers caring for this population with pain when opioids are considered.

When Less Is More: Investigating Factors Influencing the Distraction Effect of Virtual Reality From Pain

Virtual reality (VR) is a powerful method of redirecting attention away from pain. Yet, little is known about which factors modulate the size of this distraction effect. The aim of this study was to investigate the role of cognitive load and inter-individual differences in the cognitive and affective domain on heat pain thresholds during a VR game. Ninety healthy participants (mean age ± SD: 23.46 ± 3.28; 50% identified as male and 50% as female) played a low and high load version of a VR game while heat pain thresholds and heart rate were recorded. The effects of cognitive load were assessed by computing the difference in pain thresholds between the high and low load condition for each participant. In addition, we computed the difference in heart rate variability (HRV) measures between both conditions to explore whether these would be correlated with the difference in heat pain thresholds. Prior to the VR session, participants completed questionnaires about their emotional distress, pain-related cognitions, and different executive functioning tasks. Contrary to our expectations, not all participants benefitted from a higher load in terms of distraction from pain. Logistic regression analysis revealed that participants who reported more emotional distress were more likely to exhibit higher pain thresholds in the low relative to the high load condition. Accordingly, these participants tended to show marginally higher HRV in the low compared to the high load condition. Our study demonstrates that the potential benefits of an increased cognitive load in VR on pain sensitivity depends on individual differences in affective state.

Beneficial Effects of Opioid Rotation to Buprenorphine/Naloxone on Opioid Misuse, Craving, Mental Health, and Pain Control in Chronic Non-Cancer Pain Patients with Opioid Use Disorder

Patients with chronic non-cancer pain (CNCP) often use opioids for long periods of time. This may lead to opioid use disorder (OUD) and psychiatric symptoms: mainly depression and anxiety. The current study investigated the effect of buprenorphine/naloxone (BuNa) rotation on opioid misuse, craving, psychiatric symptoms and pain in patients with CNCP and OUD. Forty-three participants with CNCP and OUD were converted from a full mu-receptor agonist opioid (mean morphine equivalent dose: 328.3 mg) to BuNa, in an inpatient setting. Opioid misuse, craving, co-occurring psychiatric symptoms, and pain perception were determined at baseline and after a two-month follow-up, using the following self-report questionnaires: Current Opioid Misuse Measurement (COMM), Visual Analog Scale (VAS-craving and VAS-pain) and Depression, Anxiety and Stress Scale (DASS), respectively. VAS-craving and VAS-pain were also determined immediately after conversion. A total of 37 participants completed the protocol. The mean COMM decreased from 17.1 to 6.7 (F = 36.5; p < 0.000), the mean VAS-craving decreased from 39.3 to 5.3 (−86.6%; F = 26.5, p < 0.000), the mean DASS decreased from 12.1 to 6.6 (F = 56.3, p < 0.000), and the mean VAS-pain decreased from 51.3 to 37.2 (−27.4%, F = 3.3; p = 0.043). Rotation to BuNa in patients with CNCP and OUD was accompanied by reductions in (i) opioid misuse, (ii) opioid craving, (iii) the severity of co-occurring psychiatric symptoms, and (iv) self-reported pain. BuNa as opioid agonist treatment may therefore be a beneficial strategy in CNCP patients with OUD. The limited sample size and the observational nature of this study underline the need for the replication of the current findings in large-scale, controlled studies.

European clinical practice recommendations on opioids for chronic noncancer pain - Part 2: Special situations

BACKGROUND

Opioid use for chronic non-cancer pain (CNCP) is under debate. In the absence of pan-European guidance on this issue, a position paper was commissioned by the European Pain Federation (EFIC).

METHODS

The clinical practice recommendations were developed by eight scientific societies and one patient self-help organization under the coordination of EFIC. A systematic literature search in MEDLINE (up until January 2020) was performed. Two categories of guidance are given: Evidence-based recommendations (supported by evidence from systematic reviews of randomized controlled trials or of observational studies) and Good Clinical Practice (GCP) statements (supported either by indirect evidence or by case-series, case-control studies and clinical experience). The GRADE system was applied to move from evidence to recommendations. The recommendations and GCP statements were developed by a multiprofessional task force (including nursing, service users, physicians, physiotherapy and psychology) and formal multistep procedures to reach a set of consensus recommendations. The clinical practice recommendations were reviewed by five external reviewers from North America and Europe and were also posted for public comment.

RESULTS

The European Clinical Practice Recommendations give guidance for combination with other medications, the management of frequent (e.g. nausea, constipation) and rare (e.g. hyperalgesia) side effects, for special clinical populations (e.g. children and adolescents, pregnancy) and for special situations (e.g. liver cirrhosis).

CONCLUSION

If a trial with opioids for chronic noncancer pain is conducted, detailed knowledge and experience are needed to adapt the opioid treatment to a special patient group and/or clinical situation and to manage side effects effectively.

SIGNIFICANCE

If a trial with opioids for chronic noncancer pain is conducted, detailed knowledge and experience are needed to adapt the opioid treatment to a special patient group and/or clinical situation and to manage side effects effectively. A collaboration of medical specialties and of all health care professionals is needed for some special populations and clinical situations.

The effects of substance use and physical activity on cognition: The impact of incongruent health behaviors

BACKGROUND

Cognitive functioning refers to storage and manipulation of information and includes executive functioning (EF) and attention (ATT). While physical activity (PA) improves cognitive functioning, decrements are associated with frequent substance use. This study examined PA on cognitive functioning within the context of past-year substance use.

METHODS

Using NESARC-III data (N = 36,309), cross-sectional analysis examined interactions between self-reported past-year PA and substance use in relation to cognitive functioning.

RESULTS

As hypothesized, light-to-moderate, vigorous, and total PA conditional main effects were positively associated with both facets of cognition, while frequent substance use conditional main effects were negatively associated with ATT and EF. The positive association between PA and cognition was diminished by substance use. Frequent binge drinking, marijuana, cocaine, and opioid use weakened the impact of light-to-moderate PA on EF, and only frequent cocaine use lessened the relationship between vigorous PA on EF. When PA intensities were combined, frequent binge drinking and cocaine use weakened the PA and EF association. Infrequent stimulant use reduced the association between all levels of PA and ATT, while infrequent marijuana use unexpectedly enhanced the relation between vigorous PA and ATT.

CONCLUSIONS

Overall, PA enhanced two facets of cognitive functioning across six substances. However, these benefits are reduced in the context of frequency of substance use. The positive association between light-to-moderate PA and EF appears to be more sensitive in the context of frequent substance use than vigorous PA. Implications for public health messaging and PA as cognitive remediation treatment for substance use disorders are discussed.

Detoxification of Neuromodulation Eligible Patients by a Standardized Protocol: A Retrospective Pilot Study

OBJECTIVES

Patients eligible for spinal cord stimulation (SCS) generally experience excruciating pain, requiring more opioid consumption, which is usually an indication for SCS implantation. After final implantation, SCS has the ability to stabilize or decrease opioid usage in half of the patients. In this study, opioids were actively eliminated prior to implantation of any neuromodulation device with a standardized detoxification protocol. This pilot study aims to explore the feasibility, effectiveness, and safety of this opioid detoxification protocol prior to neuromodulation techniques.

MATERIALS AND METHODS

In this retrospective pilot study, 70 patients who were taking opioids and who were eligible for neuromodulation techniques, underwent the detoxification program. A combined in- and out-patient clinic protocol was applied, whereby clonidine was the main component of both parts of the program. A multidisciplinary team with pain physicians and psychologists was responsible for performing this detoxification program. Safety and feasibility were systematically recorded during the hospitalization.

RESULTS

No serious safety issues were reported. At the start of the program, patients reported a mild sedative effect of clonidine. Additionally, most patients presented mild symptoms of opioid withdrawal, which were partially countered by the sedative effect of clonidine. Both patients and the medical staff found this protocol feasible in clinical practice. Concerning the effectiveness, a statistically significant decrease in median morphine milligram equivalents (MMEs) was found with a MME of 175 (Q1-Q3: 118.1-240) at baseline and at the last available follow-up visit the MME was 0 (Q1-Q3: 0-16.88).

CONCLUSIONS

This standardized detoxification program has proven its effectiveness, safety, and feasibility in this single-center experience pilot study in patients eligible for neuromodulation techniques.

Prolonged Withdrawal From Escalated Oxycodone Is Associated With Increased Expression of Glutamate Receptors in the Rat Hippocampus

People suffering from opioid use disorder (OUD) exhibit cognitive dysfunctions. Here, we investigated potential changes in the expression of glutamate receptors in rat hippocampi at 2 h and 31 days after the last session of oxycodone self-administration (SA). RNA extracted from the hippocampus was used in quantitative polymerase chain reaction analyses. Rats, given long-access (9 h per day) to oxycodone (LgA), took significantly more drug than rats exposed to short-access (3 h per day) (ShA). In addition, LgA rats could be further divided into higher oxycodone taking (LgA-H) or lower oxycodone taking (LgA-L) groups, based on a cut-off of 50 infusions per day. LgA rats, but not ShA, rats exhibited incubation of oxycodone craving. In addition, LgA rats showed increased mRNA expression of GluA1-3 and GluN2a-c subunits as well as Grm3, Grm5, Grm6, and Grm8 subtypes of glutamate receptors after 31 days but not after 2 h of stopping the SA experiment. Changes in GluA1-3, Grm6, and Grm8 mRNA levels also correlated with increased lever pressing (incubation) after long periods of withdrawal from oxycodone. More studies are needed to elucidate the molecular mechanisms involved in altering the expression of these receptors during withdrawal from oxycodone and/or incubation of drug seeking.

Cognitive Function During Opioid Tapering in Patients with Chronic Pain: A Prospective Cohort Study

Purpose

Evidence for efficacy and safety lacks for long-term opioid therapy in patients with chronic non-cancer pain and adverse effects, including affection of cognitive function and quality of life, is of concern. We aimed to investigate cognitive function and health-related quality of life in patients with chronic non-cancer pain during opioid reduction.

Patients and Methods

At two multidisciplinary pain centers, all patients with planned opioid reduction were screened for eligibility. Cognitive function was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and Trail Making Test A and B. Health-related quality of life was assessed using Short Form-36 (SF36) and Hospital Anxiety and Depression Scale (HADS).

Results

We included 51 participants and 40 participants attended follow-up of median 254 (IQR 106–357) days. Baseline RBANS score was 82 (IQR 65–93) with reference population norm value of 100 (SD±15). Daily opioid consumption was reduced from median 80 (IQR 45–161) oral morphine milligram equivalents to 19 (IQR 0–60) mg. RBANS score estimate increased by 6.2 (95% CI 3.1–9.3, p=0.0004) points after tapering. No differences were observed for Trail Making Test times, HADS or SF36 scores.

Conclusion

Generally, cognitive function showed minor improvement after opioid tapering with stationary health-related quality of life, depression and anxiety scores. The clinical significance is unclear, as no minimal clinically important difference in RBANS score is available.

Mechanisms for Reducing Neuropathic Pain

Injury typically results in the development of neuropathic pain, but the pain normally decreases and disappears in paralleled with wound healing. The pain results from cells resident at, and recruited to, the injury site releasing pro-inflammatory cytokines and other mediators leading to the development of pro-inflammatory environment and causing nociceptive neurons to develop chronic ectopic electrical activity, which underlies neuropathic pain. The pain decreases as some of the cells that induce pro-inflammation, changing their phenotype leading to the blocking the release of pro-inflammatory mediators while releasing anti-inflammatory mediators, and blocking nociceptive neuron chronic spontaneous electrical activity. Often, despite apparent wound healing, the neuropathic pain becomes chronic. This raises the question of how chronic pain can be eliminated. While many of the cells and mediators contributing to the development and maintenance of neuropathic pain are known, a better understanding is required of how the injury site environment can be controlled to permanently eliminate the pro-inflammatory environment and silence the chronically electrically active nociceptive neurons. This paper examines how methods that can promote the transition of the pro-inflammatory injury site to an anti-inflammatory state, by changing the composition of local cell types, modifying the activity of pro- and anti-inflammatory receptors, inducing the release of anti-inflammatory mediators, and silencing the chronically electrically active nociceptive neurons. It also examines the hypothesis that factors released from platelet-rich plasma applied to chronic pain sites can permanently eliminate chronic inflammation and its associated chronic pain.

Tramadol prescribed use in general and chronic noncancer pain: a nationwide register-based cohort study of all patients above 16 years

Background and aims

In the Western world, it has become clear that we are facing a crisis of overuse, abuse and improperly prescribed use of opioids. As part of the ongoing discussion on opioid use, the use and prescription of tramadol have been addressed in recent years. A significant portion of this discussion should adequately address the risk factors for the use of weak opioid products such as tramadol. The risk factors which characterise the long-term tramadol use are still incompletely understood. Thus, we aimed to describe the characteristics of Danish patients using tramadol in more detail, under different scenarios and determinants of subsequent usage patterns.

Methods

We conducted a nationwide cohort study to identify individuals purchasing tramadol from 01/01/2004 to 31/12/2015 who are age 16 +  years old by using data from The Danish National Databases; these databases consist of unique information for all citizens in Denmark. Logistic regression analyses were used to assess the potential risk factors for repeated tramadol use.

Results

The final cancer-free cohort consisted of N = 941,839 tramadol users: 54.4% women, with a mean age of 53.2 years. The number of chronic noncancer pain (CNCP) was 430,641 individuals, and 56% of the total third who repeated the use of tramadol with two +  purchased prescriptions were CNCP patients. The increased risk of repeated use for CNCP was, among others, associated with: male sex (HR 1.21), age 69–110 (HR 1.72), back/spine pain men (HR 1.47), women (HR 1.46), spondylopathies (HR 1.24), male osteoporosis (HR 1.22), multimorbid ulcer/skin (HR 1.28), region of municipality Northern Jutland (HR 1.74), Central Jutland (HR 1.75), number of co-medication 4–9 (HR 1.33), dementia (HR 1.27). Factors associated with decreased risk: co-medication ischemic heart disease (HR 0.85), diagnosis headache (HR 0.70), household income highest tertile (HR 0.81), unknown (HR 0.70), single women (HR 0.96).

Conclusions

This study proved a widespread prescribed use of tramadol in Denmark, and, as know from the literature, weak opioid use may lead to long-term use of high potent opioids, this usage is inappropriate, in general, but especially for the treatment of CNCP.

Implications

When striving to reduce the overuse of opioids, focus on the extensive use of tramadol may be essential. The current study indicates an excessive and not appropriately prescribed use of tramadol among Danish CNCP patients. In addition to being inappropriate, such use may also have an impact on the growing problem of an illicit Internet market for this drug. Thus, the situation must be taken seriously. The current study confirms the recent clinical guideline and the National Recommendations in Denmark, which emphasises the risks of problematic use of tramadol. The research may also be relevant in other comparable countries. Caution must especially be taken with CNCP patients with comorbidities like diabetes, lung disease, dementia, and osteoporosis.