A comprehensive literature review of chronic pain and memory

Memory deficits in chronic low back pain patients: A scoping review

BACKGROUND

Chronic pain often results in cognitive dysfunction, with memory complaints being the most prevalent cognitive deficits. Our aim was to review the existing literature on memory deficits in the most prevalent chronic pain condition, Chronic Low Back Pain (CLBP).

METHOD

We conducted a scoping review from inception to April 2023, employing a narrow literature research without study design restrictions. We searched on five databases: MEDLINE, Cochrane Library, CINAHL, Scopus and Web of Science. We included studies that compared memory performances between Chronic Low Back Pain patients and healthy controls.

RESULTS

22,368 results were retrieved, and 15,589 were screened. 9 cross-sectional studies met our inclusion criteria. These studies had differences in definitions and measurements of memory functions. CLBP groups showed lower performances in memory tests.

CONCLUSION

This scoping review provides an overview of the literature on memory deficits in CLBP patients. We found discrepancies in definitions and measurements of memory functions, as well as a lack of quantitative data due to limited studies. In each study, CLBP patients exhibited lower performance in memory tests compared to healthy population. It would be interesting to gather more data and to standardize definitions and measurements.

High-impact chronic pain and cognitive decline among Mexicans aged 60 and older from 2012 to 2018

Pain is associated with cognitive decline, but prior research has not considered differences between high- and low-impact chronic pain or low-and middle-income countries, such as Mexico. Our objective was to evaluate the association between high-impact chronic pain and cognitive decline among older adults in Mexico. We used data from the 2012-2018 Mexican Health and Aging Study (MHAS), a nationally representative study of older Mexican adults (60+). Pain, measured at each wave, was categorized as high-impact chronic pain (pain that limits daily activities), low-impact chronic pain (pain that did not limit daily activities), and no chronic pain. Cognition was measured at each wave using the MHAS cognitive battery, and scores were standardized for global cognitive performance, memory, and non-memory domains. We used linear mixed models with inverse probability weights to evaluate the association between pain and cognition over time. At baseline (n=9056), 19.3% of participants reported high-impact pain and 20.1% reported low-impact chronic pain. Participants with high-impact pain had lower baseline global cognition [β: -0.024, 95% confidence interval (CI): -0.045, -0.004] and memory scores (β: -0.042, 95% CI: -0.074, -0.010) compared to those with no chronic pain. Change in cognition over time did not differ by pain, except for the memory domain, where those with high-impact pain experienced slower decline compared to those with no chronic pain. Low-impact chronic pain was not associated with any cognitive outcome. Better pain treatment may result in benefits in cognitive performance for those with pain. PERSPECTIVE: We found that high-impact chronic pain was associated with worse cognition at baseline, but not with cognitive decline. Memory domains were particularly affected by high-impact chronic pain. Early pain treatment and management may provide cognitive benefits for those living with pain.

Turkish adaptation, validity and reliability study of the cognitive behavior questionnaire in non-specific chronic low back pain:: CBQNSCLBP Turkish Version Validity and Reliability

BackgroundChronic low back pain (CLBP) is a complex condition with significant physical, psychological, and social impacts. The Cognitive Behavior Questionnaire for Nonspecific Chronic Low Back Pain (CBQ-NSCLBP) was developed to assess cognitive-behavioral factors.ObjectiveThe aim of this study was to translate the CBQ-NSCLBP into Turkish (CBQ-NSCLBP-Tr), evaluate its psychometric properties, and also to assess the clinicometric properties of the instrument, including its validity, reliability, and effectiveness in assessing cognitive-behavioral factors in Turkish-speaking individuals with chronic low back pain.MethodsA total of 120 participants with CLBP aged 18-65 years were recruited. Construct validity was evaluated by correlating CBQ-NSCLBP-Tr scores with established measures, including the Oswestry Disability Index(ODI), Fear Avoidance Beliefs Questionnaire(FABQ), Tampa Kinesiophobia Scale(TKS), Back Pain Attitudes Questionnaire(Back-PAQ), Beck Anxiety Inventory(BAI), and Beck Depression Inventory(BDI). Test-retest reliability was assessed using the intraclass correlation coefficient(ICC), and internal consistency was determined using Cronbach's alpha.ResultsThe CBQ-NSCLBP-Tr demonstrated excellent reliability (ICC = 0.89) and strong internal consistency significant correlations with established measures, such as the Oswestry Disability Index (ODI, r = 0.44) and Fear Avoidance Beliefs Questionnaire (FABQ, r = 0.48). According to these results, the CBQ-NSCLBP-Tr is a reliable instrument for evaluating cognitive-behavioral variables affecting chronic low back pain in Turkish-speaking individuals.ConclusionsThe CBQ-NSCLBP-Tr is a reliable and valid instrument for assessing cognitive-behavioral factors in Turkish-speaking CLBP populations. It captures critical psychological dimensions influencing pain perception and disability, complementing existing measures.

Chronic illness adjustment scale (CIAS): Development and validation

ObjectivesThe objectives of this study were to (i) develop a self-report instrument to measure adjustment to chronic illness, (ii) evaluate its core structure and (iii) study various psychometric properties in the development of this instrument.MethodThe entire process of developing and validating the instrument is conducted in different phases: item writing and content validation; exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) to extract dimensions of the instrument; reliability and validity testing. A total of 1095 participants were included in the study. The EFA was run using IBM SPSS 23 and CFA was done by AMOS 21.ResultsThe Cronbach alpha of the chronic illness adjustment scale was found to be .70. The instrument correlates positively with illness perception and well-being which supports the notion that the chronic illness adjustment scale has satisfactory convergent validity.DiscussionThe multifaceted nature of the chronic illness adjustment scale can serve as a global indicator of adjustment to chronic illness, allowing various interventions to flow toward the healthcare arena.

Orofacial pain models induce impairment in spatial learning and working memory in rodents: A systematic review and meta-analysis

Orofacial pain is one of the most common causes of chronic pain leading to physical and cognitive disability. Several clinical and pre-clinical studies suggest that chronic pain results in cognitive impairment. However, there is a lack of meta-analyses examining the effects of orofacial pain models on behavioral learning and memory in rodents. Thus, this study aimed to evaluate whether orofacial pain models can impair learning and memory in rodents. The protocol was registered in PROSPERO (CRD42023355502). We used CAMARADES and SYRCLE to estimate the quality and the publication bias by using Egger's and Begg's test. Here, 21 studies were included in this systematic review and meta-analysis. We included 12 studies with trigeminal neuralgia models, 4 with migraine-like pain models, 4 with tooth nociception, and 1 with acute orofacial pain model. Spontaneous nociception and facial mechanical allodynia were observed in orofacial pain models. Regarding spatial learning we detected that latency to find the platform in the Morris water maze (MWM) was increased in orofacial pain models (related to facial mechanical allodynia or spontaneous nociception). Although the mean quality of the articles was high, we identify publication bias in the Begg's test for the time in the quadrant in the MWM. Our findings revealed that spontaneous nociception and facial mechanical allodynia in orofacial pain models contribute to the working memory and spatial learning dysfunction. Therefore, further studies are still needed to evaluate the influence of sex, age, social isolation, and environmental enrichment in orofacial pain-related learning and memory.

Similarities and Differences in Resting-State Brain Activity Changes of Distinct Chronic Pain Types

OBJECTIVES

To explore neural similarities and differences between visceral and somatic pain by comparing spontaneous brain activity in patients with chronic temporomandibular disorder (TMD) and irritable bowel syndrome (IBS).

METHODS

Twenty eight IBS patients, 21 TMD patients, and 28 healthy controls (HC) underwent resting-state fMRI and behavioral assessments. The correlations between fMRI metrics such as the amplitude of low-frequency fluctuations (ALFF), regional homogeneity (ReHo), functional connectivity (FC), and clinical manifestations were further analyzed.

RESULTS

Compared with HC, both patient groups demonstrated increased ALFF in right parahippocampal gyrus (PHG), insula, medial superior frontal gyrus (SFGmed), precentral gyrus (PreCG), and increased ReHo in right SFGmed and left supplementary motor area (SMA). Compared with IBS patients, TMD patients exhibited reduced ALFF in right SFGmed and insula, increased ALFF in right PHG and PreCG, decreased ReHo in right SFGmed and left lingual gyrus, and increased ReHo in left SMA. Both patient groups exhibited enhanced right PHG-related FC in left precuneus and right cingulate gyrus, and right insula-related FC in left superior temporal gyrus and right paracentral lobule. Specifically, IBS patients showed higher FC between right PHG and orbitofrontal cortex than TMD patients, which was negatively correlated with mood and gastrointestinal symptoms. Mediation analysis revealed that pain in TMD and gastrointestinal symptoms in IBS mediated these relationships.

CONCLUSION

Visceral and somatic pain share abnormal activity in multiple brain networks. Abnormalities in affective region present potential neuroimaging markers for pain disorders, with depression in somatic pain linked to pain intensity and in visceral pain to gastrointestinal symptoms.

Pain Neuroscience Education Reduces Pain and Improves Psychological Variables but Does Not Induce Plastic Changes Measured by Brain-Derived Neurotrophic Factor (BDNF): A Randomized Double-Blind Clinical Trial

INTRODUCTION

PNE, focusing on cognitive aspects, aims to change patients' beliefs about pain. However, it is unclear if these cognitive changes are sufficient to influence other components such as neuroplastic changes.

OBJECTIVE

To assess whether 3-h pain neuroscience education (PNE) can induce changes in brain-derived neurotrophic factor (BDNF) levels and pain intensity in chronic pain patients.

METHODS

A double-blind randomized clinical trial was conducted with 66 participants aged 18-65 years old (50.86 ± 8.61) with chronic primary musculoskeletal pain divided into two groups: an intervention group receiving 3-h PNE lecture and a control group that received an educational booklet. Primary outcomes included plasma BDNF levels and perceived pain intensity (VAS). Secondary outcomes included anxiety (HADS-A), depression (HADS-D), catastrophizing (PCS), kinesiophobia (TSK), stress (PSS), and knowledge about pain. Measurements were taken in both groups before and after a three-hour intervention. Data were analyzed using paired t-tests and Cohen's d for effect sizes.

RESULTS

The results showed no significant changes in BDNF levels for the PNE lecture group (p = 0.708) or the educational booklet group (p = 0.298). Both groups showed significant reductions in pain intensity (PNE: p < 0.001, d = 0.70; booklet: p = 0.036, d = 0.39). Secondary variables, such as knowledge (PNE: p < 0.001, d = -0.972; booklet: p < 0.001, d = -0.975) and anxiety (PNE: p < 0.001, d = 0.70; booklet: p = 0.035, d = 0.39), also showed significant improvements.

CONCLUSIONS

PNE did not significantly change BDNF levels but effectively improved pain intensity, pain-related knowledge, and other clinical variables. These findings suggest that while PNE has cognitive benefits, it may not be sufficient to induce immediate neurobiological changes. Further research is needed to explore long-term effects and incorporate additional therapeutic domains.

Knowledge mapping and emerging trends in cognitive impairment associated with chronic pain: A 2000-2024 bibliometric study

Chronic pain is commonly recognized as a distressing symptom or a standalone disease, with over half of those affected experiencing cognitive impairment, which significantly impacts their quality of life. Despite a recent surge in literature on cognitive impairment associated with chronic pain, a comprehensive bibliometric analysis in this field has yet to be conducted. In this study, we performed a bibliometric analysis on this topic. We retrieved English-language publications on chronic pain and cognitive impairment from 2000 to 2024 using the Web of Science Core Collection database. These publications were visually analyzed using tools such as VOSviewer, CiteSpace, and the R package "bibliometrix." We identified 1656 publications from 72 countries/regions across 722 journals on the topic of chronic pain and cognitive impairment. Publication numbers showed a steady increase, peaking in 2022. The United States led in contributions, with Harvard Medical School emerging as the most prominent institution involved. The journal Pain was the most prolific and frequently co-cited in this area. Among the authors, Stefan Duschek was the most productive, while Frederick Wolfe was the most frequently co-cited. Key research areas include investigating the bidirectional long-term effects between chronic pain and cognitive impairment and exploring the mechanisms underlying cognitive changes associated with chronic pain. In conclusion, this study highlights a global surge in research on cognitive impairment related to chronic pain. Emerging hotspots and future research trends point towards brain imaging mechanisms and neuronal circuit-mediated processes.

Postoperative pain and neurocognitive outcomes after noncardiac surgery: a systematic review and dose-response meta-analysis

BACKGROUND

Postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) are common after noncardiac surgery. Postsurgical pain is frequent and can persist as chronic postsurgical pain (CPSP). The association between postsurgical pain and POD or POCD is biologically plausible. We conducted this systematic review to evaluate the association between acute postsurgical pain or CPSP and POD or POCD in adults undergoing noncardiac surgery.

METHODS

We followed Preferred Reporting Items for Systematic Review and Meta-Analyses. We searched MEDLINE, EMBASE, Cochrane, CINAHL and PSYCHINFO up to May 2023. We included cohort, case-control, and cross-sectional studies of any language. Pairs of reviewers independently screened studies, extracted data and assessed the risk of bias using the CLARITY tool and the Joanna Briggs Institute checklist. We assessed the certainty of evidence using the Grading of Recommendations Assessment, Development, and Evaluation approach. Where possible, we conducted random-effects meta-analyses to summarise our findings.

RESULTS

We analysed 30 studies (>9000 participants) that assessed the association between acute postoperative pain and POD/POCD. Dose-response meta-analyses found that postoperative pain intensity was associated with occurrence of POD (adjusted relative risk [aRR]/unit of pain intensity: 1.26; 95% confidence interval [CI]: 1.17-1.35; low certainty of evidence) and risk of developing POD (aRR/unit of pain intensity: 1.18; 95% CI: 1.08-1.30; low certainty of evidence). There was very low certainty of evidence regarding the association between postoperative pain and POCD. No studies assessed the association between CPSP and POCD. Residual confounding and substantial methodological variability between studies prevented pooling data from many of the included studies and lowered certainty of evidence.

CONCLUSIONS

Dose-response meta-analyses found that postoperative pain intensity was associated with occurrence of and risk of developing POD.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO-CRD42021192105.

Association Between Physical Activity and Sleep Health Among Community-Dwelling Adults Aged ≥50 in Ghana: The Mediating Role of Psychosomatic Factors

OBJECTIVES

Data on the direct and indirect associations between physical activity (PA) and sleep quality in old age via psychosomatic mechanisms (e.g. mobility, pain, loneliness, depression, and anxiety) remain scarce in low- and middle-income countries (LMICs). We explored the association of PA with poor sleep quality (PSQ) among individuals aged ≥ 50 in Ghana and explored the potential mediating factors in this association.

METHODS

We analyzed community-based data from the Aging, Health, Psychological Well-being, and Health-seeking Behavior Study. We assessed PA using the International Physical Activity Questionnaire (IPAQ). Two items on nighttime and daytime sleep problems in the last 30 days were used to measure PSQ. Multivariable ordinary least square (OLS) regressions and bootstrapping models were performed to evaluate the associations.

RESULTS

Overall, 1,201 participants (Mage = 66.15 ± 11.58 years; 63.3% female) were included in the analysis. PA was independently associated with decreased PSQ in the overall sample (B = -0.181, 95%I = -0.271 to -0.092) and in women (B = -0.195, 95%I = -0.305 to -0.084). The association was stronger in the ≥ 65 (B = -0.138) than in the 50-64 age group (B = -0.213). Mobility (37.06%), pain (23.66%), loneliness (6.71%), and comorbid anxiety and depression (8.95%) mediated the PA-PSQ association.

CONCLUSIONS

PA was associated with decreased PSQ levels, which was particularly explained by psychosomatic factors.

CLINICAL IMPLICATIONS

Clinicians encourage older adults to engage in regular PA and manage psychosomatic problems may improve their sleep health.

Risk Factors and Diagnostic Model Construction of Chronic Pain with Cognitive Impairment

Background

Cognitive impairment (CI) is frequently observed in patients with chronic pain (CP). CP progression increases the risk of dementia and accelerates Alzheimer's disease pathogenesis. However, risk diagnostic models and biomarkers for CP-related CI remain insufficient. Previous research has highlighted the relationships between several complete blood count parameters for CP or CI-related diseases, such as Alzheimer's disease, while the specific values of complete blood count parameters in CP-related CI patients remain unclear. This study aimed to explore the correlation between complete blood count parameters and CP-related CI to establish a risk diagnostic model for the early detection of CP-related CI.

Methods

This cross-sectional study was conducted at West China Hospital, Sichuan University. The Montreal Cognitive Assessment (MoCA) was used to classify patients into either the CP with CI group or the CP without CI group. Univariate analysis and multivariate logistic regression analysis were used to screen the related factors of CP-related CI for constructing a risk diagnostic model, and the model was evaluated using receiver operating characteristic (ROC) curve analysis.

Results

The study ultimately included 163 eligible patients. Based on analysis, age (OR, 1.037 [95% CI, 1.007-1.070]; P=0.018), duration of pain (OR, 2.546 [95% CI, 1.099-6.129]; P=0.032), VAS score (OR, 1.724 [95% CI, 0.819-3.672]; P=0.153), LMR (OR, 0.091 [95% CI, 0.024-0.275]; P<0.001), absolute neutrophil value (OR, 0.306 [95% CI, 0.115-0.767]; P=0.014), and lymphocyte percentage (OR, 6.551 [95% CI, 2.143-25.039]; P=0.002) were identified as critical factors of CP-related CI. The diagnostic model was evaluated by the ROC curve, demonstrating good diagnostic value with an area under the curve (AUC) of 0.803, a sensitivity of 0.603 and a specificity of 0.871.

Conclusion

The risk diagnostic model developed in this study for CP-related CI has significant value and enables clinicians to customize interventions based on each patient's needs.

Neuropeptide Y and Pain: Insights from Brain Research

Neuropeptide Y (NPY) is a highly conserved neuropeptide with widespread distribution in the central nervous system and diverse physiological functions. While extensively studied for its inhibitory effects on pain at the spinal cord level, its role in pain modulation within the brain remains less clear. This review aims to summarize the complex landscape of supraspinal NPY signaling in pain processing. We discuss the expression and function of NPY receptors in key pain-related brain regions, including the parabrachial nucleus, periaqueductal gray, amygdala, and nucleus accumbens. Additionally, we highlight the potent efficacy of NPY in attenuating pain sensitivity and nociceptive processing throughout the central nervous system. NPY-based therapeutic interventions targeting the central nervous system represent a promising avenue for novel analgesic strategies and pain-associated comorbidities.

Reorganization of lateral habenula neuronal connectivity underlies pain-related impairment in spatial memory encoding

ABSTRACT

Dysfunctional hyperactivity of the lateral habenula nucleus (LHb) has emerged as a critical marker for pain-related mood impairments. Acting as a central hub, the LHb filters and disseminates pertinent information to other brain structures during learning. However, it is not well understood how intra-LHb activity is altered during cognitive demand under neuropathic pain conditions. To address this gap, we implanted an optrode structure to record neuronal activity in adult male CD (rat strain without definition) rats during the execution of a delayed nonmatch-to-sample (DNMS) spatial working memory (WM) task. We selectively modulated intra-LHb network activity by optogenetically inhibiting local LHb CaMKIIα (calcium calmodulin-dependent protein kinase II alpha)-expressing neurons during the delay phase of the DNMS task. Behavioral assessments were conducted using a persistent rodent model of neuropathic pain-spared nerve injury. Our results showed that the induction of neuropathic pain disrupted WM encoding accuracy and intra-LHb functional neuronal connectivity. This disruption was reversed by optogenetic inhibition of LHb CaMKIIα-expressing neurons, which also produced antinociceptive effects. Together, our findings provide insight into how intra-LHb networks reorganize information to support different task contexts, suggesting that the abnormal pain-related intra-LHb dynamic segregation of information may contribute to poor cognitive accuracy in male rodents during pain experiences.

Impact of Experimentally Induced Pain on Logical Reasoning and Underlying Attention-Related Psychophysiological Mechanisms

BACKGROUND

Pain is known to negatively impact attention, but its influence on more complex cognitive abilities, such as logical reasoning, remains inconsistent. This may be due to compensatory mechanisms (e.g., investing additional resources), which might not be detectable at the behavioral level but can be observed through psychophysiological measures. In this study, we investigated whether experimentally induced pain affects logical reasoning and underlying attentional mechanisms, using both behavioral and electroencephalographic (EEG) measures.

METHODS

A total of 98 female participants were divided into a pain-free control group (N = 47) and a pain group (N = 51). Both groups completed the Advanced Progressive Matrices (APM) task, with EEG recordings capturing task-related power (TRP) changes in the upper alpha frequency band (10-12 Hz). We used a mixed design where all participants completed half of the APM task in a pain-free state (control condition); the second half was completed under pain induction by the pain group but not the pain-free group (experimental condition).

RESULTS

Logical reasoning performance, as measured by APM scores and response times, declined during the experimental condition, compared to the control condition for both groups, indicating that the second part of the APM was more difficult than the first part. However, no significant differences were found between the pain and pain-free groups, suggesting that pain did not impair cognitive performance at the behavioral level. In contrast, EEG measures revealed significant differences in upper alpha band power, particularly at fronto-central sites. In the pain group, the decrease in TRP during the experimental condition was significantly smaller compared to both the control condition and the pain-free group.

CONCLUSIONS

Pain did not impair task performance at the behavioral level but reduced attentional resources, as reflected by changes in upper alpha band activity. This underscores the importance of incorporating more sensitive psychophysiological measures alongside behavioral measures to better understand the impact of pain on cognitive processes.

A Systematic Review on the Neuropsychological Assessment of Patients with LBP: The Impact of Chronic Pain on Quality of Life

Background and objective: Low back pain (LBP) is most common pain syndrome in Europe, affecting approximately 50% of European citizens. LBP is a complex condition that negatively affects many aspects of an individual's life such as work productivity, mobility, and mental health. The aim of this study is to assess the impact of pain associated with chronic LBP on patients' quality of life. Methods: Clinical studies reviewed in our search with no time restrictions were identified from PubMed, Web of Science, Scopus, and Cochrane Library databases. Of the initial 1929 studies, only 15 met inclusion criteria. Results: Results of our study indicate that chronic pain has a negative impact on numerous functions and areas in which the individual is involved and that this condition leads to reduced performance. Conclusions: LBP is a debilitating condition for patients, negatively affecting quality of life. Future studies should focus on validating a standardized assessment that examines all aspects affected by LBP through a customized questionnaire.

Effects of immunosuppression after limb fracture in mice on nociceptive, cognitive, and anxiety-related outcomes

Introduction

Chronic pain is a common and problematic consequence of injuries with few proven methods for prevention or treatment. In addition to pain, functional limitations and neuropsychiatric changes such as cognitive impairment and anxiety worsen outcomes.

Objectives

To determine whether inhibiting activation of the adaptive immune response after limb fracture would reduce pain, functional loss, memory changes, and anxiety.

Methods

These experiments used a murine tibial fracture/cast immobilization model that develops these adverse outcomes. Adaptive immunity was blocked using the immunosuppressant FK506 beginning at the time of fracture.

Results

The administration of FK506 reduced mechanical allodynia and hind limb unweighting for weeks after cast removal as well as nonevoked pain measures. Fracture was associated with working memory loss in the Y-maze assay in vehicle- but not FK506-treated mice. Object recognition memory was not improved with FK506 after fracture. Also, vehicle- but not FK506-treated mice developed an anxiety phenotype. Impaired running wheel performance after cast removal over the following 2 weeks was not improved with FK506 administration. In addition, FK506 treatment blocked Immunoglobulin M (IgM) accumulation in the skin of the fractured limbs, and hippocampal enhancement of matrix metalloproteinase-8 expression, a metalloproteinase associated with neuroplastic changes after injuries, was completely blocked.

Conclusion

Taken together, our results show that blocking the adaptive immune response after limb trauma reduces the severity of nociceptive and biological changes. The same treatment may reduce the adverse consequences of anxiety and memory deficits using some measures, but other measures of memory are not affected, and activity is not enhanced.

Rosemary extract activates oligodendrogenesis genes in mouse brain and improves learning and memory ability

Rosemary (Rosmarinus officinalis L.) is a rich source of dietary bioactive compounds such as rosmarinic acid and carnosol with a large repertoire of pharmacological properties, including anti-inflammatory and neuroprotective activities. In the present study, we investigated rosemary as a potential new therapeutic agent for cognitive function and other symptoms of aging. In this present study, we have aimed to investigate the effects of oral administration of rosemary extract (RME) on learning and memory in the context of other biomarkers-related cognitive function and neurotransmitter levels in senescent accelerated prone 8 (SAMP8) mouse, a model of accelerating aging and Alzheimer's disease. The Morris water maze (MWM) test showed improved spatial learning and memory behavior in RME treated SAMP8 mouse. Moreover, RME decreased Aβ42 and inflammatory cytokine levels and increased BDNF, Sirt1, and neurotransmitter levels in SAMP8 mouse. Whole-genome microarray analysis revealed that RME significantly increased gene expression related to oligodendrocyte differentiation, myelination, and ATP production in the hippocampus and decreased gene expression related to stress, neuroinflammation, and apoptosis. Also, in the SAMP8 hippocampus, RME significantly increased Olig1 and Olig2 expression. Altogether, our study is the first to report improvement of spatial learning and memory of RME, modulation of genes important for oligodendrogenesis, and Anti-neuroinflammatory effect by suppressing Aβ42 levels in mouse brain and thus highlights the prospects of RME in the treatment of cognitive dysfunction and aging.

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.

The effects of experimental pain on episodic memory and its top-down modulation: a preregistered pooled analysis

Introduction

Pain can automatically interfere with ongoing cognitive processes such as attention and memory. The extent of pain's negative effects on cognitive functioning seems to depend on a balance between top-down and bottom-up factors.

Objectives

In this large, preregistered, pooled reanalysis of 8 studies, we investigated the robustness of the detrimental effect of acute pain on recognition memory and whether top-down mechanisms such as pain-related expectations or cognitions (pain-related fear, pain catastrophizing) modulate this effect.

Methods

Two hundred forty-seven healthy participants underwent similar experimental paradigms, including a visual categorization task with images randomly paired with (or without) concomitant painful stimulation and a subsequent unannounced recognition task. Recognition memory (ie, d', recollection, and familiarity) and categorization performance (ie, reaction time, accuracy) served as proxies for the effect of pain on cognitive performance.

Results

Acute painful stimulation significantly impaired recognition performance (d', familiarity). However, recognition performance was not significantly modulated by participants' expectations regarding the effect of pain on task performance or pain-related cognitions in this sample of healthy participants.

Conclusion

Our results corroborate the negative effects of pain on (visual) memory encoding reported in previous studies and reports of "memory problems" from patients with chronic pain. To characterize the role of bottom-up and top-down factors for the detrimental effects of pain, large-scale studies with more nuanced study designs are necessary. Future studies in patient cohorts must unravel the interaction of maladaptive pain-related cognitions and the often-reported impaired cognitive performance in chronic pain patients.

Underestimating or Overestimating Improvement in Pain on a Smartphone Pain App: Role of Disability, Negative Affect, and Pain App Engagement

Clinicians often ask people with chronic pain about their perceived benefit from interventions designed to improve their pain. The aim of this study is to identify factors that contribute to underestimating or overestimating perceived changes in daily pain intensity over a month of daily assessments. We examined data from individuals with chronic pain who provided at least 28 daily assessments using a pain app as secondary analyses. Participants provided baseline demographic information and completed questionnaires assessing pain, activity interference, mood, pain disability, and catastrophizing. Using the pain app, they entered daily ratings of pain (0 = none, 10 = worst pain possible) and impressions of perceived day-to-day change (0 = better, 5 = same, and 10 = worse). Two hundred fifty-two (N = 252) subjects with chronic pain met the inclusion criteria of completing at least 28 daily assessments. Those who underestimated their improvement tended to have higher pain intensity at baseline (P < .001), reported greater activity interference and disability (P < .001), and were prone to greater catastrophizing and anxiety and depression (P < .01). People who were more accurate in assessing their improvement engaged less with the app with fewer 2-way messages compared with those who either underestimated or overestimated their improvement and who had more 2-way messaging (P < .05). This longitudinal study suggests that those who report greater levels of catastrophizing and anxiety and depression are more likely to underestimate any improvements in their pain over time but seem to engage more with a pain app. Future research will help in our understanding of what magnitude of perceived change in pain ratings is clinically meaningful. PERSPECTIVE: Those who report greater levels of pain, disability, anxiety, depression, and catastrophizing are most prone to underestimate improvements of their pain over time.

Systematic Review of the Psychopathological Symptomatology and Neuropsychological Disorders of Chronic Primary Musculoskeletal Pain

Chronic pain can develop without tissue damage, injury, or underlying illness. There are several intervening biological, psychological, and social factors involved in its appearance that significantly affect the activities of daily life. It is also associated with significant emotional anxiety and/or functional disability. This review systematically analyses works published in the last five years that evaluate the psychopathological symptomatology and neuropsychological disorders of chronic primary musculoskeletal pain (CPMP). A bibliographic search was carried out to identify articles published in English between January 2018 and March 2023 using the Medline, Scopus, PsycInfo, and Pubmed databases. Twenty articles were obtained using the PRISMA selection method. The main results of this study provided evidence of the presence of moderate and severe chronic pain in patients suffering from musculoskeletal pain. This increase in the intensity of pain correlates with greater psychopathological symptomatology, such as depression, anxiety, insomnia, lack of attention, and hyperactivity/impulsiveness, as well as the use of maladaptive coping strategies. Furthermore, there exists dysfunction in the cerebral structures related to attention and the processing of pain in patients with CPMP. This review may help to develop and optimise the multidisciplinary treatments adapted to the deficits caused by this illness.

The autobiographical memory system and chronic pain: A neurocognitive framework for the initiation and maintenance of chronic pain

Chronic pain affects approximately 20% of the world's population, exerting a substantial burden on the affected individual, their families, and healthcare systems globally. Deficits in autobiographical memory have been identified among individuals living with chronic pain, and even found to pose a risk for the transition to chronicity. Recent neuroimaging studies have simultaneously implicated common brain regions central to autobiographical memory processing in the maintenance of and susceptibility to chronic pain. The present review proposes a novel neurocognitive framework for chronic pain explained by mechanisms underlying the autobiographical memory system. Here, we 1) summarize the current literature on autobiographical memory in pain, 2) discuss the role of the hippocampus and cortical brain regions including the ventromedial prefrontal cortex, anterior temporal lobe, and amygdala in relation to autobiographical memory, memory schemas, emotional processing, and pain, 3) synthesize these findings in a neurocognitive framework that explains these relationships and their implications for patients' pain outcomes, and 4) propose translational directions for the prevention, management, and treatment of chronic pain.

Uncertainty of treatment efficacy moderates placebo effects on reinforcement learning

The placebo-reward hypothesis postulates that positive effects of treatment expectations on health (i.e., placebo effects) and reward processing share common neural underpinnings. Moreover, experiments in humans and animals indicate that reward uncertainty increases striatal dopamine, which is presumably involved in placebo responses and reward learning. Therefore, treatment uncertainty analogously to reward uncertainty may affect updating from rewards after placebo treatment. Here, we address whether different degrees of uncertainty regarding the efficacy of a sham treatment affect reward sensitivity. In an online between-subjects experiment with N = 141 participants, we systematically varied the provided efficacy instructions before participants first received a sham treatment that consisted of listening to binaural beats and then performed a probabilistic reinforcement learning task. We fitted a Q-learning model including two different learning rates for positive (gain) and negative (loss) reward prediction errors and an inverse gain parameter to behavioral decision data in the reinforcement learning task. Our results yielded an inverted-U-relationship between provided treatment efficacy probability and learning rates for gain, such that higher levels of treatment uncertainty, rather than of expected net efficacy, affect presumably dopamine-related reward learning. These findings support the placebo-reward hypothesis and suggest harnessing uncertainty in placebo treatment for recovering reward learning capabilities.

Methyl jasmonate ameliorates pain-induced learning and memory impairments through regulating the expression of genes involved in neuroinflammation

OBJECTIVE

Orofacial pain with high prevalence is one of the substantial human health issues. The importance of this matter became more apparent when it was revealed that orofacial pain, directly and indirectly, affects cognition performances. Currently, researchers have focused on investigating pharmaceutics to alleviate pain and ameliorate its subsequent cognitive impairments.

DESIGN

In this study, the rats were first treated with the central administration of methyl jasmonate (MeJA), which is an antioxidant and anti-inflammatory bio-compound. After 20 min, orofacial pain was induced in the rats by the injection of capsaicin in their dental pulp. Subsequently, the animals' pain behaviors were analyzed, and the effects of pain and MeJA treatments on rats learning and memory were evaluated/compared using the Morris water maze (MWM) test. In addition, the expression of tumor necrosis factor-α (TNF-α), IL-1β, BDNF, and COX-2 genes in the rats' hippocampus was evaluated using real-time polymerase chain reaction.

RESULTS

Experiencing orofacial pain resulted in a significant decline in the rats learning and memory. However, the central administration of 20 μg/rat of MeJA effectively mitigated these impairments. In the MWM, the performance of the MeJA-treated rats showed a two- to threefold improvement compared to the nontreated ones. Moreover, in the hippocampus of pain-induced rats, the expression of pro-inflammatory factors TNF-α, IL-1β, and COX-2 significantly increased, whereas the BDNF expression decreased. In contrast, MeJA downregulated the pro-inflammatory factors and upregulated the BDNF by more than 50%.

CONCLUSIONS

These findings highlight the notable antinociceptive potential of MeJA and its ability to inhibit pain-induced learning and memory dysfunction through its anti-inflammatory effect.

Focal changes in alpha oscillations during short-term memorization of pain: a high-density electroencephalogram study with source localization

Memories of painful events constitute the basis for assessing patients' pain. This study explores the brain oscillatory activity during short-term memorization of a nociceptive stimulus. High-density EEG activity (128 electrodes) was recorded in 13 healthy subjects during a match-to-sample sensory discrimination task, whereby participants compared the intensity of a thumb-located electric shock (S2) with a prior stimulus to the same location (S1) delivered 8-10 s earlier. Stimuli were above or below the individual nociceptive threshold. EEG activity with intracortical source localization via LORETA source reconstruction was analysed during the inter-stimuli period and contrasted with a non-memory-related control task. The inter-stimulus memorization phase was characterized by a focal alpha-activity enhancement, significant during the nociceptive condition only, which progressed from bilateral occipital regions (cuneus and mid-occipital gyri) during the first encoding-memorization phase towards the right-superior and right mid-temporal gyri during the 2-4 s immediately preceding S2. Initial alpha enhancement in occipital areas/cuneus is consistent with rapid non-specific inhibition of task-irrelevant visual processing during initial stimulus encoding. Its transfer to the right-temporal regions was concomitant to the temporary upholding of the stimulus perceptual representation, previous to receiving S2, and suggests an active and local blockade of external interferences while these regions actively maintain internal information. These results add to a growing field indicating that alpha oscillations, while indicating local inhibitory processes, can also indirectly reveal active stimulus handling, including maintenance in short-term memory buffers, by objectivizing the filtering out of irrelevant and potentially disrupting inputs in brain regions engaged in internally driven operations.

A Comprehensive Description of the Anatomy and Histochemistry of Psychotria capillacea (Müll. Arg.) Standl. and an Investigation into Its Anti-Inflammatory Effects in Mice and Role in Scopolamine-Induced Memory Impairment

Species of the genus Psychotria are used in popular medicine for pain, inflammatory symptoms, and mental disorders. Psychotria capillacea (Müll. Arg.) Standl. (Rubiaceae) is commonly known as coffee and some scientific studies have demonstrated its therapeutic potential. The goal of this study was to investigate the anti-inflammatory and neuroprotective effects, and acetylcholinesterase (AChE) inhibitory activity of a methanolic extract obtained from leaves of P. capillacea (MEPC), as well as the micromorphology and histochemistry of the leaves and stems of this plant. In addition, the MEPC was analyzed by UHPLC-MS/MS and the alkaloidal fraction (AF) obtained from the MEPC was tested in a mouse model of inflammation. MEPC contained three indole alkaloids, one sesquiterpene (megastigmane-type) and two terpene lactones. MEPC (3, 30 and 100 mg/kg) and AF (3 and 30 mg/kg) were evaluated in inflammation models and significantly inhibited edema at 2 h and 4 h, mechanical hyperalgesia after 4 h and the response to cold 3 h and 4 h after carrageenan injection. Scopolamine significantly increased the escape latency, and reduced the swimming time and number of crossings in the target quadrant and distance, while MEPC (3, 30 and 100 mg/kg), due to its neuroprotective actions, reversed these effects. AChE activity was significantly decreased in the cerebral cortex (52 ± 3%) and hippocampus (60 ± 3%), after MEPC administration. Moreover, micromorphological and histochemical information was presented, to aid in species identification and quality control of P. capillacea. The results of this study demonstrated that P. capillacea is an anti-inflammatory and antihyperalgesic agent that can treat acute disease and enhance memory functions in mouse models.

Infliximab alleviates memory impairment in rats with chronic pain by suppressing neuroinflammation and restoring hippocampal neurogenesis

Patients with chronic pain commonly report impaired memory. Increasing evidence has demonstrated that inhibition of neurogenesis by neuroinflammation plays a crucial role in chronic pain-associated memory impairments. There is currently a lack of treatment strategies for this condition. An increasing number of clinical trials have reported the therapeutic potential of anti-inflammatory therapies targeting tumour necrosis factor-α (TNF-α) for inflammatory diseases. The present study investigated whether infliximab alleviates chronic pain-associated memory impairments in rats with chronic constriction injury (CCI). We demonstrated that infliximab alleviated spatial memory impairment and hyperalgesia induced by CCI. Furthermore, infliximab inhibited the activation of hippocampal astrocytes and microglia and decreased the release of proinflammatory cytokines in CCI rats. Furthermore, infliximab reversed the decrease in the numbers of newborn neurons and mature neurons in the dentate gyrus (DG) caused by chronic pain. Our data provide evidence that infliximab alleviates chronic pain-associated memory impairments, suppresses neuroinflammation and restores hippocampal neurogenesis in a CCI model. These facts indicate that infliximab may be a potential therapeutic agent for the treatment of chronic pain and associated memory impairments.

Predictors of patients' satisfaction after temporomandibular disorder treatment in a referral clinic

BACKGROUND

Evaluating patients' satisfaction after received care for temporomandibular disorders (TMD) pain provides oral health care professionals with knowledge and tools to improve their clinical procedures. However, knowledge on patient characteristics that determine satisfaction with the received care for TMD pain is lacking.

OBJECTIVE

To identify potential baseline predictors for patients' satisfaction regarding the management of TMD pain upon treatment completion in a referral clinic.

METHODS

Eligible patients, viz., individuals of ≥16 years of age, with a TMD-pain diagnosis according the diagnostic criteria for TMD (DC/TMD), and who were treated in a referral clinic, were included. As part of their standard care, a set of diagnostic questionnaires was filled in (e.g. TMD-pain screener, graded chronic pain scale (GCPS), etc.). After completion of the received care, patients filled in a custom-made questionnaire based on patient reported experience measures (PREMs) to quantify their satisfaction with their treatment results and received care. To identify potential predictors associated with patients' satisfaction, univariate and multivariate linear regression analyses were used.

RESULTS

Twenty-seven patients (mean 39.6, SD 15.0) were included in this study. Overall, the patients were satisfied with the treatment results and the received care. Depressive feelings were negatively associated with satisfaction of treatment results (p = .01) and positively associated with satisfaction of received care (p = .01), while pain intensity was negatively associated with satisfaction of the received care.

CONCLUSION

Depressive feelings are a significant negative predictor of patients' satisfaction with the treatment result for TMD pain, while average pain intensity is a significant negative predictor of patients' satisfaction with the received care.

Postoperative cognitive dysfunction-current research progress

Postoperative cognitive dysfunction (POCD) commonly occurs after surgery, particularly in elderly individuals. It is characterized by a notable decline in cognitive performance, encompassing memory, attention, coordination, orientation, verbal fluency, and executive function. This reduction in cognitive abilities contributes to extended hospital stays and heightened mortality. The prevalence of POCD can reach 40% within 1 week following cardiovascular surgery and remains as high as 17% 3 months post-surgery. Furthermore, POCD exacerbates the long-term risk of Alzheimer's disease (AD). As a result, numerous studies have been conducted to investigate the molecular mechanisms underlying POCD and potential preventive strategies. This article provides a review of the research progress on POCD.

Assessing cognitive biases induced by acute formalin or hotplate treatment: an animal study using affective bias test

Pain, a universal and burdensome condition, influences numerous individuals worldwide. It encompasses sensory, emotional, and cognitive facets, with recent research placing a heightened emphasis on comprehending pain's impact on emotion and cognition. Cognitive bias, which encompasses attentional bias, interpretation bias, and memory bias, signifies the presence of cognitive distortions influenced by emotional factors. It has gained significant prominence in pain-related research. Human studies have shown that individuals experiencing pain exhibit cognitive bias. Similarly, animal studies have demonstrated cognitive bias in pain-induced states across various species and disease models. In this study, we aimed to investigate the memory bias displayed by rats experiencing acute pain, using the affective bias test (ABT) as a tool and administering either hotplate or formalin to induce acute pain. Our data showed that rats demonstrated a significant preference for the control treatment-related substrate over the substrate associated with formalin treatment (p < 0.001), an indication of the prominent memory bias stimulated by acute formalin injections. However, when exposed to substrates related to hotplate treatment and control treatment, the acute pain induced by the hotplate treatment failed to generate a statistically significant choice bias in rats (p = 0.674). Our study demonstrates that the negative emotions associated with acute pain can be reflected by memory bias in ABT, at least for formalin-induced acute pain. This finding will augment our comprehension of the emotional and cognitive aspects of acute pain.

Neuropsychological Symptoms and Functional Capacity in Older Adults with Chronic Pain

The impact of chronic pain on neuropsychological functioning of older adults is under-studied. The present study examined the relationship between chronic pain, depression, anxiety, cognition, and functional capacity in community-dwelling older adults (ages 60-89) who completed an outpatient neuropsychological evaluation (N = 452). Psychometrically sound and validated measures were used to assess depression (Geriatric Depression Scale [GDS]), anxiety (Beck Anxiety Inventory [BAI]), cognitive functioning (the Mini Mental Status Exam [MMSE] and the Repeatable Battery for the Assessment of Neuropsychological Status [RBANS]), and functional capacity (Texas Functional Living Scale [TFLS] and Instrumental Activities of Daily Living Questionnaire [IADL]). Multivariate analyses of covariance (MANCOVA) were conducted to examine differences between individuals with and without chronic pain, adjusting for age, education, gender, marital status, and other medical conditions. Results indicated that participants endorsing chronic pain displayed significantly higher levels of depression and anxiety, as well as lower levels of cognitive functioning and functional capacity, than those without chronic pain. Additionally, results of hierarchical multiple regressions indicated that chronic pain explained unique variance in all outcome variables, beyond demographic characteristics and health status. Chronic pain management may be an important intervention target for clinicians to help address cognitive and psychological functioning in older adults.

Repeated (S)-ketamine administration ameliorates the spatial working memory impairment in mice with chronic pain: role of the gut microbiota-brain axis

Chronic pain is commonly linked with diminished working memory. This study explores the impact of the anesthetic (S)-ketamine on spatial working memory in a chronic constriction injury (CCI) mouse model, focusing on gut microbiome. We found that multiple doses of (S)-ketamine, unlike a single dose, counteracted the reduced spontaneous alteration percentage (%SA) in the Y-maze spatial working memory test, without affecting mechanical or thermal pain sensitivity. Additionally, repeated (S)-ketamine treatments improved the abnormal composition of the gut microbiome (β-diversity), as indicated by fecal 16S rRNA analysis, and increased levels of butyrate, a key gut - brain axis mediator. Protein analysis showed that these treatments also corrected the upregulated histone deacetylase 2 (HDAC2) and downregulated brain-derived neurotrophic factor (BDNF) in the hippocampi of CCI mice. Remarkably, fecal microbiota transplantation from mice treated repeatedly with (S)-ketamine to CCI mice restored %SA and hippocampal BDNF levels in CCI mice. Butyrate supplementation alone also improved %SA, BDNF, and HDAC2 levels in CCI mice. Furthermore, the TrkB receptor antagonist ANA-12 negated the beneficial effects of repeated (S)-ketamine on spatial working memory impairment in CCI mice. These results indicate that repeated (S)-ketamine administration ameliorates spatial working memory impairment in CCI mice, mediated by a gut microbiota - brain axis, primarily through the enhancement of hippocampal BDNF - TrkB signaling by butyrate.

Chronic pain accelerates cognitive impairment by reducing hippocampal neurogenesis may via CCL2/CCR2 signaling in APP/PS1 mice

Patients with chronic pain often have cognitive impairment; this is especially true in elderly patients with neurodegenerative diseases such as Alzheimer's disease (AD), but the mechanism underlying this association remains unclear. This was addressed in the present study by investigating the effect of chronic neuropathic pain on hippocampal neurogenesis and cognitive impairment using amyloid precursor protein/presenilin 1 (APP/PS1) double transgenic mice subjected to spared-nerve injury (SNI). The Von Frey test was performed to determine the mechanical threshold of mouse hind limbs after SNI. The Morris water maze test was used to evaluate spatial learning and memory. Doublecortin-positive (DCX+), 5-bromo-2'-deoxyuridine (BrdU)+, BrdU+/neuronal nuclei (NeuN)+, and C-C motif chemokine ligand 2 (CCL2)+ neurons in the dentate gyrus of the hippocampus were detected by immunohistochemistry and immunofluorescence analysis. CCL2 and C-C chemokine receptor type 2 (CCR2) protein levels in the mouse hippocampus were analyzed by western blotting. The results showed that APP/PS1 mice with chronic neuropathic pain induced by SNI had significant learning and memory impairment. This was accompanied by increased CCL2 and CCR2 expression and decreases in the number of DCX+, BrdU+, and BrdU+/NeuN+ neurons. These results suggest that chronic neuropathic pain is associated with cognitive impairment, which may be caused by CCL2/CCR2 signaling-mediated inhibition of hippocampal neurogenesis. Thus, therapeutic strategies that alleviate neuropathic pain can potentially slow cognitive decline in patients with AD and other neurodegenerative diseases.

The effects of pain following disbudding on calf memory

Studies have found evidence of pain in the hours following hot-iron disbudding, but little is known about longer-lasting pain following this procedure. Work on humans and rats has shown that lasting pain can have negative effects on the formation and recall of memories. The objective of this study was to assess whether lasting pain following disbudding affects learning and memory in calves. A modified hole-board apparatus was used to assess how quickly calves were able to learn the locations of 4 bottles containing milk dispersed among 11 locations with empty bottles. At 14 d of age and after 6 d of training on this task, calves (n = 30) were randomly assigned to 3 treatments: disbudding with analgesic on the day of the procedure, disbudding with analgesic throughout the study, and sham disbudding. All calves were sedated, given a lidocaine cornual local block and a single injection of an nonsteroidal anti-inflammatory drugs. Starting on the day after their disbudding treatment, calves were tested daily using the modified hole-board apparatus. After 12 d of testing, the locations of the 4 milk-containing bottles were switched, and calves then relearned the locations of the rewarded bottles over the next 6 daily test sessions. We found general working memory (i.e., short-term memory) and reference memory (i.e., long-term memory) increased over the 12 d of testing, declined when locations were switched on d 13, and then again increased over the final 6 d of testing. We did not find an effect of treatment on any measure, perhaps because there was no lasting pain or because effects were too minor to detect using this test of spatial memory.

Electroacupuncture Inhibits Pain Memory and Related Anxiety-Like Behaviors by Blockading the GABAB Receptor Function in the Midcingulate Cortex

Pain memory is commonly considered an underlying cause of chronic pain and is also responsible for a range of anxiety. Electroacupuncture (EA) has been shown to ameliorate pain memories and exert anti-anxiety effects. Previous research has indicated that GABAergic neurons and/or GABA receptors (GABARs) in the midcingulate cortex (MCC) have potential associations with chronic pain and anxiety. However, there is no known empirical research that has specifically studied the effects of EA on the GABAergic system in the MCC. Here, we used cross-injection of carrageenan to establish the pain memory rats model. Immunofluorescence were used to detect the excitability of GABAergic neurons within MCC. Von Frey filament, elevated zero maze, and open field tests were used to measure mechanical allodynia and anxiety-like behaviors, combined with chemogenetic and pharmacologic technologies. Finally, this study provides evidence that pain memories contribute to generalized negative emotions and that downregulating the activity of GABAergic neurons within MCC could block pain memories and reverse anxiety emotion. Specifically, GABABR is involved in pain memory and related anxiety-like behaviors. Activation of GABAergic neurons in the MCC did not reverse the effects of EA on pain memories and related anxiety-like behaviors, whereas these effects could be reversed by a GABABR agonist. These findings highlight the functional significance of GABABR in the EA-mediated attenuation of pain memories and related anxiety-like behaviors in rats.

The altered hippocampal functional connectivity and serum brain-derived neurotrophic factor level predict cognitive decline in patients with knee osteoarthritis

Patients with knee osteoarthritis (KOA) often suffer from cognitive decline and increased dementia risk, but the neurobiological mechanisms remain unclear. In this study, we evaluated cognitive performance and collected brain magnetic resonance imaging (MRI) data and blood samples from cognitively normal KOA patients at baseline sessions and reevaluated their cognition after 5 years. We also collected MRI data from matched healthy controls. Results showed that KOA patients exhibited dysregulated functional connectivities between the hippocampus and thalamus/superior frontal gyrus compared with healthy controls. The altered hippocampal functional connectivities were associated with serum brain-derived neurotrophic factor (BDNF) levels and spatial expression of genes enriched in synaptic plasticity. The hippocampus-thalamus functional connectivity was significantly correlated with patients' memory scores. Moreover, the baseline hippocampus-thalamus functional connectivity and BDNF levels significantly predicted the development of cognitive decline in KOA patients in the follow-up session. Our findings provide insight into the neurobiological underpinnings of KOA and cognitive decline.

Extracellular RNAs-TLR3 signaling contributes to cognitive impairment after chronic neuropathic pain in mice

Chronic pain is often associated with cognitive decline, which could influence the quality of the patient's life. Recent studies have suggested that Toll-like receptor 3 (TLR3) is crucial for memory and learning. Nonetheless, the contribution of TLR3 to the pathogenesis of cognitive decline after chronic pain remains unclear. The level of TLR3 in hippocampal neurons increased in the chronic constriction injury (CCI) group than in the sham group in this study. Importantly, compared to the wild-type (WT) mice, TLR3 knockout (KO) mice and TLR3-specific neuronal knockdown mice both displayed improved cognitive function, reduced levels of inflammatory cytokines and neuronal apoptosis and attenuated injury to hippocampal neuroplasticity. Notably, extracellular RNAs (exRNAs), specifically double-stranded RNAs (dsRNAs), were increased in the sciatic nerve, serum, and hippocampus after CCI. The co-localization of dsRNA with TLR3 was also increased in hippocampal neurons. And the administration of poly (I:C), a dsRNA analog, elevated the levels of dsRNAs and TLR3 in the hippocampus, exacerbating hippocampus-dependent memory. In additon, the dsRNA/TLR3 inhibitor improved cognitive function after CCI. Together, our findings suggested that exRNAs, particularly dsRNAs, that were present in the condition of chronic neuropathic pain, activated TLR3, initiated downstream inflammatory and apoptotic signaling, caused damage to synaptic plasticity, and contributed to the etiology of cognitive impairment after chronic neuropathic pain.

Understanding the Experience and Impacts of Brain Fog in Chronic Pain: A Scoping Review

Introduction

Approximately 15% to 40% of persons with chronic pain as a primary disorder experience brain fog. Prior research has investigated the etiology of "brain fog" in conditions in which pain presents as a key feature (e.g., fibromyalgia). However, it remains understudied in the context of chronic 10 musculoskeletal pain. Following current scoping review guidelines, we obtained stakeholder input from patient and health care professionals (HCPs) to define this phenomenon. Specific aims of this review were to (1) identify factors contributing to brain fog, (2) identify the functional correlates of brain fog and assessments used to measure them, and (3) establish a definition of brain fog that can be employed by researchers and HCPs to advance research and care.

Methods

A scoping review was conducted using recommendations of the Joanna Briggs Institute methodology of scoping reviews and the Levac et al methodology. Embase, Cinahl, PsycINFO, and Medline was searched to identify relevant sources. Findings were verified with patient and healthcare professionals.

Results

We identified four 15 key features of brain fog: perceived variability, subjective cognitive dysfunction, participation limitations, and changes in functional activities. We developed a model of brain fog illustrating the overlapping categories of contributors to brain fog in chronic musculoskeletal pain: (1) neuroanatomical and neurophysiological, (2) mental health/emotional, and (3) environmental/lifestyle.

Conclusion

The results of this scoping review conclude that the inconsistency in research regarding brain fog in 20 chronic musculoskeletal pain is obstructing a clear understanding of the phenomenon and therefore may be impeding persons with chronic pain and brain fog from receiving optimal care.

Stress specifically deteriorates working memory in peripheral neuropathic pain and fibromyalgia

This study aimed to explore the influence of chronic stress, measured through hair cortisol, on executive functions in individuals with chronic pain. We expected that there would be significant differences in chronic stress and executive functioning between pain patients and healthy controls, as well as between primary and secondary pain classifications. We also hypothesized that hair cortisol concentration was predictive of worse performance on tests of executive functions, controlling for objective and subjective covariates. For this study, 122 participants provided a hair sample (n = 40 with fibromyalgia; n = 24 with peripheral neuropathic pain; n = 58 matched healthy controls). Eighty-four of these participants also completed highly detailed testing of executive functions (n = 40 with fibromyalgia; n = 24 with peripheral neuropathic pain; n = 20 healthy controls). To assess differences in stress levels and executive functions, t-tests were used to compare patients with controls as well as fibromyalgia with peripheral neuropathic pain. Then, univariate regressions were used to explore associations between stress and executive functioning in both chronic pain classifications. Any significant univariate associations were carried over to hierarchical multivariate regression models. We found that patients with chronic pain had significantly higher cortisol levels than healthy controls, but all groups showed similar executive functioning. Hierarchical multiple regression analyses disclosed that in a model controlling for age, sex and pain medication usage, hair cortisol levels explained 8% of the variance in spatial working memory strategy in individuals with chronic pain. The overall model explained 24% of the variance in spatial working memory. In a second model using imputed data, including both objective and subjectively reported covariates, hair cortisol levels explained 9% of the variance, and the full model 31% of the variance in spatial working memory performance. Higher levels of cortisol indicated worse performance. In this study, an applied measure of chronic stress, namely hair cortisol, explained a substantial part of the variance on a spatial working memory task. The current results have important implications for understanding and treating cognitive impairments in chronic pain.

Diagnosis of Chronic Musculoskeletal Pain by Using Functional Near-Infrared Spectroscopy and Machine Learning

Chronic pain (CP) has been found to cause significant alternations of the brain's structure and function due to changes in pain processing and disrupted cognitive functions, including with respect to the prefrontal cortex (PFC). However, until now, no studies have used a wearable, low-cost neuroimaging tool capable of performing functional near-infrared spectroscopy (fNIRS) to explore the functional alternations of the PFC and thus automatically achieve a clinical diagnosis of CP. In this case-control study, the pain characteristics of 19 chronic pain patients and 32 healthy controls were measured using fNIRS. Functional connectivity (FC), FC in the PFC, and spontaneous brain activity of the PFC were examined in the CP patients and compared to those of healthy controls (HCs). Then, leave-one-out cross-validation and machine learning algorithms were used to automatically achieve a diagnosis corresponding to a CP patient or an HC. The current study found significantly weaker FC, notably higher small-worldness properties of FC, and increased spontaneous brain activity during resting state within the PFC. Additionally, the resting-state fNIRS measurements exhibited excellent performance in identifying the chronic pain patients via supervised machine learning, achieving F1 score of 0.8229 using only seven features. It is expected that potential FC features can be identified, which can thus serve as a neural marker for the detection of CP using machine learning algorithms. Therefore, the present study will open a new avenue for the diagnosis of chronic musculoskeletal pain by using fNIRS and machine learning techniques.

Increasing disclosures of older adult maltreatment: a review of best practices for interviewing older adult eyewitnesses and victims

The current article provides a contemporary review of the best practices for interviewing older adults about crimes they witnessed or experienced. Specifically, we provide a detailed overview of how investigators can use a range of interviewing adaptations and procedures to acquire detailed and accurate maltreatment disclosures from older adults. In addition to discussing well-established investigative interviewing practices (e.g. rapport building, free-recall, cognitive instructions and prompts), this article also summarizes more recent literature on the benefits of multidisciplinary investigations, use of assistive technology and interview accommodations, along with effective practices for working with minority and marginalized older adults. Lastly, several research, professional and policy recommendations are provided for supporting older adults during investigative interviews.

Pain and mild cognitive impairment among adults aged 50 years and above residing in low- and middle-income countries

BACKGROUND

Previous studies on the association between pain and cognitive decline or impairment have yielded mixed results, while studies from low- and middle-income countries (LMICs) or specifically on mild cognitive impairment (MCI) are scarce. Thus, we investigated the association between pain and MCI in LMICs and quantified the extent to which perceived stress, sleep/energy problems, and mobility limitations explain the pain/MCI relationship.

METHODS

Data analysis of cross-sectional data from six LMICs from the Study on Global Ageing and Adult Health (SAGE) were performed. MCI was based on the National Institute on Aging-Alzheimer's Association criteria. "Overall in the last 30 days, how much of bodily aches or pain did you have?" was the question utilized to assess pain. Associations were examined by multivariable logistic regression analysis and meta-analysis.

RESULTS

Data on 32,715 individuals aged 50 years and over were analysed [mean (SD) age 62.1 (15.6) years; 51.7% females]. In the overall sample, compared to no pain, mild, moderate, and severe/extreme pain were dose-dependently associated with 1.36 (95% CI = 1.18-1.55), 2.15 (95% CI = 1.77-2.62), and 3.01 (95% CI = 2.36-3.85) times higher odds for MCI, respectively. Mediation analysis showed that perceived stress, sleep/energy problems, and mobility limitations explained 10.4%, 30.6%, and 51.5% of the association between severe/extreme pain and MCI.

CONCLUSIONS

Among middle-aged to older adults from six LMICs, pain was associated with MCI dose-dependently, and sleep problems and mobility limitations were identified as potential mediators. These findings raise the possibility of pain as a modifiable risk factor for developing MCI.

Chronic pain in osteoarthritis of the hip is associated with selective cognitive impairment

INTRODUCTION

Chronic pain of various origin is known to be associated with selective cognitive impairment. Osteoarthritis (OA) of the hip is one of the leading causes of chronic pain in the adult population, but its association with cognitive performance has not been evaluated. Here, we investigate the effect of chronic pain due to unilateral OA of one hip and no further source of chronic pain on cognitive performance.

MATERIALS AND METHODS

A neuropsychological test battery, consisting of the Mini-Mental State Examination, Rey-Osterrieth complex figure test, Rivermead behavioural memory test, d2 test of attention, and F-A-S test was applied in 148 patients and 82 healthy pain-free control individuals. The influence of potentially confounding factors such as depression and anxiety was examined.

RESULTS

Patients with OA of the hip showed decreased performance in specific neuropsychological tests. Performance in verbal and visual short-term and long-term memory and selective attention tests was significantly poorer compared to healthy controls. Whereas the executive functions "updating", "set shifting", "response inhibition" and "reflection" appear intact, "problem solving" and "planning" were impaired. None of the confounders showed any influence on cognitive performance in both study groups.

CONCLUSION

We conclude that chronic pain secondary to end-stage hip OA is associated with selective cognitive impairment. Future studies are required to investigate the effect of total hip arthroplasty on cognitive performance.

Altered social decision making in patients with chronic pain

BACKGROUND

Chronic pain affects up to 20% of the population, impairs quality of life and reduces social participation. Previous research reported that pain-related perceived injustice covaries with these negative consequences. The current study probed whether chronic pain patients responded more strongly to disadvantageous social inequity than healthy individuals.

METHODS

We administered the Ultimatum Game, a neuroeconomic social exchange game, where a sum of money is split between two players to a large sample of patients with chronic pain disorder with somatic and psychological factors (n = 102) and healthy controls (n = 101). Anonymised, and in truth experimentally controlled, co-players proposed a split, and our participants either accepted or rejected these offers.

RESULTS

Chronic pain patients were hypersensitive to disadvantageous inequity and punished their co-players for proposed unequal splits more often than healthy controls. Furthermore, this systematic shift in social decision making was independent of patients' performance on tests of executive functions and risk-sensitive (non-social) decision making .

CONCLUSIONS

Our findings indicate that chronic pain is associated with anomalies in social decision making (compared to healthy controls) and hypersensitivity to social inequity that is likely to negatively impact social partaking and thereby the quality of life.

Myokines may target accelerated cognitive aging in people with spinal cord injury: A systematic and topical review

Persons with spinal cord injury (SCI) can suffer accelerated cognitive aging, even when correcting for mood and concomitant traumatic brain injury. Studies in healthy older adults have shown that myokines (i.e. factors released from muscle tissue during exercise) may improve brain health and cognitive function. Myokines may target chronic neuroinflammation, which is considered part of the mechanism of cognitive decline both in healthy older adults and SCI. An empty systematic review, registered in PROSPERO (CRD42022335873), was conducted as proof of the lack of current research on this topic in people with SCI. Pubmed, Embase, Cochrane and Web of Science were searched, resulting in 387 articles. None were considered eligible for full text screening. Hence, the effect of myokines on cognitive function following SCI warrants further investigation. An in-depth narrative review on the mechanism of SCI-related cognitive aging and the myokine-cognition link was added to substantiate our hypothetical framework. Readers are fully updated on the potential role of exercise as a treatment strategy against cognitive aging in persons with SCI.

Contribution of pain to subsequent cognitive decline or dementia: A systematic review and meta-analysis of cohort studies

BACKGROUND

Dementia is an urgent public health problem worldwide, and the determination of the contribution of pain to cognitive decline or dementia is significant for the prevention of dementia.

OBJECTIVE

To comprehensively explore the contribution of pain to subsequent cognitive decline or dementia and analyze possible influencing factors.

DESIGN

Systematic review and meta-analysis of cohort studies.

METHODS

We systematically searched MEDLINE, EMBASE, PsycINFO, CINAHL, Cochrane Library, China National Knowledge Internet, WANFANG DATA and VIP for cohort studies from database inception to January 21, 2022. Random-effects meta-analysis was used to pool odds ratios (ORs) and 95% confidence intervals (CIs) of incident cognitive decline or dementia among patients with pain. Subgroup analyses and meta-regression were used to explore the sources of heterogeneity.

RESULTS

A total of 35 cohort studies containing 1,122,503 participants were included. As a whole, pain (OR = 1.24; 95% CI = 1.17-1.31) was a risk factor for subsequent cognitive decline or dementia; headache, migraine, tension-type headache, widespread pain, and irritable bowel syndrome, but not burning mouth syndrome, were also risk factors. Pain increased the risk of all-cause dementia (OR = 1.26; 95% CI = 1.18-1.35), Alzheimer's disease (OR = 1.28; 95% CI = 1.12-1.47), and vascular dementia (OR = 1.31; 95% CI = 1.06-1.62). Pain interference (OR = 1.42; 95% CI = 1.16-1.74) was associated with an increased risk of cognitive decline or dementia, while pain intensity was not. Pooled results from studies with sample sizes less than 2000 or with relatively low quality showed that pain did not increase the risk of cognitive decline or dementia. There was no statistically significant increase in the risk of cognitive decline or dementia in people with pain aged ≥75 years.

CONCLUSIONS

Our results demonstrated that pain increased the risk of subsequent cognitive decline or dementia. Sample size, study methodological quality, types of pain, pain severity (pain interference), and age composition of the study population may affect the relationship between pain and cognitive decline or dementia.

REGISTRATION

PROSPERO (CRD42022316406).

Can we characterize A-P/IAP behavioural phenotypes in people with chronic pain?

Two behavioural phenotypes in healthy people have been delineated based on their intrinsic attention to pain (IAP) and whether their reaction times (RT) during a cognitively-demanding task are slower (P-type) or faster (A-type) during experimental pain. These behavioural phenotypes were not previously studied in chronic pain populations to avoid using experimental pain in a chronic pain context. Since pain rumination (PR) may serve as a supplement to IAP without needing noxious stimuli, we attempted to delineate A-P/IAP behavioural phenotypes in people with chronic pain and determined if PR can supplement IAP. Behavioural data acquired in 43 healthy controls (HCs) and 43 age-/sex-matched people with chronic pain associated with ankylosing spondylitis (AS) was retrospectively analyzed. A-P behavioural phenotypes were based on RT differences between pain and no-pain trials of a numeric interference task. IAP was quantified based on scores representing reported attention towards or mind-wandering away from experimental pain. PR was quantified using the pain catastrophizing scale, rumination subscale. The variability in RT was higher during no-pain trials in the AS group than HCs but was not significantly different in pain trials. There were no group differences in task RTs in no-pain and pain trials, IAP or PR scores. IAP and PR scores were marginally significantly positively correlated in the AS group. RT differences and variability were not significantly correlated with IAP or PR scores. Thus, we propose that experimental pain in the A-P/IAP protocols can confound testing in chronic pain populations, but that PR could be a supplement to IAP to quantify attention to pain.

Chronic pain domains and their relationship to personality, abilities, and brain networks

Chronic pain is a multidimensional pathological state. Recent evidence suggests that specific brain properties and patients' psychological and physical traits are distorted in chronic pain patients. However, the relationship between these alterations and pain dimensions remains poorly understood. Here, we first evaluated multiple dimensions of chronic pain by assessing a broad battery of pain-related questionnaire scores (23 outcomes) of 107 chronic low back pain patients and identified 3 distinct chronic pain domains: magnitude, affect & disability, and quality. Second, we investigated the pain domains relationship with measures of personality, social interaction, psychological traits, and ability traits (77 biopsychosocial & ability [biopsy&ab] outcomes). Pain magnitude (out-of-sample [OOS] ) is associated with emotional control, attention, and working memory, with higher pain scores showing lower capacity to regulate and adapt behaviorally. Pain affect & disability (OOS associated with anxiety, catastrophizing and social relationships dysfunction. Pain quality did not relate significantly to biopsy&ab variables. Third, we mapped these 3 pain domains to brain functional connectivity. Pain magnitude mainly associated with the sensorimotor and the cingulo-opercular networks (OOS ). Pain affect & disability related to frontoparietal and default mode networks (OOS . Pain quality integrated sensorimotor, auditory, and cingulo-opercular networks (OOS ). Mediation analysis could link functional connectivity and biopsy&ab models to respective pain domains. Our results provide a global overview of the complexity of chronic pain, showing how underlying distinct domains of the experience map to different biopsy&ab correlates and underlie unique brain network signatures.