Evidence for Cognitive Decline in Chronic Pain: A Systematic Review and Meta-Analysis

Chronic musculoskeletal pain and its relationship with cognitive function in older adults: A systematic review and meta-analysis

BACKGROUND

The relationship between chronic musculoskeletal pain and cognitive function in older adults remains unclear. This study aimed to investigate whether the cognitive function of older adults with chronic musculoskeletal pain differs from asymptomatic older adults.

METHODS

Four databases (PubMed, Science Direct, Web of Science, and Scopus) were searched. Two researchers independently reviewed the references against the eligibility criteria and performed the quality assessment of included studies using The National Institutes of Health (NIH) - Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies.

RESULTS

A total of 8484 references were found and ten articles, published between 2006 and 2021, were included. Only one study was classified as being of good quality, the remaining were of fair quality. Independent meta-analysis were performed for global cognition and specific cognitive domains (language, attention/orientation, executive function, memory, processing speed, and visuospatial skills). Differences between older adults with and without chronic musculoskeletal pain were found for the domains of general cognition (k = 10; d = -0.20; 95% CI = -0.38, -0.03; z = -2.25, p = 0.03) and language (k = 8; d =  -0.16; 95% CI = -0.28, -0.05; z = -2.72, p = 0.006), with very low certainty of evidence.

CONCLUSION

Overall, and considering the very low certainty of evidence for both global cognition and specific cognitive domains, we are uncertain about whether cognitive function differs between older adults with and without chronic musculoskeletal pain. Further research is needed comparing cognitive performance between older adults with and without chronic musculoskeletal pain, on the long-term impact of pain on cognitive functioning, and on the mechanisms underlying this potential relationship.

Perceived cognitive functioning difficulties in individuals living with endometriosis

Difficulties in cognitive functioning (e.g., memory, attention) are common in chronic conditions characterized by physical pain, fatigue and depression. Yet investigations in endometriosis are lacking. We aimed to assess: (1) perceived cognitive functioning, (2) the association of cognitive functioning with fatigue, pain and depressive symptoms, and (3) whether endometriosis treatments moderated these relationships. Participants (n = 1239) with diagnosed endometriosis completed an online survey assessing perceived cognitive functioning [Functional Assessment of Cancer Therapy-Cognitive Function (FACT-Cog)], pain, fatigue and depression. FACT-Cog scores indicated cognitive impairments in 80% of participants. Hierarchical regression analyses demonstrated that greater pain, fatigue, and depressive symptoms were associated with poorer perceived cognitive functioning. Moderation analyses indicated that taking hormonal treatments or pain medications diminished the adverse effects of depression, but exacerbated the adverse effects of pain, on cognitive functioning. The extensive perceived cognitive difficulties evident in this sample suggests that supportive interventions to enhance cognitive functioning may be warranted.

Age and Gender Differences in the Relationship Between Chronic Pain and Dementia Among Older Australians

OBJECTIVES

Chronic pain is a highly debilitating condition that affects older adults and has the potential to increase their odds of experiencing cognitive impairment. The primary objective of this study was to examine the correlation between chronic pain and dementia. Additionally, this research endeavors to ascertain whether the association between chronic pain and dementia differs by age and gender.

METHODS

Cross-sectional data were derived from the Survey of Disability, Ageing, and Carers. A total of 20 671 and 20 081 participants aged 65 years and older in 2015 and 2018, respectively, were included in this study. The pooled association between chronic pain and dementia was assessed using a multivariable logistic regression model. Furthermore, the study also examined the multiplicative interaction effects between chronic pain and age, as well as chronic pain and gender, with dementia.

RESULTS

The pooled analysis demonstrated that chronic pain was associated with a heightened odds of dementia (adjusted odds ratio 1.95; 95% CI 1.85-2.05) among older Australians compared with their counterparts without chronic pain. The interaction effect indicated that individuals with chronic pain across all age groups exhibited increased odds of living with dementia. Additionally, women with chronic pain had higher odds of dementia compared with their counterparts without chronic pain and being male.

CONCLUSIONS

A continuous, coordinated, and tailored healthcare strategy is necessary to determine the pain management goals and explore early treatment options for chronic pain in older adults, particularly in groups with the greatest need.

State-of-the-Art Personalized Therapy Approaches for Chronic Non-Specific Low Back Pain: Understanding the Mechanisms and Drivers

Chronic non-specific low back pain (CNSLBP) is a debilitating condition that affects millions of people worldwide, significantly impacting quality of life and imposing a substantial socioeconomic burden. Traditional treatment approaches often rely on a one-size-fits-all strategy, failing to account for individual variations in pathophysiological mechanisms, drivers, and the principles of personalized medicine. Furthermore, an overemphasis on biomechanical findings from imaging may lead to ineffective interventions and unnecessary surgical procedures, obscuring other important factors that contribute to pain perception. While highlighting the limitations of universal treatment approaches, in this review we present a practical clinical approach aimed at elucidating the main pathophysiological mechanisms and various factors underlying the development and maintenance of CNSLBP in order to create a personalized treatment program. In conclusion, this review underscores the need for personalized therapeutic strategies that take into account the unique characteristics of each patient, recognizing the complex interaction of biological, psychological, social, and other factors that contribute to the development of individual pain. By combining a comprehensive understanding of the complexities of this condition, we aim to improve clinical outcomes and provide information on the development of effective personalized treatment algorithms, particularly in the field of neurological practice.

Longitudinal associations between pain and cognitive decline in middle-aged and older Chinese adults: the mediating role of depressive symptoms

Objective

The primary aim of this scholarly investigation was to elucidate the correlation between Number of Pain Sites and cognitive decline within the older adult population. Additionally, the study sought to examine the potential mediating influence of depressive symptoms in moderating the association between pain and cognitive deterioration.

Methods

We analyzed 8,835 participants aged 45 and above, with data collected from 2011 to 2018. Participants were categorized into two groups-stable and rapidly declining cognitive function-using the KML3D clustering method. Binary logistic regression analysis was conducted to examine the association between pain status, depressive symptoms, and cognitive trajectories, and mediation analysis was used to assess the mediating role of depression.

Results

Multi-site pain was significantly associated with the risk of rapid cognitive decline (adjusted OR = 1.30, 95% CI: 1.14-1.48), and depressive symptoms were also a significant predictor of rapid cognitive decline (adjusted OR = 1.49, 95% CI: 1.32-1.68). Mediation analysis revealed that depression mediated the effect of pain on cognitive decline, accounting for 25.71% of the total effect.

Conclusion

Our study establishes a significant longitudinal link between Number of Pain Sites and cognitive decline, mediated in part by depressive symptoms. This finding underscores the need for interventions that address pain and depression to potentially decelerate cognitive decline in older adults.

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.

High-Impact Pain Predicts Incidence of Subjective and Objective Cognitive Decline

Chronic pain is the most common health challenge for older adults and a significant risk factor for cognitive impairments and dementia. This study examined the relationship between high-impact pain (pain that limits daily activities) and subjective cognitive decline (SCD) in 13,763 adults aged 50 and older from the Health and Retirement Study (2004-2020). High-impact pain was associated with a higher prevalence and incidence of SCD as compared to no pain and low-impact pain, adjusted for sociodemographic and clinical factors. Additionally, high-impact pain predicted an increased risk of objective cognitive impairment, particularly in individuals without the APOE4 allele. Our findings suggest that high-impact pain is a stronger predictor of future cognitive impairments than SCD alone in most of the population who do not carry the APOE4 allele. Interventions targeting high-impact pain, starting in middle age, may help mitigate the risk of cognitive decline and dementia. Future research is needed to understand potential mechanisms and develop effective cognitive aging strategies considering the impact of pain itself on cognition.

Hippocampal Functional Radiomic Features for Identification of the Cognitively Impaired Patients from Low-Back-Related Pain: A Prospective Machine Learning Study

Purpose

To investigate whether functional radiomic features in bilateral hippocampi can identify the cognitively impaired patients from low-back-related leg pain (LBLP).

Patients and Methods

For this retrospective study, a total of 95 clinically definite LBLP patients (40 cognitively impaired patients and 45 cognitively preserved patients) were included, and all patients underwent functional MRI and clinical assessments. After calculating the amplitude of low-frequency fluctuations (ALFF), regional homogeneity (ReHo), voxel-mirrored homotopic connectivity (VMHC) and degree centrality (DC) imaging, the radiomic features (n = 819) of bilateral hippocampi were extracted from these images, respectively. After feature selection, machine learning models were trained. Finally, we further analyzed the relationship between the hippocampal functional radiomic features and clinical measures, to explore the clinical significance of these features.

Results

The combined radiomic features model logistic regression algorithm superior performance in distinguishing cognitively impaired patients from LBLP (AUC = 0.970, accuracy = 92.3%, sensitivity = 92.3%, specificity = 92.3%) compared to the other models. Additionally, radiomic wavelet features were correlated with Montreal Cognitive Assessment (MoCA) and Hamilton Anxiety Scale, present pain intensity scores in cognitively impaired LBLP patients (P < 0.05, with Bonferroni correction).

Conclusion

Hippocampal functional radiomic features are valuable for diagnosing cognitively impaired patients from LBLP.

Chronic pain in older adults with disabilities is associated with cognitive impairment-a prospective cohort study

BACKGROUND

Chronic pain may be an important factor influencing cognitive impairment; however, there is limited research on that link in older adults with disabilities. We aimed to determine the association between chronic pain and cognitive impairment in older adults with disabilities.

METHODS

This 24-month prospective cohort study involved 143 Japanese older adults (≥65 years of age) with long-term care insurance. Chronic pain was defined as pain persisting for ≥3 months, and cognitive impairment was defined as a Mini-Mental State Examination score ≤ 23. We employed logistic regression analysis with chronic pain as the independent variable and cognitive impairment as the dependent variable after propensity score matching (PSM).

RESULTS

Sixty-six participants were selected using PSM, and logistic regression analysis showed that chronic pain was significantly associated with cognitive impairment (odds ratio: 4.103, 95% confidence interval: 1.455-11.567, P = 0.008).

CONCLUSION

To prevent cognitive impairment in older adults with disabilities, the management of chronic pain should be considered, as they are related.

Assessing cognitive impairment in chronic pain: a cross-sectional study with healthy controls

PURPOSE

The aim of this study is to clarify inconsistencies in the literature regarding the neuropsychological impact of chronic pain and determine how pain catastrophizing and pain intensity may explain cognitive impairment.

METHODS

This cross-sectional study involved 30 participants with chronic primary musculoskeletal pain and 30 healthy controls without pain. The instruments used were the Pain Catastrophizing Scale, the Visual Analogue Scale, the Beck Anxiety Inventory, the Beck Depression Inventory-II, the Wisconsin Card Sorting Test, the Stroop Test, and the Working Memory Index of the Wechsler Adult Intelligence Scale.

RESULTS

Chronic pain patients showed slight cognitive impairments in selective attention, sustained attention, working memory, problem solving, planning, abstract reasoning, inhibition, and resistance to interference. The data also indicate that higher levels of pain catastrophizing and pain intensity were independently associated with greater cognitive impairment in patients with pain, specifically in attention and executive functioning. Additionally, the interaction between these pain-related variables predicted further cognitive impairment.

CONCLUSIONS

This research has contributed to establishing the neuropsychological profile of patients with chronic primary musculoskeletal pain and reinforces evidence of the impact of chronic pain on cognition. These findings may help guide the design of programs aimed at improving cognitive performance.

Comparison of Cognitive Functions Between Individuals With Chronic Low Back Pain With High and Low Pain Catastrophizing and Pain-free Controls: A Cross-sectional Study

OBJECTIVES

Researchers suggested that the interruptive effects of chronic pain on cognitive functions may be modulated by the level of pain catastrophizing (PC). However, in individuals with chronic low back pain (CLBP), domains of cognitive function that may be affected by the level of PC remain largely unclear. Therefore, this study aimed to compare cognitive functions between individuals with CLBP with high and low PC and pain-free controls.

MATERIALS AND METHODS

This cross-sectional study examined cognitive functions of 42 individuals with CLBP and 21 pain-free controls. The PC scale was used to stratify participants with CLBP into high and low PC. Participants performed 5 cognitive tests from the Cambridge Neuropsychological Test Automated Battery, namely 5-choice reaction time, rapid visual processing, spatial working memory, attention switching task, and stop signal task.

RESULTS

The statistical analyses revealed that compared with individuals with CLBP with low PC and pain-free controls, individuals with high PC demonstrated greater values of the between errors ( P =0.01), reaction latency ( P <0.001), and stop signal reaction time variables ( P =0.004, 0.003, respectively) but lower values of probability of hit ( P =0.02, 0.01, respectively), A' ( P =0.01, <0.001, respectively), and percent correct trials variables ( P =0.002, <0.001, respectively).

DISCUSSION

The results of the current study showed deficits in sustained attention, working memory, cognitive flexibility, and inhibitory control in individuals with CLBP with high PC. From a clinical perspective, therapeutic interventions targeting PC should be considered to decrease catastrophic thinking about pain in individuals with CLBP. Additional research is warranted to explore cognitive functioning as an outcome of these interventions in individuals with CLBP.

Brain compensatory mechanisms in depression and memory complaints in fibromyalgia: the role of theta oscillatory activity

BACKGROUND

The different clinical presentations of fibromyalgia syndrome (FMS) might play independent roles in the unclear etiology of cognitive impairments and depressive symptoms seen in patients with FMS. Understanding how these clinical presentations are associated with the clinical and neurophysiological aspects of FMS is important for the development of effective treatments.

AIM

To explore the relationship of memory complaints and depressive symptoms with the different clinical and neurophysiological characteristics of FMS.

METHODS

Cross-sectional data analysis from a randomized clinical trial. Baseline demographics and data on physical fitness, sleep, anxiety, depression, cortical excitability, and pain (clinical and mechanistic) from 63 subjects with FMS were used. Multiple linear and logistic association models were constructed.

RESULTS

Final regression models including different sets of predictions were statistically significant (P < .001), explaining approximately 50% of the variability in cognitive complaints and depression status. Older subjects had higher levels of anxiety, poorer sleep quality, lower motor threshold, and higher relative theta power in the central area and were more likely to have clinical depression. Higher anxiety, pain, and theta power were associated with a higher likelihood of memory complaints.

CONCLUSION

Depression symptoms seem to be associated with transcranial magnetic stimulation-indexed motor threshold and psychosocial variables, whereas memory complaints are associated with pain intensity and higher theta oscillations. These mechanisms might be catalyzed or triggered by some behavioral and clinical features, such as older age, sleep disruption, and anxiety. The correlation with clinical variables suggests that the increasing of theta oscillations is a compensatory response in patients with FMS, which can be explored in future studies to improve the treatment of FMS.

TRIAL REGISTRATION

ClinicalTrials.gov ID NCT03371225.

Addressing Pain Using a Mediterranean Ketogenic Nutrition Program in Older Adults with Mild Cognitive Impairment

Chronic pain has negative physical and cognitive consequences in older adults and may lead to a poorer quality of life. Mediterranean ketogenic nutrition (MKN) is a promising nonpharmacological intervention for pain management, but long-term adherence is challenging due to the carbohydrate restrictive diet regimen. The main objective of this study was to evaluate the effects of the pilot MKN Adherence (MKNA) Program on pain in older adults with mild cognitive impairment and to assess whether improvements in self-reported pain were associated with adherence to MKN. Older adults (N = 58) aged 60-85 with possible mild cognitive impairment were randomized to a 6-week MKNA arm or an MKN Education (MKNE) program arm. Both arms received the same nutrition education and group format; however, the MKNA arm received additional motivational interviewing and cognitive behavioral skills to enhance adherence. Changes in self-reported pain (Brief Pain Inventory, Roland Morris, Patient's Global Impression of Change) and adherence to MKN (ketone levels, self-reported adherence) were assessed at baseline, 6-weeks, and 3-months post intervention. Both arms showed clinically significant reductions in pain. Greater adherence to MKN across the 6-week intervention was associated with higher ratings of pain-related changes on the Patient's Global Impression of Change scale. Based on these findings, adherence to MKN may promote improvements in self-reported pain in older adults with mild cognitive impairment and findings support the need for future full-scale randomized clinical trials evaluating MKN programs on pain. Trial Registration: Clinicaltrials.gov ID: NCT04817176.

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.

Differential behavioral response to predator odor in neuropathic pain in mice

Neuropathic pain, a type of chronic pain caused by injury or disease of the somatosensory system, affects ∼10% of the general population and is difficult to treat. It is strongly associated with mood disorder comorbidities and impairs quality of life. It was recently suggested that hypervigilance caused by chronic pain might be of advantage in some species, helping them avoid predators during injury when they are most vulnerable. Here, we sought to confirm the hypervigilance hypothesis by using two predator odor (PO) paradigms, one with transient and one with continuous odor presentation. We observed behavioral responses to PO in neuropathic and control mice in an open field setting. We find that neuropathic mice show hypervigilance to PO, confirming previous results. However, we also find increased anxiety responses to neutral odor in neuropathic mice, which manifests as maladaptive pain. This demonstrates that this maladaptive nature of pain could be an evolutionary adaptation aimed at reducing injury-induced vulnerability.

Association of Chronic Pain with Biomarkers of Neurodegeneration, Microglial Activation, and Inflammation in Cerebrospinal Fluid and Impaired Cognitive Function

OBJECTIVE

Debate surrounds the role of chronic pain as a risk factor for cognitive decline and dementia. This study aimed at examining the association of chronic pain with biomarkers of neurodegeneration using data from the Alzheimer's Disease Neuroimaging Initiative.

METHODS

Participants were classified using the ATN (amyloid, tau, neurodegeneration) classification. Chronic pain was defined as persistent or recurrent pain reported at baseline. For each ATN group, analysis of covariance models identified differences in cerebrospinal fluid (CSF) levels of amyloid β1-42 , phosphorylated tau 181 (ptau181 ), total tau (t-tau), soluble triggering receptor expressed on myeloid cells 2 (sTREM2), and cognitive function between chronic pain states. Differences in CSF levels of inflammatory markers between chronic pain states were further analyzed. Linear mixed effect models examined longitudinal changes.

RESULTS

The study included 995 individuals, with 605 (60.81%) reporting chronic pain at baseline. At baseline, individuals with suspected non-Alzheimer pathophysiology and chronic pain showed increased CSF levels of t-tau and sTREM2. Chronic pain was associated with increased tumor necrosis factor α levels, irrespective of the ATN group. Longitudinally, an increase in ptau181 CSF levels was observed in chronic pain patients with negative amyloid and neurodegeneration markers. Amyloid-positive and neurodegeneration-negative chronic pain patients showed higher memory function cross-sectionally. No significant longitudinal decline in cognitive function was observed for any ATN group.

INTERPRETATION

Our study suggests that chronic pain induces neuronal damage and microglial activation in particular subgroups of patients along the AD spectrum. Further studies are needed to confirm these findings. ANN NEUROL 2023.

Predictors of Long-COVID-19 and its Impact on Quality of Life: Longitudinal Analysis at 3, 6 and 9 Months after Discharge from a Portuguese Centre

INTRODUCTION

Long-COVID-19 impacts health-related quality of life (HR-QoL) but data is scarce. The aim of this study was to describe and prospectively assess the prevalence and risk factors for long-COVID-19 after hospital discharge, and to evaluate its impact on patient HR-QoL.

MATERIAL AND METHODS

Single-centre longitudinal study including all COVID-19 patients discharged between December 2020 and February 2021. Patients were contacted remotely at three, six and nine months. Data were collected as follows: 1) Long-COVID-19 symptoms were self-reported; 2) HRQoL were assessed using the 3-level EuroQoL-5D (EQ-5D-3L) questionnaire. Pregnant women, demented, bedridden, and non-Portuguese-speaking patients were excluded.

RESULTS

The three-, six- and nine-month assessments were completed by 152, 117 and 110 patients (median age: 61 years; male sex: 56.6%). Long-COVID-19 (≥ 1 symptom) was reported by 66.5%, 62.4% and 53.6% of patients and HR-QoL assessment showed impairment of at least some domain in 65.8%, 69.2% and 55.4% of patients at three, six and nine months, respectively. Fatigue was the most common long-COVID-19 symptom. Anxiety/depression domain was the most frequently affected in all three time-points, peaking at six months (39%), followed by pain/discomfort and mobility domains. Long-COVID-19 was associated with the impairment of all EQ-5D-3L domains except for self-care domain at each time-point. Neither intensive care unit admission nor disease severity were associated with long-COVID-19 nor with impairment of any EQ-5D-3L domain. After adjusting for sex, age, frailty status, and comorbid conditions, long-COVID-19 remained significantly associated with HR-QoL impairment at three (OR 4.27, 95% CI 1.92 - 9.52, p < 0.001), six (OR 3.46, 95% CI 1.40 - 8.57, p = 0.007) and nine months (OR 4.13, 95% CI 1.62 - 10.55, p = 0.003) after hospital discharge. In a longitudinal analysis, patients reporting long-COVID-19 at three months had an EQ-5D-3L index value decreased by 0.14 per visit (p < 0.001) compared to those without long-COVID-19 and both groups had a non-significant change in mean EQ-5D-3L index over the nine-month period (time-point assessment, Z = 0.91, p = 0.364).

CONCLUSION

Clinical sequelae associated with long-COVID-19 can persist for at least nine months after hospital discharge in most patients and can impair long-term HR-QoL in more than half of patients regardless of disease severity, and clinicodemographic characteristics.

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.

The Relationship Between Chronic Pain and Cognitive Impairment in the Elderly: A Review of Current Evidence

Chronic pain and cognitive impairment are prevalent geriatric syndromes in the population of older adults, and they are the main cause of disability in people over sixty-five years of age. As the global population continues to age, chronic pain and cognitive impairment will affect an increasing number of older adults. While numerous studies in recent years have shown that chronic pain is associated with cognitive decline, the exact mechanisms linking the two remain unclear. In this review, we aim to present the available evidence on the connection between chronic pain and cognitive impairment and to discuss the potential mechanisms by which chronic pain affects cognitive function. In addition, we review potential therapeutic interventions targeting psychological factors, microglia activation, and altered gut flora that may improve and prevent cognitive decline in people with chronic pain.

Increasing Pain Interference Is Associated With Cognitive Decline Over Four Years Among Older Puerto Rican Adults

BACKGROUND

Pain is associated with cognitive decline among older adults, but few studies have investigated bidirectional associations between pain and cognitive decline, especially in older Hispanic populations. Our objective was to assess the bidirectional association between pain interference and cognitive performance in a sample of older Puerto Rican adults.

METHODS

Data came from baseline and 4-year follow-up of the Puerto Rican Elderly: Health Conditions Study, a longitudinal representative study of Puerto Rican older adults aged 60 and older. Pain and cognitive performance were assessed at each wave. A pain interference variable was created using the sum of pain status (yes/no) and pain interference (yes/no; range 0-2). Global cognitive performance was assessed with the Mini-Mental Cabán. We tested bidirectional associations using a path model with concurrent and cross-lagged paths between pain and cognitive performance, adjusting for sociodemographic and health factors (n = 2 349).

RESULTS

Baseline pain interference was not associated with baseline cognitive performance (p = .636) or with cognitive performance at follow-up (p = .594). However, increased pain interference at follow-up was associated with greater cognitive decline at follow-up (β = -0.07, standard error [SE] = 0.02, p = .003). Greater baseline cognitive performance was associated with lower pain interference at follow-up (β = -0.07, SE = 0.02, p = .007).

CONCLUSIONS

These findings highlight the importance of worsening pain interference as a potentially modifiable risk factor for cognitive decline, as pain treatment options exist. Additionally, better baseline cognitive performance may be a protective factor for pain, providing further evidence of the dynamic relationship between pain and cognitive performance.

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.

Transcriptome Profiles of IncRNA and mRNA Highlight the Role of Ferroptosis in Chronic Neuropathic Pain With Memory Impairment

Background: Chronic neuropathic pain is commonly associated with memory loss, which increases the risk of dementia, lowers life quality and spending. On the other hand, the molecular processes are unknown, and effective therapies have yet to be discovered. Long non-coding RNAs (lncRNAs) are emerging potential therapeutic targets for chronic pain, but their role in chronic pain-induced memory impairment is unknown. Methods: We established a CCI-induced memory impairment rat model. To investigate and validate the gene expression alterations in the hippocampus of CCI-induced memory impairment, we used RNA-Seq, bioinformatics analysis, qRT-PCR, western blot, immunostaining, Nissl staining, and Diaminobenzidine-enhanced Perls' stain. Results: CCI rats displayed long-term memory deficits in the Y maze and novel objective recognition tests, and chronic mechanical and thermal pain hypersensitivity in the hind paws. We found a total of 179 differentially expressed mRNAs (DEmRNAs) (81 downregulated and 98 upregulated) and 191 differentially expressed long noncoding RNAs (DElncRNAs) (87 downregulated and 105 upregulated) between the hippocampus CA1 of CCI-induced memory impairment model and the sham control, using RNA-Seq expression profiles. The most enriched pathways involving oxidation and iron metabolism were explored using a route and function pathway analysis of DEmRNAs and DElncRNAs. We also discovered that ATF3 was considerably overexpressed in the hippocampal CA1 area, and gene markers of ferroptosis, such as GPX4, SLC7A11, SLC1A5, and PTGS2, were dysregulated in the CCI-induced memory impairment paradigm. Furthermore, in the hippocampus CA1 of CCI-induced memory impairment, lipid peroxidation and iron overload were considerably enhanced. Fer-1 treatment reversed ferroptosis damage of CCI with memory impairment model. Finally, in CCI-induced memory impairment, a competing RNA network analysis of DElncRNAs and DEmRNAs was performed to investigate the putative regulatory link of DElncRNAs on DEmRNAs via miRNA sponging. Conclusion: Using RNA-Seq, we created a genome-wide profile of the whole hippocampus of a rat model of CCI-induced memory impairment. In the hippocampus, pathways and function analyses revealed numerous intriguing genes and pathways involved in ferroptosis and memory impairment in response to chronic pain stress. As a result, our research may aid in the identification of potential and effective treatments for CCI-induced memory impairment.