Systematic review and meta-analysis on the association between chronic low back pain and cognitive function

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.

Effects of attentional focus on quiet standing balance control in individuals with non-specific chronic low back pain

Despite the widespread research about the effects of attentional focus on balance control in different populations, to the best of our knowledge, no study has yet investigated the effects of attentional focus instructions on balance control in individuals with chronic low back pain (CLBP). Therefore, this study was aimed to compare the effects of internal focus (IF) and external focus (EF) of attention on quiet standing balance control between individuals with CLBP and healthy controls. Twenty individuals with CLBP and 20 healthy controls were enrolled in this quasi-experimental study. The participants were asked to stand still with eyes open and eyes closed while performing three tasks: baseline standing with no focus instructions, internally focusing on their feet, and externally focusing on two markers were placed on the force platform. Statistical analyses showed a significant main effect of group for mean total velocity (p = 0.02), area (p = 0.01), and displacement in mediolateral (ML) direction (p = 0.003). Moreover, a significant main effect of vision was observed for mean total velocity (p < 0.001), area (p < 0.001), and displacement in anteroposterior (AP) (p < 0.001) and ML directions (p < 0.001). Also, the results revealed a significant main effect of attentional focus for mean total velocity (p < 0.001), area (p < 0.001), and displacement in AP (p < 0.001) and ML directions (p = 0.01). Our results showed that in both healthy controls and individuals with CLBP, EF led to improve quiet standing balance control compared to IF and control conditions. From a clinical perspective, it may be useful for physical therapists to consider the use of instruction cues that direct performer's attention away from the body for improving quiet standing balance control in individuals with CLBP.

Causal associations between frailty and low back pain: a bidirectional two-sample mendelian randomization study

BACKGROUND

Previous observational studies have revealed a potentially robust bidirectional relationship between frailty and low back pain (LBP). However, the precise causal relationship remains unclear.

METHODS

To examine the potential causal association between frailty and LBP, we conducted bidirectional two-sample Mendelian randomization analysis (MR) study. Genetic data on frailty index (FI) and LBP were acquired from publicly available genome-wide association studies (GWAS). Various MR methodologies were utilized, such as inverse variance weighting (IVW), weighted median, and MR-Egger, to evaluate causality. Additionally, sensitivity analyses were conducted to evaluate the robustness of the findings.

RESULTS

Genetically predicted higher FI (IVW, odds ratio [OR] = 1.66, 95% CI 1.17-2.36, p = 4.92E-03) was associated with a higher risk of LBP. As for the reverse direction, genetic liability to LBP showed consistent associations with a higher FI (IVW, OR = 1.13, 95% CI 1.07-1.19, p = 2.67E-05). The outcomes from various MR techniques and sensitivity analyses indicate the robustness of our findings.

CONCLUSION

Our research findings provide additional evidence bolstering the bidirectional causal relationship between frailty and LBP.

Association between chronic pain classes and cognitive function in older adults: A cross-sectional study based on latent class analysis

The purpose of this study was to identify latent classes of chronic pain in older adults based on perceptual, cognitive, behavioral, emotional and social factors, and to explore the associations between each class of chronic pain and different cognitive domains. A total of 629 participants were included. Three classes of chronic pain were identified: "episodic recurrent mild pain with good psychosocial state" (class 1), "episodic recurrent moderate pain with general psychosocial state" (class 2) and "continuous multilocational severe pain with attacks accompanied by poor psychosocial state and avoidance of activity" (class 3). After adjusting for relevant confounders, chronic pain presenting as class 1 was associated with worse memory; class 2 was associated with worse global cognitive function, memory, information processing speed, and executive function; and class 3 was additionally associated with worse attention compared to class 2. The findings contribute to the development of targeted programs for treating pain and improving cognitive functioning.