Relationship between chronic pain and cognition in cognitively intact older persons and in patients with Alzheimer's disease. The need to control for mood

Effects of Executive Functions and Cognitive Variables in Experimentally Induced Acute Pain Perception during a Distraction Task: A Study on Asymptomatic Pain-Free Individuals

The aim of this study was to investigate the influence of executive functioning and cognitive performance on individual experimentally induced pain perception during distractor tasks in an asymptomatic pain-free population. A total of 59 healthy pain-free subjects (59.3% women, mean age: 46.5 ± 24.7 years) completed a battery test that assessed execution functions (cognitive flexibility, working memory, mental inhibition), attention level, and psychological aspects (anxiety/depressive levels-HADS, pain catastrophizing-PCS, pain anxiety symptoms-PASS 20, sleep quality-PSQI) before conducting two n-back distraction tasks. Pain was experimentally induced with a thermal stimulus that was able to induce moderate pain (70/100 points) and applied to the non-dominant forearm. The thermal stimulus was applied before and during both (one-back and two-back) distraction tasks. The analyses consisted of separated repeated-measures ANOVA that considered the functioning on each test (cognitive flexibility, working memory, mental inhibition, selective attention) and controlled for sociodemographic and psychological aspects by comparing the pain intensity at the baseline and during the one-back and two-back distractor tasks. All ANOVAs found a significant effect of the distraction task, which indicates that the perceived pain intensity scores were lower during the one-back and two-back tasks (p < 0.001) as compared with the baseline. No interaction effect between the distractor tasks and working memory (p = 0.546), mental inhibition (p = 0.16), cognitive flexibility (p = 0.069), or selective attention (p = 0.105) was identified. The current study found that a distraction task decreased the perceived intensity of experimentally induced pain in asymptomatic pain-free individuals and that this effect was not related to executive function or attention levels.

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.

Sex and Sleep Disruption as Contributing Factors in Alzheimer's Disease

Alzheimer's disease (AD) affects more women than men, with women throughout the menopausal transition potentially being the most under researched and at-risk group. Sleep disruptions, which are an established risk factor for AD, increase in prevalence with normal aging and are exacerbated in women during menopause. Sex differences showing more disrupted sleep patterns and increased AD pathology in women and female animal models have been established in literature, with much emphasis placed on loss of circulating gonadal hormones with age. Interestingly, increases in gonadotropins such as follicle stimulating hormone are emerging to be a major contributor to AD pathogenesis and may also play a role in sleep disruption, perhaps in combination with other lesser studied hormones. Several sleep influencing regions of the brain appear to be affected early in AD progression and some may exhibit sexual dimorphisms that may contribute to increased sleep disruptions in women with age. Additionally, some of the most common sleep disorders, as well as multiple health conditions that impair sleep quality, are more prevalent and more severe in women. These conditions are often comorbid with AD and have bi-directional relationships that contribute synergistically to cognitive decline and neuropathology. The association during aging of increased sleep disruption and sleep disorders, dramatic hormonal changes during and after menopause, and increased AD pathology may be interacting and contributing factors that lead to the increased number of women living with AD.

Prevalence of Chronic Pain Among People with Dementia: A Nationwide Study Using French Administrative Data

OBJECTIVE

Alzheimer's disease or Related Dementia (ADRD) is known to disturb pain perception and reduce the ability to report it, resulting in underestimation by practitioners and sub-optimal medical management. The aim of this study was to estimate the prevalence of all types of CP among people with ADRD.

DESIGN

Nationwide cross-sectional study.

SETTINGS

French community-dwelling and nursing home residents.

PARTICIPANTS

People with ADRD, >40 years old, treated with cholinesterase inhibitors or memantine, or with a diagnosis/long-term illness of ADRD and matched with a comparison sample.

SETTINGS

French community-dwelling and nursing home residents.

PARTICIPANTS

People with ADRD, >40 years old, treated with cognitive stimulants (cholinesterase inhibitors and memantine) or with a diagnosis/long-term illness of ADRD and matched with a comparison sample (non-ADRD).

MEASUREMENTS

The capture-recapture method was performed to provide estimates of the prevalence of CP. People treated with analgesic drugs for ≥6 months consecutively or with a medical diagnosis of CP (ICD-10 codes) or referred to a pain center were considered as having CP.

RESULTS

A total of 48,288 individuals were included, of which 16,096 had ADRD and 32,192 without ADRD. The estimated prevalence of CP in people with ADRD was from 57.7% [52.9;63.3] to 57.9%[53.0;63.9], and slightly higher than the non-ADRD sample (from 49.9%[47.0;53.2] to 50.4%[47.3;53.9], p <0.001).

CONCLUSIONS

The prevalence of CP among people living with ADRD was at least the same as or better than individuals without ADRD. This result should alert practitioners' attention to the need for effective pain assessment and management in this population who has difficulties to express and feel pain.

Perspectives on pain in Down syndrome

Down syndrome (DS) or trisomy 21 is a genetic condition often accompanied by chronic pain caused by congenital abnormalities and/or conditions, such as osteoarthritis, recurrent infections, and leukemia. Although DS patients are more susceptible to chronic pain as compared to the general population, the pain experience in these individuals may vary, attributed to the heterogenous structural and functional differences in the central nervous system, which might result in abnormal pain sensory information transduction, transmission, modulation, and perception. We tried to elaborate on some key questions and possible explanations in this review. Further clarification of the mechanisms underlying such abnormal conditions induced by the structural and functional differences is needed to help pain management in DS patients.

Italian guidance on Dementia Day Care Centres: A position paper

Dementia Day Care Centres (DDCCs) are defined as services providing care and rehabilitation to people with dementia associated with behavioural and psychological symptoms (BPSD) in a semi-residential setting. According to available evidence, DDCCs may decrease BPSD, depressive symptoms and caregiver burden. The present position paper reports a consensus of Italian experts of different disciplines regarding DDCCs and includes recommendations about architectural features, requirements of personnel, psychosocial interventions, management of psychoactive drug treatment, prevention and care of geriatric syndromes, and support to family caregivers. DDCCs architectural features should follow specific criteria and address specific needs of people with dementia, supporting independence, safety, and comfort. Staffing should be adequate in size and competence and should be able to implement psychosocial interventions, especially focused on BPSD. Individualized care plan should include prevention and treatment of geriatric syndromes, a targeted vaccination plan for infectious diseases including COVID-19, and adjustment of psychotropic drug treatment, all in cooperation with the general practitioner. Informal caregivers should be involved in the focus of intervention, with the aim of reducing assistance burden and promoting the adaptation to the ever-changing relationship with the patient.

Feasibility, Acceptability, and Efficacy of Home-Based Transcranial Direct Current Stimulation on Pain in Older Adults with Alzheimer's Disease and Related Dementias: A Randomized Sham-Controlled Pilot Clinical Trial

Although transcranial direct current stimulation (tDCS) is emerging as a convenient pain relief modality for several chronic pain conditions, its feasibility, acceptability, and preliminary efficacy on pain in patients with Alzheimer's disease and related dementias (ADRD) have not been investigated. The purpose of this pilot study was to assess the feasibility, acceptability, and preliminary efficacy of 5, 20-min home-based tDCS sessions on chronic pain in older adults with ADRD. We randomly assigned 40 participants to active (n = 20) or sham (n = 20) tDCS. Clinical pain intensity was assessed using a numeric rating scale (NRS) with patients and a proxy measure (MOBID-2) with caregivers. We observed significant reductions of pain intensity for patients in the active tDCS group as reflected by both pain measures (NRS: Cohen's d = 0.69, p-value = 0.02); MOBID-2: Cohen's d = 1.12, p-value = 0.001). Moreover, we found home-based tDCS was feasible and acceptable intervention approach for pain in ADRD. These findings suggest the need for large-scale randomized controlled studies with larger samples and extended versions of tDCS to relieve chronic pain on the long-term for individuals with ADRD.

The missing mechanistic link: Improving behavioral treatment efficacy for pediatric chronic pain

Pediatric chronic pain is a significant global issue, with biopsychosocial factors contributing to the complexity of the condition. Studies have explored behavioral treatments for pediatric chronic pain, but these treatments have mixed efficacy for improving functional and psychological outcomes. Furthermore, the literature lacks an understanding of the biobehavioral mechanisms contributing to pediatric chronic pain treatment response. In this mini review, we focus on how neuroimaging has been used to identify biobehavioral mechanisms of different conditions and how this modality can be used in mechanistic clinical trials to identify markers of treatment response for pediatric chronic pain. We propose that mechanistic clinical trials, utilizing neuroimaging, are warranted to investigate how to optimize the efficacy of behavioral treatments for pediatric chronic pain patients across pain types and ages.

Pain, Opioid Analgesics, and Cognition: A Conceptual Framework in Older Adults

Chronic pain is highly prevalent in older adults and is associated with poor functional outcomes. Furthermore, opioid analgesics are commonly utilized for the treatment of pain in older adults despite well-described adverse effects. Importantly, both chronic pain and opioid analgesics have been linked with impairments in cognitive function, though data are limited. In this manuscript we summarize the evidence and critical knowledge gaps regarding the relationships between pain, opioid analgesics, and cognition in older adults. Furthermore, we provide a conceptual framework to guide future research in the development, implementation, and evaluation of strategies to optimize analgesic outcomes in older adults while minimizing deleterious effects on cognition.

Mid-term improvement of cognitive performance after total hip arthroplasty in patients with osteoarthritis of the hip : a prospective cohort study

AIMS

The aim of this study was to determine whether total hip arthroplasty (THA) for chronic hip pain due to unilateral primary osteoarthritis (OA) has a beneficial effect on cognitive performance.

METHODS

A prospective cohort study was conducted with 101 patients with end-stage hip OA scheduled for THA (mean age 67.4 years (SD 9.5), 51.5% female (n = 52)). Patients were assessed at baseline as well as after three and months. Primary outcome was cognitive performance measured by d2 Test of Attention at six months, Trail Making Test (TMT), FAS-test, Rivermead Behavioural Memory Test (RBMT; story recall subtest), and Rey-Osterrieth Complex Figure Test (ROCF). The improvement of cognitive performance was analyzed using repeated measures analysis of variance.

RESULTS

At six months, there was significant improvement in attention, working speed and concentration (d2-test; p < 0.001), visual construction and visual memory (ROCF; p < 0.001), semantic memory (FAS-test; p = 0.009), verbal episodic memory (RBMT; immediate recall p = 0.023, delayed recall p = 0.026), as well as pain (p < 0.001) with small to large effect sizes. Attention, concentration, and visual as well as verbal episodic memory improved significantly with medium effect sizes over η2 partial = 0.06. In these cognitive domains the within-group difference exceeded the minimum clinically important difference.

CONCLUSION

THA is associated with clinically relevant postoperative improvement in the cognitive functions of attention, concentration, and memory. These data support the concept of a broad interaction of arthroplasty with central nervous system function. Cite this article: Bone Joint J 2022;104-B(3):331-340.

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

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

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

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

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

Pain Processing in Cognitive Impairment and Its Association with Executive Function and Memory: Which Neurocognitive Factor Takes the Lead?

It is well established that individuals with cognitive impairment present with disturbed forms of pain processing of still unknown origin. As a neurocognitive factor, executive functions have become favored candidates for explanation. For further insights, we aimed at comparing executive functions and memory in their association with parameters indicating onset and escalation of pain perception. Subjective ratings of experimentally induced pressure pain applied in ascending series were assessed in older individuals with (N = 32) and without mild cognitive impairments (MCI) (N = 32). We investigated whether executive functioning (Trail Making Test-B (TMT-B), semantic fluency) or memory (word list and figure recall) were more closely linked to the onset and the escalation of pain. For the MCI group, a strong linkage between pain responses and the TMT-B could be found, i.e., poor test performance was associated with weak pain onset but strong pain escalation. The contribution of memory functions was less substantial and systematic. The prominent role of executive function for pain processing in individuals with MCI could be replicated by a test of cognitive flexibility. This lack of adaptability let individuals with MCI be less vigilant to pain at the beginning but allows for escalating pain in the further course. Thus, being first not sufficiently prepared and later overwhelmed as regards pain may be an early problem in MCI individuals with reduced executive functioning.

Association between Self-Reported Pain, Cognition, and Neuropathology in Older Adults Admitted to an Outpatient Memory Clinic-A Cross-Sectional Study

Cognitive impairment has been linked to reduced self-reporting of pain. However, it is unclear whether the various cognitive functions are similarly and/or independently associated with such pain report measures. In the present study, we explored how executive functioning (EF), memory, and global cognition relate to self-reported pain and investigated whether underlying neuropathology partially accounts for these results. We used Lasso categorical regression to analyze data from 179 individuals visiting a memory clinic. The data included the self-reported pain occurrence, intensity, severity and frequency, clinical diagnoses, neuropsychological scores, white matter hyperintensities, medial temporal lobe atrophy, depressive symptoms, and demographics. Our results showed that worse memory and EF performance predicted a lower pain occurrence. In those individuals who did report pain, worse memory predicted lower pain intensity, severity, and frequency levels, but for EF reversed effects were found, with worse EF predicting higher pain scores. These relationships were only partially explained by reductions in white matter and medial temporal lobe integrity. Similar effects were found for depressive symptoms. Our findings highlight the distinct associations of EF and memory with self-reported pain. A similar pattern of relationships found for both self-reported pain and depressive symptoms may reflect shared latent affective components.

Emerging Promise of Cannabinoids for the Management of Pain and Associated Neuropathological Alterations in Alzheimer's Disease

Alzheimer's disease (AD) is an irreversible chronic neurodegenerative disorder that occurs when neurons in the brain degenerate and die. Pain frequently arises in older patients with neurodegenerative diseases including AD. However, the presence of pain in older people is usually overlooked with cognitive dysfunctions. Most of the times dementia patients experience moderate to severe pain but the development of severe cognitive dysfunctions tremendously affects their capability to express the presence of pain. Currently, there are no effective treatments against AD that emphasize the necessity for increasing research to develop novel drugs for treating or preventing the disease process. Furthermore, the prospective therapeutic use of cannabinoids in AD has been studied for the past few years. In this regard, targeting the endocannabinoid system has considered as a probable therapeutic strategy to control several associated pathological pathways, such as mitochondrial dysfunction, excitotoxicity, oxidative stress, and neuroinflammation for the management of AD. In this review, we focus on recent studies about the role of cannabinoids for the treatment of pain and related neuropathological changes in AD.

Neurological dysfunction after cardiac surgery and cardiac intensive care admission: A narrative review part 2: Cognitive dysfunction after critical illness; potential contributors in surgery and intensive care; pathogenesis; and therapies to prevent/treat perioperative neurological dysfunction

Severe cognitive decline and cognitive dysfunction has been attributed to patient's stay in the cardiovascular intensive care unit. Prolonged mechanical ventilation, long duration of stay, sedation protocols, and sleep deprivation contribute to patients developing neurocognitive disorder after intensive care admission and it is associated with poor clinical outcomes. Trauma of surgery, stress of critical care, and administration of anaesthesia evoke a systemic inflammatory response and trigger neuroinflammation and oxidative stress. Anaesthetic agents modulate the function of the GABA receptors. The persistence of these effects in the postoperative period promotes development of cognitive dysfunction. A number of drugs are under investigation to restrict or prevent this cognitive decline.

Pain in dementia

The ageing revolution is changing the composition of our society with more people becoming very old with higher risks for developing both pain and dementia. Pain is normally signaled by verbal communication, which becomes more and more deteriorated in people with dementia. Thus, these individuals unnecessarily suffer from manageable but unrecognized pain. Pain assessment in patients with dementia is a challenging endeavor, with scientific advancements quickly developing. Pain assessment tools and protocols (mainly observational scales) have been incorporated into national and international guidelines of pain assessment in aged individuals. To effectively assess pain, interdisciplinary collaboration (nurses, physicians, psychologists, computer scientists, and engineers) is essential. Pain management in this vulnerable population is also preferably done in an interdisciplinary setting. Nonpharmacological management programs have been predominantly tested in younger populations without dementia. However, many of them are relatively safe, have proven their efficacy, and therefore deserve a first place in pain management programs. Paracetamol is a relatively safe and effective first-choice analgesic. There are many safety issues regarding nonsteroidal anti-inflammatory drugs, opioids, and adjuvant analgesics in dementia patients. It is therefore recommended to monitor both pain and potential side effects regularly. More research is necessary to provide better guidance for pain management in dementia.

The link between chronic pain and Alzheimer's disease

Chronic pain often occurs in the elderly, particularly in the patients with neurodegenerative disorders such as Alzheimer's disease (AD). Although studies indicate that chronic pain correlates with cognitive decline, it is unclear whether chronic pain accelerates AD pathogenesis. In this review, we provide evidence that supports a link between chronic pain and AD and discuss potential mechanisms underlying this connection based on currently available literature from human and animal studies. Specifically, we describe two intertwined processes, locus coeruleus noradrenergic system dysfunction and neuroinflammation resulting from microglial pro-inflammatory activation in brain areas mediating the affective component of pain and cognition that have been found to influence both chronic pain and AD. These represent a pathological overlap that likely leads chronic pain to accelerate AD pathogenesis. Further, we discuss potential therapeutic interventions targeting noradrenergic dysfunction and microglial activation that may improve patient outcomes for those with chronic pain and AD.

Neuropsychological functions of verbal recall and psychomotor speed significantly affect pain tolerance

Background

Effects from cognitive performance on pain tolerance have been documented, however, sample sizes are small and confounders often overlooked. We aimed to establish that performance on neuropsychological tests was associated with pain tolerance, controlling for salient confounders.

Methods

This was a cross‐sectional study nested within the Tromsø‐6 survey. Neuropsychological test performance and the cold pressor test were investigated in 4,623 participants. Due to significant interaction with age, participants were divided into three age groups (<60, ≥60 to <70 and ≥70 years). Cox proportional hazard models assessed the relationship between neuropsychological tests and cold pressure pain tolerance, using hand‐withdrawal as event. The fully adjusted models controlled for sex, education, BMI, smoking status, exercise, systolic blood pressure, sleep problems and mental distress.

Results

In the adjusted models, participants aged ≥70 years showed a decreased hazard of hand withdrawal of 18% (HR 0.82, 95% CI (0.73, 0.92) per standard deviation on immediate verbal recall, and a decreased hazard of 23% (HR 0.77, 95% CI (0.65, 0.08) per standard deviation on psychomotor speed. Participants aged ≥60 to <70 years had a significant decreased hazard of 11% (HR 0.89, 95% CI (0.80, 0.98) per standard deviation on immediate word recall. In participants aged <60 years, there was a decreased hazard of 14% (HR 0.86 95% CI: 0.76, 0.98), per standard deviation on psychomotor speed.

Conclusion

Better performance on neuropsychological tests increased pain tolerance on the cold pressor test. These exposure effects were present in all age groups.

Significance

This paper describes substantial associations between cognitive functioning and cold pressor tolerance in 4,623 participants. Reduced psychomotor speed and poor verbal recall gave greater odds for hand‐withdrawal on the cold pressor task. The associations were stronger in older participants, indicating an interaction with age.

White matter hyperintensities are related to pain intensity in an outpatient memory clinic population: preliminary findings

Background: The association between pain and dementia is complicated and may depend on underlying brain pathology. It was hypothesized that both medial temporal atrophy (MTA) and global cortical atrophy (GCA) predicted no/mild pain, while white matter hyperintensities (WMH) predicted moderate/severe pain.

Objectives: To study the association between pain intensity and measures of brain pathology, more specifically MTA, GCA, and WMH.

Methods: In total, 115 consecutive patients visiting an outpatient memory clinic were included. In total, diagnoses included dementia (N=70), mild cognitive impairment (N=30), and subjective cognitive impairment (N=15). Without administering stimuli, pain intensity was assessed with the Brief Pain Inventory. MTA, GCA, and WMH were measured with a MRI visual rating scale. Logistic regression analyses to examine the relationship between WMH, MTA, GCA, and self-reported pain intensity (no/mild pain versus moderate/severe pain) were adjusted for confounders.

Results: Mean age of the patients was 81 years (IQR: 78–85, 53% female). Moderate/severe pain was reported by 23.5% and associated with greater WMH (OR =3.34, 95% CI =1.01–10.97, p=0.047), but not MTA or GCA.

Conclusions: In contrast to the present results, earlier studies have reported either a positive or negative relationship between pain and brain volume. It is suggested that the presence of dementia may explain the absence of a relationship between pain and brain volume. WMH is positively related with pain in an older memory outpatient population. Considering the small sample size, our findings should be interpreted with caution. Hence, our conclusions are preliminary findings, warranting future replication.

The multiple faces of pain in motor neuron disease: a qualitative study to inform pain assessment and pain management

Purpose: The aim was to explore personal experiences of pain in people with motor neuron disease.Materials and methods: Sixteen participants were individually interviewed on one occasion concerning their experiences of presentation, consequences, and management of pain. Qualitative content analysis with researcher triangulation was used to synthesize and interpret data.Results: Four themes emerged as the result of the analysis: (1) The multiple faces of pain, (2) The thin line between experience of pain and no pain, (3) The negative effects of pain on role functioning (4) Successful coping with pain requiring personal effort and competent engagement. The important findings were the experiences of unpredictability of pain breakthroughs, the efforts required to manage pain, consequences for activity and quality of life, and the suffering induced by diminishment and neglect of pain from both patients and staff.Conclusions: Pain in motor neuron disease seems to have certain and multiple characteristics, which is why there is a need to develop and implement pain assessment methods adapted to this population. Such methods may help make pain more predictable, and increase the possibilities to provide effective and individually tailored pain treatment.IMPLICATIONS FOR REHABILITATIONPain is a common, but often neglected, ailment in motor neuro disease, which deserves more attention from health care.Staff should provide information about the pain being possible to treat successfully with medication, by contrast to the possibility of curing the disease itself.Pain assessments should be implemented during the entire course of the disease, covering a time frame long enough to cover characteristic fluctuations of pain.Whenever possible, facilitate the performance of painful activities of daily living as much as possible to make room for engagement in other personally valued activities of importance for individual quality of life.

The Temporal Relationship between Pain Intensity and Pain Interference and Incident Dementia

BACKGROUND

Chronic pain is common among older adults and is associated with cognitive dysfunction based on cross-sectional studies. However, the longitudinal association between chronic pain and incident dementia in community-based samples is unknown.

OBJECTIVE

We aimed to evaluate the association of pain intensity and pain interference with incident dementia in a community-based sample of older adults.

METHODS

Participants were 1,114 individuals 70 years of age or older from Einstein Aging Study (EAS), a longitudinal cohort study of community-dwelling older adults in the Bronx County, NY. The primary outcome measure was incident dementia, diagnosed using DSM-IV criteria. Pain intensity and interference in the month prior to first annual visit were measured using items from the SF-36 questionnaire. Pain intensity and pain interference were assessed as predictors of time to incident dementia using Cox proportionate hazards models while controlling for potential confounders.

RESULTS

Among participants, 114 individuals developed dementia over an average 4.4 years (SD=3.1) of follow-up. Models showed that pain intensity had no significant effect on time to developing dementia, whereas higher levels of pain interference were associated with a higher risk of dementia. In the model that included both pain intensity and interference as predictors of incident dementia, pain interference had a significant effect on incident dementia, and pain intensity remained non-significant.

CONCLUSION

As a potential remediable risk factor, the mechanisms linking pain interference to cognitive decline merit further exploration.

Pain, aging and dementia: Towards a biopsychosocial model

Dementia is a progressive disease associated with irreversible impairment and loss of cognitive abilities. About half of older people with dementia experience pain. In this paper, we propose that pain in older people with dementia can be conceptualized as the final result of the interaction of three heterogeneous phenomena, pain, aging, and dementia, which are created and influenced by the interactions of predisposing, lifelong, and current biopsychosocial factors. We review pain assessment in people with dementia using both self-report and observational/behavioral measures. We then review the biological/sensory, psychological (cognitive and affective) and social dimensions of pain in dementia. The available data suggest that dementia does not impact pain threshold or tolerance. To date, there is little research on the social dimension of pain in dementia. Changes in the affective domain in response to experimental pain have been contradictory with evidence supporting both increased and decreased unpleasantness and emotional responsiveness in people with dementia compared to healthy controls. Clinically, depression is a significant burden for older people with dementia and chronic pain. The relationship between pain and other neuropsychiatric symptoms is controversial, and there is insufficient evidence on which to base conclusions. Some of the most important dementia-related changes may arise in the cognitive domain, including impairments of semantic and episodic memory for pain, executive function, and pain anticipation. Changes in brain activation and interconnectivity support many of these conclusions. Despite methodological limitations, we conclude there are compelling preliminary data to support a biopsychosocial framework of pain and dementia. Future research directions, especially the need for improved assessment tools, are highlighted.

The Relationship Between Chronic Pain and Neurocognitive Function: A Systematic Review

OBJECTIVE

Understanding the relationship between chronic pain and neurocognition has important implications for the assessment and treatment of patient experiencing pain. This paper provides an overview of the current literature examining the neurocognition-chronic pain relationship and suggests future avenues of research, along with a discussion of clinical implications of the literature findings. Consideration of potential moderators and mediators of this relationship, as well as a brief discussion of the importance of future research in special populations at particular risk for these problems, are also a focus of this paper.

METHODS

This systematic review summarizes the findings of clinical studies in which neurocognitive performance was measured in chronic pain samples. A literature search led to the inclusion of 53 articles in the review.

RESULTS

Studies of neurocognitive performance in clinical chronic pain samples support a relationship between chronic pain and neurocognitive abnormalities, particularly on tests of memory, attention, and processing speed, with mixed data regarding executive functioning.

DISCUSSION

Several factors may moderate or mediate the relationship between chronic pain and neurocognitive functioning, including mood symptoms, medication side effects, and intensity and/or chronicity of pain. Limitations in the literature include a paucity of methodologically rigorous studies controlling for confounding variables (eg, opioid analgesia) and a limited number of studies examining the relationship between chronic pain and traumatic brain injury (a potential precipitant of both pain and neurocognitive impairment). Nonetheless, findings from the existing literature have significant clinical implications, including for populations with heightened risk of both pain and neurocognitive disorders.

Pain and Cognitive Functioning in Adults with Down Syndrome

Objective

The aim of the present study was to examine whether cognitive functioning (i.e., memory and executive functioning) is related to self-reported presence of pain (i.e., affirmative answer to the question whether the individual feels pain) and experience of pain (i.e., intensity and affect) in adults with Down syndrome (DS).

Design, Setting, and Subjects

Cross-sectional study of 224 adults with DS (mean age = 38.1 years, mild-severe intellectual disabilities) in the Netherlands.

Methods

File-based medical information was evaluated. Self-reported presence and experience of pain were assessed during a test session, both in rest and after movement (affect with the facial affective scale [FAS], intensity with the numeric rating scale [NRS]). Neuropsychological tests for memory and executive functioning were used.

Results

Participants with lower memory scores were more likely to report the presence of pain, while controlling for age, gender, physical conditions that may cause pain, language comprehension, and vocabulary ( p  = .030, 58.4% classification rate, N  = 154). No statistically significant associations were found between executive functioning and self-reported presence of pain or between cognitive functioning and self-reported pain experience.

Conclusions

Memory seems to be related to the self-reported presence of pain in adults with DS after explicit inquiry, although the clinical use of this model is yet limited. Therefore, further research is needed for insight into the role of cognitive processes in self-report (e.g., involving aspects such as acquiescence and repeated measurements) to evaluate whether neuropsychological examination could contribute to pain assessment in DS.

Cognitive Impairment in Patients with Chronic Neuropathic or Radicular Pain: An Interaction of Pain and Age

A growing body of empirical research has confirmed an association between chronic pain and cognitive dysfunction. The aim of the present study was to determine whether cognitive function is affected in patients with a diagnosis of chronic neuropathic or radicular pain relative to healthy control participants matched by age, gender, and years of education. We also examined the interaction of pain with age in terms of cognitive performance. Some limitations of previous clinical research investigating the effects of chronic pain on cognitive function include differences in the pain and cognitive scale materials used, and the heterogeneity of patient participants, both in terms of their demographics and pathological conditions. To address these potential confounds, we have used a relatively homogenous patient group and included both experimental and statistical controls. We have also specifically investigated the interaction effect of pain and age on cognitive performance. Patients (n = 38) and controls (n = 38) were administered a battery of cognitive tests measuring IQ, spatial and verbal memory, attention, and executive function. Educational level, depressive symptoms, and state anxiety were assessed as were medication usage, caffeine, and nicotine consumption to control for possible confounding effects. Both the level of depressive symptoms and the state anxiety score were higher in chronic pain patients than in matched control participants. Chronic pain patients had a lower estimated IQ than controls, and showed impairments on measures of spatial and verbal memory. Attentional responding was altered in the patient group, possibly indicative of impaired inhibitory control. There were significant interactions between chronic pain condition and age on a number of cognitive outcome variables, such that older patients with chronic pain were more impaired than both age-matched controls and younger patients with chronic pain. Chronic pain did not appear to predict performance on the Wisconsin Card Sorting Task, which was used a measure of executive function. This study supports and extends previous research indicating that chronic pain is associated with impaired memory and attention.

Perspective: Compared to healthy control participants, patients with chronic neuropathic or radicular pain showed cognitive deficits which were most pronounced in older pain patients.

Chronic Monoarthritis Pain Accelerates the Processes of Cognitive Impairment and Increases the NMDAR Subunits NR2B in CA3 of Hippocampus from 5-month-old Transgenic APP/PS1 Mice

Many factors impact cognitive impairment; however, the effects of chronic pain and the mechanisms underlying these effects on cognitive impairment are currently unknown. Here we tested the hypothesis that chronic pain accelerates the transition from normal cognition to mild cognitive impairment (MCI) in 5-month-old transgenic APP/PS1 mice, an animal model of Alzheimer’s disease (AD), and that neurotoxicity induced by N-methyl-D-aspartic acid receptor (NMDAR) subunits may be involved in this process. Chronic monoarthritis pain was induced in transgenic APP/PS1 mice and 5-month-old wild-type (WT) mice by intra- and pre-articular injections of Freund’s complete adjuvant (FCA) into one knee joint. Pain behavior, learning and memory function, and the distribution and quantity of NMDAR subunits (NR1, NR2A and NR2B) in hippocampal CA1 and CA3 regions were assessed. Our results showed that although persistent and robust monoarthritis pain was induced by the FCA injections, only the transgenic APP/PS1 mice with chronic monoarthritis pain exhibited marked learning and memory impairments. This result suggested that chronic monoarthritis pain accelerated the cognitive impairment process. Furthermore, only transgenic APP/PS1 mice with chronic monoarthritis pain exhibited an overexpression of NR2B and an increased NR2B/NR2A ratio in the hippocampus CA3. These findings suggest that chronic pain is a risk factor for cognitive impairment and that increased neurotoxicity associated with NMDAR subunit activation may underpin the impairment. Thus, NMDARs may be a therapeutic target for the prevention of chronic pain-induced cognitive impairment.

Sigma-1 Receptor Agonism Promotes Mechanical Allodynia After Priming the Nociceptive System with Capsaicin

Sigma-1 receptor antagonists promote antinociception in several models of pain, but the effects of sigma-1 agonists on nociception (particularly when the nociceptive system is primed) are not so well characterized; therefore we evaluated the effects of sigma-1 agonists on pain under different experimental conditions. The systemic administration of the selective sigma-1 agonists (+)-pentazocine and PRE-084, as well as the nonselective sigma-1 agonist carbetapentane (used clinically as an antitussive drug), did not alter sensitivity to mechanical stimulation under baseline conditions. However, they greatly promoted secondary mechanical allodynia after priming the nociceptive system with capsaicin. These effects of sigma-1 agonists were consistent in terms potency with the affinities of these drugs for sigma-1 receptors, were reversed by sigma-1 antagonists, and were not observed in sigma-1 knockout mice, indicating that they are sigma-1-mediated. Repeated systemic treatment with PRE-084 induced proallodynic effects even 24 h after treatment completion, but only after the nociceptive system was primed. However, neither the presence of this drug in the organism nor changes in sigma-1 receptor expression in areas involved in pain processing explains its long-term effects, suggesting that sustained sigma-1 agonism induces plastic changes in the nociceptive system that promote nociception.

Cognitive deficits early in the course of rheumatoid arthritis

OBJECTIVE

The aim was to examine the severity and prevalence of cognitive difficulties in persons with rheumatoid arthritis (RA) within the first three years of diagnosis.

METHOD

One hundred consecutive RA patients aged 28-67 years (90% women) were administered a battery of 6 neuropsychological tests yielding 14 cognitive indices. Self-reported measures of trait anxiety, depression, impact of disease on daily activities, and pain severity were also obtained along with physician-rated disease severity.

RESULTS

Twenty percent of RA patients were classified as cognitively impaired, defined as age- and education-adjusted scores at least 1.5 standard deviations below the population mean on 3 or more cognitive indices. Impaired performance, controlling for age, education, and premorbid cognitive capacity, was detected primarily on measures of short-term memory, immediate and delayed episodic recall, and phonemic fluency. There were modest negative associations between cognitive indices and measures of perceived disease severity (pain level, impact of disease on daily functionality, and overall health quality).

CONCLUSIONS

Cognitive deficits on several domains are frequently encountered in relatively young RA patients during the first few years of the disease and may need to be taken into account as important correlates of disease severity and progression.

Clinical Pain and Neuropsychological Functioning in Parkinson's Disease: Are They Related?

Introduction. Pain is an important nonmotor symptom of Parkinson's disease (PD). Brain areas such as the hippocampus and the prefrontal cortex play an important role in the processing of pain. Since these brain areas are also involved in cognitive functioning, for example, episodic memory and executive functions, respectively, we examined whether a relationship exists between cognitive functioning and spontaneous pain in PD. Methods. Forty-eight patients with PD and 57 controls participated. Cognitive functioning was measured by a comprehensive battery of neuropsychological tests. Both the sensory-discriminative aspect and the motivational-affective aspect of pain were assessed. Multiple linear regression analyses were performed to assess a relation between cognition and pain. Results. Cognition was related to neither the sensory nor the affective aspect of pain in our sample of PD patients. Variance in pain measures was primarily explained by symptoms of depression and anxiety. Discussion. The difference between the affective and the sensory aspect of pain might be due to the neuropathology of PD, which is mainly present in areas processing the affective aspect of pain. Pain treatment might improve when mood is taken into account. We provide several explanations for the lack of an association between pain and cognition.

Impaired recognition memory and cognitive flexibility in the rat L5-L6 spinal nerve ligation model of neuropathic pain

BACKGROUND AND AIMS

Although neuropathic pain is known to negatively affect cognition, the neural mechanisms involved are poorly understood. Chronic pain is associated with changes in synaptic plasticity in the brain which may impact on cognitive functioning. The aim of this study was to model neuropathic pain in mid-aged rats using spinal nerve ligation (SNL). Following establishment of allodynia and hyperalgesia, behaviour was assessed in a battery of cognitive tests. Expression of the presynaptic protein, synaptophysin, and its colocalisation with the vesicular GABA and glutamate transporters (vGAT and vGLUT, respectively), was investigated in the medial prefrontal cortex (mPFC) and hippocampus.

METHODS

Nine month old male Sprague Dawley rats underwent L5-L6 spinal nerve ligation or a sham procedure. Mechanical and cold allodynia and thermal hyperalgesia were assessed using von Frey, acetone and Hargreaves tests, respectively. Cognition was assessed in the novel-object recognition, air-puff passive avoidance and Morris water maze behavioural tasks. Immunohistochemistry was used to examine the expression of synaptophysin in the mPFC and CA1 region of the hippocampus and double labelling of synaptophysin and the vesicular transporters vGAT and vGlut was used to investigate the distribution of synaptophysin on GABAergic and glutamatergic neurons.

RESULTS

SNL rats displayed impaired performance in the novel-object recognition task. Passive-avoidance responding, and spatial learning and memory in the Morris water maze, were unaffected by SNL surgery. However, in the water maze reversal task, pain-related impairments were evident during training and probe trials. SNL surgery was not associated with any differences in the expression of synaptophysin or its colocalisation with vGAT or vGLUT in the mPFC or the hippocampal CA1 region.

CONCLUSIONS

These results suggest that the SNL model of neuropathic pain is associated with deficits in recognition memory and cognitive flexibility, but these deficits are not associated with altered synaptophysin expression or distribution in the mPFC and CA1.

IMPLICATIONS

Cognitive complaints are common amongst chronic pain patients. Here we modelled cognitive impairment in a well-established animal model of neuropathic pain and investigated the neural mechanisms involved. A better understanding of this phenomenon is an important prerequisite for the development of improved treatment of patients affected.

Loss in Executive Functioning Best Explains Changes in Pain Responsiveness in Patients with Dementia-Related Cognitive Decline

There is ample evidence that dementia changes the processing of pain. However, it is not known whether this change in pain processing is related to the general decline in cognitive functioning or whether it may be related to specific domains of cognitive functioning. With the present study we tried to answer this question. We assessed different cognitive domains (orientation, memory, abstract thinking/executive function, aphasia and apraxia, and information processing speed) in 70 older patients with cognitive impairment (mild cognitive impairment up to moderate degrees of dementia). Pain responsiveness was assessed by measuring the nociceptive flexion reflex (NFR) threshold and facial responses to noxious electrical stimulation. Using regression analyses, we assessed which domain of cognitive functioning best predicted variance in pain responsiveness. Variance in pain responsiveness (NFR and facial expressions) was best explained by those items assessing executive functioning even when controlling for overall cognitive performance and memory functioning. The close association between executive functioning and pain responsiveness suggests that dementia-related neurodegeneration in prefrontal areas might result not only in reduced executive functioning but also in a loss of pain inhibitory potency, rendering the patient more vulnerable to pain. Our findings also suggest that pain assessment in dementia should be regularly completed by tests of cognitive functions.

Pain, agitation, and behavioural problems in people with dementia admitted to general hospital wards: a longitudinal cohort study

Pain was common but difficult to detect in hospitals in patients with dementia who had difficulties with self-report. It was associated with aggression and anxiety.

Pain is underdetected and undertreated in people with dementia. We aimed to investigate the prevalence of pain in people with dementia admitted to general hospitals and explore the association between pain and behavioural and psychiatric symptoms of dementia (BPSD). We conducted a longitudinal cohort study of 230 people, aged above 70, with dementia and unplanned medical admissions to 2 UK hospitals. Participants were assessed at baseline and every 4 days for self-reported pain (yes/no question and FACES scale) and observed pain (Pain Assessment in Advanced Dementia scale [PAINAD]) at movement and at rest, for agitation (Cohen–Mansfield Agitating Inventory [CMAI]) and BPSD (Behavioural Pathology in Alzheimer Disease Scale [BEHAVE-AD]). On admission, 27% of participants self-reported pain rising to 39% on at least 1 occasion during admission. Half of them were able to complete the FACES scale, this proportion decreasing with more severe dementia. Using the PAINAD, 19% had pain at rest and 57% had pain on movement on at least 1 occasion (in 16%, this was persistent throughout the admission). In controlled analyses, pain was not associated with CMAI scores but was strongly associated with total BEHAVE-AD scores, both when pain was assessed on movement (β = 0.20, 95% confidence interval [CI] = 0.07-0.32, P = 0.002) and at rest (β = 0.41, 95% CI = 0.14-0.69, P = 0.003). The association was the strongest for aggression and anxiety. Pain was common in people with dementia admitted to the acute hospital and associated with BPSD. Improved pain management may reduce distressing behaviours and improve the quality of hospital care for people with dementia.

Pain in dementia: prevalence and associated factors: protocol of a multidisciplinary study

Background

Pain is a common problem in people with dementia, however the exact prevalence of pain in dementia subtypes, e.g. Alzheimer’s Disease (AD), Vascular Dementia (VaD), Frontotemporal Dementia (FTD) and dementia with Lewy Bodies (DLB), is unknown, as is the relation between pain and the different subtypes of dementia. In this study, the prevalence of pain in people with dementia will be investigated per dementia subtype and the relationship between the various subtypes of dementia and the presence of specific types of pain (i.e. musculoskeletal pain, neuropathic pain and orofacial pain) will be examined. Secondly, associations between various types of pain, cognitive functioning, neuropsychiatric symptoms and quality of life in people with dementia will be examined. A third purpose is to study the value of the assessment of autonomic responses in assessing pain in people with dementia. Finally, the effect of feedback to the attending physician on the presence of pain, based on examination by investigators with backgrounds in neuropsychology, geriatric dentistry and elderly care medicine, will be evaluated.

Methods/Design

A cross-sectional, partially longitudinal observational study in 400 participants with dementia, aged 60 years and older. Participants will be recruited from an outpatient memory clinic and dementia special care units. All participants will be examined by an elderly care medicine trainee, a dentist with experience in geriatric dentistry, and a neuropsychologist. The primary outcome is presence of pain. Secondary outcomes will include oral health, autonomic responses to pain stimulus, vital sensibility and gnostic sensibility, musculoskeletal examination, cognitive functioning, neuropsychiatric symptoms, and quality of life.

Discussion

This study will help to enhance our knowledge regarding the prevalence of different types of pain in different dementia subtypes i.e. AD, VaD, FTD and DLB. This study also aims to contribute to a better understanding of oral health status in people with dementia, the use of autonomic responses in the assessment of pain in people with dementia and the relationships between pain and cognitive symptoms, neuropsychiatric symptoms and quality of life in people with various dementia subtypes and in different stages of the disease.

Chronic pain in "probable" vascular dementia: preliminary findings

BACKGROUND

In a previous study, the levels of pain reported by patients with "possible" vascular dementia (VaD) were higher than those reported by older individuals without dementia.

OBJECTIVE

To examine experienced pain in patients with "probable" VaD, confirmed by brain imaging.

STUDY DESIGN

Observational, cross sectional.

SETTING

Nursing home.

METHODS

The participants were 20 nursing home residents (14 females, 6 males) who met the NINDS-AIREN criteria for "probable" VaD and 22 nursing home residents with a normal mental status (18 females, 4 males). The patients were in a mild to moderate stage of dementia. All of the participants were suffering from arthritis/arthrosis or osteoporosis. Global cognitive functioning was measured by the Mini-Mental State Examination. Pain was assessed by the Coloured Analogue Scale (CAS: original and modified version) and the Faces Pain Scale. The Geriatric Depression Scale and the Symptom Checklist-90 were used to assess mood.

RESULTS

The main finding was that, after controlling for mood, the pain levels indicated by patients with "probable" VaD (M = 102.32; standard deviation [SD] = 53.42) were significantly higher than those indicated by the control group (M = 59.17; SD = 38.75), only according to the CAS modified version (F[1,29]) = 5.62, P = 0.01, η2  = 0.16).

CONCLUSION

As VaD patients may experience greater pain than controls, it is essential for prescribers to be aware of the presence of this neuropathology if these patients are to receive adequate treatment.

Decreased activation of cingulo-frontal-parietal cognitive/attention network during an attention-demanding task in patients with chronic low back pain

INTRODUCTION

Attention deficits have been repeatedly reported via neuropsychological assessment in previous literature in patients with chronic low back pain (CLBP). However, there are few functional neuroimaging studies of patients with CLBP during attention processing, and the exact underlying neural mechanisms are yet to be elucidated.

METHODS

We used functional magnetic resonance imaging (fMRI) to measure the function of the cingulo-frontal-parietal (CFP) cognitive/attention network while performing a multi-source interference task (MSIT) in patients with CLBP. Thirty-six patients with CLBP and 36 healthy controls were included in this study. The fMRI data were analyzed with the FSL-FEAT software.

RESULTS

Our results indicated that patients with CLBP showed significantly less activation in the CFP network including the right dorsolateral prefrontal cortex, the dorsal anterior cingulate cortex, and bilateral superior parietal cortex during attention-demanding (MSITinterference > MSITcontrol) trials compared to the healthy controls. A significant negative correlation was found between the scores of the visual analog scale for pain and activation of the right prefrontal cortex during performing the MSIT in patients with CLBP.

CONCLUSION

Our study provides in vivo imaging evidence of abnormal CFP network function during attention-demanding condition in patients with CLBP, which might reflect partly an adaptation/maladaptation of the brain to the chronic pain states.

The Use of Visual Analog Scales to Compare Pain Between Patients With Alzheimer's Disease and Patients Without Any Known Neurodegenerative Disease and Their Caregivers

Patients diagnosed with Alzheimer's disease (AD) tend to underestimate their pain degree as disease progresses. Their caregivers are the most important source of information by providing regular pain evaluation. Our objectives were to compare pain intensity and affective pain between patients with AD and cognitively normal individuals (N) and to evaluate differences in pain perception between their caregivers. We evaluated pain scores of 121 patients with chronic osteoarticular pain, 60 AD, and 61 N using the colored pain scale/faces pain scale and the caregiver's perception. Data were analyzed using one and two-tailed paired t tests (P< .05). We found that the AD group reported less pain intensity and that their pain was less perceived by their caregiver. This study also points to the need of, when evaluating patients with AD always measure their pain degree using appropriate scales, instead of relying only on the caregiver.

When pain memories are lost: a pilot study of semantic knowledge of pain in dementia

OBJECTIVE

It has been documented that pain in people with dementia is often under-reported and poorly detected. The reasons for this are not clearly defined. This project aimed to explore semantic concepts of pain in people with dementia and whether this is associated with clinical pain report.

DESIGN

Cohort study with nested cross-sectional analysis.

SETTING

Acute general hospital medical wards for older people.

SUBJECTS

People with dementia (N = 26) and control participants (N = 13).

METHODS

Two subtests of semantic memory for pain: (1) Identifying painful situations from a standardized range of pictures; (2) Describing the concept of pain. Participants also indicated whether they were in pain or not, were observed for pain (PAINAD scale) and completed the Wong-Baker FACES scale to indicate pain severity.

RESULTS

Compared with the control group, people with dementia were less able to identify painful situations and used fewer categories to define their concept of pain. In turn, the performance on these two measures was related to the reported presence and, albeit less strongly, to the reported severity of pain, indicating that a reduction in semantic memory for pain is associated with a decline in reported pain.

CONCLUSIONS

This study is the first to show that semantic memory for pain is diminished in dementia patients. When using clinical pain tools, clinicians should consider these effects which may bias clinical pain ratings when they evaluate and manage pain in these patients. This might improve the recognition and management of pain in people with dementia.

Pain reports and pain medication treatment in nursing home residents with and without dementia

AIM

The purpose of this pilot study was to determine if a diagnosis of dementia influenced pain self-reports and pain medication use in a group of verbally communicative nursing home (NH) residents.

METHODS

The study design was a between groups, cross-sectional chart audit and a seven-question structured pain interview comparing outcomes in residents with and without a diagnosis of dementia. The study was carried out at a large metropolitan NH in the southern USA. The participants consisted of 52 long-stay NH residents capable of self-consent with at least one order for pain medication (opioid or non-narcotic) either pro re nata, scheduled or both. Approximately 40% (n = 20) had a diagnosis of dementia.

RESULTS

Although each group had similar pain-related diagnoses, residents without a dementia diagnosis were significantly more likely to have a medication order for an opioid (OR 4.37,95% CI 1.29-14.73, P = 0.018). Based on self-reported pain interview responses, no statistically significant differences were identified between the groups for chronic pain symptoms. However, among residents who reported current pain, those with a dementia diagnosis reported greater pain intensity (based on a 0-10 numeric rating scale) than did those without dementia (median 8.0 vs 6.0, respectively; P = 0.010).

CONCLUSIONS

Verbally communicative NH residents with mild and moderate cognitive impairment can report their pain symptoms and pain intensity. Nurses in long-term care might assume that residents with dementia cannot reliably self-report their pain; however, suffering from untreated severe pain could exacerbate cognitive impairment, worsen functional impairment and severely impair sleep. A brief, focused pain interview might be one method for increasing the detection of moderate to severe pain in verbally communicative NH residents with dementia.

Disruption of persistent nociceptive behavior in rats with learning impairment

Despite the subjective nature of pain experience with cognitive and affective dimensions, preclinical pain research has largely focused on its sensory dimension. Here, we examined the relationship between learning/memory and nociceptive behavior in rats with combined learning impairment and persistent nociception. Learning impairment was induced by bilateral hippocampal injection of a mixed Aβ solution, whereas persistent nociception produced in these rats by complete Freund's adjuvant-induced ankle inflammation. Those rats with learning impairment showed a diminished development of thermal hyperalgesia and mechanical allodynia and a shorter time course of nociceptive behavior without alteration of their baseline nociceptive threshold. In rats with pre-established hyperalgesia and allodynia due to ankle inflammation, bilateral intra-hippocampal injection of cycloheximide (a protein synthesis inhibitor) promoted the earlier recovery of nociceptive behavior. Moreover, expression of Aβ, NR1 subunit of the N-methyl-D-aspartate receptor, and protein kinase Cγ was upregulated, whereas the choline acetyl transferase expression was downregulated, in the hippocampus, thalamus, amygdala, and/or spinal cord of rats with combined learning impairment and persistent nociception. The data indicate that learning impairment could disrupt the response to a state of persistent nociception, suggesting an important role for cognitive maladaptation in the mechanisms of chronic pain. These results also suggest that a preclinical model of combined learning impairment and persistent nociception may be useful to explore the brain mechanisms underlying the transition from acute to chronic pain.

Pain in people with Alzheimer disease: potential applications for psychophysical and neurophysiological research

Pain management in people with dementia is a critical problem. Recently, psychophysical and neuroimaging techniques have been used to extend our understanding of pain processing in the brain as well as to identify structural and functional changes in Alzheimer disease (AD). But interpreting the complex relationship between AD pathology, brain activation, and pain reports is challenging. This review proposes a conceptual framework for designing and interpreting psychophysical and neuroimaging studies of pain processing in people with AD. Previous human studies describe the lateral (sensory) and medial (affective) pain networks. Although the majority of the literature on pain supports the lateral and medial networks, some evidence supports an additional rostral pain network, which is believed to function in the production of pain behaviors. The sensory perception of pain as assessed through verbal report and behavioral display may be altered in AD. In addition, neural circuits mediating pain perception and behavioral expression may be hyperactive or underactive, depending on the brain region involved, stage of the disease, and type of pain (acute experimental stimuli or chronic medical conditions). People with worsening AD may therefore experience pain but be unable to indicate pain through verbal or behavioral reports, leaving them at great risk of experiencing untreated pain. Psychophysical (verbal or behavioral) and neurophysiological (brain activation) approaches can potentially address gaps in our knowledge of pain processing in AD by revealing the relationship between neural processes and verbal and behavioral outcomes in the presence of acute or chronic pain.

Performance-dependent inhibition of pain by an executive working memory task

It is widely assumed that distraction reduces pain. Similarly, it is assumed that pain distracts from concurrent, unrelated cognitive processing, reducing performance on difficult tasks. Taken together, these assumptions suggest pain processing and cognitive function engage an overlapping set of domain-general, capacity-limited mental resources. However, experimental tests of this proposal have yielded mixed results, leading to alternative proposals that challenge the common model of a bidirectional relationship between concurrent pain and task performance. We tested these contrasting positions using a novel concurrent pain and executive working memory paradigm. Both task difficulty and nociceptive stimulus intensity were individually calibrated for each participant. Participants reported less pain during the working memory task than a visually matched control condition. Conversely, increasing levels of heat incrementally reduced task performance. Path analyses showed that variations in pain completely mediated this effect, and that even within a given heat level, trial-by-trial fluctuations in pain predicted decrements in performance. In sum, these findings argue that overlapping cognitive resources play a role in both pain processing and executive working memory. Future studies could use this paradigm to understand more precisely which components of executive function or other cognitive resources contribute to the experience of pain.

Reliability study in five languages of the translation of the pain behavioural scale Doloplus

Non-verbal pain assessment scales are useful tools for pain evaluation in persons with communication disorders and moderate-severe dementia. The Doloplus was one of the first scales to be developed and validated as a pain assessment tool in older adults with dementia. This study aims at evaluating the translation of the Doloplus scale in five languages, as regards test-retest and inter-rater reliability. Results show that both tests are good or excellent for the English, Italian, Portuguese and Spanish versions and moderate for the Dutch version. These results bring a unique opportunity to include the translated Doloplus scale in daily assessment of elderly persons with communication disorders, and future studies should focus on enriching the validation of the scale in each language.