Sex Differences in the Psychophysical Response to Contact Heat in Moderate Cognitive Impairment Alzheimer's Disease: A Cross-Sectional Brief Report

Dyadic Comparison of Pain and Stress in Alzheimer's Disease and Caregivers

BACKGROUND

Millions of people live with dementia worldwide, relying heavily on family caregivers. Pain is common in both people living with Alzheimer's disease (PLWAD) and their caregivers, contributing to stress and burden. To our knowledge, this is the first study to examine the relationship between pain, stress, hair cortisol, and mental health in PLWAD and their caregivers and how these factors are linked to caregiver burden.

METHODS

This exploratory pilot study included five PLWAD-caregiver dyads. Participants completed questionnaires on pain, mental health, and demographics. Hair samples were collected for cortisol analysis. Pearson correlation coefficients (r) were used to assess relationships between various factors of PLWAD and their caregivers.

RESULTS

Contrary to expectations, pain and mental health measures for PLWAD displayed a trend toward negative correlation with their hair cortisol levels. Conversely, caregiver pain and mental health measures had a trend toward positive correlation with their hair cortisol levels. There was also a trend that higher pain in PLWAD was associated with higher caregiver burden.

CONCLUSION

This exploratory pilot study showed associational trends suggesting a complex relationship between pain, mental health, and stress in PLWAD-caregiver dyads. This preliminary work will inform future studies that can help advance targeted, tailored interventions.

Mechanisms of comorbidity between Alzheimer's disease and pain

Clinical studies have revealed a significant correlation between pain and neurodegenerative diseases, particularly Alzheimer's disease (AD). However, due to cognitive and speech impairments, AD patients, especially those in moderate to severe stages, are often overlooked in pain management. The challenges in obtaining pain-related information from this population exacerbate the issue. Although recent clinical research has increasingly recognized the comorbidity of AD and pain, the pathological alterations and interactive mechanisms underlying this relationship remain inadequately explored. This review provides a comprehensive analysis of the clinical features and pathological mechanisms of AD with and without pain comorbidity. It examines underlying processes, including neuroinflammation, peripheral-central immune interactions, and neurotransmitter dynamics. Furthermore, it highlights current pain assessment and management strategies in AD patients. By offering a theoretical framework, this review aims to support the development of effective pain management approaches and serve as a reference for clinical interventions targeting AD-associated pain. HIGHLIGHTS: The comorbidity between AD and CP encompasses multiple interrelated biological pathways, such as neurodegeneration and inflammatory responses. The damage to neurons and synapses in AD patients influences the brain regions responsible for processing pain, thereby reducing the pain response. Neuroinflammation plays a vital role in the development of both AD and CP. Enhanced inflammatory responses have an impact on the CNS and promote sensitization. Common neurotransmitter alterations exist in the comorbidity of AD and CP, influencing cognition, emotion, and pain perception.

Gender Differences in Pain Threshold, Unpleasantness, and Descending Pain Modulatory Activation Across the Adult Life Span: A Cross Sectional Study

The neurobiological underpinnings of gender differences in pain perception, and how these differences may be modified by age, are incompletely understood, placing patients at risk of suboptimal pain management. Using functional magnetic resonance imaging, we examined brain responses in the descending pain modulatory system (DPMS, specifically, dorsolateral prefrontal cortex, anterior cingulate cortex, insula, hypothalamus, amygdala, and periaqueductal gray, during an evoked pain task. We investigated the interaction of age and gender in our sample of healthy adults (27 females, 32 males, 30-86 years) on DPMS response. In a perceptually matched thermal pain paradigm, we investigated pain unpleasantness and neural responses for 3 heat pain percepts: just noticeable pain, weak pain, and moderate pain (MP). Females reported just noticeable pain at a lower temperature, but reported less unpleasantness at weak pain and MP percepts, compared to males. There was a significant age-by-gender interaction during moderate pain in the right anterior cingulate cortex and bilateral insula, such that, males had a stronger positive relationship between DPMS response and age compared to females in these regions. Our results indicate that differences in DPMS responses may explain some gender differences in pain perception and that this effect may change across the adult lifespan. PERSPECTIVE: Gender differences in pain have been well-documented but the brain mechanisms for these differences are still unclear. This article describes potential differences in brain functioning during different levels of pain that could explain differences in pain responses between men and women across the adult lifespan.

Sex-Specific Acute Cerebrovascular Responses to Photothrombotic Stroke in Mice

Mechanisms underlying cerebrovascular stroke outcomes are poorly understood, and the effects of biological sex on cerebrovascular regulation post-stroke have yet to be fully comprehended. Here, we explore the overlapping roles of gonadal sex hormones and rho-kinase (ROCK), two important modulators of cerebrovascular tone, on the acute cerebrovascular response to photothrombotic (PT) focal ischemia in mice. Male mice were gonadectomized and female mice were ovariectomized to remove gonadal hormones, whereas control ("intact") animals received a sham surgery prior to stroke induction. Intact wild-type (WT) males showed a delayed drop in cerebral blood flow (CBF) compared with intact WT females, whereby maximal CBF drop was observed 48 h following stroke. Gonadectomy in males did not alter this response. However, ovariectomy in WT females produced a "male-like" phenotype. Intact Rock2+/- males also showed the same phenotypic response, which was not altered by gonadectomy. Alternatively, intact Rock2+/- females showed a significant difference in CBF values compared with intact WT females, displaying higher CBF values immediately post-stroke and showing a maximal CBF drop 48 h post-stroke. This pattern was not altered by ovariectomy. Altogether, these data illustrate sex differences in acute CBF responses to PT stroke, which seem to involve gonadal female sex hormones and ROCK2. Overall, this study provides a framework for exploring sex differences in acute CBF responses to focal ischemic stroke in mice.

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.

Gender differences in interactions and depressive symptoms among hospitalized older patients living with dementia

Alzheimer's disease or a related dementia (ADRD) disproportionately affects women with two-thirds of individuals with ADRD comprised of women. This study examined gender-related differences in the quality of staff-patient interactions and depressive symptoms among hospitalized older patients living with dementia. This secondary analysis utilized baseline data of 140 hospitalized older patients with dementia who participated in the final cohort of a randomized controlled trial (ClinicalTrials.gov identifier: NCT03046121) implementing Family centered Function-focused Care (Fam-FFC). On average, the participants (male = 46.1%, female = 52.9%) were 81.43 years old (SD = 8.29), had positive interactions with staff and lower depressive symptoms based on Quality of Interaction Schedule (QUIS) scores and Cornell Scale for Depression in Dementia (CSDD) scores, respectively. Although males had more positive interactions (male = 6.06, SD = 1.13; female = 5.59, SD = 1.51) and lesser depressive symptoms (male = 7.52, SD = 4.77; female = 8.03, SD = 6.25) than females, no statistically significant gender differences were observed in linear models with appropriate covariates or multivariant analysis of covariant (MANCOVA). However, the multigroup regression conducted to further probe marginally significant moderation effect of gender and pain on staff-patient interactions demonstrated that greater pain was significantly related to lower quality or less positive staff-patient interactions for females compared to males (χ2diff (1) = 4.84, p = .03). Continued evaluation of gender differences is warranted to inform care delivery and interventions to improve care for hospitalized older patients with dementia.

Psychophysics of Pain: A Methodological Introduction

For over 100 years, psychophysics ..÷ the scientific study between physical stimuli and sensation ... has been successfully employed in numerous scientific and healthcare disciplines, as an objective measure of sensory phenomena. This manuscript provides an overview of fundamental psychophysical concepts, emphasizing pain and research application..÷defining common terms, methods, and procedures.Psychophysics can provide systematic and objective measures of sensory perception that can be used by nursing scientists to explore complex, subjective phenomena..÷such as pain perception. While there needs to be improved standardization of terms and techniques, psychophysical approaches are diverse and may be tailored to address or augment current research paradigms. The interdisciplinary nature of psychophysics..÷like nursing..÷provides a unique lens for understanding how our perceptions are influenced by measurable sensations. While the quest to understand human perception is far from complete, nursing science has an opportunity to contribute to pain research by using the techniques and methods available through psychophysical procedures.

Increased pain unpleasantness and pain-related fMRI activation in the periaqueductal gray in Alzheimer's disease

Background

Pain continues to be underrecognized and undertreated in people with Alzheimer's disease (AD). The periaqueductal gray (PAG) is essential to pain processing and modulation yet is damaged by AD. While evidence exists of altered neural processing of pain in AD, there has not been a focused investigation of the PAG during pain in people with AD.

Purpose

To investigate the role of the PAG in sensory and affective pain processing for people living with AD.

Methods

Participants from a larger study completed pain psychophysics assessments and then a perceptually-matched heat pain task (warmth, mild, and moderate pain) during a functional MRI scan. In this cross-sectional study, we examined blood oxygenation level-dependent (BOLD) responses in the PAG and other pain-related regions in participants with AD (n = 18) and cognitively intact older adults (age- and sex-matched, n = 18). Associations of BOLD percent signal change and psychophysics were also examined.

Results

There were significant main effects of AD status on the temperature needed to reach each perception of warmth or pain, where people with AD reached higher temperatures. Furthermore, participants with AD rated mild and moderate pain as more unpleasant than controls. PAG BOLD activation was greater in AD relative to controls during warmth and mild pain percepts. No significant differences were found for moderate pain or in other regions of interest. Greater PAG activation during mild pain was associated with higher affective/unpleasantness ratings of mild pain in participants with AD but not in controls.

Conclusion

Results suggest a role for the PAG in altered pain responses in people with AD. The PAG is the primary source of endogenous opioid pain inhibition in the neuroaxis, thus, altered PAG function in AD suggests possible changes in descending pain inhibitory circuits. People with AD may have a greater risk of suffering from pain compared to cognitively intact older adults.

The Relationship Between Pain, Function, Behavioral, and Psychological Symptoms of Dementia and Quality of Life

BACKGROUND

This study evaluated the association between age, sex, comorbidities, cognition, and administration of opioids with pain and the impact of all of these variables plus function, agitation, resistiveness to care, and depression on quality of life among residents in nursing home with severe dementia.

DESIGN

This was a descriptive study using baseline data from the Evidence Integration Triangle for Behavioral and Psychological Symptoms of Dementia implementation study.

METHODS

Model testing was done using structural equation modeling. The sample included 553 residents from 55 nursing homes with a mean age of 83.88 (standard deviation = 10.44) and mean Brief Interview of Mental Status of 4.30 (standard deviation = 3.50).

RESULTS

There were significant associations showing those who were older, male, had fewer comorbidities, better cognition, and were black were more likely to have pain. Pain, in combination with the demographic and descriptive variables, explained 32% of the variance in function, 75% of the variance in depression, 88% of the variance in agitation, 98% of the variance in resistiveness to care, and 92% of the variance in quality of life. The model however did not show a good fit to the data.

SETTING

The study was done in 55 nursing homes in Maryland and Pennsylvania.

PARTICIPANTS/SUBJECTS

A total of 553 residents were included in the study.

CONCLUSIONS

The model did not have a good fit with the data which likely was due to the lack of variance in outcomes. The hypothesized paths, with the exception of opioid use, were significant.

Treating the most vulnerable: A discursive review of experimental pain in Alzheimer's disease

AIM

The purpose of this manuscript is to summarize research on how experimental pain is experienced by adults with Alzheimer's disease (AD) and to translate results into implications for nurses.

DESIGN

This discursive review synthesizes the results of three previous research studies exploring experimental pain in adults with AD.

METHODS

Using a series of fictional clinical vignettes, the authors discuss how the results from three previous papers using acute experimental pain can potentially be translated into clinical practice. The authors also introduce the reader to the concept of research-related psychophysics using introductory definitions and concepts with the impetus to encourage other nurses to consider this research methodology.

RESULTS

Pain characteristics in AD that differ from cognitively intact controls must be explored to properly address pain in this population. Nurses are well positioned to address these issues in order to provide a high quality of care to adults with AD.

Uncontrolled Pain and Risk for Depression and Behavioral Symptoms in Residents With Dementia

OBJECTIVES

Limited cohort studies have assessed the association between uncontrolled pain and risk for behavioral and psychological symptoms of dementia (BPSDs). We conducted a longitudinal cohort study to examine whether associations exist between uncontrolled pain and risk for 2 common BPSDs-depression and behavioral symptoms-among long-term care (LTC) residents with Alzheimer disease and related dementia (ADRD).

DESIGN

This retrospective cohort study analyzed quarterly data from the 5% Medicare sample linked to Minimum Data Set (MDS) 3.0 between January 1, 2011, and December 31, 2015.

SETTING AND PARTICIPANTS

LTC residents aged 50 years or older with ADRD who had chronic pain and at least 2 quarterly MDS 3.0 assessments.

METHODS

LTC residents were followed up quarterly from first observed quarterly MDS 3.0 until first outcome event or last observed quarterly MDS 3.0. Uncontrolled pain was defined as numerical rating scale >4, verbal descriptor scale of moderate or severe pain, or ≥1 pain indicators on the Checklist of Nonverbal Pain Indicators. Depression was defined as ≥10 on the Patient Health Questionnaire 9; behavioral symptoms were defined as the presence of psychotic (delusions or hallucinations) or disruptive behaviors (rejection of care, or physical, verbal, or other aggressive behaviors). Generalized linear models (GLMs) with marginal structural modeling (MSM) stabilized weights were used to examine uncontrolled pain and outcome risk.

RESULTS

The incidence rate of depression and behavioral symptoms during follow-up was 9.4 and 23.1 per 100 resident-years, respectively. Results from the MSM-GLMs showed that LTC residents with uncontrolled pain had a higher risk than those with controlled pain for developing depression [hazard ratio 1.67, 95% confidence interval (CI) 1.54-1.81] and behavioral symptoms (hazard ratio 1.28, 95% CI 1.19-1.37).

CONCLUSIONS AND IMPLICATIONS

Uncontrolled pain was associated with elevated risk for depressive and behavioral symptoms in dementia, underscoring the importance of pain assessment and control among LTC residents with ADRD.

Experimentally evoked pain in Alzheimer's disease

BACKGROUND

Pain continues to be underrecognized and undertreated in Alzheimer's disease (AD) while existing guidance about pain assessment and management in dementia is not widespread. Brain regions involved in pain processing and modulation are damaged during AD, and the pain experience in AD is not well understood. Experimental pain studies using psychophysics can further our understanding of the pain experience in AD, which may lead to improved assessment and management of pain in people living with AD.

OBJECTIVE

A systematic review was conducted to explicate the current understanding of experimentally evoked pain in AD from primary research using psychophysical methods.

DATA SOURCES

Peer-reviewed publications were found via PubMed, CINAHL, and PsycINFO. A total of 18 primary research, peer-reviewed full articles that met inclusion criteria were included, representing 929 total participants.

CONCLUSIONS

Experimentally evoked pain in people with AD demonstrates that despite cognitive impairment and a reduced ability to effectively communicate, individuals with AD experience pain similar to or more unpleasant than cognitively intact older adults. This may mean amplified pain unpleasantness in people with AD.

IMPLICATIONS FOR PRACTICE

Our current best practices need to be widely disseminated and put into clinical practice. Self-report of pain continues to be the gold standard, but it is ineffective for noncommunicative patients and those unable to understand pain scales or instructions because of memory/cognitive impairment. Instead, pain treatment should be ethically initiated based on patient reports and behaviors, caregiver/surrogate reports, review of the medical record for painful conditions, analgesic trials, and regular reassessments.

Determining the impact of age and sex on the psychophysical and neurophysiological response to thermal pain across the adult lifespan

AIMS

Determine sex- and age-associated psychophysical and neurophysiological differences in the processing of pain across the adult lifespan.

DESIGN

Preliminary, exploratory, cross-sectional study.

METHODS

Using psychophysics (to measure intensity and unpleasantness) and functional magnetic resonance imaging blood oxygenation level dependent methods (to measure stimulus-evoked brain activation), we will examine sex- and age-associated differences in thermal pain processing and their underlying neurophysiology in a broad range of healthy adults (ages 30-89). We will acquire resting state functional connectivity data for secondary analyses exploring whether resting state connectivity predicts psychophysical and neurophysiological responses to thermal pain. To examine the effects of altered blood flow, we will acquire resting-state arterial spin labeling magnetic resonance imaging data to quantify resting cerebral blood flow. We will interpret findings in the context of a proposed neural model of pain, ageing, and sex. Study funding was received in June of 2014. Ethical approval was obtained from the Vanderbilt University IRB prior to study initiation.

CONCLUSION

Exploring the biological reasons for age- and sex-associated differences in pain processing will increase our understanding of pain in older adults. The paucity of neurobiological evidence to support best practice pain management in older adults places these individuals at risk for poor pain management.

IMPACT

Poorly treated pain in older adults is a critical public health problem associated with a poor quality of life and increased healthcare costs. Understanding how age and sex have an impact on central processing of pain across the lifespan is a critical step toward improving personalized pain medicine.

Policy Implications for Pain in Advanced Alzheimer's Disease

Untreated pain in people with Alzheimer's disease continues to be a serious public health problem. Pain is a subjective and complex experience that becomes increasingly challenging to assess as cognition declines. Our understanding of pain processing is incomplete, particularly for special populations such as people living with Alzheimer's disease, and especially in the advanced stages of the disease. Pain-processing networks in the brain are altered in Alzheimer's disease, yet evidence suggests people living with Alzheimer's disease do not experience less pain. Rather, their pain is not adequately recognized or treated. Although scholarly publications provide important assistance, recent widespread reports and guidelines do not include sufficient guidance, especially as Alzheimer's disease progresses to the last stages. Additionally, current pain measurements may not accurately evaluate pain in this condition, and the existing definitions of pain are not adequate when considering the effects of Alzheimer's disease on pain-processing in the brain. There is a need for new, widespread policies, guidelines, and definitions to help clinicians adequately manage pain in people with Alzheimer's disease. These will need to hinge on continued research because it remains unclear how Alzheimer's disease impacts central pain processing, pain expression, and communication of pain. In the meantime, policies and guidelines need to highlight current best practices as well as the fact that pain continues in Alzheimer's disease.

Structural and Functional Remodeling of the Brain Vasculature Following Stroke

Maintenance of cerebral blood vessel integrity and regulation of cerebral blood flow ensure proper brain function. The adult human brain represents only a small portion of the body mass, yet about a quarter of the cardiac output is dedicated to energy consumption by brain cells at rest. Due to a low capacity to store energy, brain health is heavily reliant on a steady supply of oxygen and nutrients from the bloodstream, and is thus particularly vulnerable to stroke. Stroke is a leading cause of disability and mortality worldwide. By transiently or permanently limiting tissue perfusion, stroke alters vascular integrity and function, compromising brain homeostasis and leading to widespread consequences from early-onset motor deficits to long-term cognitive decline. While numerous lines of investigation have been undertaken to develop new pharmacological therapies for stroke, only few advances have been made and most clinical trials have failed. Overall, our understanding of the acute and chronic vascular responses to stroke is insufficient, yet a better comprehension of cerebrovascular remodeling following stroke is an essential prerequisite for developing novel therapeutic options. In this review, we present a comprehensive update on post-stroke cerebrovascular remodeling, an important and growing field in neuroscience, by discussing cellular and molecular mechanisms involved, sex differences, limitations of preclinical research design and future directions.

Multidimensional Pain Assessment Tools for Ambulatory and Inpatient Nursing Practice

BACKGROUND

One of the critical components in pain management is the assessment of pain. Multidimensional measurement tools capture multiple aspects of a patient's pain experience but can be cumbersome to administer in busy clinical settings.

AIM

We conducted a systematic review to identify brief multidimensional pain assessment tools that nurses can use in both ambulatory and acute care settings.

METHODS

We searched PUBMED/MEDLINE, PsychInfo, and CINAHL databases from January 1977 through December 2019. Eligible English-language articles were systematically screened and data were extracted independently by two raters. Main outcomes included the number and types of domains captured by each instrument (e.g., sensory, impact on function, temporal components) and tool characteristics (e.g., administration time, validity) that may affect instrument uptake in practice.

RESULTS

Our search identified eight multidimensional assessment tools, all of which measured sensory or affective qualities of pain and its impact on functioning. Most tools measured impact of pain on affective functioning, mood, or enjoyment of life. One tool used ecological momentary assessment via a web-based app to assess pain symptoms. Time to administer the varying tools ranged from less than 2 minutes to 10 minutes, and evidence of validity was reported for seven of the eight tools.

CONCLUSIONS

Our review identified eight multidimensional pain measurement tools that nurses can use in ambulatory or acute care settings to capture patients' experience of pain. The most important element in selecting a multidimensional pain measure, though, is that one tool is selected that best fits the practice and is used consistently over time.

Sex Differences in Associations of Cognitive Function with Perceptions of Pain in Older Adults

BACKGROUND

Sex differences in pain have been shown to exist in older adults with normal cognition and people with Alzheimer's disease. It is unknown if sex differences in pain in older adults exist in a range of communicative older adults with varying cognitive ability from no impairment to moderately severe cognitive impairment.

OBJECTIVE

This study proposes to compare the association between psychophysical responses to experimental thermal pain between males and females to determine if sex differences in pain exist across the cognitive spectrum.

METHODS

We conducted a secondary analysis of data from an age- and sex-matched between-groups cross-sectional study examining the psychophysical response to contact heat in people with and without dementia.

RESULTS

Median age of males (n = 38) and females (n = 38) was 73 (range: 68-87) with similar distributions of Mini-Mental State Examination (MMSE) scores (range: 11-30). Findings revealed inverse statistically significant associations with the threshold temperature of warmth (females: r = -0.41, p = 0.010; males: r = -0.33, p = 0.044). There was an apparent divergent pattern of MMSE associations with unpleasantness ratings between the groups. At the moderate pain threshold, that difference became statistically significant (p = 0.033). Females demonstrated a positive association of MMSE with unpleasantness (r = 0.30, p = 0.072), while males demonstrated an inverse association at that respective threshold (r = -0.20, p = 0.221).

CONCLUSIONS

Between-group findings suggest that patterns of responses to thermal stimulus intensity may differ between males and females with worsening cognition with females reporting significantly less unpleasantness with the percept of moderate pain and males reporting significantly higher unpleasantness with moderate pain perception.