Probable chronic pain, brain structure, and Alzheimer's plasma biomarkers in older men

Chronic pain leads to tau accumulation and hippocampal atrophy in mice. In this study, we provide one of the first assessments in humans, examining the associations of probable chronic pain with hippocampal volume, integrity of the locus coeruleus (LC)-an upstream site of tau deposition-and Alzheimer's Disease-related plasma biomarkers. Participants were mostly cognitively unimpaired men. Probable chronic pain was defined as moderate-to-severe pain in 2+ study waves at average ages 56, 62, and 68. At age 68, 424 participants underwent structural magnestic resonance imaging (MRI) of hippocampal volume and LC-sensitive MRI providing an index of LC integrity (LC contrast-to-noise ratio). Analyses adjusted for confounders including major health conditions, depressive symptoms, and opioid use. Models showed that men with probable chronic pain had smaller hippocampal volume and lower rostral-middle-but not caudal-LC contrast-to-noise ratio compared to men without probable chronic pain. Men with probable chronic pain also had higher levels of plasma total tau, beta-amyloid-42, and beta-amyloid-40 compared to men without probable chronic pain. These findings suggest that probable chronic pain is associated with tau accumulation and reduced structural brain integrity in regions affected early in the development of Alzheimer's Disease. PERSPECTIVE: Probable chronic pain was associated with plasma biomarkers and brain regions that are affected early in Alzheimer's disease (AD). Reducing pain in midlife and elucidating biological mechanisms may help to reduce the risk of AD in older adults.

Social and Neighborhood Context Moderates the Associations Between Processing Speed and Driving Mobility: A 10-year Analysis of the ACTIVE Study

Objectives: Processing speed is essential to functional independence in later life, such as driving a vehicle. Few studies have examined processing speed and driving mobility in the context of racial differences and social determinants of health (SDoH). This study characterized the longitudinal association between processing speed and driving mobility, and how it varied by race and SDoH. Methods: Using data from the control arm of the Advanced Cognitive Training in Vital Elderly study (n = 581, 24.5% Black), multilevel models examined longitudinal associations between processing speed and driving mobility outcomes (driving space, exposure, and difficulty). Race and SDoH moderations were explored. Results: Decline in processing speed measures was associated with increased self-reported driving difficulty, but only for older adults with below-average to average scores for neighborhood and built environments and social community context SDoH domains. Discussion: Findings emphasize the influence of physical and social environmental characteristics on processing speed and driving mobility.

Rostral-middle locus coeruleus integrity and subjective cognitive decline in early old age

OBJECTIVES

Abnormal tau, a hallmark Alzheimer's disease (AD) pathology, may appear in the locus coeruleus (LC) decades before AD symptom onset. Reports of subjective cognitive decline are also often present prior to formal diagnosis. Yet, the relationship between LC structural integrity and subjective cognitive decline has remained unexplored. Here, we aimed to explore these potential associations.

METHODS

We examined 381 community-dwelling men (mean age = 67.58; SD = 2.62) in the Vietnam Era Twin Study of Aging who underwent LC-sensitive magnetic resonance imaging and completed the Everyday Cognition scale to measure subjective cognitive decline along with their selected informants. Mixed models examined the associations between rostral-middle and caudal LC integrity and subjective cognitive decline after adjusting for depressive symptoms, physical morbidities, and family. Models also adjusted for current objective cognitive performance and objective cognitive decline to explore attenuation.

RESULTS

For participant ratings, lower rostral-middle LC contrast to noise ratio (LCCNR) was associated with significantly greater subjective decline in memory, executive function, and visuospatial abilities. For informant ratings, lower rostral-middle LCCNR was associated with significantly greater subjective decline in memory only. Associations remained after adjusting for current objective cognition and objective cognitive decline in respective domains.

CONCLUSIONS

Lower rostral-middle LC integrity is associated with greater subjective cognitive decline. Although not explained by objective cognitive performance, such a relationship may explain increased AD risk in people with subjective cognitive decline as the LC is an important neural substrate important for higher order cognitive processing, attention, and arousal and one of the first sites of AD pathology.

Higher cortical thickness/volume in Alzheimer's-related regions: protective factor or risk factor?

Some evidence suggests a biphasic pattern of changes in cortical thickness wherein higher, rather than lower, thickness is associated with very early Alzheimer's disease (AD) pathology. We examined whether integrating information from AD brain signatures based on mean diffusivity (MD) can aid in the interpretation of cortical thickness/volume as a risk factor for future AD-related changes. Participants were 572 men in the Vietnam Era Twin Study of Aging who were cognitively unimpaired at baseline (mean age = 56 years; range = 51-60). Individuals with both high thickness/volume signatures and high MD signatures at baseline had lower cortical thickness/volume in AD signature regions and lower episodic memory performance 12 years later compared to those with high thickness/volume and low MD signatures at baseline. Groups did not differ in level of young adult cognitive reserve. Our findings are in line with a biphasic model in which increased cortical thickness may precede future decline and establish the value of examining cortical MD alongside cortical thickness to identify subgroups with differential risk for poorer brain and cognitive outcomes.

Genetic and Environmental Influences on Structural and Diffusion-Based Alzheimer's Disease Neuroimaging Signatures Across Midlife and Early Old Age

BACKGROUND

Composite scores of magnetic resonance imaging-derived metrics in brain regions associated with Alzheimer's disease (AD), commonly termed AD signatures, have been developed to distinguish early AD-related atrophy from normal age-associated changes. Diffusion-based gray matter signatures may be more sensitive to early AD-related changes compared with thickness/volume-based signatures, demonstrating their potential clinical utility. The timing of early (i.e., midlife) changes in AD signatures from different modalities and whether diffusion- and thickness/volume-based signatures each capture unique AD-related phenotypic or genetic information remains unknown.

METHODS

Our validated thickness/volume signature, our novel mean diffusivity (MD) signature, and a magnetic resonance imaging-derived measure of brain age were used in biometrical analyses to examine genetic and environmental influences on the measures as well as phenotypic and genetic relationships between measures over 12 years. Participants were 736 men from 3 waves of the Vietnam Era Twin Study of Aging (VETSA) (baseline/wave 1: mean age [years] = 56.1, SD = 2.6, range = 51.1-60.2). Subsequent waves occurred at approximately 5.7-year intervals.

RESULTS

MD and thickness/volume signatures were highly heritable (56%-72%). Baseline MD signatures predicted thickness/volume signatures over a decade later, but baseline thickness/volume signatures showed a significantly weaker relationship with future MD signatures. AD signatures and brain age were correlated, but each measure captured unique phenotypic and genetic variance.

CONCLUSIONS

Cortical MD and thickness/volume AD signatures are heritable, and each signature captures unique variance that is also not explained by brain age. Moreover, results are in line with changes in MD emerging before changes in cortical thickness, underscoring the utility of MD as a very early predictor of AD risk.

A Traitlike Dimension of Subjective Memory Concern Over 30 Years Among Adult Male Twins

Importance

Subjective memory concern has long been considered a state-related indicator of impending cognitive decline or dementia. The possibility that subjective memory concern may itself be a heritable trait is largely ignored, yet such an association would substantially confound its use in clinical or research settings.

Objective

To assess the heritability and traitlike dimensions of subjective memory concern and its clinical correlates.

Design, Setting, and Participants

This longitudinal twin cohort study was conducted from 1967 to 2019 among male adults with a mean (SD) age of 37.75 (2.52) years to follow-up at mean ages of 56.15 (2.72), 61.50 (2.43), and 67.35 (2.57) years (hereafter, 38, 56, 62, and 67 years, respectively) in the Vietnam Era Twin Study of Aging. The study included a national community-dwelling sample with health, education, and lifestyle characteristics comparable to a general sample of US men in this age cohort. Participants were monozygotic and dizygotic twins randomly recruited from the Vietnam Era Twin Registry. Data were analyzed from May 2021 to December 2022.

Main Outcomes and Measures

Measures included subjective memory concern at 4 time points; objective memory, depressive symptoms, and anxiety at the last 3 time points; negative emotionality (trait neuroticism) at age 56 years; polygenic risk scores (PRSs) for neuroticism, depression, and Alzheimer disease; APOE genotype; and parental history of dementia. Primary outcomes were heritability and correlations between subjective memory concern and other measures.

Results

The sample included 1555 male adults examined at age 38 years, 520 at age 56 years (due to late introduction of subjective memory concern questions), 1199 at age 62 years, and 1192 at age 67 years. Phenotypically, subjective memory concerns were relatively stable over time. At age 56 years, subjective memory concern had larger correlations with depressive symptoms (r, 0.32; 95% CI, 0.21 to 0.42), anxiety (r, 0.36; 95% CI, 0.18 to 0.51), and neuroticism (r, 0.34; 95% CI, 0.26 to 0.41) than with objective memory (r, -0.24; 95% CI, -0.33 to -0.13). Phenotypic results were similar at ages 62 and 67 years. A best-fitting autoregressive twin model indicated that genetic influences on subjective memory concern accumulated and persisted over time (h2 = 0.26-0.34 from age 38-67 years). At age 56 years, genetic influences for subjective memory concern were moderately correlated with genetic influences for anxiety (r, 0.36; 95% CI, 0.18 to 0.51), negative emotionality (r, 0.51; 95% CI, 0.44-0.57), and depressive symptoms (r, 0.20; 95% CI, 0.10 to 0.29) as well as objective memory (r, -0.22; 95% CI, -0.30 to -0.14). Similar genetic correlations were seen at ages 62 and 67 years. The neuroticism PRS was associated with subjective memory concern at age 38 years (r, 0.10; 95% CI, 0.03. to 0.18) and age 67 years (r, 0.09; 95% CI, 0.01 to 0.16). Subjective memory concern was not associated with any Alzheimer disease risk measures.

Conclusions and Relevance

This cohort study found stable genetic influences underlying subjective memory concern dating back to age 38 years. Subjective memory concern had larger correlations with affect-related measures than with memory-related measures. Improving the utility of subjective memory concern as an indicator of impending cognitive decline and dementia may depend on isolating its statelike component from its traitlike component.

Erectile Function, Sexual Satisfaction, and Cognitive Decline in Men From Midlife to Older Adulthood

BACKGROUND AND OBJECTIVES

Vascular theories of cognitive aging have focused on macrovascular changes and cognitive decline. However, according to the artery-size hypothesis, microvascular changes, such as those that underlie changes in erectile function, may also play an important role in contributing to cognitive decline. Thus, we examined associations between erectile function, sexual satisfaction, and cognition starting in middle age because this represents a transition period where declines in these areas emerge.

RESEARCH DESIGN AND METHODS

We examined 818 men from the Vietnam Era Twin Study of Aging across three waves at mean ages 56, 61, and 68. Erectile function and sexual satisfaction were measured using the International Index of Erectile Function. Cognitive performance was measured using factor scores for episodic memory, executive function, and processing speed. We tested multilevel models hierarchically, adjusting for demographics, frequency of sexual activity, and physical and mental health confounders to examine how changes in erectile function and sexual satisfaction related to changes in cognitive performance.

RESULTS

Lower erectile function at baseline was related to poorer performance in all cognitive domains at baseline and faster declines in processing speed over time. However, baseline sexual satisfaction was unrelated to cognitive performance. Decreases in erectile function and sexual satisfaction were both associated with memory decline.

DISCUSSION AND IMPLICATIONS

Decreasing sexual health may signal an increased risk for cognitive decline. We discuss potential mechanisms, including microvascular changes and psychological distress. Discussing and tracking sexual health in middle-aged men may help to identify those likely to face memory decline.

The Role of Cognitive Self-Report Measure Type in Predicting Cognitive Decline Among Older Adults: A Systematic Review

Many types of items are used to measure self-reported cognition, resulting in heterogeneity across studies. Certain cognitive self-report measure types may be more predictive of future decline. Therefore, the purpose of this systematic review was to compare whether specific types of cognitive self-report measures better predict risk for cognitive decline over time when measures are directly compared within the same study. The PRISMA criteria guided the review. Eligibility criteria included: longitudinal studies, outcome of cognitive decline, at least 2 different cognitive self-report measures, and no cognitive impairment at baseline. Nineteen studies were included in the final review. A narrative synthesis of results was completed, resulting in 3 thematic groups of comparisons across self-reported measure types. Self-reported memory decline with worry and peer perceptions of memory were associated with the highest risk for cognitive decline. Future longitudinal investigations of self-reported cognitive problems should focus on using measures that may be most sensitive to predicting cognitive decline risk.

Parental dementia and subjective memory impairment in the health and retirement study

OBJECTIVES

To examine relationships between subjective memory impairment (SMI) and parental dementia among in older adults while considering the interactive influence of depressive symptoms, ethnicity, and race.

METHOD

The sample was drawn from the Health and Retirement Study, a nationally representative longitudinal study of aging (n = 3,809; M_age = 66.09; SD = 1.88; 84.20% White; 12.23% Black; 7.88% Hispanic). Biennial assessments included two measures of SMI (current memory problems and perceived memory decline), depressive symptoms, and parental dementia, over periods of up to sixteen years. Multilevel modeling analyses examined longitudinal relationships between parental dementia and SMI and whether depressive symptoms, ethnicity, and race interactively influenced this association.

RESULTS

Results showed that when older adults reported parental dementia, they were more likely to report a decline in memory in the past two years. They also reported poorer current memory problems, especially when they experienced increased depressive symptoms. Associations of parental dementia were consistent across ethnicity and race.

CONCLUSIONS

Results demonstrate the importance of considering parental dementia as a factor that may contribute to SMI in older adults.

A Longitudinal Investigation of Falls and Motor Vehicle Crashes in Older Drivers

Objective: To assess the longitudinal association between fall history reported at a driver's license screening visit and the likelihood of subsequent vehicle crashes. Method: A total of 1,127 older adults were recruited from Maryland State Motor Vehicle Administration sites and interviewed annually over 15 years. Results: Individuals who reported a previous fall were more likely to be female, perform worse on physical functioning and divided attention tasks, and report more situational driving avoidance compared with non-fallers at baseline. Females who reported a fall at baseline had a 2.6× greater likelihood of subsequently reporting a crash over the 15 years than males. Among those who reported a fall at baseline, greater weekly driving exposure over the 15 years was associated with a 23% higher likelihood of a subsequent crash. Discussion: These findings support the utility of investigating nontraditional driver screening methods to identify drivers who may be at increased risk of future driving difficulties.

FALLS AND MOTOR VEHICLE COLLISIONS: A LONGITUDINAL INVESTIGATION OF OLDER DRIVERS

Longitudinal research is needed to better understand mobility and aging, as falls and motor vehicle collisions (MVCs) are the top two leading causes of unintentional injury-related deaths for adults 65 and older in the United States. Using a longitudinal sample of older adults, prior falls were assessed as a predictor and moderator of the rate of subsequent MVCs over a 15 year time period. Using a 15-year longitudinal sample of 1,911 older adults recruited from three Maryland State Motor Vehicle Administration (MVA) sites, we conducted group differences and Generalized Estimating Equation (GEE) Poisson regressions. Individuals who reported a fall at baseline were more likely to be female, older, have poorer physical functioning, and reported more situational driving avoidance at baseline compared to those who did not report a fall. Females who reported a fall at baseline had a 2x greater risk rate of subsequently reporting a MVC over the 15 year time period than males. Furthermore, individuals, irrespective of gender, with a prior fall at baseline who drove more days per week over the 15-year time span had a 23% higher risk rate of a subsequent MVC. The current findings further the discussion on aging and mobility as it offers a longitudinal perspective on the association between falls and MVCS. These findings promote the utility of investigating non-traditional driver screening methods to identify drivers who may be at an increased rate for further driving difficulties.

PERSONALITY AND FAMILY HISTORY OF ALZHEIMER’S DISEASE AS PREDICTORS OF OLDER ADULTS’ SELF-REPORTED MEMORY PROBLEMS

Understanding individual factors (e.g., personality) associated with self-reported memory problems is important to refine identification of individuals at a higher risk of developing Alzheimer’s disease (AD). Using multilevel modeling, we examined the association of family history of AD and personality traits with self-reported memory problems in older adults (n = 421; 72.21% White; 62.95% female; Mage = 76.69). Results showed that individuals with a family history of AD reported more frequent memory problems and greater one-year memory decline. Similar findings were reported for individuals with higher extraversion scores. Further, older adults with higher neuroticism scores reported greater one- and ten-year memory decline. Neuroticism was positively related to frequency of memory problems, but only among participants with a family history of AD. Findings suggest that higher neuroticism and lower extraversion may increase older adults’ reports of memory problems. Family history of AD may further exacerbate this tendency.

Assessment of Caregiver-Targeted Interventions for Use of Motor Vehicle Passenger Safety Systems for Children: A Systematic Review and Meta-analysis

IMPORTANCE

Caregiver-targeted interventions to improve the use of child restraint systems (CRS) in motor vehicles are common and heterogeneous in their implementation. The effectiveness of these interventions is unknown.

OBJECTIVES

To quantify the effects of caregiver-targeted interventions using meta-analytic methods, assess the quality of published studies, and assess for publication bias.

DATA SOURCES

PubMed and PsychINFO (January 1, 2004, to April 1, 2019) were searched for English-language studies using a list of search terms. The search and screening process was completed between May 25, 2018, and April 1, 2019.

STUDY SELECTION

Studies met inclusion criteria if they included a caregiver-targeted intervention that focused on increasing CRS use for children (age, ≤9 years) and report the use of CRS before and after the intervention.

DATA EXTRACTION AND SYNTHESES

Cochrane and PRISMA guidelines were used for the meta-analysis and risk-of-bias review. Information was extracted on intervention type, setting, implementation, and attributes of the study independently between 2 coders. Data were pooled from independent samples, with 1 outcome measure from each intervention implementation or study.

MAIN OUTCOMES AND MEASURES

This study was an exploratory random-effects meta-analysis. Unadjusted odds ratios were calculated using the sample size and the observed number of children in incorrect or correct restraints in motor vehicles before and after the intervention to determine the odds of incorrect CRS use after completing an intervention. Setting, measurement method, randomization, use of vouchers, and types of restraint were tested as moderators. A funnel plot was used to assess for publication bias.

RESULTS

Of 1240 potential articles, 51 were deemed eligible for screening and 10 (8238 participants total) were included in the meta-analysis. Caregiver-targeted interventions were associated with a reduction in the number of children not riding in a CRS (odds ratio, 0.51; 95% CI, 0.36-0.71; P < .001). Variance in the averaged effect size was driven by self-report methods (when removed from analyses, I2 = 61.8%; R2 change = 26.3; P = .02) and hospital settings (when removed from analyses, I2 = 70.7%; R2 change = 17.4; P = .002). Risk of bias was high in most studies; however, there was low evidence for publication bias.

CONCLUSIONS AND RELEVANCE

In this meta-analysis, caregiver-targeted interventions were associated with a reduction in the number of children not riding in a CRS in motor vehicles; however, the methodological rigor of intervention studies should be enhanced.

Prevalence and Safety of Left-Footed Driving Following Right Foot Surgery Patients Including a Driving Simulation

BACKGROUND

For many patients, returning to driving after right foot and ankle surgery is a concern, and it is not uncommon for patients to ask if driving may be performed with their left foot. A paucity of literature exists to guide physician recommendations for return to driving. The purpose of this study was to describe the driving habits of patients after right-sided foot surgery and assess the safety of left-footed driving using a driving simulator.

METHODS

Patients who underwent right foot or ankle operations between January 2015 and December 2015 were retrospectively identified. A survey assessing driving habits prior to surgery and during the recovery period was administered via a REDCap database through email or telephone. Additionally, simulated driving scenarios were conducted using a driving simulator in 20 volunteer subjects to compare characteristics of left- versus right-footed driving.

RESULTS

Thirty-six of 96 (37%) patients who responded to the survey reported driving with the left foot postoperatively. No trends were found associating left-footed driving prevalence and socioeconomic status. In driving simulations, patients exceeded the speed limit significantly more (P < .001) and hit other vehicles more (P < .026) when driving with the right foot than the left. The time to fully brake and fully release the throttle in response to vehicular hazards was significantly prolonged in left-footed driving compared with right (P = .019 and P = .034, respectively).

CONCLUSION

A significant proportion of right foot ankle surgery patients engaged in left-footed driving during postoperative recovery. Driving with both the right and left foot presents a risk of compromised safety. This study provides novel objective data regarding the potential risks of unipedal left-footed driving using a standard right-footed console, which indicates that driving with the left foot may prolong brake and throttle release times. Further studies are warranted for physicians to be able to appropriately advise patients about driving after foot and ankle surgery.

LEVEL OF EVIDENCE

Level IV, case series.

A Description and Critical Analysis of the Therapeutic Uses of Transcranial Direct Current Stimulation: Implications for Clinical Practice and Research

For centuries, since the advent of harnessing magnetic and electrical energies, humans have been applying such energies to various body parts, including the brain, with the goal of improving health. Advancements over the past two decades in the production and affordability of such devices that precisely deliver such energies have resulted in novel therapeutic uses. One technique in particular, transcranial Direct Current Stimulation (tDCS), uses electrodes placed on the scalp to deliver a low electrical current to various areas on the surface of the neocortex. Such electrical currents stimulate neurons, which depending on the area of the neocortex it is applied and certain stimulation parameters, can either excite or inhibit certain functions within the brain that may result in alterations in mood, cognition, and behavior. This article provides an overview of this approach, explains how it is used, describes the hypothesized neurobiomechanisms involved, and explores its therapeutic potential. From this overview, implications for nursing practice and innovative uses for nursing research are posited.

Prevention and control of rabies in an age of global travel: a review of travel- and trade-associated rabies events--United States, 1986-2012

Rabies prevention and control efforts have been successful in reducing or eliminating virus circulation regionally through vaccination of specific reservoir populations. A notable example of this success is the elimination of canine rabies virus variant from the United States and many other countries. However, increased international travel and trade can pose risks for rapid, long-distance movements of ill or infected persons or animals. Such travel and trade can result in human exposures to rabies virus during travel or transit and could contribute to the re-introduction of canine rabies variant or transmission of other viral variants among animal host populations. We present a review of travel- and trade-associated rabies events that highlight international public health obligations and collaborative opportunities for rabies prevention and control in an age of global travel. Rabies is a fatal disease that warrants proactive coordination among international public health and travel industry partners (such as travel agents, tour companies and airlines) to protect human lives and to prevent the movement of viral variants among host populations.