Epidemiology of cognitive aging and Alzheimer's disease: contributions of the cache county utah study of memory, health and aging

Association between loneliness and cognitive function, and brain volume in community-dwelling elderly

Introduction

We investigated the relationship between loneliness, cognitive impairment, and regional brain volume among elderly individuals residing in the Korean community.

Methods

Data from the ARIRANG aging-cognition sub-cohort, collected between 2020 and 2022, were utilized for the present study. Loneliness was assessed using the UCLA-Loneliness Scale (UCLA-LS) questionnaire and the relevant item from Center for Epidemiologic Studies Depression Scale Korean version (CES-D-K). Cognitive impairment was measured through Mini-Mental State Examination (K-MMSE-2) and Seoul Neuropsychological Screening Battery (SNSB-C), with five sub-categories: attention, memory, visuospatial function, language, and executive function. Logistic regression was employed for prevalence ratios related to cognitive impairment, while linear regression was used for regional brain volume including white matter hyperintensity (WMH) and cortical thickness.

Results

Our analysis involved 785 participants (292 men and 493 women). We observed increased cognitive impairment assessed by K-MMSE-2 [UCLA-LS: odds ratio (OR) 3.133, 95% confidence interval (CI) 1.536-6.393; loneliness from CES-D: OR 2.823, 95% CI 1.426-5.590] and SNSB-C total score (UCLA-LS: OR 2.145, 95% CI 1.304-3.529) in the lonely group compared to the non-lonely group. Specifically, the lonely group identified by UCLA-LS showed an association with declined visuospatial (OR 1.591, 95% CI 1.029-2.460) and executive function (OR 1.971, 95% CI 1.036-3.750). The lonely group identified by CES-D-K was associated with impaired memory (OR 1.577, 95% CI 1.009-2.466) and executive function (OR 1.863, 95% CI 1.036-3.350). In the regional brain volume analysis, loneliness was linked to reduced brain volume in frontal white matter (left: -1.24, 95% CI -2.37 ∼-0.12; right: -1.16, 95% CI -2.31 ∼ -0.00), putamen (left: -0.07, 95% CI -0.12 ∼-0.02; right: -0.06, 95% CI -0.11 ∼-0.01), and globus pallidus (-15.53, 95% CI -30.13 ∼-0.93). There was no observed association in WMH and cortical thickness.

Conclusion

Loneliness is associated with cognitive decline and volumetric reduction in the frontal white matter, putamen, and globus pallidus.

Exercise as an Aging Mimetic: A New Perspective on the Mechanisms Behind Exercise as Preventive Medicine Against Age-Related Chronic Disease

Age-related chronic diseases are among the most common causes of mortality and account for a majority of global disease burden. Preventative lifestyle behaviors, such as regular exercise, play a critical role in attenuating chronic disease burden. However, the exact mechanism behind exercise as a form of preventative medicine remains poorly defined. Interestingly, many of the physiological responses to exercise are comparable to aging. This paper explores an overarching hypothesis that exercise protects against aging/age-related chronic disease because the physiological stress of exercise mimics aging. Acute exercise transiently disrupts cardiovascular, musculoskeletal, and brain function and triggers a substantial inflammatory response in a manner that mimics aging/age-related chronic disease. Data indicate that select acute exercise responses may be similar in magnitude to changes seen with +10-50 years of aging. The initial insult of the age-mimicking effects of exercise induces beneficial adaptations that serve to attenuate disruption to successive "aging" stimuli (i.e., exercise). Ultimately, these exercise-induced adaptations reduce the subsequent physiological stress incurred from aging and protect against age-related chronic disease. To further examine this hypothesis, future work should more intricately describe the physiological signature of different types/intensities of acute exercise in order to better predict the subsequent adaptation and chronic disease prevention with exercise training in healthy and at-risk populations.

Association of Hospitalization with Long-Term Cognitive Trajectories in Older Adults

IMPORTANCE

Hospitalizations are associated with cognitive decline in older adults.

OBJECTIVE

To determine the association between hospitalization characteristics and the trajectory of cognitive function in older adults.

DESIGN

Population-based longitudinal study of cognitive aging.

SETTING

Olmsted Medical Center and Mayo Clinic, the only centers in Olmsted County, Minnesota, with hospitalization capacity.

PARTICIPANTS

Individuals without dementia at baseline, with consecutive cognitive assessments from 2004 through 2017, and at least one visit after the age of 60.

MEASUREMENTS

The primary outcome was longitudinal changes in global cognitive z-score. Secondary outcomes were changes in four cognitive domains: memory, attention/executive function, language, and visuospatial skills. Hospitalization characteristics analyzed included elective versus nonelective, medical versus surgical, critical care versus no critical care admission, and long versus short duration admissions.

RESULTS

Of 4,587 participants, 1,622 had 1 and more hospital admission. Before hospitalization, the average slope of the global z-score was -0.031 units/year. After hospitalization, the rate of annual global z-score accelerated by -0.051 (95% CI = -0.057, -0.045) units, P < .001, resulting in an estimated annual slope after the first hospitalization of -0.082. The accelerated decline was found in all four cognitive domains (memory, visuospatial, language, and executive, all P < .001). The acceleration of the decline in global z-score following hospitalization was greater for medical compared to surgical hospitalizations (slope change following hospitalization = -0.064 vs -0.034 for medical vs surgical, P < .001), and nonelective compared to elective admissions (slope change following hospitalization = -0.075 vs -0.037 for nonelective vs elective, P < .001). The acceleration of cognitive decline was not different for hospitalization with intensive care unit admission versus not.

CONCLUSIONS

Hospitalization of older adults is associated with accelerated decline of global and domain-specific cognitive domains, with the rate of decline dependent upon type of admission. The clinical impact of this accelerated decline will depend on the individual's baseline cognitive reserve and expected longevity.

Anesthesia With and Without Nitrous Oxide and Long-term Cognitive Trajectories in Older Adults

BACKGROUND

We evaluated the hypothesis that the rate of postoperative decline in global cognition is greater in older adults exposed to general anesthesia with nitrous oxide (N2O) compared to general anesthesia without N2O.

METHODS

Longitudinal measures of cognitive function were analyzed in nondemented adults, 70-91 years of age, enrolled in the Mayo Clinic Study of Aging. Linear mixed-effects models with time-varying covariates assessed the relationship between exposure to surgery with general anesthesia (surgery/GA) with or without N2O and the rate of long-term cognitive changes. Global cognition and domain-specific cognitive outcomes were defined using z scores, which measure how far an observation is, in standard deviations, from the unimpaired population mean.

RESULTS

The analysis included 1819 participants: 280 exposed to GA without N2O following enrollment and before censoring during follow-up (median [interquartile range {IQR}] follow-up of 5.4 [3.9-7.9] years); 256 exposed to GA with N2O (follow-up 5.6 [4.0-7.9] years); and 1283 not exposed to surgery/GA (follow-up 4.1 [2.5-6.4] years). The slope of the global cognitive z score was significantly more negative following exposure to surgery/GA after enrollment (change in slope of -0.062 [95% confidence interval {CI}, -0.085 to -0.039] for GA without N2O, and -0.058 [95% CI, -0.080 to -0.035] for GA with N2O, both P < .001). The change in slope following exposure to surgery/GA did not differ between those exposed to anesthesia without versus with N2O (estimated difference -0.004 [95% CI, -0.035 to 0.026], P = .783).

CONCLUSIONS

Exposure to surgery/GA is associated with a small, but statistically significant decline in cognitive z scores. Cognitive decline did not differ between anesthetics with and without N2O. This finding provides evidence that the use of N2O in older adults does not need to be avoided because of concerns related to decline in cognition.

Association Between Critical Care Admissions and Cognitive Trajectories in Older Adults

OBJECTIVES

Patients requiring admission to an ICU may subsequently experience cognitive decline. Our objective was to investigate longitudinal cognitive trajectories in older adults hospitalized in ICUs. We hypothesized that individuals hospitalized for critical illness develop greater cognitive decline compared with those who do not require ICU admission.

DESIGN

A retrospective cohort study using prospectively collected cognitive scores of participants enrolled in the Mayo Clinic Study of Aging and ICU admissions retrospectively ascertained from electronic medical records. A covariate-adjusted linear mixed effects model with random intercepts and slopes assessed the relationship between ICU admissions and the slope of global cognitive z scores and domains scores (memory, attention/executive, visuospatial, and language).

SETTING

ICU admissions and cognitive scores in the Mayo Clinic Study of Aging from October 1, 2004, to September 11, 2017.

PATIENTS

Nondemented participants age 50 through 91 at enrollment in the Mayo Clinic Study of Aging with an initial cognitive assessment and at least one follow-up visit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 3,673 participants, 372 had at least one ICU admission with median (25-75th percentile) follow-up after first ICU admission of 2.5 years (1.2-4.4 yr). For global cognitive z score, admission to an ICU was associated with greater decline in scores over time compared with participants not requiring ICU admission (difference in annual slope = -0.028; 95% CI, -0.044 to -0.012; p < 0.001). ICU admission was associated with greater declines in memory (-0.029; 95% CI, -0.047 to -0.011; p = 0.002), attention/executive (-0.020; 95% CI, -0.037 to -0.004; p = 0.016), and visuospatial (-0.013; 95% CI, -0.026 to -0.001; p = 0.041) domains. ICU admissions with delirium were associated with greater declines in memory (interaction p = 0.006) and language (interaction p = 0.002) domains than ICU admissions without delirium.

CONCLUSIONS

In older adults, ICU admission was associated with greater long-term cognitive decline compared with patients without ICU admission. These findings were more pronounced in those who develop delirium while in the ICU.

Cognitive function after surgery with regional or general anesthesia: A population-based study

INTRODUCTION

Our aim was to examine whether surgery with regional anesthesia (RA) is associated with accelerated long-term cognitive decline comparable with that previously reported after general anesthesia (GA).

METHODS

Longitudinal cognitive function was analyzed in a cohort of 1819 older adults. Models assessed the rate of change in global and domain-specific cognition over time in participants exposed to RA or GA.

RESULTS

When compared with those unexposed to anesthesia, the postoperative rate of change of the cognitive global z-score was greater in those exposed to both RA (difference in annual decline of -0.041, P = .011) and GA (-0.061, P < .001); these rates did not differ. In analysis of the domain-specific scores, an accelerated decline in memory was observed after GA (-0.065, P < .001) but not RA (-0.011, P = .565).

CONCLUSIONS

Older adults undergoing surgery with RA experience decline of global cognition similar to those receiving GA; however, memory was not affected.

[Neurocognitive aging and cognitive disorders]

Aging is the leading risk factor of the most common cognitive disorders, primarily Alzheimer's disease and vascular dementia. These diseases have a progressive course and pathological underlying processes develop long before the onset of clinical signs of cognitive impairment. In the context of current trends in population aging and the steady increase in the number of patients with dementia, the search for factors contributing to the acceleration of neurocognitive aging processes, as well as factors with a modifying effect on these processes, is a key element in the effective management of elderly patients.

Association between exposure to anaesthesia and surgery and long-term cognitive trajectories in older adults: report from the Mayo Clinic Study of Aging

BACKGROUND

The link between exposure to general anaesthesia and surgery (exposure) and cognitive decline in older adults is debated. We hypothesised that it is associated with cognitive decline.

METHODS

We analysed the longitudinal cognitive function trajectory in a cohort of older adults. Models assessed the rate of change in cognition over time, and its association with exposure to anaesthesia and surgery. Analyses assessed whether exposure in the 20 yr before enrolment is associated with cognitive decline when compared with those unexposed, and whether post-enrolment exposure is associated with a change in cognition in those unexposed before enrolment.

RESULTS

We included 1819 subjects with median (25th and 75th percentiles) follow-up of 5.1 (2.7-7.6) yr and 4 (3-6) cognitive assessments. Exposure in the previous 20 yr was associated with a greater negative slope compared with not exposed (slope: -0.077 vs -0.059; difference: -0.018; 95% confidence interval: -0.032, -0.003; P=0.015). Post-enrolment exposure in those previously unexposed was associated with a change in slope after exposure (slope: -0.100 vs -0.059 for post-exposure vs pre-exposure, respectively; difference: -0.041; 95% confidence interval: -0.074, -0.008; P=0.016). Cognitive impairment could be attributed to declines in memory and attention/executive cognitive domains.

CONCLUSIONS

In older adults, exposure to general anaesthesia and surgery was associated with a subtle decline in cognitive z-scores. For an individual with no prior exposure and with exposure after enrolment, the decline in cognitive function over a 5 yr period after the exposure would be 0.2 standard deviations more than the expected decline as a result of ageing. This small cognitive decline could be meaningful for individuals with already low baseline cognition.

Neuropsychologic assessment

In this chapter, we review the use of neuropsychologic assessment in epidemiologic studies. First, we provide a brief introduction to the history of clinical neuropsychology and neuropsychologic assessment. We expand on the principal components of a neuropsychologic assessment and cognitive domains most commonly examined. This chapter also seeks to highlight specific domains and tests with validated psychometric properties that are widely accepted in clinical practice, as well as how data from a neuropsychologic test should be interpreted. Additionally, the important roles that neuropsychologic assessments play in tracking normative changes, patient diagnoses, care, and research will be discussed. Factors to consider when deciding on the inclusion of test instruments for a research study will also be reviewed. Lastly, we shed light on the contributions that neuropsychology has played in epidemiologic studies, as well as some challenges frequently faced when participating in this field of research.

Normal cognitive aging

Even those who do not experience dementia or mild cognitive impairment may experience subtle cognitive changes associated with aging. Normal cognitive changes can affect an older adult's everyday function and quality of life, and a better understanding of this process may help clinicians distinguish normal from disease states. This article describes the neurocognitive changes observed in normal aging, followed by a description of the structural and functional alterations seen in aging brains. Practical implications of normal cognitive aging are then discussed, followed by a discussion of what is known about factors that may mitigate age-associated cognitive decline.

The Cache County Study on Memory in Aging: factors affecting risk of Alzheimer's disease and its progression after onset

The Cache County Study on Memory in Aging is a longitudinal, population-based study of Alzheimer's disease (AD) and other dementias. Initiated in 1995 and extending to 2013, the study has followed over 5,000 elderly residents of Cache County, Utah (USA) for over twelve years. Achieving a 90% participation rate at enrolment, and spawning two ancillary projects, the study has contributed to the literature on genetic, psychosocial and environmental risk factors for AD, late-life cognitive decline, and the clinical progression of dementia after its onset. This paper describes the major study contributions to the literature on AD and dementia.