Navigational abilities decline with age, but the cognitive underpinnings of this cognitive decline remain partially understood. Navigation is guided by landmarks and self-motion cues, that we address when estimating our location. These sources of spatial information are often associated with noise and uncertainty, thus posing a challenge during navigation. To overcome this challenge, humans and other species rely on navigational cues according to their reliability: reliable cues are highly weighted and therefore strongly influence our spatial behavior, compared to less reliable ones. We hypothesize that older adults do not efficiently weigh spatial cues, and accordingly, the reliability levels of navigational cues may not modulate their spatial behavior, as with younger adults. To test this, younger and older adults performed a virtual navigational task, subject to modified reliability of landmarks and self-motion cues. The findings revealed that while increased reliability of spatial cues improved navigational performance across both age groups, older adults exhibited diminished sensitivity to changes in landmark reliability. The findings demonstrate a cognitive mechanism that could lead to impaired navigation abilities in older adults.

Aging is a complex and diverse biological process characterized by progressive molecular, cellular, and tissue damage, resulting in a loss of physiological integrity and heightened vulnerability to pathology. This biological diversity corresponds with highly variable cognitive trajectories, which are further confounded by genetic and environmental factors that influence the resilience of the aging brain. Given this complexity, there is a need for neurophysiological indicators that not only discern physiologic and pathologic aging but also closely align with cognitive trajectories. Transcranial Magnetic Stimulation (TMS) may have utility in this regard as a non-invasive brain stimulation tool that can characterize features of cortical excitability. Particularly, as a proxy for central cholinergic function, short-afferent inhibition (SAI) dysfunction is robustly associated with cognitive deficits in the latter stages of Alzheimer\'s Disease and Related Dementia (ADRD). In this study, we evaluated SAI in healthy young adults and older adults who, though absent clinical diagnoses, were algorithmically classified as cognitively normal (CN) or cognitively impaired (CI) according to the Jak/Bondi actuarial criteria. We report that SAI is preserved in the Old-CN cohort relative to the young adults, and SAI is significantly diminished in the Old-CI cohort relative to both young and CN older adults. Additionally, diminished SAI was significantly associated with impaired sustained attention and working memory. As a proxy measure for central cholinergic deficits, we discuss the potential value of SAI for discerning physiological and pathological aging.

BACKGROUND: Cognitive decline is most often assessed mean group differences on static measures of cognitive abilities (MacDonald et al., 2009). Another, perhaps more dynamic, method to understanding cognitive functioning is to evaluate variability in performance within an individual, termed intraindividual variability (IIV), which has been associated with reduction in gray matter and less efficient cognitive processing. Using results from a multi-site, longitudinal ARMADA study that validated NIH Toolbox across the cognitive aging spectrum, we investigated whether IIV in reaction time processing can differentiate between older adults with normal cognition, mild cognitive impairment (MCI), or dementia of the Alzheimer type (DAT), as well as the relative magnitude of differences between groups.
METHODS: As part of the Advancing Reliable Measurement in Alzheimer\'s Disease and cognitive Aging study (ARMADA; Weintraub et al 2020), participants completed the NIH Toolbox Cognition Battery, including two measures of executive functioning, Dimensional Change Card Sort and Flanker Inhibitory Control, which include granular reaction time data in milliseconds. We analyzed standard deviation and mean absolute deviation of item-level data of all trials, correct trials only, and incorrect trials only for three groups: normal controls, those with amnestic MCI, and those with mild DAT.
RESULTS: We observe large effect sizes of reaction time by clinical group, with the mild DAT group demonstrating mean standard error across trials of approximately .5 seconds throughout, compared with .25 seconds for MCI and .10 seconds for the control group (Figure 1). This translates to an approximate 5-fold increase in processing speed in the most severe clinical group. Examining time trends, we see that while the NC and MCI group were faster as the test progressed; there is no similar learning effect for the mild DAT group. Similar effect sizes were observed for the Flanker test.
CONCLUSIONS: This study represents one of the first studies to examine clinical performance using process data from two executive functioning measures on the NIH Toolbox across the cognitive aging spectrum. Future work will explore more definitions of IIV to determine which measure will maximally differentiate between established clinical groups and examine longitudinal differences.

Companion dogs are a valuable model for aging research, including studies of cognitive decline and dementia. With advanced age, some dogs spontaneously develop cognitive impairments and neuropathology resembling features of Alzheimer\'s disease. These processes have been studied extensively in laboratory beagles, but the cognitive assays used in that context-which rely on time-consuming operant procedures-are not easily scalable to large samples of community-dwelling companion dogs. We developed a battery of five short-form tasks targeting three aspects of cognition that are impaired in Alzheimer\'s disease: spatial memory, executive functions, and social cognition. In Experiment 1, we tested a cross-sectional sample of dogs (N = 123) and estimated associations between age and task performance. Older dogs scored lower on measures of spatial learning, memory, and response flexibility, and spent less time near, but more time gazing at, the experimenter. We found no differences in associations between age and performance across dogs of different body masses, a proxy for expected lifespan. In Experiment 2, we demonstrated the feasibility of these measures in clinical settings (N = 35). Dogs meeting clinical criteria for moderate or severe cognitive impairment scored lower, on average, than dogs characterized as mildly impaired and healthy agers, although these distributions overlapped. However, few dogs in our study cohort met the criteria for moderate or severe impairment. The measures presented here show promise for deployment in large-scale longitudinal studies of companion dogs, such as the Dog Aging Project.

Despite evidence that aerobic exercise benefits the aging brain, in particular the hippocampus and memory, controlled clinical trials have not comprehensively evaluated effects of aerobic exercise training on human memory in older adults. The central goal of this study was to determine chronic effects of moderate-to-vigorous intensity aerobic exercise on the hippocampus and memory in non-demented, inactive adults ages 55-80 years. We determine effects of aerobic exercise training with a 6-month randomized controlled trial (RCT) comparing 150 min/week of home-based, light intensity exercise with progressive moderate-to-vigorous intensity aerobic exercise. For the first time in a large trial, we examined temporal mechanisms by determining if individual differences in the rapid, immediate effects of moderate intensity exercise on hippocampal-cortical connectivity predict chronic training-related changes over months in connectivity and memory. We examined physiological mechanisms by testing the extent to which chronic training-related changes in cardiorespiratory fitness are a critical factor to memory benefits. The Exercise Effects on Brain Connectivity and Learning from Minutes to Months (Brain-EXTEND) trial is conceptually innovative with advanced measures of hippocampal-dependent learning and memory processes combined with novel capture of the physiological changes, genetic components, and molecular changes induced by aerobic exercise that change hippocampal-cortical connectivity. Given that hippocampal connectivity deteriorates with Alzheimer\'s and aerobic exercise may contribute to reduced risk of Alzheimer\'s, our results could lead to an understanding of the physiological mechanisms and moderators by which aerobic exercise reduces risk of this devastating and costly disease.

A healthy lifestyle can be an important prerequisite to prevent or at least delay the onset of dementia. However, the large number of physically inactive adults underscores the need for developing and evaluating intervention approaches aimed at improving adherence to a physically active lifestyle. In this regard, hybrid physical training, which usually combines center- and home-based physical exercise sessions and has proven successful in rehabilitative settings, could offer a promising approach to preserving cognitive health in the aging population. Despite its potential, research in this area is limited as hybrid physical training interventions have been underused in promoting healthy cognitive aging. Furthermore, the absence of a universally accepted definition or a classification framework for hybrid physical training interventions poses a challenge to future progress in this direction. To address this gap, this article informs the reader about hybrid physical training by providing a definition and classification approach of different types, discussing their specific advantages and disadvantages, and offering recommendations for future research. Specifically, we focus on applying digital technologies to deliver home-based exercises, as their use holds significant potential for reaching underserved and marginalized groups, such as older adults with mobility impairments living in rural areas.

Several therapies have been developed to reduce cognitive decline associated with aging. Aquatic exercises, which are widely used to enhance functional capacity, may play a role in stimulating cognitive functions. This study investigated the effects of a 3-month aquatic exercise program on cognitive functions in community-dwelling older adults. In this prospective, single-blinded, controlled clinical trial, 31 participants were allocated to either the experimental (aquatic exercises) or control (no-exercise) group. The intervention program consisted of exercises conducted twice a week in a 1.2 m deep indoor pool. The main outcome measures were cognitive functions, assessed using Raven\'s Progressive Matrices test and the Wisconsin Card Sorting Test. A repeated-measures analysis of variance was used to assess the impact of the exercise program. The effect sizes (η2p) were reported when a level of significance was achieved (p < 0.05). Compared with the control group, the participants who underwent aquatic exercises showed positive outcomes in Raven\'s Progressive Matrices test (p = 0.046; η2p = 0.131) and the Wisconsin Card Sorting Test (p = 0.001, η2p = 0.589). Complementary analyses of the Wisconsin Card Sorting Test indicated that the benefits of the aquatic exercise were observed in terms of the number of trials (p = 0.001, η2p = 0.478), number of errors (p = 0.001, η2p = 0.458), and number of non-perseverative errors (p = 0.001, η2p = 0.302). The results indicate that a period of three months of aquatic exercise was beneficial for stimulating specific aspects of the cognitive function of community-dwelling older individuals. Aquatic exercise should be prescribed to this population.

BACKGROUND: In this paper, we use the Health and Retirement Study (HRS) to examine the relationship between an estimated measure of pulse wave velocity (ePWV) and cognitive impairment with no dementia and dementia, respectively.
METHODS: We modeled the relationship between ePWV and cognitive status in 2006/2008 using data from 8,492 men and women (mean age 68.6 years) controlling for age, blood pressure, sociodemographic and socioeconomic characteristics (sex, race and ethnicity, education, income, wealth), health behaviors (smoking and physical activity), body mass index (BMI), health status and related medication use (history of cardiovascular disease, diabetes, and stroke), and cerebrovascular disease (CVD)-related biomarkers (C-reactive protein, cystatin-C, hemoglobin A1c, total cholesterol, high-density lipoprotein [HDL] cholesterol). We assess cognitive function with the 27-item Langa-Weir Telephone Interview for Cognitive Status (TICS) scale. ePWV is derived from an equation based on participant age and resting blood pressure.
RESULTS: In a model that controlled for the constituent components of ePWV (age, age squared, systolic and diastolic blood pressure), ePWV is associated with increased odds of having cognitive impairment with no dementia (OR=2.761) and dementia (OR=6.344) relative to a group with no cognitive impairment or dementia. After controlling for the constituent components of ePWV, sociodemographic and socioeconomic characteristics, health status and medication use, health behaviors, BMI, and CVD-related biomarkers, ePWV remains significantly associated with dementia (OR=3.969) but not cognitive impairment with no dementia (OR=1.782).
CONCLUSIONS: These findings suggest that ePWV may be a novel research tool and biomarker of vascular aging that can be used in large, population-representative studies to examine cognitive aging and dementia risk.

OBJECTIVE: Adult child socioeconomic status (SES) has been identified as a predictor of older parents\' cognitive aging. However, studies have primarily relied on educational attainment as the sole measure of adult child SES. We evaluated the relationship between adult children\'s financial disadvantage and cognitive outcomes of older parents in the United States.
METHODS: We used data from U.S. Health and Retirement Study (2000-2014, n = 15,053 respondents ≥51 years with at least 1 adult child). Adult child financial disadvantage was measured with 3 indicators of extremely low income, unemployment, and lack of homeownership. We used linear mixed models to estimate the association between adult child financial disadvantage and the rate of decline in verbal memory scores, controlling for respondents\' sociodemographic characteristics.
RESULTS: Having at least 1 adult child (vs no adult children) with extremely low income was found to be associated with lower verbal memory (b = -0.041, 95% confidence interval [CI]: -0.043, -0.039) at baseline. There was a small but significant association with the rate of decline in verbal memory z-scores (b = 0.004, 95% CI: 0.000, 0.008) and some evidence of heterogeneity by parent gender, marital status, and SES.
CONCLUSIONS: Offspring financial disadvantage may be influential for older parents\' initial level of memory function, although evidence of associations with memory decline was weak. Public policy interventions aimed at improving the economic conditions of adult children may indirectly benefit the cognitive performance of disadvantaged parents in their later life.

In celebration of the National Institute on Aging\'s (NIA) 50th anniversary, this paper highlights the significant advances in cognitive aging research and the promotion of cognitive health among older adults. Since its inception in 1974, the NIA has played a pivotal role in understanding cognitive aging, including cognitive epidemiology, interventions, and methods, for measuring cognitive change. Key milestones include the shift toward understanding cognitive impairment and Alzheimer\'s disease and Alzheimer\'s disease-related dementias (AD/ADRD), the development of large-scale longitudinal studies, and the incorporation of AD/ADRD-related biomarkers in cognitive aging cohorts. Additionally, NIA has championed diversifying the scientific workforce through initiatives, such as the Resource Centers for Minority Aging Research and the Butler-Williams Scholars Program. The next 50 years will continue to emphasize the importance of inclusion, innovation, and impactful research to enhance the cognitive health and well-being of older adults.