To cross-validate the psychometric properties of the abbreviated Late-Life Function and Disability Instrument (LL-FDI), a measure of perceived functional limitations and disability.
Baseline and 12-month follow-up assessments conducted across the course of a 12-month exercise program.
University research community.
Older healthy adults (N=179; mean ± SD age, 66.43±5.67y) at baseline; 145 were retained at follow-up.
Main Outcome Measures
LL-FDI and functional performance measures.
Factor analyses confirmed the factor structure of the abbreviated LL-FDI, and all subscales met minimal criteria for temporal invariance. Significant correlations also were found between functional limitations subscales and an array of physical function performance measures, supporting the scale’s construct validity.
The abbreviated LL-FDI with some modifications appears to be temporally invariant in community-dwelling older adults. Additionally, moderate relationships between functional limitations and functional performance provide further support for these being conceptually distinct constructs.
Geriatrics; Longitudinal studies; Psychometrics; Rehabilitation
There is a growing trend of inactivity among children, which may not only result in poorer physical health, but also poorer cognitive health. Previous research has shown that lower fitness has been related to decreased cognitive function for tasks requiring perception, memory, and cognitive control as well as lower academic achievement.
To investigate the relationship between aerobic fitness, learning, and memory on a task that involved remembering names and locations on a fictitious map. Different learning strategies and recall procedures were employed to better understand fitness effects on learning novel material.
Forty-eight 9–10 year old children (n = 24 high fit; HF and n = 24 low fit; LF) performed a task requiring them to learn the names of specific regions on a map, under two learning conditions in which they only studied (SO) versus a condition in which they were tested during study (TS). The retention day occurred one day after initial learning and involved two different recall conditions: free recall and cued recall.
There were no differences in performance at initial learning between higher fit and lower fit participants. However, during the retention session higher fit children outperformed lower fit children, particularly when the initial learning strategy involved relatively poor recall performance (i.e., study only versus test-study strategy).
We interpret these novel data to suggest that fitness can boost learning and memory of children and that these fitness-associated performance benefits are largest in conditions in which initial learning is the most challenging. Such data have important implications for both educational practice and policy.
Over the next twenty years the number of Americans diagnosed with dementia is expected to more than double (CDC 2007). It is, therefore, an important public health initiative to understand what factors contribute to the longevity of a healthy mind. Both default mode network (DMN) function and increased aerobic fitness have been associated with better cognitive performance and reduced incidence of Alzheimer’s disease among older adults. Here we examine the association between aerobic fitness, functional connectivity in the DMN, and cognitive performance. Results showed significant age-related deficits in functional connectivity in both local and distributed DMN pathways. However, in a group of healthy elderly adults, almost half of the age-related disconnections showed increased functional connectivity as a function of aerobic fitness level. Finally, we examine the hypothesis that functional connectivity in the DMN is one source of variance in the relationship between aerobic fitness and cognition. Results demonstrate instances of both specific and global DMN connectivity mediating the relationship between fitness and cognition. We provide the first evidence for functional connectivity as a source of variance in the association between aerobic fitness and cognition, and discuss results in the context of neurobiological theories of cognitive aging and disease.
cognitive aging; fMRI; functional connectivity; aerobic exercise; executive function; spatial memory
The ability to perform multiple tasks simultaneously has become increasingly important as technologies such as cell phones and portable music players have become more common. In the current study, we examined dual-task costs in older and younger adults using a simulated street crossing task constructed in an immersive virtual environment with an integrated treadmill so that participants could walk as they would in the real world. Participants were asked to cross simulated streets of varying difficulty while either undistracted, listening to music, or conversing on a cell phone. Older adults were more vulnerable to dual-task impairments than younger adults when the crossing task was difficult; dual-task costs were largely absent in the younger adult group. Performance costs in older adults were primarily reflected in timeout rates. When conversing on a cell phone older adults were less likely to complete their crossing compared to when listening to music or undistracted. Analysis of time spent next to the street prior to each crossing, where participants were presumably analyzing traffic patterns and making decisions regarding when to cross, revealed that older adults took longer than younger adults to initiate their crossing, and that this difference was exacerbated during cell phone conversation, suggesting impairments in cognitive planning processes. Our data suggest that multi-tasking costs may be particularly dangerous for older adults even during everyday activities such as crossing the street.
Dual-task; attentional control; aging; cell phones; locomotion
Aging is marked by a decline in cognitive function, which is often preceded by losses in gray matter volume. Fortunately, higher cardiorespiratory fitness (CRF) levels are associated with an attenuation of age-related losses in gray matter volume and a reduced risk for cognitive impairment. Despite these links, we have only a rudimentary understanding of whether fitness-related increases in gray matter volume lead to elevated cognitive function. In this cross-sectional study, we examined whether the association between higher aerobic fitness levels and elevated executive function was mediated by greater gray matter volume in the prefrontal cortex (PFC). One hundred and forty-two older adults (mean age = 66.6 years) completed structural magnetic resonance imaging (MRI) scans, CRF assessments, and performed Stroop and spatial working memory (SPWM) tasks. Gray matter volume was assessed using an optimized voxel-based morphometry approach. Consistent with our predictions, higher fitness levels were associated with (a) better performance on both the Stroop and SPWM tasks, and (b) greater gray matter volume in several regions, including the dorsolateral PFC (DLPFC). Volume of the right inferior frontal gyrus and precentral gyrus mediated the relationship between CRF and Stroop interference while a non-overlapping set of regions bilaterally in the DLPFC mediated the association between CRF and SPWM accuracy. These results suggest that specific regions of the DLPFC differentially relate to inhibition and spatial working memory. Thus, fitness may influence cognitive function by reducing brain atrophy in targeted areas in healthy older adults.
cardiorespiratory fitness; executive function; voxel-based morphometry; cortical volume; prefrontal cortex; mediation
Observers often fail to notice even dramatic changes to their environment, a phenomenon known as change blindness. If training could enhance change detection performance in general, then it might help to remedy some real-world consequences of change blindness (e.g. failing to detect hazards while driving). We examined whether adaptive training on a simple change detection task could improve the ability to detect changes in untrained tasks for young and older adults. Consistent with an effective training procedure, both young and older adults were better able to detect changes to trained objects following training. However, neither group showed differential improvement on untrained change detection tasks when compared to active control groups. Change detection training led to improvements on the trained task but did not generalize to other change detection tasks.
The perceptual load theory of attention proposes that the degree to which visual distractors are processed is a function of the attentional demands of a task—greater demands increase filtering of irrelevant distractors. The spatial configuration of such filtering is unknown. Here, we used steady-state visual evoked potentials (SSVEPs) in conjunction with time-domain event-related potentials (ERPs) to investigate the distribution of load-induced distractor suppression and task-relevant enhancement in the visual field. Electroencephalogram (EEG) was recorded while subjects performed a foveal go/no-go task that varied in perceptual load. Load-dependent distractor suppression was assessed by presenting a contrast reversing ring at one of three eccentricities (2, 6, or 11°) during performance of the go/no-go task. Rings contrast reversed at 8.3 Hz, allowing load-dependent changes in distractor processing to be tracked in the frequency-domain. ERPs were calculated to the onset of stimuli in the load task to examine load-dependent modulation of task-relevant processing. Results showed that the amplitude of the distractor SSVEP (8.3 Hz) was attenuated under high perceptual load (relative to low load) at the most proximal (2°) eccentricity but not at more eccentric locations (6 or 11°). Task-relevant ERPs revealed a significant increase in N1 amplitude under high load. These results are consistent with a center-surround configuration of load-induced enhancement and suppression in the visual field.
attention; perceptual load; steady-state visual evoked potential (SSVEP); N1
Previous research has found age-related deficits in a variety of cognitive processes. However, some studies have demonstrated age-related sparing on tasks where individuals have substantial experience, often attained over many decades. Here, the authors examined whether decades of experience in a fast-paced demanding profession, air traffic control (ATC), would enable older controllers to perform at high levels of proficiency. The authors also investigated whether older controllers would show diminished age-related decrements on domain-relevant cognitive abilities. Both young and old controllers and noncontrollers performed a battery of cognitive and ATC tasks. Results indicate that although high levels of experience can reduce the magnitude of age-related decline on the component processes that underlie complex task performance, this sparing is limited in scope. More important, however, the authors observed experience-based sparing on simulated ATC tasks, with the sparing being most evident on the more complex air traffic control tasks. These results suggest that given substantial experience, older adults may be quite capable of performing at high levels of proficiency on fast-paced demanding real-world tasks. The implications of these findings for global skilled labor shortages are discussed.
cognitive aging; human performance; air traffic control; workforce shortage
The goal of the current study was to investigate the relationship between sport expertise and perceptual and cognitive skills, as measured by the component skills approach. We hypothesized that athletes would outperform non-athlete controls in a number of perceptual and cognitive domains and that sport expertise would minimize gender differences. A total of 154 individuals (87 professional volleyball players and 67 non-athlete controls) participated in the study. Participants performed a cognitive battery, which included tests of executive control, memory, and visuo-spatial attention. Athletes showed superior performance speed on three tasks (two executive control tasks and one visuo-spatial attentional processing task). In a subset of tasks, gender effects were observed mainly in the control group, supporting the notion that athletic experience can reduce traditional gender effects. The expertise effects obtained substantiate the view that laboratory tests of cognition may indeed enlighten the sport-cognition relationship.
cognition; expertise; sport
PMID: 20876588 CAMSID: cams2562
Declines in executive function and dual-task performance have been related to falls in older adults, and recent research suggests that older adults at risk for falls also show impairments on real-world tasks, such as crossing a street. The present study examined whether falls risk was associated with driving performance in a high-fidelity simulator. Participants were classified as high or low falls risk using the Physiological Profile Assessment and completed a number of challenging simulated driving assessments in which they responded quickly to unexpected events. High falls risk drivers had slower response times (~2.1 seconds) to unexpected events compared to low falls risk drivers (~1.7 seconds). Furthermore, when asked to perform a concurrent cognitive task while driving, high falls risk drivers showed greater costs to secondary task performance than did low falls risk drivers, and low falls risk older adults also outperformed high falls risk older adults on a computer-based measure of dual-task performance. Our results suggest that attentional differences between high and low falls risk older adults extend to simulated driving performance.
This study used functional magnetic resonance imaging (fMRI) to examine the influence of a 9-month physical activity program on task-evoked brain activation during childhood. The results demonstrated that 8- to 9-year-old children who participated in 60+ min of physical activity, 5 days per week, for 9 months, showed decreases in fMRI brain activation in the right anterior prefrontal cortex coupled with within-group improvements in performance on a task of attentional and interference control. Children assigned to a wait-list control group did not show changes in brain function. Furthermore, at post-test, children in the physical activity group showed similar anterior frontal brain patterns and incongruent accuracy rates to a group of college-aged young adults. Children in the wait-list control group still differed from the young adults in terms of anterior prefrontal activation and performance at post-test. There were no significant changes in fMRI activation in the anterior cingulate cortex (ACC) for either group. These results suggest that physical activity during childhood may enhance specific elements of prefrontal cortex function involved in cognitive control.
activation; brain; children; fitness; fMRI; physical activity
Evidence suggests that a history of head trauma is associated with memory deficits later in life. The majority of previous research has focused on moderate-to-severe traumatic brain injury (TBI), but recent evidence suggests that even a mild TBI (mTBI) can interact with the aging process and produce reductions in memory performance. This study examined the association of mTBI with memory and the brain by comparing young and middle-aged adults who have had mTBI in their recent (several years ago) and remote (several decades ago) past, respectively, with control subjects on a face-scene relational memory paradigm while they underwent functional magnetic resonance imaging (fMRI). Hippocampal volumes were also examined from high-resolution structural images. Results indicated middle-aged adults with a head injury in their remote past had impaired memory compared to gender, age, and education matched control participants, consistent with previous results in the study of memory, aging, and TBI. The present findings extended previous results by demonstrating that these individuals also had smaller bilateral hippocampi, and had reduced neural activity during memory performance in cortical regions important for memory retrieval. These results indicate that a history of mTBI may be one of the many factors that negatively influence cognitive and brain health in aging.
mTBI; hippocampus; aging; relational memory; fMRI
This study examined whether individual differences in aerobic fitness are associated with differences in activation of cognitive control brain networks in preadolescent children. As expected, children performed worse on a measure of cognitive control compared to a group of young adults. However, individual differences in aerobic fitness were associated with cognitive control performance among children. Lower-fit children had disproportionate performance cost in accuracy with increasing task difficulty, relative to higher-fit children. Brain activation was compared between performance-matched groups of lower- and higher-fit children. Fitness groups differed in brain activity for regions associated with response execution and inhibition, task set maintenance, and top-down regulation. Overall, differing activation patterns coupled with different patterns of brain-behavior correlations suggest an important role of aerobic fitness in modulating task strategy and the efficiency of neural networks that implement cognitive control in preadolescent children.
exercise; physical activity; aerobic fitness; executive control; fMRI; development
This study examines differential trajectories of exercise-related self-efficacy beliefs across a 12-month randomized controlled exercise trial.
Previously inactive older adults (N = 144; M age = 66.5) were randomly assigned to one of two exercise conditions (walking, flexibility-toning-balance) and completed measures of barriers self-efficacy (BARSE), exercise self-efficacy (EXSE), and self-efficacy for walking (SEW) across a 12-month period. Changes in efficacy were examined according to efficacy type and inter-individual differences. Latent growth curve modeling was employed to (a) examine average levels and change in each type of efficacy for the collapsed sample and by intervention condition, and (b) explore subpopulations (i.e., latent classes) within the sample that differ in their baseline efficacy and trajectory.
Analyses revealed two negative trends in BARSE and EXSE at predicted transition points, in addition to a positive linear trend in SEW. Two subgroups with unique baseline efficacy and trajectory profiles were also identified.
These results shed new light on the relationship between exercise and self-efficacy in older adults, and highlight the need for strategies for increasing and maintaining efficacy within interventions, namely targeting participants who start with a disadvantage (lower efficacy) and integrating efficacy-boosting strategies for all participants prior to program end.
exercise; self-efficacy; trajectories of change; aging
The purpose of this study was to extend our earlier work to determine the extent to which cardiorespiratory fitness is associated with the frequency of memory problems via its effects on the hippocampus and spatial working memory. We hypothesized that age, sex, education, body composition, and physical activity were direct determinants of fitness which, in turn, influenced frequency of forgetting indirectly through hippocampal volume and spatial working memory.
We conducted assessments of hippocampal volume, spatial working memory, frequency of forgetting, BMI, physical activity, demographic characteristics, and cardiorespiratory fitness in 158 older adults (M age = 66.49). Path analyses within a covariance modeling framework were used to examine relationships among these constructs.
Sex, age, BMI, and education were all significant determinants of cardiorespiratory fitness. The hypothesized path models testing the effects of fitness on frequency of forgetting through hippocampal volume and accuracy and speed of spatial working memory all fit the data well.
Our findings suggest that older adults with higher levels of fitness show greater preservation of hippocampal volume which, in turn, is associated with more accurate and faster spatial memory and fewer episodes of forgetting. Given the proportion of older adults reporting memory problems, it is necessary to determine whether improvements in fitness brought about by physical activity interventions can result in subsequent attenuation of memory problems or potentially improvements in memory.
Frequency of Forgetting; Hippocampus Volume; Cardiorespiratory Fitness; Spatial Memory; Older Adults
Self-efficacy and the use of self-regulatory strategies are consistently associated with physical activity behavior. Similarly, behavioral inhibition and cognitive resource allocation, indices of executive control function, have also been associated with this health behavior.
The purpose of this study was to examine the hypothesis that self-efficacy mediates the relationship between self-regulatory processes, such as executive function, and sustained exercise behavior.
Older adults (N = 177, mean age = 66.44 years) completed measures of executive function, self-reported use of self-regulatory strategies and self-efficacy prior to and during the first month of a 12-month exercise intervention. Percentage of exercise classes attended over the following 11 months was used to represent adherence. Data were collected from 2007 to 2010 and analyzed in 2010–2011. Structural equation models were tested examining the effect of executive function and strategy use on adherence via efficacy.
As hypothesized, results showed significant direct effects of two elements of executive function and of strategy use on self-efficacy and of efficacy on adherence. In addition, there were significant indirect effects of strategy use and executive function on adherence via self-efficacy.
Higher levels of executive function and use of self-regulatory strategies at the start of an exercise program enhance beliefs in exercise capabilities, which in turn leads to greater adherence.
The basal ganglia play a central role in regulating the response selection abilities that are critical for mental flexibility. In neocortical areas, higher cardiorespiratory fitness levels are associated with increased gray matter volume, and these volumetric differences mediate enhanced cognitive performance in a variety of tasks. Here we examine whether cardiorespiratory fitness correlates with the volume of the subcortical nuclei that make up the basal ganglia and whether this relationship predicts cognitive flexibility in older adults. Structural MRI was used to determine the volume of the basal ganglia nuclei in a group of older, neurologically healthy individuals (mean age 66 years, N = 179). Measures of cardiorespiratory fitness (VO2max), cognitive flexibility (task switching), and attentional control (flanker task) were also collected. Higher fitness levels were correlated with higher accuracy rates in the Task Switching paradigm. In addition, the volume of the caudate nucleus, putamen, and globus pallidus positively correlated with Task Switching accuracy. Nested regression modeling revealed that caudate nucleus volume was a significant mediator of the relationship between cardiorespiratory fitness, and task switching performance. These findings indicate that higher cardiorespiratory fitness predicts better cognitive flexibility in older adults through greater grey matter volume in the dorsal striatum.
There is increasing evidence that cardiorespiratory fitness (CRF) is associated with brain structure and function, and improvements in CRF through exercise training have been associated with neural and cognitive functioning in older adults. The objectives of this study were to validate the use of a non-exercise estimate of CRF, and to examine its association with cognitive function, brain structure and subjective memory complaints. Low active, older adults (N = 86; M age= 65.14) completed a physician-supervised maximal exercise test, a 1-mile timed walk, several measures of cognitive function, and a 3 Tesla structural MRI. Fitness was also calculated from an equation derived by (Jurca et al., 2005) based on age, sex, body mass index, resting heart rate, and self-reported physical activity level. Analyses indicated that all three measures of CRF were significantly correlated with one another. In addition, measures of cognitive function, hippocampus volume, and memory complaints were significantly correlated with each measure of fitness. These findings have implications for using a low-risk, low-cost, non-exercise estimate of CRF in determining fitness associations with brain structure and cognitive function in older adults. As such, this measure may have utility for larger population based studies. Further validation is required, as is determination of whether such relationships hold over the course of exercise interventions.
Equation-derived CRF; cognitive function; hippocampus; older adults
To investigate the relationship between aerobic fitness and cognitive variability in preadolescent children.
Forty-eight preadolescent children (25 males, 23 females, mean age = 10.1 years) were grouped into higher- and lower-fit groups according to their performance on a test of aerobic capacity (VO2max). Cognitive function was measured via behavioral responses to a modified flanker task. The distribution in reaction time was calculated within each participant to assess intra-individual variability of performance. Specifically, the standard deviation and coefficient variation of reaction time were used to represent cognitive variability.
Preadolescent children, regardless of fitness, exhibited longer reaction time, increased response variability, and decreased response accuracy to incongruent compared to congruent trials. Further, higher-fit children were less variable in their response time and more accurate in their responses across conditions of the flanker task, while no group differences were observed for response speed.
These findings suggest that fitness is associated with better cognitive performance during a task that varies cognitive control demands, and extends this area of research to suggest that intra-individual variability may be a useful measure to examine the relationship between fitness and cognition during preadolescence.
Physical Activity; Executive Control; Standard Deviation; Coefficient of Variation; Reaction Time
Aerobic exercise is a promising form of prevention for cognitive decline; however, little is known about the molecular mechanisms by which exercise and fitness impacts the human brain. Several studies have postulated that increased regional brain volume and function are associated with aerobic fitness because of increased vascularization rather than increased neural tissue per se. We tested this position by examining the relationship between cardiorespiratory fitness and N-acetylaspartate (NAA) levels in the right frontal cortex using magnetic resonance spectroscopy. NAA is a nervous system specific metabolite found predominantly in cell bodies of neurons. We reasoned that if aerobic fitness was predominantly influencing the vasculature of the brain, then NAA levels should not vary as a function of aerobic fitness. However, if aerobic fitness influences the number or viability of neurons, then higher aerobic fitness levels might be associated with greater concentrations of NAA. We examined NAA levels, aerobic fitness, and cognitive performance in 137 older adults without cognitive impairment. Consistent with the latter hypothesis, we found that higher aerobic fitness levels offset an age-related decline in NAA. Furthermore, NAA mediated an association between fitness and backward digit span performance, suggesting that neuronal viability as measured by NAA is important in understanding fitness-related cognitive enhancement. Since NAA is found exclusively in neural tissue, our results indicate that the effect of fitness on the human brain extends beyond vascularization; aerobic fitness is associated with neuronal viability in the frontal cortex of older adults.
Aging; brain; exercise; fitness; human; N-acetylaspartate; working memory
Acquisition of complex skills is a universal feature of human behavior that has been conceptualized as a process that starts with intense resource dependency, requires effortful cognitive control, and ends in relative automaticity on the multi-faceted task. The present study examined the effects of different theoretically based training strategies on cortical recruitment during acquisition of complex video game skills. Seventy-five participants were recruited and assigned to one of three training groups: (1) Fixed Emphasis Training (FET), in which participants practiced the game, (2) Hybrid Variable-Priority Training (HVT), in which participants practiced using a combination of part-task training and variable priority training, or (3) a Control group that received limited game play. After 30 h of training, game data indicated a significant advantage for the two training groups relative to the control group. The HVT group demonstrated enhanced benefits of training, as indexed by an improvement in overall game score and a reduction in cortical recruitment post-training. Specifically, while both groups demonstrated a significant reduction of activation in attentional control areas, namely the right middle frontal gyrus, right superior frontal gyrus, and the ventral medial prefrontal cortex, participants in the control group continued to engage these areas post-training, suggesting a sustained reliance on attentional regions during challenging task demands. The HVT group showed a further reduction in neural resources post-training compared to the FET group in these cognitive control regions, along with reduced activation in the motor and sensory cortices and the posteromedial cortex. Findings suggest that training, specifically one that emphasizes cognitive flexibility can reduce the attentional demands of a complex cognitive task, along with reduced reliance on the motor network.
skill acquisition; training strategies; attentional control; functional MRI
The present investigation is the first to explore the association between childhood aerobic fitness and basal ganglia structure and function. Rodent research has revealed that exercise influences the striatum by increasing dopamine signaling and angiogenesis. In children, higher aerobic fitness levels are associated with greater hippocampal volumes, superior performance on tasks of attentional and interference control, and elevated event-related brain potential indices of executive function. The present study used magnetic resonance imaging to investigate if higher-fit and lower-fit 9- and 10-year-old children exhibited differential volumes of other subcortical brain regions, specifically the basal ganglia involved in attentional control. The relationship between aerobic fitness, dorsal and ventral striatum volumes and performance on an attention and inhibition Eriksen flanker task was also examined. The results indicated that higher-fit children showed superior flanker task performance compared to lower-fit children. Higher-fit children also showed greater volumes of the dorsal striatum, and dorsal striatum volume was negatively associated with behavioral interference. The results support the claim that the dorsal striatum is involved in cognitive control and response resolution and that these cognitive processes vary as a function of aerobic fitness. No relationship was found between aerobic fitness, the volume of the ventral striatum and flanker performance. The findings suggest that increased childhood aerobic fitness is associated with greater dorsal striatal volumes and that this is related to enhanced cognitive control. Because children are becoming increasingly overweight, unhealthy and unfit, understanding the neurocognitive benefits of an active lifestyle during childhood has important public health and educational implications.
Brain; Development; Exercise; MRI; Physical activity; Neurocognition; Neuroimaging; Striatum
Alterations in gray and white matter have been well documented in individuals with multiple sclerosis. Severity and extent of such brain tissue damage have been associated with cognitive impairment, disease duration and neurological disability, making quantitative indices of tissue damage important markers of disease progression. In this study, we investigated the association between cardiorespiratory fitness and measures of gray matter atrophy and white matter integrity. Employing a voxel-based approach to analyses of gray matter and white matter, we specifically examined whether higher levels of fitness in multiple sclerosis participants were associated with preserved gray matter volume and integrity of white matter. We found a positive association between cardiorespiratory fitness and regional gray matter volumes and higher focal fractional anisotropy values. Statistical mapping revealed that higher levels of fitness were associated with greater gray matter volume in the midline cortical structures including the medial frontal gyrus, anterior cingulate cortex and the precuneus. Further, we also found increasing levels of fitness were associated with higher fractional anisotropy in the left thalamic radiation and right anterior corona radiata. Both preserved gray matter volume and white-matter tract integrity were associated with better performance on measures of processing speed. Taken together, these results suggest that fitness exerts a prophylactic influence on the cerebral atrophy observed early on preserving neuronal integrity in multiple sclerosis, thereby reducing long-term disability.
Cortical atrophy; normal appearing gray matter; normal appearing white matter; cardiorespiratory fitness; processing speed; relapsing-remitting multiple sclerosis; neuroplasticity
Deterioration of the hippocampus occurs in elderly individuals with and without dementia, yet individual variation exists in the degree and rate of hippocampal decay. Determining the factors that influence individual variation in the magnitude and rate of hippocampal decay may help promote lifestyle changes that prevent such deterioration from taking place. Aerobic fitness and exercise are effective at preventing cortical decay and cognitive impairment in older adults and epidemiological studies suggest that physical activity can reduce the risk for developing dementia. However, the relationship between aerobic fitness and hippocampal volume in elderly humans is unknown. In this study, we investigated whether individuals with higher levels of aerobic fitness displayed greater volume of the hippocampus and better spatial memory performance than individuals with lower fitness levels. Furthermore, in exploratory analyses, we assessed whether hippocampal volume mediated the relationship between fitness and spatial memory. Using a region-of-interest analysis on magnetic resonance images in 165 nondemented older adults, we found a triple association such that higher fitness levels were associated with larger left and right hippocampi after controlling for age, sex, and years of education, and larger hippocampi and higher fitness levels were correlated with better spatial memory performance. Furthermore, we demonstrated that hippocampal volume partially mediated the relationship between higher fitness levels and enhanced spatial memory. Our results clearly indicate that higher levels of aerobic fitness are associated with increased hippocampal volume in older humans, which translates to better memory function.
aging; MRI; spatial memory; cognition; brain