Protective effects of physical activity on episodic memory during aging are explained by executive functioning.

Aging is marked by a memory decline related to an executive function decline. Physical activity (PA) has beneficial effects on both executive functions and memory, especially in aging. The protective effects of PA on these two cognitive abilities have always been studied separately, despite the well-established relationship between memory and executive functions. Our objective was to explore whether the benefits of PA on memory could be explained by reduced age-related changes in executive functions.Nineteen young adults (27.16 years old) and 25 older adults (69.64 years old) performed a resource-dependent memory task, three executive tasks and completed a PA questionnaire (measuring sports and leisure PA). Age group and PA effects on memory and executive performance were analyzed with generalized linear models. Mediation analyses were calculated using method of causal steps approach with a non-parametric bootstrapping procedure.The results confirmed the effects of age and PA on memory and executive performance. A significant interaction confirmed the protective effect of PA on age-related cognitive performance. PA was positively correlated with performance in both memory and executive tasks, but only in the older adults. Although each predictor alone (age, executive functions and PA) significantly explained memory performance in older adults, only the effect of PA on memory performance remained significant when all the predictors were introduced in the analyses.PA mediates the effects of age and executive functions on memory performance. This suggests that PA protects older adults against memory decline by reducing the decline in executive functioning.

Kinematic observation reduces effect of aging on episodic memory performance.

This study investigated the influence of kinematics observation (i.e., observing action from only the motion of the main joints of an actor) on episodic memory performance differences between young and older adults. To this end, 42 young (20-35 years) and 45 older (60-75 years) participants performed a free recall task in two different conditions: either after an encoding phase consisting of the visual presentation and reading of action verbs or after an encoding phase consisting of the visual presentation and naming of point-light displays of humans performing the same actions. Results showed a beneficial effect of point-light display encoding for both young and older participants but with a more pronounced benefit for the older participants compared to young adults. These findings are discussed in relation to the embodied view of memory which considers that memory is directly linked to the sensorimotor experiences and the environmental support hypothesis which postulates that elaborate processing can improve memory performance. In conclusion, kinematic observation could constitute an interesting potential intervention for supporting memory in older adults.

Impact of working memory capacity on predominance of parietal over frontal P300 amplitude.

Working memory-related neural activity varies with task load, and these neural variations can be constrained by working memory capacity (WMC). For instance, some studies suggest that parietal and frontal P300 amplitudes, reflecting working memory functioning, vary differentially with task load and WMC. The present study explored whether the predominance of parietal over frontal P300 amplitude is related to WMC, and whether this relationship varies according to task load. Thirty-one adults aged 20-40 years performed a Sternberg task with two set sizes (2 vs. 6 items), during which event-related potentials were recorded. This allowed us to explore the P300 and estimate the magnitude of its parietal over frontal predominance, calculated as a parietal over frontal predominance index (PFPI). Participants also performed the Digit Span and alpha span tests, which were used to compute an independent index of WMC. Results revealed the classic parietal over frontal P300 predominance. They also indicated that the PFPI decreased as task load increased, owing mainly to an increase in frontal P300 amplitude. Interestingly, WMC was positively correlated with the PFPI, suggesting that individuals with greater WMC exhibited greater parietal over frontal predominance. These correlations did not vary across set sizes. Parietal over frontal predominance was reduced in individuals with lower WMC, who relied more on frontal neural resources. This frontal upregulation may have reflected the recruitment of supplementary attentional executive operations to compensate for less efficient working memory maintenance operations.

The respective contribution of cognitive control and working memory to semantic and subjective organization in aging.

Organizing information is beneficial to episodic memory performance. Among several possible organizational strategies, two consist of organizing the information in semantic clusters (semantic organization) or self-organizing the information based on new associations that do not exist in semantic memory (subjective organization). Here, we investigated in a single study how these two organizational behaviors were underlined by different controlled processes and whether these relations were subjected to age-related differences. We tested 123 younger adults (n = 63) and older adults (n = 60) on two episodic memory tasks, one where the words were organizable and another where the words were not organizable, allowing for semantic and subjective organization, respectively. Additionally, participants were tested on three cognitive control tasks (Wisconsin Card Sorting Test, Stroop Test and Trail Making Test) and three working memory tasks (Backward Digit Span, Alpha Span and N-back test). Results revealed well-established age-related differences in terms of recall performance and organizational strategy implementation. More importantly, we found evidence that the different cognitive tests statistically yielded two different latent factors, a cognitive control factor and a working memory factor. Based on this dissociation, we found that only cognitive control contributed to semantic organization in all age groups whereas only working memory contributed to subjective organization, also in all age groups. These results shed new lights on our understanding of how controlled processes differently contribute to organizational behaviors in episodic memory. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The protective effect of educational level varies as a function of the difficulty of the memory task in ageing.

This study aimed to explore the effects of age and educational level on recall performance and organisational strategies used during recall as a function of the level of memory task difficulty. Younger (n = 55, age range = 20-39 years) and older (n = 45, age range = 65-75 years) adults learned a word list where the words were either already semantically grouped (easier) or presented in pseudo-random order (harder), and then recalled the words. The number of words recalled was calculated, and an index of clustering was computed to assess organisational strategies. Older adults recalled less words than the younger ones. Older adults with a higher educational level recalled more words than their counterparts with a lower educational level when the memory task was easier, but they all performed similarly on the harder memory task. Moreover, we noted a strong positive association between educational level and semantic organisation in older adults when the memory task was easier. Regardless of educational level, older adults used semantic organisation as much as younger adults when the memory task was easier. However, when the memory task was harder, older adults showed significantly less organisational strategies than younger adults, the latter using semantic organisation to boost their recall performance. In sum, the protective effect of educational level seems to be restricted on recall performance, but not organisational strategies, in easy memory tasks providing sufficient external information about the most efficient mnemonic strategy to use. Supplementary Information: The online version contains supplementary material available at 10.1007/s10433-022-00724-z.

Involvement of executive control in neural capacity related to working memory in aging: an ERP P300 study.

Executive control could be involved in neural capacity, which corresponds to the modulation of neural activity with increased task difficulty. Thus, by exploring the P300-an electrophysiological correlate of working memory-we examined the role played by executive control in both the age-related decline in working memory and neural capacity in aging. Event-related potentials (ERPs) were recorded while younger and older participants performed a Sternberg task with two set sizes (2 vs. 6 items), allowing us to calculate a neural capacity index. Participants also completed two control tasks (Stroop and 3-back tests), which were used to calculate a composite executive control index. Results indicated that working memory performance decreased with aging and difficulty. At the neural level, results indicated that the P300 amplitude varied with aging and also with task difficulty. In the low difficulty condition, frontal P300 amplitude was higher for older than for younger adults, whereas in the high difficulty condition, the amplitude of frontal and parietal P300 did not differ between both age groups. Results also suggest that task difficulty led to a decrease in parietal amplitude in both age groups and to an increase in frontal amplitude in younger but not older adults. Both executive control and frontal neural capacity mediated the age-related variance in working memory for older adults. Moreover, executive control mediated the age-related variance in the frontal neural capacity of older adults. Thus, the present study suggests a model for older adults in which executive control deficits with advancing age lead to less efficient frontal recruitment to cope with task difficulty (neural capacity), which in turn has a negative impact on working memory functioning.

Metamemory mediates the protective effect of cognitive reserve on episodic memory during aging.

The present study investigated the impact of cognitive reserve on episodic memory and metamemory control during aging using a multidimensional index of cognitive reserve and a measure of metamemory control abilities. We tested the hypotheses that cognitive reserve may play a protective role against age-related differences in episodic memory and metamemory control and that metamemory control may mediate the effect of cognitive reserve on episodic memory during aging. Young and older adults carried out a readiness-recall task in which task difficulty was manipulated through a variation of the nature of the cue-target pair link (weak vs. strong semantic associates). Episodic memory was assessed through recall performance, and metamemory by a task difficulty index reflecting the ability to adjust study time to task difficulty. Results confirmed that older adults recall fewer words, indicating an age-related deficit in episodic memory, and that older adults adjust less to task difficulty, suggesting impaired metamemory control. Findings also showed that metamemory control moderates the age-related decline in episodic memory and that cognitive reserve plays a protective role against age-related deficits in episodic memory and metamemory control. In addition, metamemory abilities mediated the beneficial effect of cognitive reserve on episodic memory performance during aging. Hence, this study sheds new light on the mechanisms underlying the impact of cognitive reserve on cognitive aging, highlighting the role of metacognitive processes.

The age-related effect on electrophysiological correlates of successful episodic memory encoding supports the hypothesis of a deficit in self-initiated encoding processes in aging.

Episodic memory decline with aging may be due to an age-related deficit in encoding processing, older adults having increasing difficulty to self-initiate encoding strategies that support later retrieval. Using event-related potentials (ERPs), the present study explored for the first time the neural correlates of successful encoding in a resource-dependent episodic memory task, in which participants had to self-initiate processes at both encoding and retrieval. At the behavioral level, results confirm the better memory performance of young than older adults. Comparing the neural activity elicited by studied items that were and were not subsequently recalled (Subsequent Memory Effect, SME), electrophysiological data revealed that younger adults showed a significant and sustained SME, shifting from parietal to frontal areas, suggesting that they self-initiated deep encoding strategies. In older adults, the duration of brain activity was shorter and located more in the parietal than frontal areas, suggesting that they used shallow rather than deep processes. Consistent with the hypothesis of a deficit in self-initiated strategies in aging, our findings suggest that when older adults are faced with a difficult memory task (no encoding support and no cue at retrieval), they engage fewer elaborative strategies than young adults, resulting in impaired episodic memory performance.

Influence of current physical exercise on the relationship between aging and episodic memory and fluid intelligence.

The present study examined the effects of current physical exercise and age on episodic memory and fluid intelligence, assessed with a free-recall task and the Culture Fair Intelligence Test (Cattell, 1963) respectively, while statistically controlling for other cognitive reserve factors (educational level, leisure activities, and vocabulary level). Two hundred and eight participants aged 20 to 85 participated in the study. Physical exercise level was indexed by weekly frequency over the last 12 months using self-reported measurement (from none to 4 times a week). Overall, results show a beneficial effect of physical exercise especially from a weekly practice of 2 times, and significant interaction between physical exercise and age on episodic memory and fluid intelligence capacities indicating a reduced effect of age in more physically active participants. These results reinforce the view that physical exercise is a strong and specific reserve factor that reduces decline in some cognitive functions during aging.

Effect of self-reported internal memory strategy use on age-related episodic and working memory decline: Contribution of control processes.

We explored whether control processes could account for age-related differences in internal strategy use, which in turn would contribute to episodic and working memory decline in aging. Young and older adults completed the internal strategy subscale of the Metamemory in Adulthood (MIA) questionnaire, a free-recall task (FRT), a reading span task (RST), and 3 executive control tasks (the Wisconsin Card Sorting Test, the Initial Letter Fluency Test, and the Digit Symbol Substitution Test) allowing us to calculate a composite index of control processes. Results indicated that both self-reported internal strategy use and control processes index accounted for a significant proportion of the age-related variance in the FRT and the RST. However, once the control processes index was controlled for, variance in both the FRT and RST explained by internal strategy use were significantly reduced. Additionally, age-related variance in internal strategy use was mediated by the control processes index. These results suggest a cascade model in which individual control level would mediate age-related differences in internal strategy use, which in turn would mediate age-related differences in episodic and working memory performance. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Neural correlates of episodic memory change in increasing age: a longitudinal event-related potential study.

Using a longitudinal design, we examined whether event-related brain potentials (ERPs) correlates of successful episodic memory retrieval varied over a 4-year period according to the level of memory change. ERPs were recorded while participants performed a word-stem cued-recall task, and this procedure was repeated 4 years later. We compared the ERP old/new effect patterns of participants whose memory performance remained stable over time (stable group) with those of participants experiencing episodic memory decline (decline group). The pattern of change of the old/new effect differed between groups. At T1, the two groups exhibited the same pattern, with a positive frontal and parietal old/new effect. For the decline group, the old/new effect pattern did not change between T1 and T2. By contrast, for the stable group, the positive parietal old/new effect at T1 no longer appeared at T2, but a negative old/new effect was exhibited at frontal sites. This brain reorganization pattern could be a compensatory mechanism supporting strategic processes and allowing memory abilities to be maintained over time.

Differential protective role of control and representation against age-related memory decline.

Control and representation (Craik & Bialystok, 2006, 2008) could be considered as potential cognitive resources playing a protective role against age-related memory decline. The main objective of this study was to explore whether the protective role (passive vs. active) associated with these resources varies according to the characteristics of the memory task. Young and older adults' memory performance was assessed using a cued-recall and a recognition task. Control and representation were measured, using the Excluded Letter Fluency Test and the Mill Hill vocabulary test, respectively. The results revealed that both control and representation had a significant positive impact on performance in both memory tasks. However, in the cued-recall task, age interacted only with control and not with representation level. Memory performance in this task was correlated with the control measure only for the older adults, indicating that memory decline in this task is moderated by control level. By contrast, for the recognition task, results showed that age interacted only with representation, indicating that the association between representation and recognition performance was greater for the older than the younger adults. This suggests that age-related recognition decline is moderated by representation level. These results suggest that the role played by both control and representation as protective resources against age-related memory decline depends on the task features; control would have an active protective role for cued-recall tasks, which involve more self-initiated and strategic processes, whereas representation would play this active protective role in a recognition task, which is heavily dependent upon semantic processes. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Benefit of Practice of the Stroop Test in Young and Older Adults: Pattern of Gain and Impact of Educational Level.

Back-Ground/Study Context: The goal of this study was to examine how repeated practice of an inhibition test could improve performance in the test in young and older adults. In particular, we wished to explore whether the gains made during a practice program varied between age groups, and how educational level influenced practice-related gains in older adults. Thus, we tried to disentangle two hypotheses explaining the benefits of practice, namely compensation (greater gain by the lowest performers) and magnification (greater gain by the highest performers).Method: Thirty-three younger adults and 60 older adults were divided into two groups each: (1) Groups in the Practice condition had 10 sessions practicing different versions of Card C of the Stroop Test, (2) groups in the Control condition completed only the pretest and posttest.Results: Overall, results showed that the performance of both young and older adults improved more in the practice condition than in the control condition. The older adults benefited more from practice than the young adults, with earlier and more regular improvement over the 10 sessions. Moreover, the older adults with a higher educational level benefited most.Discussion: These findings seem to support both the compensation and the magnification hypotheses, depending on the variable (age or educational level).

The effect of ageing on the neural substrates of incidental encoding leading to recollection or familiarity.

It is well-known that the ageing process disrupts episodic memory. The aim of this study was to use an fMRI visual recognition task to characterize age-related changes in cerebral regions activated, during encoding, for images that would subsequently lead to a recollection-based or to a familiarity-based recognition. Results show that, for subsequent recollection, young adults activated regions related to semantic processing more extensively than older ones. On the other hand, despite putatively producing less semantic elaboration, older adults activated contralateral regions supplementary to those found in young adults (which might represent attempted compensation), as well as regions of the default-mode network. These results suggest older adults could achieve subsequent recollection through different processes, for instance an appraisal of the self-relevance of the stimuli. For subsequent familiarity, the comparisons only revealed greater activations in young adults, in the dorsal frontoparietal attention system as well as in the hippocampus, again suggesting that, even if older adults are able to produce recollection- and familiarity-based recognition, the semantic processing might still be weaker in old adults, who might nonetheless use qualitatively different strategies in order to produce such responses. Further studies are necessary in order to characterize those strategies.

Event-related brain potential correlates of brain reorganization of episodic memory throughout the adult lifespan.

The main aim of this study was to characterize the age-related evolution of the event-related brain potentials correlates of successful to tackle the neural reorganization patterns associated with this episodic retrieval. We thus examined the evolution of the event-related brain potential old/new effect across the adult lifespan, in five groups, aged 21-70 years (21-30, 31-40, 41-50, 51-60, and 61-70 years), equalized on their memory performance through a word-stem cued-recall task. This procedure makes it possible to examine the evolution of age-related changes in brain organization during adulthood and to specify the age onset of these changes. Results confirm the hypothesis that aging is associated with major changes in brain functioning. These changes appear to be consistent with both the HAROLD and PASA hypotheses, which postulate an age-related reduction in hemispheric asymmetry and a shift from posterior to anterior areas, respectively. What is notable is that these patterns of brain reorganization are not specific to older stages of life as they begin to develop very early in adult life, around the 30s, and the shift toward frontal regions strengthens in the 60s.

Brain tissue pulsatility mediates cognitive and electrophysiological changes in normal aging: Evidence from ultrasound tissue pulsatility imaging (TPI).

Aging is characterized by a cognitive decline of fluid abilities and is also associated with electrophysiological changes. The vascular hypothesis proposes that brain is sensitive to vascular dysfunction which may accelerate age-related brain modifications and thus explain age-related neurocognitive decline. To test this hypothesis, cognitive performance was measured in 39 healthy participants from 20 to 80 years, using tests assessing inhibition, fluid intelligence, attention and crystallized abilities. Brain functioning associated with attentional abilities was assessed by measuring the P3b ERP component elicited through an auditory oddball paradigm. To assess vascular health, we used an innovative measure of the pulsatility of deep brain tissue, due to variations in cerebral blood flow over the cardiac cycle. Results showed (1) a classical effect of age on fluid neurocognitive measures (inhibition, fluid intelligence, magnitude and latency of the P3b) but not on crystallized measures, (2) that brain pulsatility decreases with advancing age, (3) that brain pulsatility is positively correlated with fluid neurocognitive measures and (4) that brain pulsatility strongly mediated the age-related variance in cognitive performance and the magnitude of the P3b component. The mediating role of the brain pulsatility in age-related effect on neurocognitive measures supports the vascular hypothesis of cognitive aging.

Successful aging: The role of cognitive gerontology.

This commentary explores the relationships between the construct of successful aging and the experimental psychology of human aging-cognitive gerontology. What can or should cognitive gerontology contribute to understanding, defining, and assessing successful aging? Standards for successful aging reflect value judgments that are culturally and historically situated. Fundamentally, they address social policy; they are prescriptive. If individuals or groups are deemed to be aging successfully, then their characteristics or situations can be emulated. If an individual or a group is deemed to be aging unsuccessfully, then intervention should be considered. Although science is never culture-free or ahistorical, cognitive gerontology is primarily descriptive of age-related change. It is not prescriptive. It is argue that cognitive gerontology has little to contribute to setting standards for successful aging. If, however, better cognitive function is taken as a marker of more successful aging-something not universally accepted-then cognitive gerontology can play an important assessment role. It has a great deal to contribute in determining whether an individual or a group evidences better cognitive function than another. More importantly, cognitive gerontology can provide tools to evaluate the effects of interventions. It can provide targeted measures of perception, attention, memory, executive function, and other facets of cognition that are more sensitive to change than most clinical measures. From a deep understanding of factors affecting cognitive function, cognitive gerontology can also suggest possible interventions. A brief narrative review of interventions that have and have not led to improved cognitive function in older adults. Finally, the enormous range is addressed in the estimates of the proportion of the population that meets a standard for aging successfully, from less than 10% to more than 90%. For research purposes, it would be better to replace absolute cutoffs with correlational approaches (e.g., Freund & Baltes, 1998, Psychology and Aging, 13, 531-543). For policy purposes, cutoffs are necessary, but we propose that assessments of successful aging be based not on absolute cutoffs but on population proportions. An example of one possible standard is this: Those more than 1 standard deviation above the mean are aging successfully; those more than 1 standard deviation below the mean are aging unsuccessfully; those in between are aging usually. Adoption of such a standard may reduce the wide discrepancies in the incidence of successful aging reported in the literature.

What can ERPs tell us about the generation effect?

The present experiment aimed to gain further understanding of the generation effect by investigating its neural correlates during encoding using event-related potentials (ERPs). Participants first encoded pairs of words under either a read or a generate condition and then completed a cued-recall task. Results confirmed the benefit of generation on memory performance. In addition, ERPs associated with the successfully encoded words had greater magnitude for generated than read words, from 900 to 1800ms post-stimulus, on middle and bilateral frontal and parietal electrodes sites, mostly on the right hemisphere. Analyses also revealed that this greater activity was significantly correlated with executive control abilities but not with semantic knowledge. These findings show that generation is associated with greater later neural activity, suggesting the use of additional processes. Our findings also provide some evidence in support of the cognitive effort hypothesis of the generation effect.

Neural correlates of successful memory retrieval in aging: Do executive functioning and task difficulty matter?

The current experiment aimed to explore age differences in brain activity associated with successful memory retrieval in older adults with different levels of executive functioning, at different levels of task demand. Memory performance and fMRI activity during a recognition task were compared between a young group and two older groups characterized by a low (old-low group) vs. high (old-high group) level of executive functioning. Participants first encoded pictures, presented once (Hard condition) or twice (Easy condition), and then completed a recognition memory task. Old-low adults had poorer memory performance than the two other groups, which did not differ, in both levels of task demands. In the Easy condition, even though older adults demonstrated reduced activity compared to young adults in several regions, they also showed additional activations in the right superior frontal gyrus and right parietal lobule (positively correlated to memory accuracy) for the old-high group and in the right precuneus (negatively correlated to memory accuracy), right anterior cingulate gyrus and right supramarginal gyrus for the old-low group. In the Hard condition, some regions were also more activated in the young group than in the older groups. Vice versa, old-high participants demonstrated more activity than either the young or the old-low group in the right frontal gyrus, associated with more accurate memory performance, and in the left frontal gyrus. In sum, the present study clearly showed that age differences in the neural correlates of retrieval success were modulated by task difficulty, as suggested by the CRUNCH model, but also by interindividual variability, in particular regarding executive functioning.

Age-Related Differences in the Reliance on Executive Control in Working Memory: Role of Task Demand.

We examined the hypothesis that age-related differences in the reliance on executive control may be better explained by variations of task demand than by a mechanism specifically linked to aging. To this end, we compared the relationship between the performance of young and older adults on two executive functioning tests and an updating working-memory task with different load levels. The results revealed a significant interaction between age, task demand, and individual executive capacities, indicating that executive resources were only involved at lower loads in older adults, and only at higher loads in young adults. Overall, the results are not consistent with the proposition that cognition places greater demand on executive control in older adults. However, they support the view that how much young and older adults rely on executive control to accomplish cognitive tasks depends on task demand. Finally, interestingly these results are consistent with the CRUNCH model accounting for age-related differences in brain activations.