Performance Of Older Participants Research Articles

Relationship between Mitochondrial Quality Control Markers, Lower Extremity Tissue Composition, and Physical Performance in Physically Inactive Older Adults.

Altered mitochondrial quality and function in muscle may be involved in age-related physical function decline. The role played by the autophagy-lysosome system, a major component of mitochondrial quality control (MQC), is incompletely understood. This study was undertaken to obtain initial indications on the relationship between autophagy, mitophagy, and lysosomal markers in muscle and measures of physical performance and lower extremity tissue composition in young and older adults. Twenty-three participants were enrolled, nine young (mean age: 24.3 ± 4.3 years) and 14 older adults (mean age: 77.9 ± 6.3 years). Lower extremity tissue composition was quantified volumetrically by magnetic resonance imaging and a tissue composition index was calculated as the ratio between muscle and intermuscular adipose tissue volume. Physical performance in older participants was assessed via the Short Physical Performance Battery (SPPB). Protein levels of the autophagy marker p62, the mitophagy mediator BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3), the lysosomal markers transcription factor EB, vacuolar-type ATPase, and lysosomal-associated membrane protein 1 were measured by Western immunoblotting in vastus lateralis muscle biopsies. Older adults had smaller muscle volume and lower tissue composition index than young participants. The protein content of p62 and BNIP3 was higher in older adults. A negative correlation was detected between p62 and BNIP3 and the tissue composition index. p62 and BNIP3 were also related to the performance on the 5-time sit-to-stand test of the SPPB. Our results suggest that an altered expression of markers of the autophagy/mitophagy-lysosomal system is related to deterioration of lower extremity tissue composition and muscle dysfunction. Additional studies are needed to clarify the role of defective MQC in human muscle aging and identify novel biological targets for drug development.

Executive Functions in Aging: An Experimental and Computational Study of the Wisconsin Card Sorting and Brixton Spatial Anticipation Tests

ABSTRACT In order to explore the effect of normal aging on executive function, we tested 25 younger adults and 25 neurologically healthy older adults on the Wisconsin Card Sorting Test (WCST) and the Brixton Spatial Anticipation Test (BRXT), two classic tests of executive function. We found that older participants were more likely than younger participants to err on both tasks, but the additional errors of older participants tended to be related to task set maintenance and rule inference rather than perseveration. We further found that the tendency to perseverate (across all participants) on the WCST was related to the tendency to produce stimulus or response perseverations on the BRXT, rather than any tendency to perseverate on BRXT rule application. Finally, on both tasks, older participants were also slower, particularly on trials following an error, than younger participants. To explore the neurocomputational basis for the observed behaviours we then extended an existing model of schema-modulated action selection on the WCST to the BRXT. We argue on the basis of the model that the performance of older participants on both tasks reflects a slower update of schema thresholds within the basal ganglia, coupled with a decrease in sensitivity to feedback.

Reduced frontal white matter microstructure in healthy older adults with low tactile recognition performance

The aging of the nervous system is a heterogeneous process. It remains a significant challenge to identify relevant markers of pathological and healthy brain aging. A central aspect of aging are decreased sensory acuities, especially because they correlate with the decline in higher cognitive functioning. Sensory and higher cognitive processing relies on information flow between distant brain areas. Aging leads to disintegration of the underlying white matter tracts. While this disintegration is assumed to contribute to higher cognitive decline, data linking structural integrity and sensory function are sparse. The investigation of their interrelation may provide valuable insight into the mechanisms of brain aging. We used a combined behavioral and neuroimaging approach and investigated to what extent changes in microstructural white matter integrity reflect performance declines in tactile pattern recognition with aging. Poor performance in older participants was related to decreased integrity in the anterior corpus callosum. Probabilistic tractography showed that this structure is connected to the prefrontal cortices. Our data point to decreased integrity in the anterior corpus callosum as a marker for advanced brain aging. The correlation between impaired tactile recognition and disintegration in frontal brain networks could provide an explanation why the decrease of sensory function predicts cognitive decline.

Numeracy Skills, Cognitive Reserve, and Psychological Well-Being: What Relationship in Late Adult Lifespan?

Background: The capacity of understanding and manipulating numerical stimuli (i.e., numeracy) can impact decision making. This investigation was conducted to examine whether number comprehension and mental calculation predict hedonic (i.e., Scale of Positive and Negative Experience, SPANE) and eudaimonic (i.e., Flourishing Scale) well-being in late adulthood, and whether cognitive reserve (i.e., education, time spent for gardening, and time spent for leisure activities) and non-verbal reasoning predict numeracy skills of old adults. Additionally, the effect of age on numeracy was examined, controlling for the effect of education and cognitive efficiency. Methods: One hundred and fifty-eight (i.e., 65–94 years old) community-dwellers completed a battery of tools assessing numeracy, cognitive and metacognitive efficiency, and psychological well-being. Results: Number comprehension, metacognition, time spent for leisure, and perceived physical health accounted for 23% of the variance in the SPANE condition, whereas metacognition, perceived physical health, time for leisure, and education explained 15% of the variance in the Flourishing condition. Moreover, cognitive reserve assessed in terms of vocabulary and education predicted mental calculation. Finally, aging significantly impacted the mental calculation performance of older participants. Conclusions: These findings suggest that numeracy skills can selectively impact the mental health and daily life of older adults.

Learning by task repetition enhances object individuation and memorization in the elderly

A decline in visuospatial Working Memory (vWM) is a hallmark of cognitive aging across various tasks, and facing this decline has become the target of several studies. In the current study we tested whether older adults can benefit from task repetition in order to improve their performance in a vWM task. While learning by task repetition has been shown to improve vWM performance in young adulthood, little is known on whether a similar enhancement can be achieved also by the aging population. By combining different behavioral and electrophysiological measures, we investigated whether practicing a specific task (delayed match-to-sample judgement) over four consecutive sessions could improve vWM in healthy aging, and which are the neurophysiological and cognitive mechanisms modulated by learning. Behavioral data revealed that task repetition boosted performance in older participants, both in terms of sensitivity to change (as revealed by d’ measures) as well as capacity estimate (as measured by k values). At the electrophysiological level, results indicated that only after task repetition both target individuation (as evidenced by the N2pc) and vWM maintenance (as reflected by the CDA) were modulated by target numerosity. Our results suggest that repetition learning is effective in enhancing vWM in aging and acts through modifications at different stages of stimulus processing.

Functional Connectivity of the Anterior and Posterior Hippocampus: Differential Effects of Glucose in Younger and Older Adults.

The hippocampus features structurally and functionally distinct anterior and posterior segments. Relatively few studies have examined how these change during aging or in response to pharmacological interventions. Alterations in hippocampal connectivity and changes in glucose regulation have each been associated with cognitive decline in aging. A distinct line of research suggests that administration of glucose can lead to a transient improvement in hippocampus-dependent memory. Here, we probe age, glucose and human cognition with a special emphasis on resting-state functional connectivity (rsFC) of the hippocampus along its longitudinal axis to the rest of the brain. Using a randomized, placebo-controlled, double-blind, crossover design 32 healthy adults (16 young and 16 older) ingested a drink containing 25 g glucose or placebo across two counter balanced sessions. They then underwent resting-state functional magnetic resonance imaging (rs-fMRI) and cognitive testing. There was a clear dissociation in the effects of glucose by age. Magnitude change in rsFC from posterior hippocampus (pHPC) to medial frontal cortex (mPFC) was correlated with individual glucose regulation and gains in performance on a spatial navigation task. Our results demonstrate that glucose administration can attenuate cognitive performance deficits in older adults with impaired glucose regulation and suggest that increases in pHPC-mPFC rsFC are beneficial for navigation task performance in older participants.

No evidence for a common factor underlying visual abilities in healthy older people.

The world's population is aging at an increasing rate. Even in the absence of neurodegenerative disorders, healthy aging affects perception and cognition. In the context of cognition, common factors are well established. Much less is known about common factors for vision. Here, we tested 92 healthy older and 104 healthy younger participants in 19 visual tests (including visual search and contrast sensitivity) and three cognitive tests (including verbal fluency and digit span). Unsurprisingly, younger participants performed better than older participants in almost all tests. Surprisingly, however, the performance of older participants was mostly uncorrelated between visual tests, and we found no evidence for a common factor. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Age moderates the relationship between cortical thickness and cognitive performance

Findings from cross-sectional and longitudinal magnetic resonance imaging (MRI) studies indicate that cortical thickness declines across the adult lifespan, with regional differences in rate of decline. Global and regional thickness have also been found to co-vary with cognitive performance. Here we examined the relationships between age, mean cortical thickness, and associative recognition performance across three age groups (younger, middle-aged and older adults; total n = 133). Measures of cortical thickness were obtained using a semi-automated method. Older age was associated with decreased memory performance and a reduction in mean cortical thickness. After controlling for the potentially confounding effects of head motion, mean cortical thickness was negatively associated with associative memory performance in the younger participants, but was positively correlated with performance in older participants. A similar but weaker pattern was evident in the relationships between cortical thickness and scores on four cognitive constructs derived from a neuropsychological test battery. This pattern is consistent with prior findings indicating that the direction of the association between cortical thickness and cognitive performance reverses between early and later adulthood. In addition, head motion was independently and negatively correlated with associative recognition performance in younger and middle-aged, but not older, participants, suggesting that variance in head motion is determined by multiple factors that vary in their relative influences with age.

Recognition memory shielded from semantic but not perceptual interference in normal aging

Normal aging impairs long-term declarative memory, and evidence suggests that this impairment may be driven partly by structural or functional changes in the medial temporal lobe (MTL). Theories of MTL memory function therefore make predictions for age-related memory loss. One theory – the Representational-Hierarchical account – makes two specific predictions. First, recognition memory performance in older participants should be impaired by feature-level interference, in which studied items contain many shared, and thus repeatedly appearing, perceptual features. Second, if the interference in a recognition memory task – i.e., the information that repeats across items – resides at a higher level of complexity than simple perceptual features, such as semantic gist, older adults should be less impacted by such interference than young adults. We tested these predictions using the Deese-Roediger-McDermott paradigm, by creating feature-level (i.e., perceptual) interference with phonemically/orthographically related word categories, and higher-level associative interference with semantically related word categories. We manipulated category size in order to compare the effect of less versus more interference (i.e., small versus large category size), which served to (1) avoid potential item confounds arising from systematic differences between words belonging to perceptually- versus semantically-related categories, and (2) ensure that any effect of interference was due to information encoded at study, rather than pre-experimentally. Further, we used signal detection theory (SDT) to interpret our data, rather than examining false alarm (FA) rates in isolation. The d′ measure derived from SDT avoids contamination of the memory measure by response bias, and lies on an interval scale, allowing memory performance in different conditions to be compared without violating assumptions of the statistical tests. Older participants were relatively more impaired by perceptual interference and less impaired by semantic interference than young adults. This pattern is at odds with many current theories of age-related memory loss, but is in line with the Representational-Hierarchical account.

Neural activity patterns between different executive tasks are more similar in adulthood than in adolescence.

BackgroundAdolescence is a time of ongoing neural maturation and cognitive development, especially regarding executive functions. In the current study, age‐related differences in the neural correlates of different executive functions were tracked by comparing three age groups consisting of adolescents and young adults.MethodsBrain activity was measured with functional magnetic resonance imaging (fMRI) from 167 human participants (13‐ to 14‐year‐old middle adolescents, 16‐ to 17‐year‐old late adolescents and 20‐ to 24‐year‐old young adults; 80 female, 87 male) while they performed attention and working memory tasks. The tasks were designed to tap into four putative sub‐processes of executive function: division of attention, inhibition of distractors, working memory, and attention switching.ResultsBehaviorally, our results demonstrated superior task performance in older participants across all task types. When brain activity was examined, young adult participants demonstrated a greater degree of overlap between brain regions recruited by the different executive tasks than adolescent participants. Similarly, functional connectivity between frontoparietal cortical regions was less task specific in the young adult participants than in adolescent participants.ConclusionsTogether, these results demonstrate that the similarity between different executive processes in terms of both neural recruitment and functional connectivity increases with age from middle adolescence to early adulthood, possibly contributing to age‐related behavioral improvements in executive functioning. These developmental changes in brain recruitment may reflect a more homogenous morphological organization between process‐specific neural networks, increased reliance on a more domain‐general network involved in executive processing, or developmental changes in cognitive strategy.

Tracking developmental trajectories on neurocognitive testing in young athletes ages 5–12

ObjectiveDespite increased attention to sports-related concussion, there is a lack of research on younger athletes. The purpose of this study was to establish developmental trajectories on neurocognitive testing in younger athletes ages 5 to 12.DesignPre-Test Only Design.SettingMulti-site study from numerous locations in the Eastern USA and Canada.ParticipantsA total of 788 youth athletes, 73% male, assigned to groups on the basis of age: Ages 5–6 (N=128), Ages 7–8 (N=282), Ages 9–10 (N=284), Ages 11–12 (N=94).InterventionAn iPad-based Paediatric version of the ImPACT test was administered individually to participants in a quiet office setting.Outcome measuresAccuracy scores were documented on: Word List Learning (Immediate, Delayed, Recognition); and accuracy and timing scores on Design Rotation, Choice Reaction Time, Visual Sequencing and Visual Memory.Main resultsOne-way ANOVAs with Bonferroni correction for multiple comparisons, and Scheffé post-hoc comparisons were conducted between age groups on the dependent measures. All measures showed statistically significant changes (p< 0.001) across the developmental age groups, with better performance in older participants and lower performance in younger participants.ConclusionsYouth athletes between the ages of 5 and 12 are underrepresented with respect to age-appropriate assessment measures, and these results document the need for developmentally- and age-appropriate measures and normative data, in order to capture neurocognitive change across developmental stages.Competing interestsDr. Schatz serves on the ImPACT Scientific Advisory Board.None.

To What Extent Does the Existence of Functional Relations in a Learning Setting Change the Pattern of Differences Between Younger and Older Adults’ Performances?

Background/Study Context: The study directly compared the learning performance of younger and older participants in two situations, one in which they had the possibility of detecting functional relations in the learning setting, and one in which they did not. Functional relations were defined as functional correspondences that could be established between abstract properties extracted from the sets of stimulus items and an abstract property extracted from the set of response items.Methods: A total of 112 adults (18–90 years old) had to learn to predict the values of a numerical variable (the criterion) on the basis of two words (a plant and an animal) as cues. Five plants and five animals were graded according to size. The plant × animal design was orthogonal. The values of the criterion were obtained using an additive, linear scheme under the functional relations condition, and using random associations under the zero relations condition.Results: The hypothesis was well supported by the data. In the absence of functional relations, the difference between younger and older participants’ performances was shown to be practically as great as it could be in the experimental situation that was chosen. When functional relations were present, age differences were significantly reduced, to the extent that the performance of the older participants was almost as good as that achieved by the younger group.Conclusion: The existence of functional relations in a learning setting considerably changes the pattern of differences between younger and older adults’ performance. In both the absence and the presence of functional relations, older and younger participants spontaneously approached the learning task in a functional spirit, and conceived a priori the cues and the criterion as directly related. Future studies should examine the way in which participants approach learning tasks, and the characteristics of the tasks that determine participants’ spontaneous learning attitudes.

Diminished acquired equivalence yet good discrimination performance in older participants

We asked younger and older human participants to perform computer-based configural discriminations that were designed to detect acquired equivalence. Both groups solved the discriminations but only the younger participants demonstrated acquired equivalence. The discriminations involved learning the preferences [“like” (+) or “dislike” (−)] for sports [e.g., tennis (t) and hockey (h)] of four fictitious people [e.g., Alice (A), Beth (B), Charlotte (C), and Dorothy (D)]. In one experiment, the discrimination had the form: At+, Bt−, Ct+, Dt−, Ah−, Bh+, Ch−, Dh+. Notice that, e.g., Alice and Charlotte are “equivalent” in liking tennis but disliking hockey. Acquired equivalence was assessed in ancillary components of the discrimination (e.g., by looking at the subsequent rate of “whole” versus “partial” reversal learning). Acquired equivalence is anticipated by a network whose hidden units are shared when inputs (e.g., A and C) signal the same outcome (e.g., +) when accompanied by the same input (t). One interpretation of these results is that there are age-related differences in the mechanisms of configural acquired equivalence.

Reconstructing Wholes From Parts

In this study, the effects of age, hearing loss, and modality on the ability to integrate partial information in degraded stimuli, either speech or text, were examined using isolated words. It was hypothesized that the ability to make use of partial information in speech diminishes with age. It was also hypothesized that additional contributions of cochlear pathology underlying hearing loss would be manifest as a further decrement in performance for older adults with hearing loss, relative to older adults with normal hearing. Furthermore, it was hypothesized that, if the ability to integrate partial information in speech is amodal, then recognition performance for degraded speech would be associated with recognition performance for parallel measures of degraded text. Last, it was hypothesized that, if the nature of the amodal ability to integrate partial information is cognitive, then the performance on auditory and visual measures of word recognition would be correlated with performance on measures of working memory. Twenty-five young adults with normal hearing, 20 older adults with normal hearing, and 21 older adults with hearing loss participated in this study. All participants completed three auditory and two parallel visual tasks consisting of listening to or reading degraded words or text. Older participants also completed a working-memory test battery. Group effects were examined for each of the auditory and visual measures. Performance of older participants on cognitive measures was compared with available data from a younger group participating in a different study in our laboratory (with similar protocol). Correlations between auditory and visual measures of speech recognition were examined for all participants. In addition, correlations between perceptual and cognitive measures were computed for the older participants. Finally, the relationship between dependent auditory measures and other independent measures in older adults were further examined using stepwise linear regression analyses. Of the 10 possible comparisons between the young and the two older groups for the five primary dependent measures, the young performed significantly better than the elderly did, 8 of the 10 times. The two older groups performed similarly for most tasks. In young adults, performance among the auditory tasks and between the two visual tasks was significantly and moderately to strongly correlated. In addition, performance on one of the visual tasks was weakly to moderately significantly correlated with performance on each of the three auditory tasks. Similar moderate to strong correlations were found within the auditory and visual modalities in older adults. However, none of the between-modality correlations were significant in the elderly. In summary, the results of this study suggest that the ability to integrate partial information in degraded words diminishes with age. Once audibility is accounted for, this ability does not seem to diminish with cochlear pathology. In young adults, both modality-specific factors and amodal cognitive factors seem to contribute to this ability. In older adults, although modality-specific factors continue to be important, it seems that the perceptual mechanisms that underlie the processing of degraded speech and text are separate, at least for isolated words. Our results suggest that, when peripheral factors are accounted for, some higher-level, yet-to-be identified, age-related factors contribute to speech-communication difficulties in the elderly.

Myopia for the future or hypersensitivity to reward? Age-related changes in decision making on the Iowa Gambling Task.

It has been shown that older adults perform less well than younger adults on the Iowa Gambling Task (IGT), a real-world type decision-making task that factors together reward, punishment, and uncertainty. To explore the reasons behind this age-related decrement, we administered to an adult life span sample of 265 healthy participants (Mdn age = 62.00 +/- 16.17 years; range [23-88]) 2 versions of the IGT, which have different contingencies for successful performance: A'B'C'D' requires choosing lower immediate reward (paired with lower delayed punishment); E'F'G'H' requires choosing higher immediate punishment (paired with higher delayed reward). There was a significant negative correlation between age and performance on the A'B'C'D' version of the IGT (r = -.16, p = .01), while there was essentially no correlation between age and performance on the E'F'G'H' version (r = -.07, p = .24). In addition, the rate of impaired performance in older participants was significantly higher for the A'B'C'D' version (23%) compared with the E'F'G'H' version (13%). A parsimonious account of these findings is an age-related increase in hypersensitivity to reward, whereby the decisions of older adults are disproportionately influenced by prospects of receiving reward, irrespective of the presence or degree of punishment.

Compensation through Increased Functional Connectivity: Neural Correlates of Inhibition in Old and Young

With increasing age, people experience more difficulties with suppressing irrelevant information, which may have a major impact on cognitive functioning. The extent of decline of inhibitory functions with age is highly variable between individuals. In this study, we used ERPs and phase locking analyses to investigate neural correlates of this variability in inhibition between individuals. Older and younger participants performed a selective attention task in which relevant and irrelevant information was presented simultaneously. The participants were split into high and low performers based on their level of inhibition inefficiency, that is, the slowing of RTs induced by information that participants were instructed to ignore. P1 peak amplitudes were larger in low performers than in high performers, indicating that low performers were less able to suppress the processing of irrelevant stimuli. Phase locking analyses were used as a measure of functional connectivity. Efficient inhibition in both age groups was related to the increased functional connectivity in the alpha band between frontal and occipito-parietal ROIs in the prestimulus interval. In addition, increased power in the alpha band in occipito-parietal ROIs was related to better inhibition both before and after stimulus onset. Phase locking in the upper beta band before and during stimulus presentation between frontal and occipito-parietal ROIs was related to a better performance in older participants only, suggesting that this is an active compensation mechanism employed to maintain adequate performance. In addition, increased top-down modulation and increased power in the alpha band appears to be a general mechanism facilitating inhibition in both age groups.

Age-related differences in timing with breaks.

Two groups of participants differing in age were compared on a time production task during which timing was temporarily interrupted. Produced intervals lengthened with increasing delay before the break occurrence, and the effect was more pronounced in older than in younger adults. A reaction time response to the signal beginning the break period was required also. Older participants responded more slowly to this signal, but they benefited to a greater extent from a lengthening of the time preceding its presentation. These results suggest that performance of older participants is affected by attention sharing and preparation involved in timing with breaks.