Hand Dominance and Age Have Interactive Effects on Motor Cortical Representations

Older adults exhibit more bilateral motor cortical activity during unimanual task performance than young adults. Interestingly, a similar pattern is seen in young adults with reduced hand dominance. However, older adults report stronger hand dominance than young adults, making it unclear how handedness is manifested in the aging motor cortex. Here, we investigated age differences in the relationships between handedness, motor cortical organization, and interhemispheric communication speed. We hypothesized that relationships between these variables would differ for young and older adults, consistent with our recent proposal of an age-related shift in interhemispheric interactions. We mapped motor cortical representations of the right and left first dorsal interosseous muscles using transcranial magnetic stimulation (TMS) in young and older adults recruited to represent a broad range of the handedness spectrum. We also measured interhemispheric communication speed and bimanual coordination. We observed that more strongly handed older adults exhibited more ipsilateral motor activity in response to TMS; this effect was not present in young adults. Furthermore, we found opposing relationships between interhemispheric communication speed and bimanual performance in the two age groups. Thus, handedness manifests itself differently in the motor cortices of young and older adults and has interactive effects with age.     

Are There Age-Related Differences in the Ability to Learn Configural Responses?

Age is often associated with a decline in cognitive abilities that are important for maintaining functional independence, such as learning new skills. Many forms of motor learning appear to be relatively well preserved with age, while learning tasks that involve associative binding tend to be negatively affected. The current study aimed to determine whether age differences exist on a configural response learning task, which includes aspects of motor learning and associative binding. Young (M = 24 years) and older adults (M = 66.5 years) completed a modified version of a configural learning task. Given the requirement of associative binding in the configural relationships between responses, we predicted older adults would show significantly less learning than young adults. Older adults demonstrated lower performance (slower reaction time and lower accuracy). However, contrary to our prediction, older adults showed similar rates of learning as indexed by a configural learning score compared to young adults. These results suggest that the ability to acquire knowledge incidentally about configural response relationships is largely unaffected by cognitive aging. The configural response learning task provides insight into the task demands that constrain learning abilities in older adults.     

Sequence Skill Acquisition and Off-Line Learning in Normal Aging

It is well known that certain cognitive abilities decline with age. The ability to form certain new declarative memories, particularly memories for facts and events, has been widely shown to decline with advancing age. In contrast, the effects of aging on the ability to form new procedural memories such as skills are less well known, though it appears that older adults are able to acquire some new procedural skills over practice. The current study examines the effects of normal aging on procedural memory more closely by comparing the effects of aging on the encoding or acquisition stage of procedural learning versus its effects on the consolidation, or between-session stage of procedural learning. Twelve older and 14 young participants completed a sequence-learning task (the Serial Reaction Time Task) over a practice session and at a re-test session 24 hours later. Older participants actually demonstrated more sequence skill during acquisition than the young. However, older participants failed to show skill improvement at re-test as the young participants did. Age thus appears to have a differential effect upon procedural learning stages such that older adults'' skill acquisition remains relatively intact, in some cases even superior, compared to that of young adults, while their skill consolidation may be poorer than that of young adults. Although the effect of normal aging on procedural consolidation remains unclear, aging may actually enhance skill acquisition on some procedural tasks.     

Nonuniform activation of the agonist muscle does not covary with index finger acceleration in old adults.

This study examined the patterns of activation in the superficial and deep parts of the first dorsal interosseus muscle and in the antagonist muscle, second palmar interosseus, during postural tasks (position holding) and slow movements (position tracking) of the index finger performed by young and old adults. The position-tracking task involved the index finger lifting light loads (2.5, 10, and 35% of maximum) with shortening and lengthening contractions as steadily as possible. Steadiness was quantified in both tasks as the standard deviation of index finger acceleration. The fluctuations in acceleration during the two tasks were greater for the old subjects (62-72 yr) compared with young subjects (19-27 yr), especially with the lightest loads. The two groups of subjects activated the superficial and deep parts of first dorsal interosseus at similar intensities during the position-holding task, whereas the deep part was more active during the shortening and lengthening contractions of the position-tracking task. The nonuniform activation of first dorsal interosseus, therefore, was not associated with the difference in the standard deviation of acceleration between the young and old subjects. Furthermore, there was no association between the average level of coactivation by the antagonist muscle and the standard deviation of acceleration for either group of subjects across these tasks. Thus the greater variability in motor output exhibited by the older adults could not be explained by either the nonuniform activation of the agonist muscle or the average level of coactivation by the antagonist muscle.     

Biological discrimination between calcium and strontium in kidneys and bone of young and adult rats

Effects of aging on the biological discrimination between calcium (Ca) and strontium (Sr) by the kidneys and bone were studied in male and female rats of 5 to 50 wk of age by examining Sr/Ca ratios in the plasma, urine, and bone. The Ca-Sr discrimination at the reabsorption process in the kidneys was not affected by aging in male or female rats. On the other hand, discrimination between the two elements was shown to be age-related at the absorption process in the digestive tract, and became more strict with age. The reverse situation was observed in the discrimination of Ca and Sr in the femur; younger rats discriminated the two elements more strictly than older animals.     

Intranasal volume and olfactory function

The aim of this exploratory study was to identify the volume intranasal segments as they relate to parameters of olfactory function. Fifty healthy male volunteers (age range 22-59 years, mean age 28.5 years) were included. Olfactory function was measured by lateralized phenyl ethyl alcohol odor thresholds and odor discrimination, and by bilateral odor identification. Magnetic resonance imaging of the nasal cavity was performed immediately following olfactometry. To correlate the results of olfactometry with intranasal volume, each nasal cavity was divided into 11 segments. Significant correlations were found between the odor thresholds and volumes of the anterior part of the lower and upper meatus of the right nasal cavity. These results reveal that two nasal segments are important for inter-individual differences of odor thresholds in healthy subjects: (i) the segment in the upper meatus below the cribriform plate and (ii) the anterior segment of the inferior meatus. The latter finding is of special interest for nasal surgery, which allows modification of this volume through resection of the inferior turbinate and/or septoplasty.     

Decline in taste and odor discrimination abilities with age, and relationship between gustation and olfaction

It is important to learn about changes in both taste and odor perceptions with increasing age, because the taste of foods we encounter in our daily life is strongly affected by their smell. This study discusses the difference in qualitative taste and odor discrimination between the elderly and the young. Tastants and odorants used in this study were presented not as single stimuli but as a taste mixture (sucrose and tartaric acid) and an odor mixture (beta-phenylethyl alcohol and gamma-undecalactone). The results showed that quality discrimination abilities of the elderly subjects for both taste and odor were significantly lower than those of the young subjects, indicating a decline in quality discrimination abilities related to age. Also, a moderate but significant correlation was observed between the taste discrimination ability and the odor discrimination ability. We measured thresholds for single-taste and odor components in mixtures and compared them between the elderly and the young to investigate the cause for these findings.     

The smell of age: perception and discrimination of body odors of different ages

Our natural body odor goes through several stages of age-dependent changes in chemical composition as we grow older. Similar changes have been reported for several animal species and are thought to facilitate age discrimination of an individual based on body odors, alone. We sought to determine whether humans are able to discriminate between body odor of humans of different ages. Body odors were sampled from three distinct age groups: Young (20-30 years old), Middle-age (45-55), and Old-age (75-95) individuals. Perceptual ratings and age discrimination performance were assessed in 41 young participants. There were significant differences in ratings of both intensity and pleasantness, where body odors from the Old-age group were rated as less intense and less unpleasant than body odors originating from Young and Middle-age donors. Participants were able to discriminate between age categories, with body odor from Old-age donors mediating the effect also after removing variance explained by intensity differences. Similarly, participants were able to correctly assign age labels to body odors originating from Old-age donors but not to body odors originating from other age groups. This experiment suggests that, akin to other animals, humans are able to discriminate age based on body odor alone and that this effect is mediated mainly by body odors emitted by individuals of old age.     

Reaching a Better Understanding of the Control of Bimanual Movements in Older Adults

The ability to interact skilfully with the environment is essential for independent living and therefore a critical factor for the aging population. Here we investigate the differences between young and older adults in a bimanual reaching task where the goal is to bring two objects together to the same location with a synchronous placement. Older (mean age 74) and young (mean age 20) adults were asked to pick up two spatially disparate objects, one in each hand, and bring them together to place them in one of three trays laid out in front of them from left to right. The results showed that the older adults were no more detrimentally affected than the young by asymmetric bimanual movements compared to symmetric ones, and both groups completed their movements in the same time. Nevertheless, compared to the young, the older adult group produced reaches characterised by higher peak velocities (although this effect was marginal), shorter hover times, and where the movement distance varied for each hand the scaling of the kinematic profile across the two limbs diverged from that found with younger participants. They then spent longer than the young in the final adjustment phase and during this phase they made more adjustments than the young, and as a result were more synchronous in terms of the final placement of the objects. It seems that the older adults produced reach movements that were designed to reach the vicinity of the tray quite rapidly, after which time they made discreet adjustments to their initial trajectories in order to exercise the precision necessary to place the objects in the tray. These findings are consistent with the idea that older adults have problems using online control (as they wait until they can fixate both objects before making adjustments).     

Demographic and cognitive predictors of cued odor identification: evidence from a population-based study

This study investigated demographic and cognitive correlates of cued odor identification in a population-based sample from the Betula project: 1906 healthy adults varying in age from 45 to 90 years were assessed in a number of tasks tapping various cognitive domains, including cognitive speed, semantic memory and executive functioning. The results revealed a gradual and linear deterioration in cued odor identification across the adult life span. Overall, females identified more odors than men, although men and women performed at the same level in the oldest age cohort (85-90 years). Hierarchical regression analyses revealed that age, sex, education, cognitive speed and vocabulary were reliable correlates of performance in the odor identification task. In addition, age-related deficits in the included demographic and cognitive variables could not fully account for the observed age-related impairment in identification, suggesting that additional factors are underlying the observed deterioration. Likely candidates here are sensory abilities such as olfactory detection and discrimination.     

Vertical jumping reorganization with aging: a kinematic comparison between young and elderly men

To our knowledge jumping kinematics have never been studied in elderly persons. This study was aimed at examining the influence of aging on vertical jump performance and on interjoint coordination. Two groups of adults, 11 young men ages 18-25 years and 11 older men ages 79-100 years, were filmed while performing a maximal squat jump. Compared to young adults, jump height was significantly decreased by 28 cm in the elderly. Older adults spontaneously jumped from a more extended position of the hip. Results showed a decrease in hip, knee, and ankle linear velocity and angular amplitude with aging. The decrease in jump height was attributed to a decrease in explosive force and in the range of shortening of extensor muscles. In agreement with the literature, a proximo-distal coordination pattern was observed in young adults. Older adults used a simultaneous pattern. This may indicate that adults adjust their pattern of joint coordination as they age.     

Diferencias en función de la edad y la autopercepción del envejecimiento en ansiedad,tristeza, soledad y sintomatología comórbida ansioso-depresiva durante el confinamiento por la COVID-19

ObjectivesTo analyze differences by age group in anxiety, depression, loneliness and comorbid anxiety and depression in young people, middle aged adults and older adults during the lock-down period at home due to the COVID-19 pandemic, and to explore the association between negative self-perceptions of aging and psychological symptoms controlling by age group.MethodParticipants are 1501 people (age range 18 to 88 years). Anxiety, sadness, loneliness and self-perceptions of aging were assessed. The sample was divided according to the age group and quartiles (lower, intermediate levels, and higher) of anxiety, sadness, loneliness and self-perceptions of aging.ResultsOlder adults reported lower levels of anxiety and sadness than middle aged adults, and middle aged adults reported lower levels than younger participants. Middle aged adults reported the lowest loneliness, followed by older adults and younger participants. For each age group, those with more negative self-perceptions of aging reported higher anxiety, sadness and loneliness. More comorbid anxiety and sadness was found in younger adults and less in older adults; more depressed participants in the middle aged group, and more older adults and less younger participants were found in the group with the lowest levels of anxiety and sadness. For all the age groups, participants with high levels of comorbid anxiety and sadness are those who report the highest scores in negative self-perceptions of aging.ConclusionsOlder adults reported lower psychological anxiety, sadness and loneliness than the other age groups. Having negative self-perceptions of aging damage psychological health irrespective of the chronological age.     

Do Aging and Dual-Tasking Impair the Capacity to Store and Retrieve Visuospatial Information Needed to Guide Perturbation-Evoked Reach-To-Grasp Reactions?

A recent study involving young adults showed that rapid perturbation-evoked reach-to-grasp balance-recovery reactions can be guided successfully with visuospatial-information (VSI) retained in memory despite: 1) a reduction in endpoint accuracy due to recall-delay (time between visual occlusion and perturbation-onset, PO) and 2) slowing of the reaction when performing a concurrent cognitive task during the recall-delay interval. The present study aimed to determine whether this capacity is compromised by effects of aging. Ten healthy older adults were tested with the previous protocol and compared with the previously-tested young adults. Reactions to recover balance by grasping a small handhold were evoked by unpredictable antero-posterior platform-translation (barriers deterred stepping reactions), while using liquid-crystal goggles to occlude vision post-PO and for varying recall-delay times (0-10s) prior to PO (the handhold was moved unpredictably to one of four locations 2s prior to vision-occlusion). Subjects also performed a spatial- or non-spatial-memory cognitive task during the delay-time in a subset of trials. Results showed that older adults had slower reactions than the young across all experimental conditions. Both age groups showed similar reduction in medio-lateral end-point accuracy when recall-delay was longest (10s), but differed in the effect of recall delay on vertical hand elevation. For both age groups, engaging in either the non-spatial or spatial-memory task had similar (slowing) effects on the arm reactions; however, the older adults also showed a dual-task interference effect (poorer cognitive-task performance) that was specific to the spatial-memory task. This provides new evidence that spatial working memory plays a role in the control of perturbation-evoked balance-recovery reactions. The delays in completing the reaction that occurred when performing either cognitive task suggest that such dual-task situations in daily life could increase risk of falling in seniors, particularly when combined with the general age-related slowing that was observed across all experimental conditions.     

A missing piece in the puzzle: HIV in mature adults in sub-Saharan Africa

Healthcare and social needs for mature adults aged 50 years or older differ from those of younger adults due to stigma concerning HIV in older people, beliefs that engagement in sexual activity no longer applies, age driven comorbidities and responses to antiretroviral treatment, which complicate HIV diagnosis and management. In the face of a growing HIV epidemic in mature adults, mostly due to infected people aging with HIV, but also due to new infections in this age group, HIV services, which mostly cater for HIV in young adults and children, and HIV education messages and interventions, which mainly target young adults, leave the mature adult exposed and vulnerable to HIV transmission and to a lack of care and treatment thereafter.     

Age and gender differences in body composition, energy expenditure, and glucoregulation of adult rhesus monkeys

The purpose of this study was to examine the relationship of age to body composition, glucoregulation, activity, and energy expenditure in male and female rhesus monkeys. The animals were studied in three groups, young adults (YA, 7-9 years), middle-aged adults (MA, 13-17 years), and older adults (OA, > 23 years) adults. OA had a lower (P < 0.05) lean body mass than the YA and MA. OA also had the lowest values (P < 0.06) for energy expenditure (kJ/minute). Age-related differences (P < 0.05) were observed in time spent resting and moving. The OA spent the most time resting and the least time in vertical movement. There was a trend towards an age-related decrease in acute insulin response to glucose, while other glucoregulatory parameters were not changed with age. These results are similar to findings in humans, providing further evidence that the rhesus monkey is an appropriate model of human aging.     

Odor identification, consistency of label use, olfactory threshold and their relationships to odor memory over the human lifespan.

The purpose of this study was to investigate olfactory threshold, odor identification, consistency of label use and their relationships to odor memory in the context of semantic/episodic memory across the human lifespan. A total of 137 subjects aged 4-90 years were tested with several olfactory test procedures. We found that olfactory sensitivity was well developed in children despite the finding that their odor naming and odor memory were inferior to that of adults. In the elderly population, olfactory functions gradually declined, with odor memory and odor identification demonstrating the most significant decline. Semantic encoding was differentially related to odor memory over the human age span. Whereas consistency of label use was the main predictor for odor memory in children and young adults, olfactory identification ability was the main predictor in the elderly study group. We also calculated response bias for the separate age groups and found no differences between children, young adults and elderly. However, with age false alarm rates increased. We conclude that children possess equal olfactory sensitivity compared with adults; however, due to limitations in linguistic capabilities and familiarity to odorants, odor memory and odor identification performance was limited. Additionally, our data indicate major alterations of olfactory processing in advanced age with substantial losses in odor memory and odor identification performance.     

Effect of Aging on Hedonic Appreciation of Pleasant and Unpleasant Odors

Does hedonic appreciation evolve differently for pleasant odors and unpleasant odors during normal aging? To answer this question we combined psychophysics and electro-encephalographic recordings in young and old adults. A first study showed that pleasant odorants (but not unpleasant ones) were rated as less pleasant by old adults. A second study validated this decrease in hedonic appreciation for agreeable odors and further showed that smelling these odorants decreased beta event-related synchronization in aged participants. In conclusion, the study offers new insights into the evolution of odor hedonic perception during normal aging, highlighting for the first time a change in processing pleasant odors.     

Ischemia/reperfusion unveils impaired capacity of older adults to restrain oxidative insult

Age independently predicts poor outcome in a variety of medical settings, including sepsis, trauma, severe burns, and surgery. Because these conditions are associated with oxidative stress, we hypothesized that the capacity to constrain oxidative insult diminishes with age, leading to more extensive oxidative damage during trauma. To test this hypothesis, we used suprasystolic inflation of an arm blood pressure cuff to safely induce localized forearm ischemia/reperfusion (I/R) and quantified plasma F₂-isoprostane (IsoP) levels in serial blood samples. Before I/R, IsoP levels were similar in young (20–33 years) and older adults (62–81 years). After I/R challenge, the magnitude and duration of increased IsoP levels was significantly greater in older adults. Because aging is associated with declining levels of sex hormones that contribute to the regulation of antioxidant enzyme expression, we then examined the response to I/R in older women receiving hormone replacement therapy and found that these women did not manifest the amplified IsoP response found in untreated older women. These findings demonstrate that aging impairs the ability to restrain oxidative damage after an acute insult, which may contribute to the increased vulnerability of older adults to traumatic conditions and establishes a useful method to identify effective interventions to ameliorate this deficiency.     

Genetic testing for hemochromatosis: attitudes and acceptability among young and older adults

Hemochromatosis is a genetic disorder of iron overload common in persons of northern European descent. We examined attitudes about testing for hemochromatosis in 118 young adults (YA) (19.7 years +/- 1.9) and 50 older adults (OA) (58.5 years +/- 13.7). Participants read about hemochromatosis and two related tests: transferrin saturation measurement (iron test) and HFE genotyping (HFE test). Interest in each test and attitudes about genetic testing were assessed. More than 80% of all participants were willing to undergo either test, if offered. A majority preferred the iron test because of the information it provides about current health. A majority of participants identified at least one benefit of genetic testing, with improved health through early detection/prevention being most common. YA were more likely to report disadvantages of genetic testing (p < 0.001) and were more concerned about potential negative psychological effects (p < 0.005). OA were more concerned about potential discrimination (p < 0.0001). These findings suggest that young and older adults view genetic testing as beneficial and would accept HFE testing were it offered as part of a screening program.     

Relationship between Auditory and Cognitive Abilities in Older Adults

Objective

The objective was to evaluate the association of peripheral and central hearing abilities with cognitive function in older adults.

Methods

Recruited from epidemiological studies of aging and cognition at the Rush Alzheimer’s Disease Center, participants were a community-dwelling cohort of older adults (range 63–98 years) without diagnosis of dementia. The cohort contained roughly equal numbers of Black (n=61) and White (n=63) subjects with groups similar in terms of age, gender, and years of education. Auditory abilities were measured with pure-tone audiometry, speech-in-noise perception, and discrimination thresholds for both static and dynamic spectral patterns. Cognitive performance was evaluated with a 12-test battery assessing episodic, semantic, and working memory, perceptual speed, and visuospatial abilities.

Results

Among the auditory measures, only the static and dynamic spectral-pattern discrimination thresholds were associated with cognitive performance in a regression model that included the demographic covariates race, age, gender, and years of education. Subsequent analysis indicated substantial shared variance among the covariates race and both measures of spectral-pattern discrimination in accounting for cognitive performance. Among cognitive measures, working memory and visuospatial abilities showed the strongest interrelationship to spectral-pattern discrimination performance.

Conclusions

For a cohort of older adults without diagnosis of dementia, neither hearing thresholds nor speech-in-noise ability showed significant association with a summary measure of global cognition. In contrast, the two auditory metrics of spectral-pattern discrimination ability significantly contributed to a regression model prediction of cognitive performance, demonstrating association of central auditory ability to cognitive status using auditory metrics that avoided the confounding effect of speech materials.