Age-related decline in divided-attention: from theoretical lab research to practical real-life situations

Functional near-infrared spectroscopy evidence of cognitive-motor interference in different dual tasks

Dual tasks (DTs) combining walking with a cognitive task can cause various levels of cognitive-motor interference, depending on which brain resources are recruited in each case. However, the brain activation and functional connectivity underlying cognitive-motor interferences remain to be elucidated. Therefore, this study investigated the neural correlation during different DT conditions in 40 healthy young adults (mean age: 27.53 years, 28 women). The DTs included walking during subtraction or N-Back tasks. Cognitive-motor interference was calculated, and brain activation and functional connectivity were analysed. Portable functional near-infrared spectroscopy was utilized to monitor haemodynamics in the prefrontal cortex (PFC), motor cortex and parietal cortex during each task. Walking interference (decrease in walking speed during DT) was greater than cognitive interference (decrease in cognitive performance during DT), regardless of the type of task. Brain activation in the bilateral PFC and parietal cortex was greater for walking during subtraction than for standing subtraction. Furthermore, brain activation was higher in the bilateral motor and parietal and PFCs for walking during subtraction than for walking alone, but only increased in the PFC for walking during N-Back. Coherence between the bilateral lateral PFC and between the left lateral PFC and left motor cortex was significantly greater for walking during 2-Back than for walking. The PFC, a critical brain region for organizing cognitive and motor functions, played a crucial role in integrating information coming from multiple brain networks required for completing DTs. Therefore, the PFC could be a potential target for the modulation and improvement of cognitive-motor functions during neurorehabilitation.

Engagement in a structured physical activity program and its effects upon health-related quality of life in elderly women: An observational study

Aging is a complex process associated with an impairment in functional capacity and low health-related quality of life (HRQoL) due to a high frequency of chronic diseases in the elderly population. Regular physical activity (PA) may limit some physiological effects of sedentary lifestyle and increase life expectancy. An observational was conducted to measure the HRQoL among older adults living in the community, by comparing a convenience sample of elderly females practicing a structured program of PA from 2 to 3 times per week in 60-min sessions (i.e., active females, AFs) to a sample of participants adopting lifestyle behaviors expending little energy (i.e., sedentary females, SFs). A validated questionnaire (the RAND 36-item) was used as outcome measure. All participants were assessed in terms of cognitive status (Montreal Cognitive Assessment, MoCA) to exclude mild cognitive impairment, divided attention/executive functioning (Trail Making Test, Stroop Test) and psychopathological dimensions of anxiety (Geriatric Anxiety Inventory, GAI), and depression (Geriatric Depression Scale, GDS). Non-parametric analysis revealed that AFs and SFs differed significantly in the RAND Energy/Fatigue (E/F), Emotional Wellbeing (EW), and Social Functioning (SoF), that was however influenced by education level. Moreover, E/F and EW were negatively associated to anxiety and depression, while SoF was influenced by divided attention. PA results in a healthful behavior for combating feelings of fatigue and low energy as well as emotional distress that can affect health status perception in older women.

Sustained visual attentional load modulates audiovisual integration in older and younger adults

Previous studies have shown that attention influences audiovisual integration (AVI) in multiple stages, but it remains unclear how AVI interacts with attentional load. In addition, while aging has been associated with sensory-functional decline, little is known about how older individuals integrate cross-modal information under attentional load. To investigate these issues twenty older adults and 20 younger adults were recruited to conduct a dual task including a multiple object tracking (MOT) task, which manipulated sustained visual attentional load, and an audiovisual discrimination task, which assesses AVI. The results showed that response times were shorter and hit rate was higher for audiovisual stimuli than for auditory or visual stimuli alone and in younger adults than in older adults. The race model analysis showed that AVI was higher under the load_3 condition (monitoring two targets of the MOT task) than under any other load condition (no-load [NL], one or three targets monitoring). This effect was found regardless of age. However, AVI was lower in older adults than younger adults under NL condition. Moreover, the peak latency was longer, and the time window of AVI was delayed in older adults compared to younger adults under all conditions. These results suggest that slight visual sustained attentional load increased AVI but that heavy visual sustained attentional load decreased AVI, which supports the claim that attention resource was limited, and we further proposed that AVI was positively modulated by attentional resource. Finally, there were substantial impacts of aging on AVI; AVI was delayed in older adults.

Executive function abilities in cognitively healthy young and older adults-A cross-sectional study

A prominent feature of cognitive aging is the decline of executive function (EF) abilities. Numerous studies have reported that older adults perform poorer than younger adults in such tasks. In this cross-sectional study, the effect of age on four EFs, inhibition, shifting, updating, and dual-tasking, was examined in 26 young adults (mean 21.18  years) and 25 older adults (mean 71.56  years) with the utilization of a pair of tasks for each EF. The tasks employed for DT were the Psychological Refractory Period paradigm (PRP) and a modified test for everyday attention, for inhibition the Stroop and Hayling sentence completion test (HSCT), for shifting a task switching paradigm and the trail making test (TMT), and for updating the backward digit span (BDS) task and a n-back paradigm. As all participants performed all tasks, a further aim was to compare the size of the age-related cognitive decline among the four EFs. Age-related decline was observed in all four EFs in one or both of the tasks employed. The results revealed significantly poorer performance in the older adults in the response times (RTs) of the PRP effect, interference score of the Stroop, RT inhibition costs of the HSCT, RT and error-rate shifting costs of the task switching paradigm, and the error-rate updating costs of the n-back paradigm. A comparison between the rates of decline revealed numerical and statistically significant differences between the four EFs, with inhibition showing the greatest decline, followed by shifting, updating, and dual-tasking. Thus, we conclude that with age, these four EFs decline at different rates.

Using Cognitive-Motor Dual-Tasks and Functional Near-Infrared Spectroscopy to Characterize Older Adults with and without Subjective Cognitive Decline

BACKGROUND

Subjective cognitive decline (SCD) refers to individuals who report persistent cognitive deficits but perform normally on neuropsychological tests. Performance may be facilitated by increased prefrontal cortex activation, known as neural compensation, and could be used to differentiate between older adults with and without SCD.

OBJECTIVE

This cross-sectional pilot study measured changes in the hemodynamic response (ΔHbO2) using functional near-infrared spectroscopy (fNIRS) as well as cognitive and motor performance during fine and gross motor dual-tasks in older adults with and without SCD.

METHODS

Twenty older adults over 60 years old with (n = 10) and without (n = 10) SCD were recruited. Two experiments were conducted using 1) gross motor walking and 2) fine motor finger tapping tasks that were paired with an n-back working memory task. Participants also completed neuropsychological assessments and questionnaires on everyday functioning.

RESULTS

Repeated measures ANOVAs demonstrated slower response times during dual-task gait compared to the single task (p = 0.032) and in the non-SCD group, slower gait speed was also observed in the dual compared to single task (p = 0.044). Response times during dual-task finger tapping were slower than the single task (p = 0.049) and greater ΔHbO2 was observed overall in the SCD compared to non-SCD group (p = 0.002).

CONCLUSIONS

Examining neural and performance outcomes revealed differences between SCD and non-SCD groups and single and dual-tasks. Greater brain activation during dual-task finger tapping may reflect neural compensation, which should be examined in a larger sample and longitudinally to better characterize SCD.

Exploring cognitive and brain oxygenation changes over a 1-year period in physically active individuals with mild cognitive impairment: a longitudinal fNIRS pilot study

BACKGROUND

Aging is associated with an increased likelihood of developing dementia, but a growing body of evidence suggests that certain modifiable risk factors may help prevent or delay dementia onset. Among these, physical activity (PA) has been linked to better cognitive performance and brain functions in healthy older adults and may contribute to preventing dementia. The current pilot study investigated changes in behavioral and brain activation patterns over a 1-year period in individuals with mild cognitive impairment (MCI) and healthy controls taking part in regular PA.

METHODS

Frontal cortical response during a dual-task walking paradigm was investigated at baseline, at 6 months (T6), and at 12 months (T12) by means of a portable functional Near-Infrared Spectroscopy (fNIRS) system. The dual-task paradigm included a single cognitive task (2-back), a single motor task (walking), and a dual-task condition (2-back whilst walking).

RESULTS

Both groups showed progressive improvement in cognitive performance at follow-up visits compared to baseline. Gait speed remained stable throughout the duration of the study in the control group and increased at T6 for those with MCI. A significant decrease in cortical activity was observed in both groups during the cognitive component of the dual-task at follow-up visits compared to baseline, with MCI individuals showing the greatest improvement.

CONCLUSIONS

The observations of this pilot study suggest that taking part in regular PA may be especially beneficial for both cognitive performance and brain functions in older adulthood and, especially, in individuals with MCI. Our findings may serve as preliminary evidence for the use of PA as a potential intervention to prevent cognitive decline in individuals at greater risk of dementia.

Prefrontal hyperactivation during dual-task walking related to apathy symptoms in older individuals

Increasing evidence associates apathy with worsening in cognitive performance and greater risk of dementia, in both clinical and healthy older populations. In older adults with neurocognitive disorders, apathy has also been related to specific fronto-subcortical structural abnormalities, thus differentiating apathy and major depressive disorder. Yet, the neural mechanisms associated with apathy in healthy older adults are still unclear. In the present study, we investigated the frontal cortical response during a dual-task walking paradigm in forty-one healthy older adults with and without apathy symptoms, controlling for depressive symptoms. The dual-task walking paradigm included a single cognitive task (2-back), a single motor task (walking), and a dual-task condition (2-back whilst walking). The cortical response was measured by means of functional Near-Infrared Spectroscopy (fNIRS). The results revealed that participants with apathy symptoms showed greater activation of subregions of the prefrontal cortex and of the premotor cortex compared to healthy controls during the single cognitive component of the dual-task paradigm, whilst cognitive performance was equivalent between groups. Moreover, increased cortical response during the cognitive task was associated with higher odds of exhibiting apathy symptoms, independently of depressive symptoms. These findings suggest that apathy may be related to differential brain activation patterns in healthy older individuals and are in line with previous evidence of the distinctiveness between apathy and depression. Future research may explore the long-term effects of apathy on the cortical response in healthy older adults.

The Specificity of Cognitive-Motor Dual-Task Interference on Balance in Young and Older Adults

Standing upright on stable and unstable surfaces requires postural control. Postural control declines as humans age, presenting greater risk of fall-related injury and other negative health outcomes. Secondary cognitive tasks can further impact balance, which highlights the importance of coordination between cognitive and motor processes. Past research indicates that this coordination relies on executive function (EF; the ability to control, maintain, and flexibly direct attention to achieve goals), which coincidentally declines as humans age. This suggests that secondary cognitive tasks requiring EF may exert a greater influence on balance compared to non-EF secondary tasks, and this interaction could be exaggerated among older adults. In the current study, we had younger and older adults complete two Surface Stability conditions (standing upright on stable vs. unstable surfaces) under varying Cognitive Load; participants completed EF (Shifting, Inhibiting, Updating) and non-EF (Processing Speed) secondary cognitive tasks on tablets, as well as a single task control scenario with no secondary cognitive task. Our primary balance measure of interest was sway area, which was measured with an array of wearable inertial measurement unit sensors. Replicating prior work, we found a main effect of Surface Stability with less sway on stable surfaces compared to unstable surfaces, and we found an interaction between Age and Surface Stability with older adults exhibiting significantly greater sway selectively on unstable surfaces compared to younger adults. New findings revealed a main effect of Cognitive Load on sway, with the single task condition having significantly less sway than two of the EF conditions (Updating and Shifting) and the non-EF condition (Processing Speed). We also found an interaction of Cognitive Load and Surface Stability on postural control, where Surface Stability impacted sway the most for the single task and two of the executive function conditions (Inhibition and Shifting). Interestingly, Age did not interact with Cognitive Load, suggesting that both age groups were equally impacted by secondary cognitive tasks, regardless the presence or type of secondary cognitive task. Taken together, these patterns suggest that cognitive demands vary in their impact on posture control across stable vs. unstable surfaces, and that EF involvement may not be the driving mechanism explaining cognitive-motor dual-task interference on balance.

Neural correlates of dual-task walking in people with central neurological disorders: a systematic review

BACKGROUND

People with central neurological disorders experience difficulties with dual-task walking due to disease-related impairments. The objective of this review was to provide a comprehensive examination of the neural correlates (structural/functional brain changes) of dual-task walking in people with Parkinson's disease (PD), multiple sclerosis (MS), stroke, and Alzheimer's disease (AD).

METHODS

A systematic review of the literature was conducted, following PRISMA guidelines, on Medline, Embase, and Scopus. Included studies examined the relationship between structural and functional brain imaging and dual-task walking performance in people with PD, MS, stroke, and AD. Articles that met the inclusion criteria had baseline characteristics, study design, and behavioral and brain outcomes extracted. Twenty-three studies were included in this review.

RESULTS

Most structural imaging studies (75%) found an association between decreased brain integrity and poor dual-task performance. Specific brain regions that showed this association include the striatum regions and hippocampus in PD and supplementary motor area in MS. Functional imaging studies reported an association between increased prefrontal activity and maintained (compensatory recruitment) or decreased dual-task walking performance in PD and stroke. A subset (n = 2) of the stroke papers found no significant correlations. Increased supplementary motor area activity was associated with decreased performance in MS and stroke. No studies on AD were identified.

CONCLUSION

In people with PD, MS, and stroke, several neural correlates of dual-task walking have been identified, however, the direction of the association between neural and performance outcomes varied across the studies. The type of cognitive task used and presentation modality (e.g., visual) may have contributed to these mixed findings.

Physical Exercise Training Effect and Mediation Through Cardiorespiratory Fitness on Dual-Task Performances Differ in Younger-Old and Older-Old Adults

OBJECTIVE

It has often been reported that dual-task (DT) performance declines with age. Physical exercise can help improve cognition, but these improvements could depend on cognitive functions and age groups. Moreover, the mechanisms supporting this enhancement are not fully elucidated. This study investigated the impacts of physical exercise on single- and dual-task performance in younger-old (<70) and older-old (70+) adults. The study also assessed whether the training effect on cognition was mediated by improvement in cardiorespiratory fitness.

METHODS

One hundred forty-three participants (65-89 years) took part in a physical exercise intervention for 3 months or were assigned to a control group. All participants completed a DT paradigm and an estimated measure of cardiorespiratory fitness. Regression models were used to test the training effect on these outcomes, and mediation analyses were used to determine whether the training-related cognitive changes were mediated by changes in cardiorespiratory fitness.

RESULTS

In 70+, training predicted improved processing speed (βc = -.33) and cardiorespiratory fitness (βa = .26) and the effect of training on processing speed was fully mediated by change in cardiorespiratory fitness (βab = -.12). In <70, training predicted improvement in task-set cost (βc = -.26) and change in cardiorespiratory fitness (βa = .30) but improvement in task-set cost was not entirely mediated by change in cardiorespiratory fitness.

DISCUSSION

Results are discussed in terms of the mechanisms supporting DT performance improvement following physical exercise training in older adults.

EEG beta-modulations reflect age-specific motor resource allocation during dual-task walking

The parallel execution of two motor tasks can lead to performance decrements in either one or both of the tasks. Age-related declines can further magnify the underlying competition for cognitive resources. However, little is known about the neural dynamics underlying motor resource allocation during dual-task walking. To better understand motor resource conflicts, this study investigated sensorimotor brain rhythms in younger and older adults using a dual-task protocol. Time-frequency data from two independent component motor clusters were extracted from electroencephalography data during sitting and walking with an additional task requiring manual responses. Button press-related desynchronization in the alpha and beta frequency range were analyzed for the impact of age (< 35 years, ≥ 70 years) and motor task (sitting, walking). Button press-related desynchronization in the beta band was more pronounced for older participants and both age groups demonstrated less pronounced desynchronizations in both frequency bands during walking compared to sitting. Older participants revealed less power modulations between sitting and walking, and less pronounced changes in beta and alpha suppression were associated with greater slowing in walking speed. Our results indicate age-specific allocations strategies during dual-task walking as well as interdependencies of concurrently performed motor tasks reflected in modulations of sensorimotor rhythms.

Postural Control While Listening in Younger and Middle-Aged Adults

OBJECTIVES

The motivation for this research is to determine whether a listening-while-balancing task would be sensitive to quantifying listening effort in middle age. The premise behind this exploratory work is that a decrease in postural control would be demonstrated in challenging acoustic conditions, more so in middle-aged than in younger adults.

DESIGN

A dual-task paradigm was employed with speech understanding as one task and postural control as the other. For the speech perception task, participants listened to and repeated back sentences in the presence of other sentences or steady-state noise. Targets and maskers were presented in both spatially-coincident and spatially-separated conditions. The postural control task required participants to stand on a force platform either in normal stance (with feet approximately shoulder-width apart) or in tandem stance (with one foot behind the other). Participants also rated their subjective listening effort at the end of each block of trials.

RESULTS

Postural control was poorer for both groups of participants when the listening task was completed at a more adverse (vs. less adverse) signal-to-noise ratio. When participants were standing normally, postural control in dual-task conditions was negatively associated with degree of high-frequency hearing loss, with individuals who had higher pure-tone thresholds exhibiting poorer balance. Correlation analyses also indicated that reduced speech recognition ability was associated with poorer postural control in both single- and dual-task conditions. Middle-aged participants exhibited larger dual-task costs when the masker was speech, as compared to when it was noise. Individuals who reported expending greater effort on the listening task exhibited larger dual-task costs when in normal stance.

CONCLUSIONS

Listening under challenging acoustic conditions can have a negative impact on postural control, more so in middle-aged than in younger adults. One explanation for this finding is that the increased effort required to successfully listen in adverse environments leaves fewer resources for maintaining balance, particularly as people age. These results provide preliminary support for using this type of ecologically-valid dual-task paradigm to quantify the costs associated with understanding speech in adverse acoustic environments.

Sustained Auditory Attentional Load Decreases Audiovisual Integration in Older and Younger Adults

The modulation of attentional load on the perception of auditory and visual information has been widely reported; however, whether attentional load alters audiovisual integration (AVI) has seldom been investigated. Here, to explore the effect of sustained auditory attentional load on AVI and the effects of aging, nineteen older and 20 younger adults performed an AV discrimination task with a rapid serial auditory presentation task competing for attentional resources. The results showed that responses to audiovisual stimuli were significantly faster than those to auditory and visual stimuli (AV > V ≥ A, all p < 0.001), and the younger adults were significantly faster than the older adults under all attentional load conditions (all p < 0.001). The analysis of the race model showed that AVI was decreased and delayed with the addition of auditory sustained attention (no_load > load_1 > load_2 > load_3 > load_4) for both older and younger adults. In addition, AVI was lower and more delayed in older adults than in younger adults in all attentional load conditions. These results suggested that auditory sustained attentional load decreased AVI and that AVI was reduced in older adults.

Fostering Self-Management of Everyday Memory in Older Adults: A New Intervention Approach

Traditional memory strategy training interventions improve older adults' performance on tests of episodic memory, but have limited transfer to episodic memory tasks, let alone to everyday memory. We argue that an alternative approach is needed to assist older adults to compensate for age-related cognitive declines and to maintain functional capacity in their own natural ecologies. We outline a set of principles regarding how interventions can successfully train older adults to increase successful goal pursuit to reduce risks of everyday memory failures. We argue that training individuals to use metacognitive self-regulatory strategies to proactively manage formulation and pursuit of daily goals can compensate for age-related cognitive changes and increase the likelihood of goal attainment. We then describe an intervention approach that instantiates these principles in a multi-modal intervention that is unique in its three-phase approach: (1) individualized assessment of an individual's current approaches to self-regulation; (2) training memory strategies, self-management skills, and new habits of mind in a group training context; and (3) a behavioral shaping period in which individuals receive coaching and feedback on their efforts to use trained procedures to improve everyday cognition. A recently completed study conducted an initial test of the intervention, with highly encouraging results. We advocate further efforts to replicate, extend, and fine-tune this type of intervention. The ultimate goal is to be able to deliver the intervention in a way that increases its potential reach, including to subpopulations of older adults at risk for everyday cognitive impairments.

Stimulus Specific to Age-Related Audio-Visual Integration in Discrimination Tasks

Age-related audio-visual integration (AVI) has been investigated extensively; however, AVI ability is either enhanced or reduced with ageing, and this matter is still controversial because of the lack of systematic investigations. To remove possible variates, 26 older adults and 26 younger adults were recruited to conduct meaningless and semantic audio-visual discrimination tasks to assess the ageing effect of AVI systematically. The results for the mean response times showed a significantly faster response to the audio-visual (AV) target than that to the auditory (A) or visual (V) target and a significantly faster response to all targets by the younger adults than that by the older adults (A, V, and AV) in all conditions. In addition, a further comparison of the differences between the probability of audio-visual cumulative distributive functions (CDFs) and race model CDFs showed delayed AVI effects and a longer time window for AVI in older adults than that in younger adults in all conditions. The AVI effect was lower in older adults than that in younger adults during simple meaningless image discrimination (63.0 ms vs. 108.8 ms), but the findings were inverse during semantic image discrimination (310.3 ms vs. 127.2 ms). In addition, there was no significant difference between older and younger adults during semantic character discrimination (98.1 ms vs. 117.2 ms). These results suggested that AVI ability was impaired in older adults, but a compensatory mechanism was established for processing sematic audio-visual stimuli.

Age-Related Shifts in Theta Oscillatory Activity During Audio-Visual Integration Regardless of Visual Attentional Load

Audio-visual integration (AVI) is higher in attended conditions than in unattended conditions. Here, we explore the AVI effect when the attentional recourse is competed by additional visual distractors, and its aging effect using single- and dual-tasks. The results showed the highest AVI effect under single-task-attentional-load condition than under no- and dual-task-attentional-load conditions (all P < 0.05) in both older and younger groups, but the AVI effect was weaker and delayed for older adults compared to younger adults for all attentional-load conditions (all P < 0.05). The non-phase-locked oscillation for AVI analysis illustrated the highest theta and alpha oscillatory activity for single-task-attentional-load condition than for no- and dual-task-attentional-load conditions, and the AVI oscillatory activity mainly occurred in the Cz, CP1 and Oz of older adults but in the Fz, FC1, and Cz of younger adults. The AVI effect was significantly negatively correlated with FC1 (r² = 0.1468, P = 0.05) and Cz (r² = 0.1447, P = 0.048) theta activity and with Fz (r² = 0.1557, P = 0.043), FC1 (r² = 0.1042, P = 0.008), and Cz (r² = 0.0897, P = 0.010) alpha activity for older adults but not for younger adults in dual task. These results suggested a reduction in AVI ability for peripheral stimuli and a shift in AVI oscillation from anterior to posterior regions in older adults as an adaptive mechanism.

Synergistic Effects of Cognitive Training and Physical Exercise on Dual-Task Performance in Older Adults

BACKGROUND

Studies report benefits of physical exercise and cognitive training to enhance cognition in older adults. However, most studies did not compare these interventions to appropriate active controls. Moreover, physical exercise and cognitive training seem to involve different mechanisms of brain plasticity, suggesting a potential synergistic effect on cognition.

OBJECTIVE

This study investigated the synergistic effect of cognitive training and aerobic/resistance physical exercise on dual-task performance in older adults. Intervention effects were compared to active controls for both the cognitive and the exercise domain.

METHOD

Eighty-seven older adults completed one of 4 different combinations of interventions, in which computer lessons was active control for cognitive training and stretching/toning exercise control for aerobic/resistance training: (a) cognitive dual-task training and aerobic/resistance training (COG+/AER+), (b) computer lessons and aerobic/resistance training (COG-/AER+), (c) cognitive dual-task training and stretching/toning exercises (COG+/AER-), and (d) computer lessons and stretching/toning exercises (COG-/AER-). The primary outcome was performance in an untrained transfer dual task. Stepwise backward removal regression analyses were used to predict pre- versus post-test changes in groups that have completed the dual-task training, aerobic/resistance or both interventions.

RESULTS

Participation in AER+ did not predict improvement in any dual-task outcomes. Participation in COG+ predicted reduction in dual-task cost and participation in COG+/AER+ predicted reduction in task-set cost.

DISCUSSION

Results suggest that the combination of cognitive and physical training protocols exerted a synergistic effect on task-set cost which reflects the cost of maintaining multiple response alternatives, whereas cognitive training specifically improved dual-task cost, which reflects the ability of synchronizing concurrent tasks.

Brain networks mediating the influence of background music on selective attention

Prevalent across societies and times, music has the ability to enhance attention, a property relevant to clinical applications, but the underlying brain mechanisms remain unknown. It is also unclear whether music produces similar or differential effects with advancing age. Here, we used event-related functional magnetic resonance imaging to investigate the influence of music exposure evoking four types of emotions on distinct attentional components measured with a modified attention network test, across 19 young (21 ± 2.6) and 33 old participants (72 ± 5.4). We then determined whether music-related effects differed across age groups and whether they were associated with particular acoustic features. Background music during selective attention requiring distractor conflict resolution was associated with faster response times and greater activations of fronto-parietal areas during happy and high-arousing music, whereas sad and low-valence music was associated with slower responses and greater occipital recruitment. Shifting and altering components of attention were unaffected. The influence of music on performance and brain networks was similar between age groups. These behavioral and neuroimaging results demonstrate the importance of affective music dimensions, particularly arousal, in enhancing selective attention processes. This study adds novel support to the benefits of music in the rehabilitation of attention functions.

Crossmodal Congruency Enhances Performance of Healthy Older Adults in Visual-Tactile Pattern Matching

One of the pivotal challenges of aging is to maintain independence in the activities of daily life. In order to adapt to changes in the environment, it is crucial to continuously process and accurately combine simultaneous input from different sensory systems, i.e., crossmodal or multisensory integration. With aging, performance decreases in multiple domains, affecting bottom-up sensory processing as well as top-down control. However, whether this decline leads to impairments in crossmodal interactions remains an unresolved question. While some researchers propose that crossmodal interactions degrade with age, others suggest that they are conserved or even gain compensatory importance. To address this question, we compared the behavioral performance of older and young participants in a well-established crossmodal matching task, requiring the evaluation of congruency in simultaneously presented visual and tactile patterns. Older participants performed significantly worse than young controls in the crossmodal task when being stimulated at their individual unimodal visual and tactile perception thresholds. Performance increased with adjustment of stimulus intensities. This improvement was driven by better detection of congruent stimulus pairs, while the detection of incongruent pairs was not significantly enhanced. These results indicate that age-related impairments lead to poor performance in complex crossmodal scenarios and demanding cognitive tasks. Crossmodal congruency effects attenuate the difficulties of older adults in visuotactile pattern matching and might be an important factor to drive the benefits of older adults demonstrated in various crossmodal integration scenarios. Congruency effects might, therefore, be used to develop strategies for cognitive training and neurological rehabilitation.

Cognitive and neural plasticity in old age: A systematic review of evidence from executive functions cognitive training

Cognitive training is a popular intervention aimed at attenuating age-related cognitive decline, however, the effects of this intervention on brain structure and function have not been thoroughly explored. Core executive functions (working memory, inhibition, cognitive flexibility) are dependent upon prefrontal brain regions-one of the most vulnerable areas of age-related decline. They are also implicated in numerous cognitive processes and higher-order functions. Training executive functions should therefore promote cognitive and neural enhancements in old age. This systematic review examined the effects of executive functions training on brain and cognition amongst healthy older adults across 20 studies. Behavioral performance consistently improved on trained cognitive tasks, though mixed findings were reported for untrained tasks. Training-related structural changes were reported, evidenced through increases in grey matter and cortical volume. Functional changes were not consistent, though a general pattern of increased subcortical and decreased frontal and parietal activation emerged across studies, indicating that training may potentially reduce reliance on compensatory neural mechanisms. Training executive functions appears to promote cognitive and neural plasticity in old age, though further research is required to develop a more comprehensive framework which connects and elucidates the mechanisms underlying cognitive training, cognitive transfer, and cognitive aging.

Bidirectional Interference Between Simulated Driving and Speaking

Purpose This study relied on acoustic measures of connected speech and several indices of driving performance to quantify interference between speaking and simulated driving. Method Three groups of 20 younger (ages 20-30 years), middle-age (ages 40-50 years), and older (ages 60-71 years) adults produced monologues and completed a simulated driving task, which involved maintaining a constant speed and lane position on a freeway. Both tasks were completed separately and concurrently. Results There were significant divided attention effects, with a reduced speaking time ratio, and increases in vocal intensity, speed variability, and steering wheel adjustments. There was a significant between-subjects age effect for intensity and fundamental frequency as the younger group had less variation with these variables compared to the other age groups across conditions. There was a significant between-subjects age effect for lane position, steering wheel position, and speed as the younger group had less variation in lane position compared to the other 2 groups, and the older group had more variation in speed and steering wheel position compared to the other 2 groups across the experimental conditions. Conclusion These findings reveal that divided attention conditions can impact both speech and simulated driving performance. The results also shed some light on the effects of age on speech and driving tasks, although the degree of interference from divided attention did not differ by age.

Higher cardiovascular fitness level is associated to better cognitive dual-task performance in Master Athletes: Mediation by cardiac autonomic control

INTRODUCTION/PURPOSE

This study compared cognitive performances and cardiac autonomic measures of higher fit and lower fit middle-aged and older highly active adults. The working hypotheses were that higher fit (master athletes) would show cognitive benefits in executive control conditions due to a high level of fitness compared to lower fit people and that this effect would be mediated by better cardiac autonomic adaptations in athletes.

METHODS

We recruited 39 highly active middle aged and older adults from Master Athletes' organizations. All participants performed a Rockport walking test and a computerized dual-task. Cardiac autonomic control was assessed with a measure of heart rate variability. Based on the V̇O_2max estimated by the Rockport test, a median split was performed to assess the influence of fitness level on cognitive performance and the link with heart rate variability. Those with the highest fitness level were considered Master Athletes.

RESULTS

Master Athletes showed better dual-task performances than lower fit individuals. A positive relationship between the V̇O_2max and dual-task performances was also observed. Master Athletes demonstrated a lower resting HR and higher RR interval than lower fit individuals, and this index was specifically related to the executive conditions of the dual task.

CONCLUSION

Our results highlight the role of fitness level on executive function in highly active middle aged and older adults and suggest that the better performances observed in highly fit individuals is mediated by cardiac autonomic control.

Guidelines for Gait Assessments in the Canadian Consortium on Neurodegeneration in Aging (CCNA)

Background

Motor and cognitive impairments are common among older adults and often co-exist, increasing their risk of dementia, falls, and fractures. Gait performance is an accepted indicator of global health and it has been proposed as a valid motor marker to detect older adults at risk of developing mobility and cognitive declines including future falls and incident dementia. Our goal was to provide a gait assessment protocol to be used for clinical and research purposes.

Methods

Based on a consensus that identified common evaluations to assess motor–cognitive interactions in community-dwelling older individuals, a protocol on how to evaluate gait in older adults for the Canadian Consortium on Neurodegeneration in Aging (CCNA) was developed.

Results

The CCNA gait assessment includes preferred and fast pace gait, and dual-task gait that comprises walking while performing three cognitively demanding tasks: counting backwards by ones, counting backwards by sevens, and naming animals. This gait protocol can be implemented using an electronic-walkway, as well as by using a regular stopwatch. The latter approach provides a simple manner to evaluate quantitative gait performance in clinics.

Conclusions

Establishing a standardized gait assessment protocol will help to assess motor–cognitive interactions in aging and neurodegeneration, to compare results across studies, and to feasibly implement and translate gait testing in clinics for detecting impending cognitive and mobility decline.

Does Combined Physical and Cognitive Training Improve Dual-Task Balance and Gait Outcomes in Sedentary Older Adults?

Everyday activities like walking and talking can put an older adult at risk for a fall if they have difficulty dividing their attention between motor and cognitive tasks. Training studies have demonstrated that both cognitive and physical training regimens can improve motor and cognitive task performance. Few studies have examined the benefits of combined training (cognitive and physical) and whether or not this type of combined training would transfer to walking or balancing dual-tasks. This study examines the dual-task benefits of combined training in a sample of sedentary older adults. Seventy-two older adults (≥60 years) were randomly assigned to one of four training groups: Aerobic + Cognitive training (CT), Aerobic + Computer lessons (CL), Stretch + CT and Stretch + CL. It was expected that the Aerobic + CT group would demonstrate the largest benefits and that the active placebo control (Stretch + CL) would show the least benefits after training. Walking and standing balance were paired with an auditory n-back with two levels of difficulty (0- and 1-back). Dual-task walking and balance were assessed with: walk speed (m/s), cognitive accuracy (% correct) and several mediolateral sway measures for pre- to post-test improvements. All groups demonstrated improvements in walk speed from pre- (M = 1.33 m/s) to post-test (M = 1.42 m/s, p < 0.001) and in accuracy from pre- (M = 97.57%) to post-test (M = 98.57%, p = 0.005).They also increased their walk speed in the more difficult 1-back (M = 1.38 m/s) in comparison to the 0-back (M = 1.36 m/s, p < 0.001) but reduced their accuracy in the 1-back (M = 96.39%) in comparison to the 0-back (M = 99.92%, p < 0.001). Three out of the five mediolateral sway variables (Peak, SD, RMS) demonstrated significant reductions in sway from pre to post test (p-values < 0.05). With the exception of a group difference between Aerobic + CT and Stretch + CT in accuracy, there were no significant group differences after training. Results suggest that there can be dual-task benefits from training but that in this sedentary sample Aerobic + CT training was not more beneficial than other types of combined training.

Comparable Cerebral Oxygenation Patterns in Younger and Older Adults during Dual-Task Walking with Increasing Load

The neuroimaging literature on dual-task gait clearly demonstrates increased prefrontal cortex (PFC) involvement when performing a cognitive task while walking. However, findings from direct comparisons of the cerebral oxygenation patterns of younger (YA) and older (OA) adults during dual-task walking are mixed and it is unclear how YA and OA respond to increasing cognitive load (difficulty) while walking. This functional near infra-red (fNIRS) study examined cerebral oxygenation of YA and OA during self-paced dual-task treadmill walking at two different levels of cognitive load (auditory n-back). Changes in accuracy (%) as well as oxygenated (HbO) and deoxygenated (HbR) hemoglobin were examined. For the HbO and HbR measures, eight regions of interest (ROIs) were assessed: the anterior and posterior dorsolateral and ventrolateral PFC (aDLPFC, pDLPFC, aVLPFC, pVLPFC) in each hemisphere. Nineteen YA (M = 21.83 years) and 14 OA (M = 66.85 years) walked at a self-selected pace while performing auditory 1-back and 2-back tasks. Walking alone (single motor: SM) and performing the cognitive tasks alone (single cognitive: SC) were compared to dual-task walking (DT = SM + SC). In the behavioural data, participants were more accurate in the lowest level of load (1-back) compared to the highest (2-back; p < 0.001). YA were more accurate than OA overall (p = 0.009), and particularly in the 2-back task (p = 0.048). In the fNIRS data, both younger and older adults had task effects (SM < DT) in specific ROIs for ΔHbO (three YA, one OA) and ΔHbR (seven YA, eight OA). After controlling for walk speed differences, direct comparisons between YA and OA did not reveal significant age differences, but did reveal a difficulty effect in HbO in the left aDLPFC (p = 0.028) and significant task effects (SM < DT) in HbR for six of the eight ROIs. Findings suggest that YA and OA respond similarly to manipulations of cognitive load when walking on a treadmill at a self-selected pace.

Dual-task costs in aging are predicted by formal education

The capacity to manage different concurrent tasks at the same time decays in older adults. There is however a considerable amount of inter-individual variability in this capacity even in healthy aging. The purpose of this empirical study is to investigate which factors help explaining this variability. A dual-task paradigm was administered to 64 older adults and 31 younger controls. In this paradigm, a primary simple response time task had to be carried out either by itself (single-task condition) or while concurrently performing a secondary subtraction task (dual-task condition). Dual-task costs were operationalized by comparing dual-task and single-task conditions. Older adults showed higher dual-task interference than younger controls. Within the older group, the influence of age, general cognitive abilities, performance on the secondary task, and years of formal education was assessed with a multiple regression analysis. The results showed that years of formal education in older adults were the best predictor that significantly explained a portion of the variance in dual-task performance. These findings extend previous literature by showing that formal education provides an important dose of cognitive reserve, which is useful to successfully implement cognitive dual-task management despite aging.

Executive functions in men and postmenopausal women

INTRODUCTION

This study was designed to assess sex differences in older adults (55-65 years old) in executive functions and to examine the influence of hormone therapy (HT) in postmenopausal women.

METHOD

We have assessed task performance in memory, visuospatial, and executive functions in 29 women using HT, 29 women who never used HT, and 30 men.

RESULTS

Men outperformed never users in task switching and updating. HT users outperformed never users in updating. HT users outperformed never users and men in visual divided attention.

DISCUSSION

The present study support previous findings that sex and HT impact cognition and bring new insights on sex and HT-related differences in executive functions.

Effects of age and syntactic complexity on speech motor performance

PURPOSE

This study investigated the effect of age on articulatory movement and stability in young, middle-age, and older adults. It also examined the potential influence of linguistic complexity on speech motor control across utterances that differed in their length and grammatical complexity.

METHOD

There were 60 participants in 3 age groups: 20-30 years, 40-50 years, and 60-70 years, with equal numbers of men and women in each group. The speakers produced 10 repetitions of 5 different stimuli-each of which included the same bilabial-loaded phrase in different grammatical contexts-while their lip movements were recorded.

RESULTS

Participants from the 60-year-old group had significantly longer utterance durations, whereas those from the 20-year-old group had the highest jaw spatiotemporal index (STI) values. There were significant differences in the upper lip STI, displacement, and velocity as well as in vocal intensity for the longer, complex conditions compared with the shorter, phrase-only task. Overall, the differences in performance were minimal across grammatical complexity levels that were equal in length.

CONCLUSION

These findings suggest that speech motor control matures beyond young adulthood and that linguistic complexity in a repetitive task does not appear to have a consistent effect on measures of speech movement.

Individual differences effects on the psychological refractory period

The goal of this study was to assess the impact of individual neuropsychological differences on the ability to share attention between concurrent tasks. Participants (n = 20) were trained on six single task practice sessions and dual-task was assessed with reaction time performance on a psychological refractory period (PRP) paradigm. Neuropsychological test scores were also acquired. Furthermore, one of the known variables that can influence performances on neuropsychological tests is gender, which was added as a potential predictor. Results show that the small PRP group was associated with better performances in processing speed, inhibition, flexibility and working memory on neuropsychological tests. Gender also had an impact on the PRP, males having a lower PRP than females. A multiple regression was performed to determine which variables explained the most PRP duration, which showed that 49.1% of the variance of the PRP length could be explained by gender, reaction times of the PRP practice trials at the sixth session, the denomination and flexibility conditions of the Modified Stroop Task as well as results on the Symbol Search Test. Gender was the variable that explained the PRP variance the most (23%). Processing speed also seemed to be a great determinant of the PRP as well as the ability to alternate between task-sets as assessed by the Flexibility condition of the Modified Stroop Task. Thus, this study reveals that good performances on certain neuropsychological tests could predict one's ease to manage two tasks simultaneously with a higher chance for males to perform better.