Decreased automaticity contributes to dual task decrements in older compared to younger adults

Influence of cognitive and emotional factors on motor dual-task performance in nursing home residents. The mediating and moderating roles of cognition, concerns about falling, well-being, and depressive symptoms. A cross-sectional observational study

BACKGROUND

This study aimed (1) to compare walking performance under single (ST) and dual-task (DT) conditions with varying cognitive tasks and degrees of difficulty, (2) to investigate the association of concerns about falling, depressive symptomatology, and psychological and physical well-being with ST and DT walking performance as well as cognitive and motor DT costs (cDTC; mDTC); and (3) to examine whether depressive symptomatology and well-being mediate or moderate the association between concerns about falling and DT performance in a large sample of German nursing home residents.

METHODS

We analyzed data from a cross-sectional study with 449 ambulatory nursing home residents (mean age 84.1 ± 7.87 years). Performance on three cognitive tasks with different cognitive loads (serial subtraction in one's [SST_1] and three's [SST_3]; verbal fluency [VFT]; number of correctly reproduced responses) and (walking speed) was recorded each under ST and DT conditions (walking plus additional cognitive task). In addition, we assessed concerns about falling, depressive symptomatology, and psychological and physical well-being using the Falls Efficacy Scale - International (FESI), the Center for Epidemiologic Studies Depression Scale (CESD), and the Short-Form-Health Survey (SF-12), respectively.

RESULTS

We observed significant differences in ST walking and walking while performing an additional cognitive task. Walking speed was higher in ST walking than walking during the SST_1, SST_3, and VFT (all p < 0.001). In both the ST walking and the SST_1 DT condition, the concerns about falling (and physical well-being) explained a low proportion of variance in walking speed. Physical well-being had a minor but significant mediating effect on the relationship between concerns about falling and walking speed in the ST walking and SST_1 DT condition.

CONCLUSIONS

Concerns about falling and physical well-being seem to exert a small yet statistically significant effect on ST walking under conditions of lower cognitive demand. The effect is diminished by increasing the cognitive load, as compensation becomes impossible. Interventions focusing on decreasing concerns about falling and maintaining physical well-being might compensate for limitations in walking performance of nursing home residents in ST and DT situations. Reducing fall concerns, promoting physical well-being, and adjusting cognitive demands can improve nursing home residents' walking performance.

TRIALS REGISTRATION

DRKS00014957 (BfArM - Deutsches Register Klinischer Studien (DRKS)).

Locomotor-cognitive dual-tasking is reduced in older adults relative to younger: A systematic review with meta-analysis

BACKGROUND

The capacity to dual-task is critically important over the lifespan, enabling an individual to respond to demands in their environment, both safely and efficiently.

RESEARCH QUESTION

Does recent evidence suggest that relative to younger adults, older adults are most disadvantaged when performing locomotor-cognitive dual-tasks under conditions that are more representative of the real-world?

METHOD

A literature search of major electronic databases was conducted to find relevant peer-reviewed papers published since 2011. Thirty-nine studies that compared proportional dual-task costs (pDTC) between older and younger adults on a locomotor-cognitive dual-task were included. Study quality was assessed using the Appraisal tool for Cross-Sectional Studies.

RESULTS

pDTC were calculated for a total of 504 motor and 53 cognitive outcomes. Weighted means showed that older adults experienced larger pDTCs than younger adults for motor (mean difference = -6.97) and cognitive (mean difference = -8.15) outcomes. Velocity variability measures produced the largest group difference on motor pDTC (mean difference = -32.83), as did cognitive tasks that targeted arithmetic (mean difference = -18.57) and texting skills (mean difference = -17.43). Cognitive tasks that were 'most representative' resulted in the largest age differences on motor pDTC (mean difference = -16.89).

SIGNIFICANCE

This meta-analysis showed that dual-tasking challenged the ability of older adults to maintain consistency in the sequential timing of their gait. As well, older adults demonstrated greater pDTCs on motor outcomes, especially when the cognitive tasks were more representative of day-to-day activities. Taken together, this suggests that clinical assessments should focus on measures of variability rather than absolute measures of temporal and spatial gait. It is recommended that future research use more representative paradigms that are sensitive to dual-task interference and predictive of real-world behaviour.

Regional brain activity and neural network changes in cognitive-motor dual-task interference: A functional near-infrared spectroscopy study

Previous neuroimaging studies have reported dual-task interference (DTi) and deterioration of task performance in a cognitive-motor dual task (DT) compared to that in a single task (ST). Greater frontoparietal activity is a neural signature of DTi; nonetheless, the underlying mechanism of cortical network in DTi still remains unclear. This study aimed to investigate the regional brain activity and neural network changes during DTi induced by highly demanding cognitive-motor DT. Thirty-four right-handed healthy young adults performed the spiral-drawing task. They underwent a paced auditory serial addition test (PASAT) simultaneously or independently while their cortical activity was measured using functional near-infrared spectroscopy. Motor performance was determined using the balanced integration score (BIS), a balanced index of drawing speed and precision. The cognitive task of the PASAT was administered with two difficulty levels defined by 1 s (PASAT-1 s) and 2 s (PASAT-2 s) intervals, allowing for the serial addition of numbers. Cognitive performance was determined using the percentage of correct responses. These motor and cognitive performances were significantly reduced during DT, which combined a drawing and a cognitive task at either difficulty level, compared to those in the corresponding ST conditions. The DT conditions were also characterized by significantly increased activity in the right dorsolateral prefrontal cortex (DLPFC) compared to that in the ST conditions. Multivariate Granger causality (GC) analysis of cortical activity in the selected frontoparietal regions of interest further revealed selective top-down causal connectivity from the right DLPFC to the right inferior parietal cortex during DTs. Furthermore, changes in the frontoparietal GC connectivity strength between the PASAT-2 s DT and ST conditions significantly correlated negatively with changes in the percentage of correct responses. Therefore, DTi can occur even in cognitively proficient young adults, and the right DLPFC and frontoparietal network being crucial neural mechanisms underlying DTi. These findings provide new insights into DTi and its underlying neural mechanisms and have implications for the clinical utility of cognitive-motor DTs applied to clinical populations with cognitive decline, such as those with psychiatric and brain disorders.

Frontal cortex neurometabolites and mobility in older adults: a preliminary study

BACKGROUND

The frontal cortex, relevant to global cognition and motor function, is recruited to compensate for mobility dysfunction in older adults. However, the in vivo neurophysiological (e.g., neurometabolites) underpinnings of the frontal cortex compensation for mobility dysfunction remain poorly understood. The purpose of this study was to investigate the relationships among frontal cortex neurophysiology, mobility, and cognition in healthy older adults.

METHODS

Magnetic Resonance Spectroscopy (MRS) quantified N-acetylasparate (tNAA) and total choline (tCho) concentrations and ratios in the frontal cortex in 21 older adults. Four inertial sensors recorded the Timed Up & Go (TUG) test. Cognition was assessed using the Flanker Inhibitory Control and Attention Test which requires conflict resolution because of response interference from flanking distractors during incongruent trials. Congruent trials require no conflict resolution.

RESULTS

tNAA concentration significantly related to the standing (p = 0.04) and sitting (p = 0.03) lean angles. tCho concentration (p = 0.04) and tCho ratio (p = 0.02) significantly related to TUG duration. tCho concentration significantly related to incongruent response time (p = 0.01). tCho ratio significantly related to both congruent (p = 0.009) and incongruent (p < 0.001) response times. Congruent (p = 0.02) and incongruent (p = 0.02) Flanker response times significantly related to TUG duration.

CONCLUSIONS

Altered levels of frontal cortex neurometabolites are associated with both mobility and cognitive abilities in healthy older adults. Identifying neurometabolites associated with frontal cortex compensation of mobility dysfunction could improve targeted therapies aimed at improving mobility in older adults.

The prefrontal cortex hemodynamic responses to dual-task paradigms in older adults: A systematic review and meta-analysis

Background

Functional near-infrared spectroscopy (fNIRS) is a method to measure cerebral hemodynamics. Determining the changes in prefrontal cortex (PFC) hemodynamics during dual-task paradigms is essential in explaining alterations in physical activities, especially in older adults.

Aims

To systematically review and meta-analyze the effects of dual-task paradigms on PFC hemodynamics in older adults.

Methods

The search was conducted in PubMed, Scopus, and Web of Science from inception until March 2023 to identify studies on the effects of dual-task paradigms on PFC hemodynamics. The meta-analysis included variables of cerebral hemodynamics, such as oxygenated hemoglobin (HbO₂) and deoxygenated hemoglobin (HbR). The heterogeneity of the included studies was determined using the I² statistic. Additionally, subgroup analysis was conducted to compare the effects of different types of cognitive tasks.

Results

A total of 37 studies were included in the systematic review, 25 studies comprising 2224 older adults were included in the meta-analysis. Our findings showed that inhibitory control and working memory tasks significantly increased HbO₂ in the PFC by 0.53 (p < 0.01, 95% CI = 0.37 to 0.70) and 0.13 (p < 0.01, 95% CI = 0.08 to 0.18) μmol/L, respectively. Overall, HbO₂ was significantly increased during dual-task paradigms by 0.36 μmol/L (P < 0.01, 95% CI = 0.27 to 0.45). Moreover, dual-task paradigms also decreased HbR in the PFC by 0.04 (P < 0.01, 95% CI = -0.07 to -0.01). Specifically, HbR decreased by 0.08 during inhibitory control tasks (p < 0.01, 95% CI = -0.13 to -0.02), but did not change during working memory tasks.

Conclusion

Cognitive tasks related to inhibitory control required greater cognitive demands, indicating higher pfc activation during dual-task paradigms in older adults. for clinical implications, the increase in pfc oxygenated hemoglobin and decrease in pfc deoxygenated hemoglobin may help explain why older adults are more likely to fall during daily activities.

Dyspnea induced by inspiratory loading limits dual-tasking in healthy young adults

OBJECTIVES

Dyspnea is a common and multidimensional experience of healthy adults and those with respiratory disorders. Due to its neural processing, it may limit or interfere with cognition, which may be examined with a dual-task paradigm. The aim of this study was to compare single-task performance of Stroop Colour and Word Test (SCWT) or inspiratory threshold loading (ITL) to their combined dual-task performance. Secondly, whether mood was related to dyspnea or cognitive performance was also evaluated.

MATERIALS & METHODS

A virtual pre-post design examined single (SCWT and ITL) and dual-task (SCWT+ITL) performance. For ITL, a Threshold Trainer™ was used to elicit a "somewhat severe" rating of dyspnea. The SCWT required participants to indicate whether a colour-word was congruent or incongruent with its semantic meaning. The Depression, Anxiety and Stress Scale-21 (DASS-21) was completed to assess mood. Breathing frequency, Borg dyspnea rating, and breathing endurance time were ascertained.

RESULTS

Thirty young healthy adults (15F, 15M; median age = 24, IQR [23-26] years) completed the study. SCWT+ITL had lower SCWT accuracy compared to SCWT alone (98.6%, [97.1-100.0] vs 99.5%, [98.6-100.0]; p = 0.009). Endurance time was not different between ITL and SCWT+ITL (14.5 minutes, [6.9-15.0]) vs 13.7 minutes, [6.1-15.0]; p = 0.59). DASS-21 scores positively correlated with dyspnea scores during ITL (rho = 0.583, p<0.001) and SCWT+ITL (rho = 0.592, p<0.001).

CONCLUSIONS

ITL significantly reduced dual-task performance in healthy young adults. Lower mood was associated with greater perceived dyspnea during single and dual-task ITL. Considering the prevalence of dyspnea in respiratory disorders, the findings of this dual task paradigm warrant further exploration to inform dyspnea management during daily activities.

Paradoxical improvement of cognitive control in older adults under dual-task walking conditions is associated with more flexible reallocation of neural resources: A Mobile Brain-Body Imaging (MoBI) study

Combining walking with a demanding cognitive task is traditionally expected to elicit decrements in gait and/or cognitive task performance. However, it was recently shown that, in a cohort of young adults, most participants improved performance when walking was added to performance of a Go/NoGo response inhibition task. The present study aims to extend these previous findings to an older adult cohort, to investigate whether this improvement when dual-tasking is observed in healthy older adults. Mobile Brain/Body Imaging (MoBI) was used to record electroencephalographic (EEG) activity, three-dimensional (3D) gait kinematics and behavioral responses in the Go/NoGo task, during sitting or walking on a treadmill, in 34 young adults and 37 older adults. Increased response accuracy during walking, independent of age, was found to correlate with slower responses to stimuli (r = 0.44) and with walking-related EEG amplitude modulations over frontocentral regions (r = 0.47) during the sensory gating (N1) and conflict monitoring (N2) stages of inhibition, and over left-lateralized prefrontal regions (r = 0.47) during the stage of inhibitory control implementation. These neural activity changes are related to the cognitive component of inhibition, and they were interpreted as signatures of behavioral improvement during walking. On the other hand, aging, independent of response accuracy during walking, was found to correlate with slower treadmill walking speeds (r = -0.68) and attenuation in walking-related EEG amplitude modulations over left-dominant frontal (r = -0.44) and parietooccipital regions (r = 0.48) during the N2 stage, and over centroparietal regions (r = 0.48) during the P3 stage. These neural activity changes are related to the motor component of inhibition, and they were interpreted as signatures of aging. Older adults whose response accuracy 'paradoxically' improved during walking manifested neural signatures of both behavioral improvement and aging, suggesting that their flexibility in reallocating neural resources while walking might be maintained for the cognitive but not for the motor inhibitory component. These distinct neural signatures of aging and behavior can potentially be used to identify 'super-agers', or individuals at risk for cognitive decline due to aging or neurodegenerative disease.

Impact of cognitive capacity on physical performance in chronic obstructive pulmonary disease patients: A scoping review

Background: Chronic obstructive pulmonary disease (COPD) is often accompanied by impaired cognitive and physical function. However, the role of cognitive function on motor control and purposeful movement is not well studied. The aim of the review was to determine the impact of cognition on physical performance in COPD. Methods: Scoping review methods were performed including searches of the databases: MEDLINE, EMBASE, Cochrane Systematic Reviews, Cochrane (CENTRAL), APA PsycINFO, and CINAHL. Two reviewers independently assessed articles for inclusion, data abstraction, and quality assessment. Results: Of 11,252 identified articles, 44 met the inclusion criteria. The review included 5743 individuals with COPD (68% male) with the forced expiratory volume in one second range of 24-69% predicted. Cognitive scores correlated with strength, balance, and hand dexterity, while 6-min walk distance (n = 9) was usually similar among COPD patients with and without cognitive impairment. In 2 reports, regression analyses showed that delayed recall and the trail making test were associated with balance and handgrip strength, respectively. Dual task studies (n = 5) reported impaired balance or gait in COPD patients compared to healthy adults. Cognitive or physical Interventions (n = 20) showed variable improvements in cognition and exercise capacity. Conclusions: Cognition in COPD appears to be more related to balance, hand, and dual task function, than exercise capacity.

Loss of Neural Automaticity Contributes to Slower Walking in COPD Patients

The physical impairments (e.g., slower walking speed) in patients with chronic obstructive pulmonary disease (COPD) have been attributed to peripheral characteristics (e.g., muscle atrophy). However, cognitive impairment may compromise motor control including walking automaticity. The objective of this study was to investigate PFC neural activity, evaluated using changes in oxygenated hemoglobin (ΔO₂Hb), during preferred paced walking (PPW) in COPD patients and age-matched controls. The ΔO₂Hb from the left and right dorsolateral PFC was measured using functional near-infrared spectroscopy. Fifteen COPD patients (age: 71 ± 8) and twenty age-matched controls (69 ± 7 years) participated. Two-way mixed ANOVA demonstrated that O₂Hb in both groups decreased during PPW from the start (quintile 1; Q1) to the end (quintile 5; Q5) in the left dorsolateral and medial PFC. Q1 was comprised of the data during the first 20% of the task, while Q5 included data collected in the last 20% of the task duration. PPW duration ranged between 30.0 and 61.4 s in the control group and between 28.6 and 73.0 s in COPD patients. COPD patients demonstrated a higher O₂Hb in Q5 compared to the negative O₂Hb in controls in the right medial and dorsolateral PFC during PPW. PPW velocity was lower in COPD patients compared to controls (1.02 ± 0.22 vs. 1.22 ± 0.14 m/s, p = 0.005). Healthy older controls exhibited automaticity during walking unlike patients with COPD. The lesser decrease in O₂Hb in COPD patients may be attributed to increased executive demands or affect-related cues (e.g., pain or dyspnea) during walking.