Neural Correlates of Stepping in Healthy Elderly: Parietal and Prefrontal Cortex Activation Reflects Cognitive-Motor Interference Effects

Exploratory study of dual-task digital device in children and adolescents with attention-deficit/hyperactivity disorder

Aim

The study aimed to assess the efficacy and safety of SDT-001, a digital therapeutic, in Japanese children and adolescents with attention-deficit/hyperactivity disorder (ADHD).

Methods

This phase 2, multicenter, randomized, double-blind, sham-controlled study (jRCT1080225158) was conducted for a duration of up to 14 weeks. After screening, eligible participants were randomized to receive SDT-001 or single-task intervention for 25 min/day for 6 weeks and followed for 4 weeks after the intervention. A post hoc analysis was also performed to compare the effects of SDT-001 or a single-task to a nonrandomized, open-labeled, observational group (as the reference follow-up group; without single- or dual-task training; and continuing psychosocial treatment, including environmental adjustment).

Results

Overall, 262 participants were enrolled in the study between July 2020 and July 2021. Of these, 261 participants were included in the analysis (SDT-001, n = 108; single-task, n = 107; observation, n = 46). ADHD Rating Scale-IV (ADHD-RS-IV) scores (physician's assessment) decreased gradually, with greater reduction in SDT-001 versus the single-task group at week 6 (ADHD-RS-IV-Total score, least-squares mean change from baseline [95% confidence interval] -7.5 [9.0, -6.1] vs. -6.5 [-7.9, -5.0], P = 0.2112). Reductions in inattention and hyperactivity/impulsivity scores were maintained during 4-week follow-up after treatment completion. At week 6, the scores of both groups improved compared to the nonrandomized observation group in post hoc analysis.

Conclusion

These findings suggest SDT-001 as a promising treatment option, addressing the challenges of psychosocial treatment and pharmacotherapy in Japanese children and adolescents with ADHD.

Efficacy and safety of SDT-001, a dual-task digital device, in managing attention-deficit/hyperactivity disorder symptoms in children and adolescents: a phase 3, randomized, standard treatment-controlled study

AIM

This phase 3, multicenter, open-label study aimed to evaluate the efficacy and safety of SDT-001, a dual-task digital device, compared to standard treatment (environmental and/or psychosocial treatment: treatment as usual; TAU) in the comparison part and to evaluate the safety, tolerability, and long-term efficacy of SDT-001 in the repetition part in Japanese children and adolescents with attention-deficit/hyperactivity disorder (ADHD).

METHODS

In the comparison part, participants on standard treatment were randomized (2:1) to SDT-001 (n = 109; 25 min/day for 6 weeks, with a 4-week follow-up) or TAU (n = 55) groups. Participants (n = 126) from the comparison part transitioned to a single-arm repetition part with SDT-001 (6 weeks and followed for 12 weeks). Primary endpoint in the comparison part was changed from baseline to 6 weeks in ADHD rating scale IV (ADHD-RS-IV) inattention scores.

RESULTS

In the comparison part, SDT-001 demonstrated superiority to TAU, with significantly greater improvements from baseline to week 6 in ADHD-RS-IV inattention (adjusted mean difference [95% confidence interval], -2.97 [-4.38, -1.56]; P < 0.0001), total (-4.56 [-6.75, -2.38]; P < 0.0001), and hyperactivity-impulsivity (-1.55 [-2.64, -0.46]; P = 0.0056) scores. Additionally, other secondary endpoints showed improvements in symptoms in the SDT-001 group. In the repetition part, SDT-001 showed sustained reductions in ADHD-RS-IV scores till 12 weeks after completion of the 6-week treatment. No new severe adverse events or safety concerns were reported.

CONCLUSION

SDT-001 demonstrated superior efficacy at week 6 in ADHD-RS-IV compared to TAU, and reductions in scores were maintained up to the following 12 weeks, indicating its potential as a novel digital therapeutic option for ADHD management.

Frontal and parietal cortices activation during walking is repeatable in older adults based on fNIRS

Purpose

This study aimed to explore the test-retest reliability of fNIRS in measuring frontal and parietal cortices activation during straight walking and turning walking in older adults, in order to provide a theoretical foundation for selecting assessment tools for clinical research on motor control and some diseases such as Parkinson's disease in older adults.

Methods

18 healthy older participants (69.1 ± 0.7 years) were included in this study. The participants completed straight walking and figure-of-eight turning walking tasks at self-selected speeds. Intra-class correlation coefficients (ICCs) and Bland-Altman scatter plots were used to assess the test-retest reliability of oxyhemoglobin (HbO2) changes derived from fNIRS. p < 0.05 was considered statistically significant.

Results

The test-retest reliability of HbO2 in prefrontal cortex (ICC, 0.67-0.78) was good and excellent, in frontal motor cortex (ICC, 0.51-0.61) and parietal sensory cortex (ICC, 0.53-0.62) is fair and good when the older adults performed straight and turning walking tasks. Bland-Altman diagram shows that the data consistency is fair and good.

Conclusion

fNIRS can be used as a clinical measurement method to evaluate the brain activation of the older adults when walking in a straight line and turning, and the results are acceptable repeatability and consistency. However, it is necessary to strictly control the testing process and consider the possible changes in the repeated measurements.

Using virtual reality-based neurocognitive testing and eye tracking to study naturalistic cognitive-motor performance

Natural human behavior arises from continuous interactions between the cognitive and motor domains. However, assessments of cognitive abilities are typically conducted using pen and paper tests, i.e., in isolation from "real life" cognitive-motor behavior and in artificial contexts. In the current study, we aimed to assess cognitive-motor task performance in a more naturalistic setting while recording multiple motor and eye tracking signals. Specifically, we aimed to (i) delineate the contribution of cognitive and motor components to overall task performance and (ii) probe for a link between cognitive-motor performance and pupil size. To that end, we used a virtual reality (VR) adaptation of a well-established neurocognitive test for executive functions, the 'Color Trails Test' (CTT). The VR-CTT involves performing 3D reaching movements to follow a trail of numbered targets. To tease apart the cognitive and motor components of task performance, we included two additional conditions: a condition where participants only used their eyes to perform the CTT task (using an eye tracking device), incurring reduced motor demands, and a condition where participants manually tracked visually-cued targets without numbers on them, incurring reduced cognitive demands. Our results from a group of 30 older adults (>65) showed that reducing cognitive demands shortened completion times more extensively than reducing motor demands. Conditions with higher cognitive demands had longer target search time, as well as decreased movement execution velocity and head-hand coordination. We found larger pupil sizes in the more cognitively demanding conditions, and an inverse correlation between pupil size and completion times across individuals in all task conditions. Lastly, we found a possible link between VR-CTT performance measures and clinical signatures of participants (fallers versus non-fallers). In summary, performance and pupil parameters were mainly dependent on task cognitive load, while maintaining systematic interindividual differences. We suggest that this paradigm opens the possibility for more detailed profiling of individual cognitive-motor performance capabilities in older adults and other at-risk populations.

Neural correlates of the sound facilitation effect in the modified Simon task in older adults

Introduction

The ability to resolve interference declines with age and is attributed to neurodegeneration and reduced cognitive function and mental alertness in older adults. Our previous study revealed that task-irrelevant but environmentally meaningful sounds improve performance on the modified Simon task in older adults. However, little is known about neural correlates of this sound facilitation effect.

Methods

Twenty right-handed older adults [mean age = 72 (SD = 4), 11 female] participated in the fMRI study. They performed the modified Simon task in which the arrows were presented either in the locations matching the arrow direction (congruent trials) or in the locations mismatching the arrow direction (incongruent trials). A total of 50% of all trials were accompanied by task-irrelevant but environmentally meaningful sounds.

Results

Participants were faster on the trials with concurrent sounds, independently of whether trials were congruent or incongruent. The sound effect was associated with activation in the distributed network of auditory, posterior parietal, frontal, and limbic brain regions. The magnitude of the behavioral facilitation effect due to sound was associated with the changes in activation of the bilateral auditory cortex, cuneal cortex, and occipital fusiform gyrus, precuneus, left superior parietal lobule (SPL) for No Sound vs. Sound trials. These changes were associated with the corresponding changes in reaction time (RT). Older adults with a recent history of falls showed greater activation in the left SPL than those without falls history.

Conclusion

Our findings are consistent with the dedifferentiation hypothesis of cognitive aging. The facilitatory effect of sound could be achieved through recruitment of excessive neural resources, which allows older adults to increase attention and mental alertness during task performance. Considering that the SPL is critical for integration of multisensory information, individuals with slower task responses and those with a history of falls may need to recruit this region more actively than individuals with faster responses and those without a fall history to overcome increased difficulty with interference resolution. Future studies should examine the relationship among activation in the SPL, the effect of sound, and falls history in the individuals who are at heightened risk of falls.

Dry EEG measurement of P3 to evaluate cognitive load during sitting, standing, and walking

Combining brain imaging with dual-task paradigms provides a quantitative, direct metric of cognitive load that is agnostic to the motor task. This work aimed to quantitatively assess cognitive load during activities of daily living-sitting, standing, and walking-using a commercial dry encephalography headset. We recorded participants' brain activity while engaging in a stimulus paradigm that elicited event-related potentials. The stimulus paradigm consisted of an auditory oddball task in which participants had to report the number of oddball tones that were heard during each motor task. We extracted the P3 event-related potential, which is inversely proportional to cognitive load, from EEG signals in each condition. Our main findings showed that P3 was significantly lower during walking compared to sitting (p = .039), suggesting that cognitive load was higher during walking compared to the other activities. There were no significant differences in P3 between sitting and standing. Head motion did not have a significant impact on the measurement of cognitive load. This work validates the use of a commercial dry-EEG headset for measuring cognitive load across different motor tasks. The ability to accurately measure cognitive load in dynamic activities opens new avenues for exploring cognitive-motor interactions in individuals with and without motor impairments. This work highlights the potential of dry EEG for measuring cognitive load in naturalistic settings.

Long-term levodopa ameliorates sequence effect in simple, but not complex walking in early Parkinson's disease patients

BACKGROUND

The sequence effect (SE) is characterized by the progressive decrement of movements and is often observed in Parkinson's disease (PD) patients. While acute effect of levodopa does not ameliorate the SE, the effect of long-term levodopa treatment for the SE remains unknown.

OBJECTIVE

We aimed to elucidate the SEs during various gait conditions and their response to long-term levodopa treatment in drug-naïve PD patients.

METHODS

Nineteen drug-naïve PD patients and 21 healthy controls were enrolled. Gait parameters were measured via wearable inertial sensors in the following conditions:1) straight walking, 2) circular walking: walking a circle of 1 m diameter in a clock-wise direction for 3 laps, 3) straight or circular walking under cognitive-motor dual-task (serial 7s subtractions). PD patients were evaluated at baseline, within 1 h after intravenous administration of levodopa, and after one, three, and six months treatment with levodopa. The SE was measured by a linear regression slope by plotting consecutive stride lengths over steps. Patients were also separately analyzed depending on laterality of symptoms.

RESULTS

Long-term levodopa treatment ameliorated the SE only during single-task straight walking. The SE during circular walking was exacerbated after long-term levodopa treatment for right-side dominant patients. During dual-task straight walking, the SE at baseline was greater in right-side dominant PD patients.

CONCLUSIONS

The SE only during single-task straight walking can be ameliorated by long-term levodopa treatment. However, the SE may be exaggerated by cognitive motor interference or by asymmetrical stride length with/without long-term levodopa treatment, depending on the laterality of symptoms.