Prefrontal activity and heart rate variability during cognitive tasks may show different changes in young and older adults with and without mild cognitive impairment.

Background: Age-related decline in cognitive function is often linked to changed prefrontal cortex (PFC) activity and heart rate variability (HRV). Mild cognitive impairment (MCI), a transitional stage between normal aging and dementia, might have further degeneration beyond aging. This study aimed to investigate the differences between young and older adults with or without MCI in cognitive functions, task-induced PFC activation and HRV changes. Methods: Thirty-one healthy young adults (YA), 44 older adults (OA), and 28 older adults with MCI (OA-MCI) were enrolled and compared in this cross-sectional study. Each participant received a one-time assessment including cognitive and executive functions, as well as the simultaneous recording of PFC activity and HRV during a cognitive task paradigm. Results: We observed age-related decrease in global cognitive functions, executive functions, HRV, and increase in PFC activity. The MCI further deteriorated the global cognitive and executive performances, but not the HRV or the prefrontal activation. Conclusion: Older people showed lower performances in general cognitive function and executive function, compensatory increase of PFC activity, and reduced HRV. Older people with MCI had further deterioration in cognitive performance, but not in PFC activation and HRV.

Gait performance and prefrontal cortex activation during single and dual task walking in older adults with different cognitive levels.

Background: Growing evidence shows the cognitive function influences the motor performance. The prefrontal cortex (PFC) as a part of the executive locomotor pathway is also important for cognitive function. This study investigated the differences in motor function and brain activity among older adults with different cognitive levels, and examined the significance of cognition on motor functions. Methods: Normal control (NC), individuals with mild cognitive impairment (MCI) or mild dementia (MD) were enrolled in this study. All participants received a comprehensive assessment including cognitive function, motor function, PFC activity during walking, and fear of fall. The assessment of cognitive function included general cognition, attention, executive function, memory, and visuo-spatial. The assessment of motor function included timed up and go (TUG) test, single walking (SW), and cognitive dual task walking (CDW). Results: Individuals with MD had worse SW, CDW and TUG performance as compared to individuals with MCI and NC. These gait and balance performance did not differ significantly between MCI and NC. Motor functions all correlated with general cognition, attention, executive function, memory, and visuo-spatial ability. Attention ability measured by trail making test A (TMT-A) was the best predictor for TUG and gait velocity. There were no significant differences in PFC activity among three groups. Nevertheless, the PFC activated more during CDW as compared with SW in individuals with MCI (p = 0.000), which was not demonstrated in the other two groups. Conclusion: MD demonstrated worse motor function as compared to NC and MCI. The greater PFC activity during CDW in MCI may be considered as a compensatory strategy for maintaining the gait performance. Motor function was related to the cognitive function, and the TMT A was the best predictor for the gait related performance in present study among older adults.

Multiarea Brain Activation and Gait Deterioration During a Cognitive and Motor Dual Task in Individuals With Parkinson Disease.

BACKGROUND AND PURPOSE: In people with Parkinson disease (PD), gait performance deteriorating during dual-task walking has been noted in previous studies. However, the effects of different types of dual tasks on gait performance and brain activation are still unknown. The purpose of this study was to investigate cognitive and motor dual-task walking performance on multiarea brain activity in individuals with PD. METHODS: Twenty-eight participants with PD were recruited and performed single walking (SW), walking while performing a cognitive task (WCT), and walking while performing a motor task (WMT) at their self-selected speed. Gait performance including walking speed, stride length, stride time, swing cycle, temporal and spatial variability, and dual-task cost (DTC) was recorded. Brain activation of the prefrontal cortex (PFC), premotor cortex (PMC), and supplementary motor areas (SMA) were measured using functional near-infrared spectroscopy during walking. RESULTS: Walking performance deteriorated upon performing a secondary task, especially the cognitive task. Also, a higher and more sustained activation in the PMC and SMA during WCT, as compared with the WMT and SW, in the late phase of walking was found. During WMT, however, the SMA and PMC did not show increased activation compared with during SW. Moreover, gait performance was negatively correlated with PMC and SMA activity during different walking tasks. DISCUSSION AND CONCLUSIONS: Individuals with mild to moderate PD demonstrated gait deterioration during dual-task walking, especially during WCT. The SMA and PMC were further activated in individuals with PD when performing cognitive dual-task walking.Supplemental Digital Content is Available in the Text.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A383 ).

Effects of transcranial direct current stimulation followed by exercise on neuropathic pain in chronic spinal cord injury: a double-blinded randomized controlled pilot trial.

STUDY DESIGN: Double-blinded randomized controlled pilot trial. OBJECTIVES: The present study aimed to investigate the effects of multiple sessions of tDCS followed by exercise on neuropathic pain and brain activity in individuals with chronic SCI. SETTING: Rehabilitation center in Taipei, Taiwan. METHODS: Twelve individuals with neuropathic pain after SCI were randomized into the experimental (real) or control (sham) tDCS group. All participants received 12 sessions of real or sham tDCS, and moderate upper body exercises over 4-6 weeks. Pain intensity, characters of pain, self-rating change of pain, brain activity, and quality of life were assessed at pre, posttest, and 4-week follow-up. RESULTS: The between-group differences (95% CI) of pain intensity at posttest and at 4-week follow-up were -2.2/10 points (-3.0 to 1.0, p = 0.060) and -2.0/10 points (-5.0 to -0.4, p = 0.035), respectively. The between-group differences of paresthesia/dysesthesia pain character were -2.0/10 points (-3.2 to 1.0, p = 0.053) at posttest and -2.3/10 points (-5.0 to 2.5, p = 0.054) at follow-up. No significant changes in brain activity and quality of life were noted at post-intervention and follow-up in both groups. CONCLUSIONS: The multiple sessions of anodal tDCS combined with moderate upper body exercise were feasible for individuals with neuropathic pain after spinal cord injury. However, the analgesic effect was not superior to exercise alone after 12 sessions of intervention, and the beneficial effect was observed at 4-week follow-up.

The effects of Ai Chi for balance in individuals with chronic stroke: a randomized controlled trial.

This study investigated the effectiveness of Ai Chi compared to conventional water-based exercise on balance performance in individuals with chronic stroke. A total of 20 individuals with chronic stroke were randomly allocated to receive either Ai Chi or conventional water-based exercise for 60 min/time, 3 times/week, and a total of 6 weeks. Balance performance assessed by limit of stability (LOS) test and Berg balance scale (BBS). Fugl-Meyer assessment (FMA) and gait performance were documented for lower extremity movement control and walking ability, respectively. Excursion and movement velocity in LOS test was significantly increased in anteroposterior axis after receiving Ai Chi (p = 0.005 for excursion, p = 0.013 for velocity) but not conventional water-based exercise. In particular, the improvement of endpoint excursion in the Ai Chi group has significant inter-group difference (p = 0.001). Both groups showed significant improvement in BBS and FMA yet the Ai Chi group demonstrated significantly better results than control group (p = 0.025). Ai Chi is feasible for balance training in stroke, and is able to improve weight shifting in anteroposterior axis, functional balance, and lower extremity control as compared to conventional water-based exercise.

Polymer/Ordered mesoporous carbon nanocomposite platelets as superior sensing materials for gas detection with surface acoustic wave devices.

We have prepared nanocomposites of polymers and platelet CMK-5-like carbon and have demonstrated their superior performance for gravimetric gas detection. The zirconium-containing platelet SBA-15 was used as hard template to prepare CMK-5-like carbon, which was then applied as a lightweight and high-surface-area scaffold for the growth of polymers by radical polymerization. Mesoporous nanocomposites composed of four different polymers were used as sensing materials for surface acoustic wave devices to detect ppm-level ammonia gas. The sensors showed much better sensitivity and reversibility than those coated with dense polymer films, and the sensor array could still generate a characteristic pattern for the analyte with a concentration of 16 ppm. The results show that the nanocomposite sensing materials are promising for highly sensitive gravimetric-type electronic nose applications.