Effect of automaticity induced by treadmill walking on prefrontal cortex activation and dual-task performance in older adults.

As individuals age, they may experience a decline in gait automaticity, which requires increased attentional resources for the control of gait. This age-related decline in gait automaticity has been shown to contribute to higher prefrontal cortex (PFC) activation and lower dual-task performance during dual-task walking in older adults. This study is to investigate the effect of treadmill walking on PFC activation and dual-task performance in older adults. A total of 20 older adults (mean age, 64.35 ± 2.74 years) and 20 younger adults (mean age, 30.00 ± 3.15 years) performed single- and dual-task walking in overground and treadmill conditions. A wearable functional near-infrared spectroscopy and gait analyzer were used to analyze PFC activation and dual-task performance, respectively. To determine the dual-task (gait and cognitive) performance, the dual-task cost (DTC) was calculated using the following formula: (single-task - dual-task)/single-task × 100. In both groups, dual-task treadmill walking led to reduced PFC activation and reduced DTC compared to dual-task overground walking. Furthermore, despite a higher DTC in gait variability, correct response, total response, response index and a higher error score in older adults than in younger adults during overground walking, there was no difference in treadmill walking. The difference in PFC activation between single- and dual-tasks was also observed only in overground walking. Performing dual-task walking on a treadmill compared to overground walking results in different levels of dual-task performance and PFC activity. Specifically, older adults are able to maintain similar levels of dual-task performance as younger adults while walking on a treadmill, with reduced PFC activation due to the automaticity induced by the treadmill. Therefore, older adults who exhibit low dual-task performance during overground walking may be able to improve their performance while walking on a treadmill with fewer attentional resources.

Change in activity patterns in the prefrontal cortex in different phases during the dual-task walking in older adults.

BACKGROUND: Studies using functional near-infrared spectroscopy (fNIRS) have shown that dual-task walking leads to greater prefrontal cortex (PFC) activation compared to the single-task walking task. However, evidence on age-related changes in PFC activity patterns is inconsistent. Therefore, this study aimed to explore the changes in the activation patterns of PFC subregions in different activation phases (early and late phases) during both single-task and dual-task walking in both older and younger adults. METHODS: Overall, 20 older and 15 younger adults performed a walking task with and without a cognitive task. The activity of the PFC subregions in different phases (early and late phases) and task performance (gait and cognitive task) were evaluated using fNIRS and a gait analyzer. RESULTS: The gait (slower speed and lower cadence) and cognitive performance (lower total response, correct response and accuracy rate, and higher error rate) of older adults was poorer during the dual task than that of younger adults. Right dorsolateral PFC activity in the early period in older adults was higher than that in younger adults, which declined precipitously during the late period. Conversely, the activity level of the right orbitofrontal cortex in the dual-task for older adults was lower than for younger adults. CONCLUSIONS: These altered PFC subregion-specific activation patterns in older adults would indicate a decline in dual-task performance with aging.

Impact of intensive rehabilitation on long-term prognosis after stroke: A Korean nationwide retrospective cohort study.

An increasing number of patients are receiving rehabilitation after stroke. But the impact of intensive rehabilitation on the long-term prognosis of patients with stroke remains to be elucidated. The purpose of this study was to identify the impact of intensive rehabilitation on the long-term prognosis of patients with stroke using data from the National Health Insurance Service database. This is a register-based, retrospective cohort study. Using data from the National Health Insurance Service database, we included the patients who received rehabilitation for stroke from 2006 to 2013. Of the 14,984 patients diagnosed with stroke, 2483 died within 1 year, and 2866 did not receive rehabilitation; hence, they were also excluded. The final sample included 9635 (49.2% men, 50.8% women) patients. After correcting for covariates, the Cox model was used to evaluate the effects of physical therapy (PT) and occupational therapy (OT) on survival. We estimated the independent contribution of each factor to the risk of death from the initiation of rehabilitation. Significant differences in mortality were observed according to age, Charlson comorbidity index (CCI), income level, and stroke type. Patients with stroke who received both PT and OT had a better long-term prognosis than those who received either treatment alone. Therapy performed by a physical therapist with more than 120 hours of training effectively improved the patients' long-term prognosis. Intensive PT and OT will help improve the long-term prognosis of patients with stroke. This study emphasizes the importance of intensive rehabilitation in these patients.