Mini-Review of Studies Testing the Cardiorespiratory Hypothesis With Near-Infrared Spectroscopy (NIRS): Overview and Perspectives

A Wearable Device Towards Automatic Detection and Treatment of Opioid Overdose

Opioid-induced overdose is one of the leading causes of death among the US population under the age of 50. In 2021 alone, the death toll among opioid users rose to a devastating number of over 80,000. The overdose process can be reversed by the administration of naloxone, an opioid antagonist that rapidly counteracts the effects of opioid-induced respiratory depression. The idea of a closed-loop opioid overdose detection and naloxone delivery has emerged as a potential engineered solution to mitigate the deadly effects of the opioid epidemic. In this work, we introduce a wrist-worn wearable device that overcomes the portability issues of our previous work to create a closed-loop drug-delivery system, which includes (1) a Near-Infrared Spectroscopy (NIRS) sensor to detect a hypoxia-driven opioid overdose event, (2) a MOSFET switch, and (3) a Zero-Voltage Switching (ZVS) electromagnetic heater. Using brachial artery occlusion (BAO) with human subjects (n = 8), we demonstrated consistent low oxygenation events. Furthermore, we proved our device's capability to release the drug within 10 s after detecting a hypoxic event. We found that the changes in the oxyhemoglobin, deoxyhemoglobin and oxygenation saturation levels ( SpO2) were different before and after the low-oxygenation events ( 0.001). Although additional human experiments are needed, our results to date point towards a potential tool in the battle to mitigate the effects of the opioid epidemic.

Effect of the Level of Physical Activity on Prefrontal Cortex Hemodynamics in Older Adults During Single- and Dual-Task Walking

The present study aimed to examine the impact of the level of physical activity on prefrontal cortex activation in older adults during single- and dual-task walking. Thirty physically inactive and 36 active older adults (60-85 years old) performed six 2-min tasks on a treadmill: two static cognitive tasks, two single-task walking tests, and two dual-task walking tests. Hemodynamics at the level of the prefrontal cortex were measured continuously using functional near-infrared spectroscopy to evaluate cortical activation. The perceived difficulty of the task, cognitive performance, and gait parameters were also measured. During the walking tasks, the level of prefrontal cortex activation, the perceived difficulty of the task, cognitive performance, and motor parameters were not significantly different between active and inactive older adults. This unchanged activation with physical activity was likely the consequence of a similar motor and cognitive load and cardiorespiratory fitness in both active and inactive older adults.

Effects of Chronic Physical Exercise or Multicomponent Exercise Programs on the Mental Health and Cognition of Older Adults Living in a Nursing Home: A Systematic Review of Studies From the Past 10 Years

Some nursing homes for the elderly provide holistic care that integrates several interventions, including physical exercise. The aim of this systematic review is to summarize the effects of physical exercise or multicomponent exercise programs on the mental health (wellbeing, anxiety and depression) and cognitive functions of older adults with/without dementia who live in a nursing home and do/do not require wheelchair assistance. To this end, PubMed, PsycInfo and Web of Science are using to identify clinical trials and randomized controlled studies conducted during the period January 2011 to December 2021 to examine the progression of research in this field over the past ten years. In total, 2597 articles are identifying and 21 are including in the systematic review. After selecting articles according to the PRISMA standards, the data extraction and methodological quality assessment of the eligible studies are performing individually by two reviewers and then pooled together. The synthesis of the studies shows that physical exercise or multicomponent exercise programs have a beneficial effect on mental health and cognitive functions. However, this effect is more common among older adults without dementia, compared to their counterparts who have dementia or use wheelchairs. The explanatory mechanisms, lack of benefits from physical exercise and the need to standardize methods are discussing in this regard. Finally, future studies must examine the effects of an innovative and adaptive physical activity program on the mental health and cognitive functions of older adults living in nursing homes.

Effects of Cardiorespiratory Fitness on Cerebral Oxygenation in Healthy Adults: A Systematic Review

Introduction

Exercise is known to improve cognitive functioning and the cardiorespiratory hypothesis suggests that this is due to the relationship between cardiorespiratory fitness (CRF) level and cerebral oxygenation. The purpose of this systematic review is to consolidate findings from functional near-infrared spectroscopy (fNIRS) studies that examined the effect of CRF level on cerebral oxygenation during exercise and cognitive tasks.

Methods

Medline, Embase, SPORTDiscus, and Web of Science were systematically searched. Studies categorizing CRF level using direct or estimated measures of V̇O_2max and studies measuring cerebral oxygenation using oxyhemoglobin ([HbO₂]) and deoxyhemoglobin ([HHb]) were included. Healthy young, middle-aged, and older adults were included whereas patient populations and people with neurological disorders were excluded.

Results

Following PRISMA guidelines, 14 studies were retained following abstract and full-text screening. Cycle ergometer or treadmill tests were used as direct measures of CRF, and one study provided an estimated value using a questionnaire. Seven studies examined the effects of CRF on cerebral oxygenation during exercise and the remaining seven evaluated it during cognitive tasks. Increased [HbO₂] in the prefrontal cortex (PFC) was observed during cognitive tasks in higher compared to lower fit individuals. Only one study demonstrated increased [HHb] in the higher fit group. Exercise at submaximal intensities revealed increased [HbO₂] in the PFC in higher compared to lower fit groups. Greater PFC [HHb] was also observed in long- vs. short-term trained males but not in females. Primary motor cortex (M1) activation did not differ between groups during a static handgrip test but [HHb] increased beyond maximal intensity in a lower compared to higher fit group.

Conclusion

Consistent with the cardiorespiratory hypothesis, higher fit young, middle-aged, and older adults demonstrated increased cerebral oxygenation compared to lower fit groups. Future research should implement randomized controlled trials to evaluate the effectiveness of interventions that improve CRF and cerebral oxygenation longitudinally.

Concurrent Performance of Executive Function during Acute Bouts of Exercise in Adults: A Systematic Review

The purpose of the study was to systematically review the evidence on the effects of an acute bout of exercise on concurrent performance of core executive function (EF) during exercise in adults. Four electronic databases (i.e., PubMed, Web of Science, PsycINFO, and SportDiscus) were searched from inception dates to 30 December 2020. The literature searches were conducted using the combinations of two groups of relevant items related to exercise and executive function. Articles were limited to human studies in adults. The search process, study selection, data extraction, and study quality assessments were carried out independently by two researchers. A total of 4899 studies were identified. Twenty-two studies met our inclusion criteria. Of the 42 reported outcomes in the 22 studies, 13 (31%) of the 42 outcomes showed that core EF performance was enhanced during exercise and 14 (33%) found that core EF performance did not differ from control conditions. Fifteen (36%) found that core EF performance was impaired. Notably, improved EF performances tend to be observed during moderate-intensity exercise, whereas impaired EF performances were more likely to be observed at vigorous-high intensity. The review suggests mixed findings regarding the effects of an acute bout of exercise on concurrent performance of core EF. Exercise intensity seems to influence the effects. The underlying neural mechanisms remain to be elucidated.