Peter Wayne, Osher Center for Integrative Medicine, Brigham and Women's Hospital and Harvard Medical School
12 May 2014
Preventing falls among older adults is an urgent public health challenge worldwide with significant direct and indirect costs to society. This challenge has led to extensive efforts to improve our understanding of the complex physiology underlying age-related decline of postural control, to identify interventions to reduce the risk of falling in adults, and to develop markers to accurately measure the short- and long-term impact of interventions targeting gait health and fall risk. The study by Mirelman and colleagues (JNER, 2014) combines a thoughtful experimental design with emerging functional neuroimaging technology to understand important cognitive processes related postural control during dual task gait and balance challenges in healthy younger adults. Their approach and findings lays the foundation for a variety of important future studies addressing significant clinical and public health matters.
A substantial body of research to date supports that healthy gait and postural control rely on cognitive resources, especially those associated with frontal lobe activation. However, due to the practical challenges of collecting functional measures of gait and balance simultaneous with brain imaging, less is known about the neural basis of cognitive-motor interactions during gait. The authors of this study employ functional near-infrared spectroscopy (fNIRS), a relatively non-invasive, safe, portable, and low-cost method of monitoring of brain activity to detect changes in the prefrontal cortex during gait. Building on previous studies that have used fNIRS to demonstrate increased activation in the frontal cortex during dual task walking vs. quiet walking, the present study demonstrates a clear graded dose response related to the impact of cognitive load on frontal lobe activity - with walking during serial subtractions of 7 having a bigger impact on blood flow (i.e. cognitive demand) than walking and simply counting, which in turn had a greater impact on blood flow than usual walking with no dual task. This results confirms for the first time that changes in gait and frontal blood flow during dual tasks are not simply due to verbalization of words, but rather likely due to competition for cognitive resources. The latter view is further supported by the observation in this study that changes in frontal lobe blood flow were not observed during dual task quiet standing, only during in the more attention demanding dynamic gait task.
While these results in an of themselves are an important contribution, this study's strength lies in its outlining of a rich set of protocols that can be applied to multiple avenues of future research. Logical pressing issues that would benefit from the approach Mirelman and colleagues outline in this study include how fNRI-assessed cognitive costs during gait vary with age and neurological impairments that are known to alter cognitive-motor interactions (e.g., Parkinson disease, mild cognitive impairment). The approach would also provide excellent markers for evaluating the efficacy and mechanisms of a wide range of novel interventions that are explicitly designed to impact dual tasks function - including high tech videogaming systems (Anguera et al 2013) as well as traditional mind-body exercises like Tai Chi (Wayne et al 2013).
References:
Anguera JA, Boccanfuso J, Rintoul JL, Al-Hashimi O, Faraji F, Janowich J, Kong E, Larraburo Y, Rolle C, Johnston E, Gazzaley A. Video game training enhances cognitive control in older adults. Nature. 2013 Sep 5;501(7465):97-101. doi: 10.1038/nature12486.
Wayne PM, Walsh JN, Taylor-Piliae RE, Wells RE, Papp KV, Donovan NJ, Yeh GY. The impact of Tai Chi on cognitive performance in older adults: A systematic review and meta-analysis. Journal American Geriatric Society, 2014;62:25-39. PMC Journal: In Process.
'Minding' our steps
12 May 2014
Preventing falls among older adults is an urgent public health challenge worldwide with significant direct and indirect costs to society. This challenge has led to extensive efforts to improve our understanding of the complex physiology underlying age-related decline of postural control, to identify interventions to reduce the risk of falling in adults, and to develop markers to accurately measure the short- and long-term impact of interventions targeting gait health and fall risk. The study by Mirelman and colleagues (JNER, 2014) combines a thoughtful experimental design with emerging functional neuroimaging technology to understand important cognitive processes related postural control during dual task gait and balance challenges in healthy younger adults. Their approach and findings lays the foundation for a variety of important future studies addressing significant clinical and public health matters.
A substantial body of research to date supports that healthy gait and postural control rely on cognitive resources, especially those associated with frontal lobe activation. However, due to the practical challenges of collecting functional measures of gait and balance simultaneous with brain imaging, less is known about the neural basis of cognitive-motor interactions during gait. The authors of this study employ functional near-infrared spectroscopy (fNIRS), a relatively non-invasive, safe, portable, and low-cost method of monitoring of brain activity to detect changes in the prefrontal cortex during gait. Building on previous studies that have used fNIRS to demonstrate increased activation in the frontal cortex during dual task walking vs. quiet walking, the present study demonstrates a clear graded dose response related to the impact of cognitive load on frontal lobe activity - with walking during serial subtractions of 7 having a bigger impact on blood flow (i.e. cognitive demand) than walking and simply counting, which in turn had a greater impact on blood flow than usual walking with no dual task. This results confirms for the first time that changes in gait and frontal blood flow during dual tasks are not simply due to verbalization of words, but rather likely due to competition for cognitive resources. The latter view is further supported by the observation in this study that changes in frontal lobe blood flow were not observed during dual task quiet standing, only during in the more attention demanding dynamic gait task.
While these results in an of themselves are an important contribution, this study's strength lies in its outlining of a rich set of protocols that can be applied to multiple avenues of future research. Logical pressing issues that would benefit from the approach Mirelman and colleagues outline in this study include how fNRI-assessed cognitive costs during gait vary with age and neurological impairments that are known to alter cognitive-motor interactions (e.g., Parkinson disease, mild cognitive impairment). The approach would also provide excellent markers for evaluating the efficacy and mechanisms of a wide range of novel interventions that are explicitly designed to impact dual tasks function - including high tech videogaming systems (Anguera et al 2013) as well as traditional mind-body exercises like Tai Chi (Wayne et al 2013).
References:
Anguera JA, Boccanfuso J, Rintoul JL, Al-Hashimi O, Faraji F, Janowich J, Kong E, Larraburo Y, Rolle C, Johnston E, Gazzaley A. Video game training enhances cognitive control in older adults. Nature. 2013 Sep 5;501(7465):97-101. doi: 10.1038/nature12486.
Wayne PM, Walsh JN, Taylor-Piliae RE, Wells RE, Papp KV, Donovan NJ, Yeh GY. The impact of Tai Chi on cognitive performance in older adults: A systematic review and meta-analysis. Journal American Geriatric Society, 2014;62:25-39. PMC Journal: In Process.
Competing interests
The author has no competing interests to declare.