Neurological Gait Abnormalities Moderate the Functional Brain Signature of the Posture First Hypothesis

Abstract

The posture first hypothesis suggests that under dual-task walking conditions older adults prioritize gait over cognitive task performance. Functional neural confirmation of this hypothesis, however, is lacking. Herein, we determined the functional neural correlates of the posture first hypothesis and hypothesized that the presence of neurological gait abnormalities (NGA) would moderate associations between brain activations, gait and cognitive performance. Using functional near-infrared spectroscopy we assessed changes in oxygenated hemoglobin levels in the pre-frontal cortex (PFC) during normal walk and walk while talk (WWT) conditions in a large cohort of non-demented older adults (n = 236; age = 75.5 ± 6.49 years; female = 51.7 %). NGA were defined as central (due to brain diseases) or peripheral (neuropathic gait) following a standardized neurological examination protocol. Double dissociations between brain activations and behavior emerged as a function of NGA. Higher oxygenation levels during WWT were related to better cognitive performance (estimate = 0.145; p < 0.001) but slower gait velocity (estimate = −6.336, p <0.05) among normals. In contrast, higher oxygenation levels during WWT among individuals with peripheral NGA were associated with worse cognitive performance (estimate = −0.355; p <0.001) but faster gait velocity (estimate = 14.855; p <0.05). Increased activation in the PFC during locomotion may have a compensatory function that is designed to support gait among individuals with peripheral NGA.

Cognitive Remediation to Enhance Mobility in Older Adults: the Crem Study

“…In subsequent fNIRS studies, we have demonstrated that internal consistency of HbO 2 measurements, determined by split-half intraclass correlations, was excellent for NPW (0.830) and WWT (0.849) [39]. Furthermore, we have replicated the original finding demonstrating increased activation levels in the PFC in WWT compared with NPW in a large cohort of older adults [39], elucidated the role of the PFC in cognitive control of attentiondemanding locomotion in groups stratified by the presence of peripheral and central gait abnormalities [45] and reported on the effect of mild Parkinsonian symptoms on the involvement of the PFC in balance [46].…”

Neural correlates of obstacle negotiation in older adults: An fNIRS study

“…The sample consisted of community-dwelling older adults enrolled in “Central Control of Mobility in Aging” (CCMA) (6, 11). Participants received a telephone interview prior to inclusion in the study, which consisted of a medical history questionnaire, a mobility questionnaire, and cognitive screens to rule out dementia (17).…”

“…Recent research has shown that seniors with mobility limitations, attributed to peripheral causes, demonstrated greater PFC activations during dual-task walking compared to controls (11). Peripheral impairments are related to slow gait (12), which is a robust and relatively easy measure to assess, making it advantageous for both clinical and research settings.…”

Review of functional near-infrared spectroscopy in neurorehabilitation

“…Interestingly, it is also reported that in patients with neuropathic gait disturbance, larger prefrontal activation is correlated with faster gait speed and worse cognitive performance, suggesting that the strategy for attentional allocation was different between patients and normal elderly. 34 In patients with stroke with hemiparesis, gait-related cortical activation showed an asymmetric pattern in the SMC and intervention by therapists could alter cortical activation. 35 A recent study revealed that a light haptic touch of an unaffected finger could facilitate cortical activation and diminish asymmetric cortical activation patterns during gait in patients with stroke.…”