Mild Cognitive Impairments Attenuate Prefrontal Cortex Activations during Walking in Older Adults.

Roee Holtzer,Meltem Izzetoglu

doi:10.3390/brainsci10070415

Roee Holtzer, Meltem Izzetoglu

Open Access

https://doi.org/10.3390/brainsci10070415

Copy DOI

Abstract

The presence of Mild Cognitive Impairments (MCI) is associated with worse gait performance. However, the effect of MCI on cortical control of gait, as assessed during active walking, is unknown. We hypothesized that MCI would be associated with attenuated activations and limited improvement in efficiency in the Prefrontal cortex (PFC) under cognitively-demanding walking conditions. Functional Near-Infrared Spectroscopy (fNIRS) was used to assess Oxygenated Hemoglobin (HbO2) in the PFC during Single-Task-Walk (STW), cognitive interference (Alpha) and Dual-Task-Walk (DTW) conditions. Three repeated trials in each experimental condition were administered. Healthy control (n = 71; mean age = 76.82 ± 6.21 years; %female = 50.7) and MCI (n = 11; mean age = 78.27 ± 4.31 years; %female = 45.5) participants were included. The increase in HbO2 from STW to DTW was attenuated among MCI participants compared to controls (estimate = 0.505; p = 0.001). Whereas, among controls, HbO2 increased from Alpha to DTW, the opposite was observed among MCI participants (estimate = 0.903; p < 0.001). In DTW, the decline in HbO2 from trial 1 to 2 was attenuated in MCI participants compared to controls (estimate = 0.397; p = 0.008). Moreover, whereas HbO2 declined from trial 1 to 3 among controls, MCI participants showed the opposite trend (estimate = 0.946; p < 0.001). MCI was associated with attenuated brain activation patterns and compromised ability to improve PFC efficiency during dual-task walking.

Highlights

Mild Cognitive Impairments (MCI) is an established risk factor for Alzheimer’s dementia [1].The presence of MCI is determined via established diagnostic procedures requiring evidence for objective cognitive impairment [2] based on performance cutoff scores on a neuropsychological tests [3].The development of relatively minor declines in instrumental activities of daily living due to cognitive impairments is used to support the diagnosis of MCI [2,4]
A recent review using functional-Near-Infrared Spectroscopy revealed reduced task-related oxygenation in the frontal cortex in patients with MCI, which was further reduced in those diagnosed with dementia [8]
Limitations [25,26] as a conceptual framework, we evaluated the effect of MCI on functional-Near-Infrared Spectroscopy (fNIRS)-derived HbO2 in the Prefrontal cortex (PFC) during and over repeated trials of active walking under STW and DTW conditions

Summary

Introduction

Mild Cognitive Impairments (MCI) is an established risk factor for Alzheimer’s dementia [1].The presence of MCI is determined via established diagnostic procedures requiring evidence for objective cognitive impairment [2] based on performance cutoff scores on a neuropsychological tests [3].The development of relatively minor declines in instrumental activities of daily living due to cognitive impairments is used to support the diagnosis of MCI [2,4]. Mild Cognitive Impairments (MCI) is an established risk factor for Alzheimer’s dementia [1]. The presence of MCI is determined via established diagnostic procedures requiring evidence for objective cognitive impairment [2] based on performance cutoff scores on a neuropsychological tests [3]. MCI is associated with reduced grey matter volume in the whole brain, entorhinal cortex, and hippocampus (for review and meta-analysis see [5]). Structural and functional brain networks in MCI are both disrupted and associated with compromised cognitive performance [7]. A recent review using functional-Near-Infrared Spectroscopy (fNIRS) revealed reduced task-related oxygenation in the frontal cortex in patients with MCI, which was further reduced in those diagnosed with dementia [8]

Results

Discussion

Conclusion