Date of Award

5-2023

Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)

Department

Exercise and Health Science

First Advisor

Azizah J. Jor'dan

Second Advisor

Tongjian You

Third Advisor

Richard Viskochil

Abstract

Introduction

Type II diabetes mellitus (T2DM) is associated with a multitude of complications including hyperglycemia, decreased insulin responsiveness, microvascular and macrovascular disease, as well as cerebrovascular complications such as tissue hypoperfusion. These complications impact cerebral arteries (i.e., anterior, posterior, and middle cerebral arteries (MCA). The MCA, specifically, is the largest terminal branch of the internal carotid artery and is the most common cerebral artery affected by disease, many of which include symptoms affecting cerebral blood velocity, (e.g., blood velocity measured at the MCA, MCAv) and tissue perfusion. When this affects the executive function center, a decline in cognitive performance has been observed. Sensorimotor, visual, and executive processing areas of the brain are supplied blood by the MCA and are components of physiologically complex postural regulation. Multiscale entropy analysis of postural sway metrics (e.g., path length and acceleration) use multiple scales of time and systems to depict the complexity of systems used in postural regulation. A higher complexity is associated with a more robust potential to adapt to postural stressors, and a lower complexity with a poorer and less integrated systemic resources to assist with regulation against outside stressors. Dual tasking is the ability to maintain attentional resources on more than one skill in tandem (e.g., regulating upright posture while talking on the phone, reading a menu, or holding a conversation) and is a common everyday occurrence and requirement of independent living. A greater decrease can be observed among many chronic diseases. The relationship between MCAv and postural sway complexity during a dual task paradigm has not yet been explored.

Purpose and Specific Aims

This study aims to 1) compare MCAv during performance of a VSDT paradigm with two levels of difficulty (i.e., low and high) in healthy older adults (HOA) and adults with T2DM and, 2) to compare postural sway complexity during the VSDT paradigm with varied difficulty levels. Additionally, 3) investigate the relationship between MCAv and postural sway complexity in HOA and older adults with T2DM. We hypothesized that the T2DM group would demonstrate a lower MCAv, and postural sway complexity compared to HOA, and a diminished change in response in MCAv between conditions. Further, across participants, the MCAv and postural sway complexity will increase during the LDVST when compared to the blank condition and remain elevated during the HDVST condition.

Methods

This analysis used existing data collected from 48 older adult participants. T2DM (n = 18, aged 76 ± 7 years) and healthy older adults (n=18, aged 76.7 (± 6.5) performed multiple 60-second trials of quiet standing (i.e., looking at a blank screen) and performing a VST. The VST consisted of a low difficulty (LD) (i.e., counting the frequency of one designated letter in a random grid of letters) and high difficulty (HD) (i.e., counting two different letters simultaneously) condition. MCAv was measured using Transcranial Doppler ultrasound probes. The complexity of the postural sway acceleration signals in the an¬terior-posterior (AP) and medial-lateral (ML) directions were quantified using multiscale entropy analysis (MSE). .

Results

An ANOVA revealed no differences between groups in MCAv and postural sway complexity in the ML or AP planes. Across participants, the LDVST elicited a significant increase in MCAv from the blank condition. A significant decrease from the LDVST to the HDVST and blank conditions was also observed while this trend was not established in postural sway complexity. No differences between groups were observed and when adjusted for sex, age, race, group, BMI, and education level this difference disappeared. A Pearson’s correlation revealed no correlation between postural sway complexity and MCAv across participants or within groups.

Conclusion

T2DM is associated with many complications that can impact MCAv, which can lead to cognitive a decline in cognitive performance which is already common among aging adults. This analysis revealed no group differences in MCAv during a VSDT paradigm though differences between conditions were observed. Across participants, MCAv was significantly higher during the LDVST when compared with the blank and HDVST conditions. There was no association between postural sway complexity and MCAv and the T2DM group demonstrated a lower postural sway complexity when compared to HOA. Though controlled, participants among both groups were being pharmacologically treated for hyperglycemia, hypercholesterolemia, hypertension, and hypothyroidism, which could have impacted the MCAv results. Future research should continue to use the VSDT paradigm to understand the physiological components driving cognitive and postural changes in aging and T2DM.

Comments

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