The influence of asthma on walking in older adults: brain predictors, medication adherence and asthma control

The increased prevalence of asthma among older adults and its associations with multiple adverse health outcomes including poor cognition are of significant public health concern. Walking is a robust measure of health across healthy and disease populations. Mobility impairments are common, debilitating and predictive of poor health outcomes. Scarce literature suggests that asthma is associated with self-reported and performance-based mobility limitations among older adults but putative mechanisms that may underlie this relationship have not been identified. The current proposal aims to address this critical gap in knowledge by examining neurological (e.g., gray matter volume and thickness, white matter integrity) and behavioral processes (e.g., medication adherence) involved in the influence of asthma on walking. Specifically, we aim to focus on asthma-related modifiable factors that are amenable to biobehavioral interventions. The fronto-striatal circuitry, critical for brain control of locomotion, is disrupted in asthma suggesting its key role in asthma-related mobility impairments. Poor controller medication adherence and reduced asthma control are proposed as mechanistic targets implicated in mobility impairments in older persons with asthma (OPWA). We aim to use a validated dual-task walking paradigm predictive of health outcomes, a burst measurement (i.e., repeated trials) design, and functional-near- infrared spectroscopy (fNIRS) to determine the influence of asthma on brain activation levels and trajectories of walking in 120 OPWA (age 60-80 years) and 120 controls without asthma. We will use multiple MRI methods to determine disruptions in the fronto-striatal circuitry to identify mechanisms of brain control of walking in OPWA. Furthermore, we will examine the impact of a 30-day medication adherence protocol and repeated asthma control assessments (pulmonary function, self-report) on walking performance and its associated brain activation patterns and learning trajectories. Brain activation patterns and learning trajectories of walking and improvements in their efficiency due to practice may be novel biomarkers to identify OPWA at risk of developing mobility impairments as they survive into older age. Such findings, their underlying asthma-specific fronto-striatal circuitry disruptions, and variability in controller medication adherence and asthma control will inform bio- behavioral interventions to improve walking, prevent mobility impairments, and improve related health outcomes among OPWA.