Evidence for a Specific Association Between Sustained Attention and Gait Speed in Middle-to-Older-Aged Adults

 We need this research in stroke which your doctors and stroke hospitals will never initiate because there are no problems in stroke to solve.

The whole problem is the stroke world thinks nothing needs to be done as proven by this meme on World Stroke Day a few years ago. Whomever approved that is a complete blithering idiot.

What a lying piece of shit

Evidence for a Specific Association Between Sustained Attention and Gait Speed in Middle-to-Older-Aged Adults

Hannah Park^1,2†, Courtney Aul^1,3†, Joseph DeGutis^1,4,5, On-Yee Lo^6,7,8, Victoria N. Poole⁹, Regina McGlinchey^4,5,10, Jonathan F. Bean^10,11,12, Elizabeth Leritz^4,5,10 and Michael Esterman^1,3,4,13*

• ¹Boston Attention and Learning Laboratory (BALLAB), VA Boston Healthcare System, Boston, MA, United States
• ²Department of Psychology, Brandeis University, Waltham, MA, United States
• ³National Center for PTSD, VA Boston Healthcare System, Boston, MA, United States
• ⁴Translational Research Center for TBI and Stress Disorders (TRACTS), VA Boston Healthcare System, Boston, MA, United States
• ⁵Department of Psychiatry, Harvard Medical School, Boston, MA, United States
• ⁶Hinda and Arthur Marcus Institute for Aging Research, Hebrew SeniorLife, Boston, MA, United States
• ⁷Division of Gerontology, Beth Israel Deaconess Medical Center, Boston, MA, United States
• ⁸Department of Medicine, Harvard Medical School, Boston, MA, United States
• ⁹Rush Alzheimer's Disease Center and Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL, United States
• ¹⁰New England Geriatric Research, Educational and Clinical Center (NEGRECC), VA Boston Healthcare System, Boston, MA, United States
• ¹¹Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, United States
• ¹²Spaulding Rehabilitation Hospital, Boston, MA, United States
• ¹³Department of Psychiatry, Boston University School of Medicine, Boston, MA, United States

Although cognitive decline has previously been associated with mobility limitations and frailty, the relationship between sustained attention and gait speed is incompletely characterized. To better quantify the specificity of the sustained attention and gait speed association, we examined the extent to which this relationship is unique rather than accounted for by executive functioning and physical health characteristics. 58 middle-to-older-aged community-dwelling adults without overt evidence of cognitive impairment (45–90 years old; 21 females) participated in the study. Each participant completed a 4-meter gait speed assessment and validated neuropsychological tests to examine various domains of executive functioning including working memory (i.e., Digit Span), inhibitory control (i.e., D-KEFS Color-Word Interference), and task switching (i.e., D-KEFS Number/Letter Switching). Multiple physical and vascular risk factors were also evaluated. Sustained attention was assessed using the gradual onset continuous performance task (gradCPT), a well-validated go/no-go sustained attention task. A series of linear regression models were used to examine how different aspects of cognition, including sustained attention and traditional measures of executive functioning, related to gait speed while controlling for a variety of physical and vascular risk factors. Among all predictors, gradCPT accuracy explained the most variance in gait speed (R² = 0.19, p < 0.001) and was the only significant predictor (β = 0.35, p = 0.01) when accounting for executive functioning and other physical and vascular risk factors. The present results indicate that sustained attention may be uniquely sensitive and mechanistically linked to mobility limitations in middle-to-older adults.

Introduction

Across the older adult population mobility has been identified as a critical determinant of well-being. In particular, walking speed is an easy to execute, reliable, and valid indicator of functional capacity (Middleton et al., 2015) as well as overall health (Cesari et al., 2005; Studenski et al., 2011). Slow gait speed is one of Fried's defining criteria for the frailty phenotype (Fried et al., 2001), as it increases susceptibility to negative outcomes, including the development of physical disability (Clegg et al., 2013), and is a verified predictor of falls, morbidity, and mortality (e.g., Fried et al., 2001; Studenski et al., 2011; Welch et al., 2020). Diminished gait speed is further linked to increased risk for adverse cardiovascular events, including coronary heart disease (Dumurgier et al., 2009), and poor cognitive aging outcomes, such as dementia (Alfaro-Acha et al., 2007). Given its relationship to healthy aging, gait is considered the “sixth vital sign” (Fritz and Lusardi, 2009; Middleton et al., 2015) to assess functional status. As gait speed is associated with various factors that critically impact quality of life, understanding these multifaceted relationships has significant translational implications for older adults. The present study aims to better understand how specific aspects of cognition relate to gait speed.

Executive functions, including working memory, task switching, and inhibitory control (Miyake et al., 2000), are critical for fundamental aspects of daily life. Executive functioning deficits are often accompanied with functional disability (e.g., Hajjar et al., 2009), and there is an association between age-related mobility loss and executive decline (Hajjar et al., 2009; Vazzana et al., 2010; McGough et al., 2011). For instance, reduced task switching abilities have been directly related to diminished gait speed (Hirota et al., 2010; McGough et al., 2011) and future mobility impairment (Vazzana et al., 2010). These processes depend on several large-scale brain networks, especially frontal-parietal control networks, which are susceptible to age-related alterations (Campbell et al., 2012). Additionally, gait speed in older adults is associated with activity in executive control and attention networks (Jordan et al., 2017; Zhou et al., 2020), suggesting overlap in the neural correlates of these processes. As we age, walking may become less automatic due to multiple factors, including attenuated somatosensory input (Clark et al., 2014), which increases reliance on alternative resources to maintain optimal functioning. Executive functions may compensate for this reduction in automaticity, and therefore mediate the rate of decline (Yogev-Seligmann et al., 2008; Clark et al., 2014). However, if executive function capacity degrades due to general age-related or neurodegenerative processes, mobility loss will likely be exacerbated (Yogev-Seligmann et al., 2008). As executive dysfunction is a predictor of mobility impairment and is associated with negative outcomes in older adults, the interplay between executive and motor function has important implications for quality of life.

Previous work regarding the relationship between executive function and gait predominantly examines transient acts of cognitive control. Another critical aspect of cognition, less often characterized as an executive function, is the ability to sustain attentional control. The capacity to maintain task-set and goal-directed attention over time, or sustain attention, is necessary for various higher-level cognitive processes (Fortenbaugh et al., 2017b), including other aspects of executive functioning such as working memory and inhibitory control (deBettencourt et al., 2019). Sustained attention is also critical for everyday activities, such as safe driving (Yanko and Spalek, 2013), and is related to numerous functional outcomes, including motor function recovery following stroke (Robertson et al., 1997). The ability to sustain attention declines with age (Fortenbaugh et al., 2015) and the presence of cardiovascular risk factors (Wooten et al., 2019). Prior research demonstrates that sustained attention deficits are related to mobility loss, even in the absence of explicit cognitive impairment (O'Halloran et al., 2011, 2014; Killane et al., 2014). Studies examining gait and cognition found that poorer sustained attention, quantified by reaction time variability on the Sustained Attention to Response Task (SART), retrospectively predicted falls within the last year (O'Halloran et al., 2011), progression into frailty (O'Halloran et al., 2014), and reduced gait speed when the task required additional motor coordination (Killane et al., 2014). These findings are in line with the reduction of automaticity model, wherein cognitive resources moderate age-related mobility loss.

Expanding our comprehension of the relationship between sustained attention and gait is critical for understanding the aging process and for the development of interventions to attenuate functional decline. As such, there are several limitations of previous work relating sustained attention to mobility. First, while previous studies have demonstrated the importance of sustained attention in healthy aging, they have also revealed a relationship between reduced processing speed and other aspects of executive dysfunction with diminished gait speed (e.g., Killane et al., 2014). Thus, it is unclear if sustained attention is a unique predictor of gait that surpasses more global cognitive decline. Second, previous measures of sustained attention were based solely on reaction time variability (Killane et al., 2014; O'Halloran et al., 2014). Although reaction time variability is a marker of sustained attention (Fortenbaugh et al., 2015), it may also be related to impaired motor processes or processing speed, therefore task accuracy is potentially a more direct sustained attention measure. Additionally, previous studies have relied on a single, albeit well-characterized, measure of sustained attention, the SART (O'Halloran et al., 2011, 2014; Killane et al., 2014), and convergence using alternative measures would provide more compelling evidence for a robust relationship between sustained attention and mobility. While the SART is a well-established assessment of sustained attention, we have developed the gradual-onset continuous performance task (gradCPT) (Esterman et al., 2013), which eliminates the exogenous effects of abrupt onsets and isolates endogenous attentional control (Fortenbaugh et al., 2017b). This task is a well-validated and sensitive measure of sustained attention, with established lifespan trajectories (Fortenbaugh et al., 2015) and sensitivity to a number of clinical disorders (e.g., Esterman et al., 2019). Finally, it is unclear whether the relationship between sustained attention and mobility is unique when controlling for health factors such as a comprehensive cardiovascular risk profile, which is also associated with sustained attention impairments (Wooten et al., 2019), and mobility loss (Hajjar et al., 2009). Thus, we aimed to replicate and extend previous work linking sustained attention and gait using gradCPT accuracy (d′) as our primary measure. We then investigated whether the predictive power of sustained attention was greater than traditional neuropsychological measures of executive functioning, while controlling for a range of demographic and health factors. We hypothesized that sustained attention would uniquely predict gait speed.