Excess disability may explain, in part, the potential for great success with exercise and mobility interventions in this population. If individuals with AD are provided with physical and
functional challenges and are given the opportunity to work to their potential, they may regain lost abilities.
EVIDENCE-BASED REHABILITATION FOR INDIVIDUALS WITH ALZHEIMER’S AND OTHER DEMENTIAS
Physiological impact of exercise: Neural plasticity The knowledge that rehabilitation therapies can impact central nervous system plasticity is a powerful tool for clinicians. Animal studies have laid a rich foundation for research on the role of exercise interventions in AD and continue to provide great insights; there are also many human studies now to confirm the physiological impact of exercise. The neuroprotective mechanisms by which exercise is thought to impact cognitive and physical function include the following: ● Increased expression of neurotrophic factors : Exercise facilitates an up-regulation in BDNF, a neuroprotective agent, and other growth factors (e.g., insulin-like growth factor-1, vascular endothelial growth factor; Archer, 2011; Chieffi et al., 2017; Coelho et al., 2014; Foster, Rosenblatt, & Kuljiš, 2011; Intlekofer & Cotman, 2013; Jensen, Hasselbalch, Waldemar, & Simonsen, 2015; Saraulli, Costanzi, Mastrorilli, & Farioli-Vecchioli, 2017). Individuals with AD were historically excluded from research studies and clinical interventions under the assumption that they would not be able to fully participate because of their cognitive deficits. This notion has proven to be unfounded. The feasibility of supervised exercise and/or physical activity programs for older adults with dementia has been repeatedly demonstrated both in institutionalized and community-dwelling individuals and is no longer in question. Early systematic reviews examining the effectiveness of exercise with individuals who have dementia identified many methodological problems with published studies, and therefore advised careful interpretation of positive study findings (Forbes et al., 2008; Hauer, Becker, Lindemann, & Beyer, 2006). More recent systematic reviews continue to identify issues with research rigor, but evidence is mounting to confirm that exercise in older adults with cognitive impairment and/or dementia improves physical functioning and ADL status (Lam et al., 2018; Lee, Park, & Park, 2016; Lewis, Peiris, & Shields, 2017) as well as balance and falls (Burton et al., 2015; Chan et al., 2015; Lam et al., 2018; Lewis et al., 2017). Cognitive and behavioral benefits from physical exercise interventions have been reported, but strong evidence for these findings is lacking in this population (Barreto, Demougeot, Pillard, Lapeyre-Mestre, & Rolland, 2015; Cai & Abrahamson, 2015; Fleiner, Leucht, Förstl, Zijlstra, & Haussermann, 2017; Groot et al., 2016). Many of the exercise interventions represented in the literature are multimodal in design, so it is difficult to draw specific conclusions about strength, aerobic, and/or balance training interventions. Recent reviews also share the benefits of congruent and integrated physical and cognitive training interventions in older adults with MCI and dementia (Booth, Hood, & Kearney, 2016; Lipardo, Aseron, Kwan, & Tsang, 2017), given the real-life implications of superimposing cognitive demands on physical demands. The following are brief summaries related to the evidence supporting different dimensions of exercise interventions and some pragmatic suggestions related to types of exercise interventions.
● Angiogenesis : Exercise, particularly aerobic activity, impacts brain vascularization and perfusion (Archer, 2011; Chieffi et al., 2017; Intlekofer & Cotman, 2013). ● Metabolic adaptations : The oxidative stress of exercise promotes neuroprotective metabolic adaptations (e.g., improved glucose utilization; Foster et al., 2011; Intlekofer & Cotman, 2013). ● Immune system adaptations : Exercise boosts immune system function, which can modulate damaging overactive inflammatory reactions in the pathological or aging brain (Foster et al., 2011; Intlekofer & Cotman, 2013). ● AD-specific exercise impact : There is evidence to support
● Neurogenesis, dendritic arborization, and synaptic plasticity : BDNF and other growth factors are thought to play a role in enhancing the integrity and communicability of nerve cells (Archer, 2011; Chieffi et al., 2017; Foster et al., 2011; Intlekofer & Cotman, 2013; Saraulli et al., 2017). the above neurophysiological changes with exercise in individuals with MCI and dementia (Stigger, Marcolino, Portela, & Plentz, 2018) as well as enhanced hippocampal volume and blood flow as a result of exercise (Chieffi et al., 2017; Coelho et al., 2014; Duzel, van Praag, & Sendtner, 2016; Erickson et al., 2012; Ma et al., 2017). Additionally, there is some preliminary indication of impact on specific AD pathology (i.e., decreased abnormal beta-amyloid protein, decreased abnormal tau accumulation) as a result of exercise (Foster et al., 2011; Intlekofer & Cotman, 2013; Phillips, Baktir, Das, Lin, & Salehi, 2015; Saraulli et al., 2017). Existing evidence for exercise or activity interventions in individuals with Alzheimer’s and other dementias
Strength training Age-related muscle atrophy, or sarcopenia, commonly impacts functional mobility in older adults. There is some evidence that loss of bone mineral density and lean body mass is accelerated in individuals with AD (Burns, Johnson, Watts, Swerdlow, & Brooks, 2010; Loskutova, Honea, Vidoni, Brooks, & Burns, 2009). Resistance training is considered the safest and most effective intervention to combat sarcopenia (Jones et al., 2009). It is well established that progressive resistance exercise (PRE) improves strength and function in older adults (C. Liu, 2009), so it is not surprising that individuals with dementia would show these same benefits. The same basic physiological principles of resistance training that are relevant for strengthening in a general population (e.g., overload, adaptation, specificity) are relevant for older adults and individuals with AD. In geriatric medicine, physicians and health professionals must recognize the importance of endorsing and creating programs that are appropriately rigorous to allow for neuromuscular and physiological improvements in the given exercise domain (e.g., aerobic, strength training); however, submaximal training is better than no training, and clinical improvements in muscle power, muscle endurance, and function may result from strengthening programs that are at a lower threshold or disguised as functional tasks. Lower extremity strength, specifically quadriceps strength, in nursing home residents with dementia has been shown to be related to, and predictive of, lower extremity function, such as transfers, gait, toileting, and lower body dressing (Suzuki et al., 2012). This serves as excellent motivation to maintain or improve lower extremity strength early and throughout the disease process. Garuffi et al. (2013), comparing participants in a PRE protocol to a control group that met for social gatherings, demonstrated positive effects on functional outcome measures (i.e., climbing stairs, rising from the floor, donning socks) in the experimental group as compared to the control group. Many intervention protocols for individuals with dementia have included a strength training component, but this study used PRE exclusively, in the form of weight training machinery and free weights, which proved to be feasible for this population with mild to moderate AD. Because individuals with AD have difficulty learning new skills, some individuals may not respond
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