New horizons in understanding oral health and swallowing function within the context of frailty

Abstract

Frailty is a complex and multidimensional condition wherein declines in physiologic reserve and function place individuals in a state of heightened vulnerability and decreased resiliency. There has been growing interest in both research and clinical settings to understand how to best define, assess and characterise frailty in older adults. To this end, various models and clinical assessment tools have been used to define and measure frailty. While differences exist among these models and tools, a common unifying theme is a focus on physical function and activity. Notably absent across many available conceptual models and clinical tools are items directly related to oral and swallowing function. This is an important oversight as widespread changes to both oral and swallowing function are evident in older adults. Indeed, emerging evidence suggests many of the functional domains affected in frail older adults, such as nutrition and sarcopenia, have cyclical relationships with impairments in oral (oral hypofunction) and swallowing function (dysphagia) as well. The increasing appreciation for the interrelationships among oral hypofunction, dysphagia and frailty provides an opportunity for refinement of frailty assessment and characterisation in older adults to incorporate metrics specific to oral and swallowing function.

Keywords: dysphagia; frailty; older people; oral health; oral hypofunction.

Figure 1

An overview of components related to the clinical conceptualization of frailty. Facetsof oral hypofunction and dysphagia (represented by light green boxes), which have historically gone unrecognized in the conceptualization of frailty, are also considered in the broader context of frailty development. Components of frailty that have direct associations to oral hypofunction and dysphagia are represented with dark green boxes.

Figure 2

A conceptual representation of homeostenosis based on previous work by Taffett [88]. In the early stages of the lifespan, there is adequate functional reserve throughout the body’s structures and physiologic systems to tolerate physiologic stressors. In this healthy state, individuals are in the ‘safe’ zone where the amount of functional reserve outweighs the amount of functional reserve in use. With ageing, there are progressive declines in functional reserve (homeostenosis) and physiologic capacity. This decline in functional capacity necessitates that more functional reserves are employed to maintain baseline function which places individuals in a ‘danger’ zone where they have very little functional reserve available to tolerate physiologic stressors.