From cognitive to motor impairment and from sarcopenia to cognitive impairment: a bidirectional pathway towards frailty and disability

Abstract

Cognitive and motor/physical functions may evolve at different speeds along the entire lifespan, and with different impact on aging processes, although running parallel along the same temporal continuum. The investigation of the shared association between cognitive and motor/physical functions has represented a challenging subject of debate in the last decades. However, the direction of this cognitive-motor link still needs to be furtherly clarified. A first approach suggests that pre-clinical cognitive decline, such as the MCI, may have a negative impact also on strength, walking speed and balance. Conversely, the presence of earlier motor dysfunction has been discussed as a potential predictor of further cognitive impairment, such in the Motoric Cognitive Risk syndrome, which is characterized by primary reduced gait speed in absence of cognitive deficits. Moreover, reduced handgrip strength has been discussed as a risk factor for the onset of further cognitive impairment. Recent studies have started to investigate the association between cognitive and motor/physical functions in a bidirectional way, suggesting instead both the predictive role of strength on the onset of further cognitive decline, as well as the predictive role of cognitive status on progressively higher risk to develop strength reduction. In conclusion, cognitive and motor/physical decline could often identify a common way, rather than parallel pathways. This integrated perspective should be addressed in the context of geriatric assessments, and it may also promote an increasingly multi-dimensional approach to frailty, together with a significant concern in the end of life stages such as disability and mortality.

Keywords: Bidirectional pathway; Cognitive impairment; Frailty; Gait speed; Sarcopenia.