Mastering the ability of being mobile takes time (especially in primates), but it seems to happen intuitively. After that, we are on the constant “go” until we slowdown or even stop, due to injury or just old age.
The loss of mobility, particularly as we age, comes with a double whammy. The newly immobile person loses both the ability to move about, AND their independence. For many people, the loss of independence is the more terrifying fear.
If not caught early, mobility loss is difficult to reverse (Leveille, Penninx, Melzer, Izmirlian, & Guralnik, 2000). Therefore, the sooner the onset of disability is found the better the chances of not losing one’s independence. But how far ahead of time can a future loss of mobility be seen?
Osawa et al. embarked on a study to identify biomarkers in blood that have the potential of foretelling mobility loss later in life (Osawa et al., 2020). The team analyzed blood samples of elderly people who took part in a study called Invecchiare [aging] in Chianti. In this study, one of the tests the participants did involve quickly walking 400 meters at the start of the study and repeating the walk after about 8.5 years. Using our proteomic technology, they found that 75 different proteins can be correlated with mobility loss over that time. Many of these proteins play a role in the pathways that govern cell’s fate (i.e., growth, cell cycle regulation, survival and proliferation), pathways that pertain to the phagosome (a mechanism the immune system uses to protect the body from bacteria), and pathways that involve cytokine interacting with a cytokine receptor (an event central to the immune response).
Amongst those 75 proteins, three were highly elevated proteins and may be long-sought biomarkers for mobility loss. Why are these proteins (cathepsin S, growth and differentiation factor 15 and thrombospondin) such stand outs? The authors of the paper note it might be due to emerging problems with the heart and the body’s response to tissue damage, but more work is required to find out why these three signal a high risk of mobility loss.
Although this work must be repeated with more individuals of diverse backgrounds, it is quite remarkable how proteomics opened the door for potential new insights and perhaps identifies appropriate interventions into a problem all too commonly experienced. Let us hope this work leads to new tests that can give a person a heads up about the future loss of mobility (perhaps even as far in advance as nine years), leads to appropriate interventions to stay mobile as long as possible, and thus allows the person to keep their independence.
Leveille, S. G., Penninx, B. W., Melzer, D., Izmirlian, G., & Guralnik, J. M. (2000). Sex differences in the prevalence of mobility disability in old age: the dynamics of incidence, recovery, and mortality. J Gerontol B Psychol Sci Soc Sci, 55(1), S41-50. doi:10.1093/geronb/55.1.s41
Osawa, Y., Semba, R. D., Fantoni, G., Candia, J., Biancotto, A., Tanaka, T., . . . Ferrucci, L. (2020). Plasma proteomic signature of the risk of developing mobility disability: A 9-year follow-up. Aging Cell, 19(4), e13132. doi:10.1111/acel.13132