Aging progresses at different rates among individuals, underscoring the need for better indicators of functional decline. The inventors showed that the
T cell energy metabolism in the elderly reveals that high mitochondrial
oxidative phosphorylation, especially in CD4 T regulatory cells, is associated with a reduced probability of being frail / prefrail, independent of age, sex, or comorbidities. When
mitochondrial respiration drops below a
critical threshold, it adversely affects intrinsic capacity. Furthermore, a low level of
oxidative phosphorylation in CD4 T helper cells, particularly in central and
effector memory subsets, was significantly associated with a faster decline in intrinsic capacity over time, suggesting that
T cell mitochondrial bioenergetics represents a key biomarker for managing functional decline in older adults. Accordingly, the present invention relates to a method for determining the risk of age-related functional decline in a subject comprising the step of measuring the mitochondrial dependency in a
population of T cells wherein the mitochondrial dependency (MitoDep) correlates with the age-related functional decline.