Frailty Index as a clinical measure of biological age in psychiatry

Background: Serious mental illnesses may be characterized by accelerated biological aging, and over the last years the research on the topic has been stimulated by studies exploring the molecular underpinnings of senescence. Methods: In the present manuscript we propose that measuring frailty, a general product of organismal ageing, through the "Frailty Index" (FI), a recently-emerged macroscopic indicator of functional status and biological age, adds an important marker to the measurements currently implemented in the study of accelerated biological age in psychiatric illnesses. Results: The FI quantifies functional negative health attributes and measures their cumulative effect, thus providing a useful estimate of the individual's biological age and risk profile. Recent studies in older adults have observed significant associations between FI and molecular measures of aging. Limitations: High FI values can be driven by causes different from aging per se, so FI may be a sensitive but not specific measure of biological aging. Conclusions: FI, which is extensively used in geriatrics and gerontology but it has rarely been used in relation to mental health, may be of relevance in the evaluation of age-related phenomena associated with psychiatric diseases.