Quantitative measures of healthy aging and biological age

Abstract

Numerous genetic and non-genetic factors contribute to aging. To facilitate the study of these factors, various descriptors of biological aging, including ‘successful aging’ and ‘frailty’, have been put forth as integrative functional measures of aging. A separate but related quantitative approach is the ‘frailty index’, which has been operationalized and frequently used. Various frailty indices have been constructed. Although based on different numbers and types of health variables, frailty indices possess several common properties that make them useful across different studies. We have been using a frailty index termed FI34 based on 34 health variables. Like other frailty indices, FI34 increases non-linearly with advancing age and is a better indicator of biological aging than chronological age. FI34 has a substantial genetic basis. Using FI34, we found elevated levels of resting metabolic rate linked to declining health in nonagenarians. Using FI34 as a quantitative phenotype, we have also found a genomic region on chromosome 12 that is associated with healthy aging and longevity.

Single nucleotide polymorphisms linked to mitochondrial uncoupling protein genes UCP2 and UCP3 affect mitochondrial metabolism and healthy aging in female nonagenarians

“…UCP2/3 are expressed predominantly in tissues other than fat, especially in skeletal muscle, and FFM is associated with FI 34 in the females, as stated earlier. Physical activity energy expenditure is related to skeletal muscle mass and function, and our studies have shown that it is related to FI 34 (Kim and Jazwinski 2015). Therefore, we included FFM and EESI in multiple regression analyses (Table 5).…”

“…Although RMR goes down with age overall (Kim and Jazwinski 2015), it goes up with FI 34 among nonagenarians, which was observed after adjustment for FFM, FM, and age (Kim et al 2014). This suggests increasing resting energy consumption with deteriorating health.…”

“…Normally, the amount of energy consumed for resting metabolism exceeds that for physical activity several-fold (Ruggiero and Ferrucci 2006). Both of these major forms of energy expenditure decline with increasing age (Kim and Jazwinski 2015). In nonagenarians, elevated RMR is associated with declining health, which is represented by increased FI 34 , a frailty index based on 34 health variables (Kim et al 2013).…”

Frail or hale: Skeletal frailty indices in Medieval London skeletons

“…We developed the SFI to assess frailty in skeletal materials following extensive observations on biomarkers of frailty in modern living humans [2–7]. Originally, we proposed a SFI including 13 skeletal biomarkers observable on human skeletons, representing four categories of stressors: trauma, nutrition/disease, physical activity, and growth disruptions.…”

Social Factors and Healthy Aging: Findings from the Louisiana Healthy Aging Study (LHAS)

“…One potentially important direction for future research would be to consider a boarder assessment of psychosocial variables that may impact heath. Additional research to examine the role of genetic factors would also provide insight into biological variables that may inevitably thwart healthy aging (Kim & Jazwinski, 2015), an exciting possibility that awaits future research.…”