Body Composition, IGF1 Status, and Physical Functionality in Nonagenarians: Implications for Osteosarcopenia.

Area of Science:

• Gerontology
• Body Composition Research
• Metabolic Bone Disease

Background:

• Aging is associated with significant changes in body composition, including loss of muscle mass (sarcopenia) and bone density (osteoporosis).
• The co-occurrence of sarcopenia and osteoporosis, termed osteosarcopenia, presents a complex challenge in the oldest old, potentially impacting physical function and health outcomes.
• Insulin-like growth factor 1 (IGF1) plays a crucial role in muscle and bone metabolism, but its specific involvement in osteosarcopenia in very elderly individuals remains unclear.

Purpose of the Study:

• To investigate the functional consequences of combined sarcopenia and osteoporosis in nonagenarians.
• To explore the potential role of insulin-like growth factor 1 (IGF1) in the development of osteosarcopenia among the oldest old.
• To examine sex-specific differences in IGF1 levels and their association with body composition phenotypes and physical function.

Main Methods:

• Eighty-seven nonagenarians were categorized into four phenotypes: control (CO), osteoporotic (O), sarcopenic (S), and osteosarcopenic (OS) based on appendicular lean mass (ALM) and bone mineral density (BMD).
• Sex- and age-specific IGF1-Standard Deviation Scores (SDS) were calculated.
• Physical function was assessed using the Continuous Scale-Physical Functional Performance (CS-PFP) test.

Main Results:

• Osteosarcopenic men exhibited significantly lower IGF1-SDS compared to control men, while IGF1-SDS levels were similar across all phenotypes in women.
• In men, appendicular lean mass (ALM) was positively associated with IGF1-SDS, independent of age and C-reactive protein.
• No significant associations were found between IGF1-SDS and bone mineral density (BMD) or physical functional performance (CS-PFP) in either sex.

Conclusions:

• Insulin-like growth factor 1 (IGF1) sensitivity in skeletal muscle and bone may differ between sexes in the oldest old.
• IGF1 status did not appear to influence physical functionality in this cohort.
• Further investigation into the determinants and characteristics of osteosarcopenia is required to establish definitive diagnostic criteria.