Individual changes in anthropometric measures after age 60 years: a 15-year longitudinal population-based study

Area of Science:

• Gerontology
• Human Physiology
• Epidemiology

Background:

• Weight loss is a common observation during ageing.
• Body Mass Index (BMI), calf circumference (CC), and mid-arm circumference (MAC) are key indicators of body composition.
• Understanding age-related changes in body composition is crucial for maintaining health in older adults.

Purpose of the Study:

• To explore the trajectory of body mass index (BMI) and muscle mass proxies (CC and MAC) in older adults.
• To identify determinants influencing these trajectories.
• To differentiate between younger-old and older-old adults regarding body composition changes.

Main Methods:

• Utilized data from 2,155 dementia-free participants (≥60 years) in the SNAC-K cohort over 15 years.
• Measured BMI, CC, and MAC at baseline and follow-ups.
• Employed linear mixed-effect models, stratified by age groups (younger-old [<78 years] vs. older-old [≥78 years]), analyzing sociodemographic, lifestyle, and health factors.

Main Results:

• BMI remained stable in those aged 60 at baseline but declined significantly in those ≥66 years.
• CC and MAC showed significant declines across all age groups over 15 years.
• Higher education was linked to slower declines in younger-old adults, while vascular disorders and diabetes accelerated declines. In older-old adults, physical activity slowed declines, and vascular disorders accelerated them.

Conclusions:

• Calf circumference (CC) and mid-arm circumference (MAC) decline earlier and more steeply than body mass index (BMI) with ageing.
• Cardiometabolic disorders exacerbate these declines.
• Higher education and physical activity demonstrate potential to counteract age-related body composition changes.