Life-course body shape trajectories and cerebral oxygen metabolism in community-dwelling older adults.

Overweight status was associated with lower global cerebral metabolic rate of oxygen (CMRO₂) in community-dwelling older adults.

• β = -1.12 μmol/100 g/min, 95% CI = (-1.96, -0.28) for overweight compared to normal weight
• Higher Body Roundness Index (BRI) was also associated with lower CMRO₂: β = -1.31, 95% CI = (-2.36, -0.27)
• Sample included 303 community-dwelling adults aged 50 years and older
• Global CMRO₂ was derived from TRUST and phase-contrast MRI

The negative association between adiposity and CMRO₂ was stronger with advancing age.

• Age interactions were estimated using general linear models
• Both BMI and BRI showed stronger effects on CMRO₂ with advancing age
• This age-dependent pattern was observed for both overweight status and higher BRI measures

CMRO₂ mediated the association between BMI and medial temporal atrophy (MTA) specifically among participants aged 70 years.

• Indirect β = 0.06, 95% CI = (0.01, 0.14) for the mediation of CMRO₂ between BMI and MTA
• Age-stratified mediation analysis was used to test CMRO₂ as a mediator
• MTA grading was derived from T1-weighted MPRAGE volumetry
• The mediation effect was specific to the age-70 stratum

Three distinct adulthood body-shape trajectories were identified across the life course, and higher-risk trajectories were associated with lower CMRO₂.

• Body shape was assessed at ages 25, 40, 60, and current age using BMI and BRI
• The moderate increasing trajectory group had lower CMRO₂: β = -11.40, 95% CI = (-20.90, -1.90)
• The high-rising trajectory group also had lower CMRO₂: β = -12.23, 95% CI = (-23.56, -0.90)
• Trajectories were modeled using body shape data across four time points in adulthood

Metabolism-related brain regions were larger in higher-risk body-shape trajectory groups, particularly the left hypothalamus.

• Structural brain differences were assessed using T1-weighted MPRAGE volumetry
• The left hypothalamus showed particularly notable volumetric differences across trajectory groups
• Higher-risk body-shape patterns (moderate increasing and high-rising) were associated with larger metabolism-related regions

Life-course adiposity patterns, not just current body shape, were independently associated with reduced cerebral oxygen metabolism in older adults.

• Body shape trajectories spanning from age 25 to current age were modeled
• Both current adiposity measures (BMI, BRI) and life-course trajectory groups were associated with CMRO₂
• The study design included community-dwelling adults aged 50 years and older (n = 303)
• Findings suggest that prolonged exposure to adiposity compounds the impact on cerebral metabolism