Supplementary Material for: The influence of birthweight, socioeconomic status, and adult health on brain volumes during aging

Introduction
Greater late-life brain volumes are associated with resilience against dementia. We examined relationships between birthweight, life-long socioeconomic status and health with late-life brain volumes. We hypothesised that early-life factors directly affect late-life brain volumes.
Methods
Adults aged 59-67y underwent MRI and brain volumes were measured. Birthweight and lifelong health, and socioeconomic status were quantified and the principle components of each extracted. Relationships were examined using regression and structural equation analysis.
Results
Birthweight (β=0.095, p=0.017) and childhood socioeconomic status (β=0.091, p=0.033, n=280) were directly associated with brain volume. Childhood socioeconomic status was further associated with grey matter volume (β=0.04, p=0.047). Adult health was linked to increased brain volume (β=0.15, p=0.003).
Conclusion
Birthweight and childhood socioeconomic status are associated with whole and regional brain volume through direct mechanisms. Optimal fetal development, reduced childhood poverty and good adult health could reduce brain atrophy and delay dementia onset in late-life.