Multisystem Dysregulation and Bone Strength: Findings From the Study of Midlife in the United States

Abstract

Accumulated dysregulation across multiple physiological systems, or allostatic load (AL), has been proposed as the biological pathway from psychosocial adversity to poor health. The objective of the study was to examine whether AL, constructed using biomarkers and medication data from seven systems (sympathetic, parasympathetic, hypothalamic-pituitary-adrenal axis, cardiovascular regulation, inflammation, and lipid and glucose metabolism), is associated with lower bone strength in a national sample. This was a cross-sectional study. Seven hundred three community-dwelling men and women from the Study of Midlife in the United States participated in the study. Bone mineral density (BMD) was measured in the femoral neck and lumbar spine. Femoral neck BMD was combined with bone size and body size to create composite indices of femoral neck strength relative to load in three failure modes: compression, bending, and impact. In mixed-effects linear regression controlling for clustering within families and adjusted for age, gender, race/ethnicity, body mass index, menopausal transition stage, childhood socioeconomic status, adult finances, education level, and study center, each SD increment in AL score was associated with between 0.10 and 0.11 SD decrements in lumbar spine BMD and each of the three composite strength indices (all values of P < .05). Gender modified the association of AL only with femoral neck BMD; each SD increment in AL score was associated with 0.21 SD decrement in femoral neck BMD in men (P < .01) but not in women. Accumulation of dysregulation across systems was modestly associated with lower bone strength. This study adds to the accumulating evidence that multisystem dysregulation, or AL, predicts a variety of adverse health outcomes.