Bone Abstracts

Objective: Autism Spectrum Disorder (ASD) is associated with lower bone mass in children. Physical activity and nutrition influence bone pathophysiology, and differences in these lifestyle factors are observed between children with vs. without ASD; however, whether these factors contribute to bone differences is unknown. We examined if: 1) differences existed in bone mineral density (BMD), content (BMC), or bone geometry in boys with vs without ASD and 2) whether physical activity and/or total energy-intake influenced those differences.

Methods: Preliminary case-control data included 44 boys (22 with (cases) and 22 without (controls) ASD), matched for age (12.3(±1.8) yrs) and height (155(±11) cm). Lumbar spine, total hip, femoral-neck (FN) and total-body-less-head BMD and BMC were assessed with dual energy X-ray absorptiometry. Hip structural analyses estimated bone geometry (cross-sectional area (CSA), minimal-neck-width and section modulus (Z)) (Encore v16.2). Moderate-to-vigorous physical activity (MVPA) was measured using Actigraph accelerometers, and total energy-intake was assessed using a 3-day food diary. BMD, BMC, and bone geometry were compared between groups, and multivariable regression models were used to investigate whether MVPA and/or total energy-intake influenced bone differences between cases and controls.

Results: In weight-adjusted models, cases had 8–13% lower BMD at all sites than controls (all P<0.05): in fully adjusted models, neither total energy-intake nor MVPA explained these differences. After adjusting for weight, cases vs controls had 11% lower BMC; however, in contrast to BMD, this was only observed at the FN. After BMC models were further adjusted for lifestyle factors, associations at the FN were sustained (β −0.262, S.E.±0.107, P=0.02): energy-intake was significantly associated in this model, but not MVPA. For bone geometry, and independent of weight, cases vs controls had 11% lower CSA (P=0.01). In fully adjusted models, energy-intake contributed to lower CSA (β −12.269, S.E.±4.931, P=0.02) in cases; however, Z did not differ (P=0.30), suggesting a preservation of strength in bending.

Conclusion: Boys with ASD had lower BMD and BMC that were not explained by differences in total energy-intake or MVPA. Further work should examine whether and to what degree specific patterns of dietary intake and physical activity contribute to underlying pathophysiological differences in bone.

Disclosure: The authors declared no competing interests.