Bone Density in Adolescents and Young Adults with Autism Spectrum Disorders.

Nine children with autism spectrum disorder were identified, and the paper says 3 children were excluded from the current analysis, but it does not clearly state the final number analysed or the number of controls analysed. The autism group was a chart review of children who had already received scans, not a random sample of all adolescents with autism spectrum disorder. Not all children recommended for scans could get them because they needed to stay still for at least 30 seconds, and only scans done within the institution were available. Scans were obtained for clinical concerns, including vitamin D status, medication use, limited activity or hypotonia, so children with lower bone density may have been selected for the scan rather than representing all children with autism spectrum disorder. Reliable pubertal stage data were unavailable for most subjects. The study did not examine whether diet, physical activity, calcium or vitamin D intake explained the lower bone density scores, and dietary restrictions were unavailable for controls. Many participants were taking medicines reported in the study, including antiepileptic medications, an anticoagulant, proton pump inhibitors, SSRIs and antipsychotics, and inhaled glucocorticoids; the contribution of any single medicine cannot be separated. Because this was an observational comparison, it cannot show that autism spectrum disorder caused lower bone density or that any treatment changed it.

Do not read this as proof that autism spectrum disorder itself causes low bone density or that exercise will raise it. The study looked at a small chart review of children already referred for scans because of concerns such as vitamin D status, medication use, limited activity or hypotonia, and it did not test these factors.