Bone mineral density in adults with Down syndrome.

This study analyzed data of bone mineral density (BMD) from a large cohort of adults with Down syndrome (DS). BMD was found to decrease with age more rapidly in these subjects than in the general population, exposing adults with DS to an increased risk of osteoporosis and bone fracture.

INTRODUCTION: Down syndrome (DS) in adulthood presents with a high prevalence of osteoporosis. However, in DS, bone mineral density (BMD) can be underestimated due to short stature. Furthermore, the rate of age-related decline in BMD and its association with gender in DS has been rarely evaluated or compared with the general population. The present study is aimed at assessing the variation of BMD with age and gender in a sample of adults with DS and to compare these data with those of the general population, after adjusting for anthropometric differences.

METHODS: Adults with DS, aged 18 or older, were assessed dual-energy-X-ray-absorptiometry (DXA) at the femoral neck and at the lumbar spine. They were compared with the general population enrolled in the National Health and Nutrition Examination Survey (NHANES) 2009-2010 dataset. Bone mineral apparent density (BMAD) was calculated for each individual.

RESULTS: DXA was evaluated in 234 subjects with DS (mean age 36.93 ± 11.83 years, ranging from 20 to 69 years; 50.4% females). In the lumbar spine both mean BMD (DS 0.880 ± 0.141 vs. NHANES 1.062 ± 0.167, p < 0.001) and BMAD (DS 0.138 ± 0.020 vs. NHANES 0.152 ± 0.020, p < 0.001) were significantly lower in the DS sample than in the NAHNES cohort. The same trend was observed at the femoral neck in both BMD (DS 0.658 ± 0.128 vs. NHANES 0.835 ± 0.137, p < 0.001) and BMAD (DS 0.151 ± 0.030 vs. NHANES 0.159 ± 0.028, p<0.001). Age was associated with lower femoral neck BMAD in both samples; importantly, this association was significantly stronger in the DS sample. In the lumbar spine region, no significant association between BMAD and age could be observed in both samples.

CONCLUSIONS: Adults with DS have lower bone mineral density compared to the general population and they experience a steeper decline with age. Early screening programs are needed in DS population.