Bone mineral density in adults with Down syndrome: a cross-sectional study in a Brazilian sample

Espírito Santo R, Dubey VP, Agostinis-Sobrinho C. Handgrip strength measurement protocols in individuals with Down syndrome: a systematic review and meta-regression

BACKGROUND

Handgrip strength (HGS) serves as a robust predictor of overall strength across various populations, including individuals with Down Syndrome (DS).

OBJECTIVE

To analyze the HGS measurement protocols used in studies involving individuals with DS.

METHODS

Primary sources were sourced from six databases: PubMed, Scopus, Ovid, Embase, ERIC, and Web of Science, spanning from inception to 23rd December 2023. Inclusion criteria focused on individuals with DS, compared with control groups, and examined HGS measurement protocols and outcomes. Meta-regression was utilized to assess bias associated with HGS values concerning different measurement protocols.

RESULTS

Out of 29 studies involving 1816 participants, most controlled for body position (65%), arm position (82%), elbow position (82%), wrist position (62%), handgrip duration (55%), hand adjustment to dynamometer (62%), verbal encouragement (75%), and familiarization (44.8%). The number of reported variables in the HGS protocol was significantly associated with an increase in HGS, with a mean estimate of 20.59 units (SE = 2.59, p < 0.0001, 95% CI [15.49-25.68]), though there was notable heterogeneity (I2 = 94.33%). The spline regression analysis showed that the model explained 82.66% of the variation in HGS, with adults having 47.61 units higher HGS than children (p = 0.0009), while obesity was linked to a decrease of 15.68 units (p = 0.0675). Sample size and group had no significant effects.

CONCLUSION

Overall, protocols for assessing HGS in DS studies are comprehensive yet heterogeneous. Higher HGS values correlated with adherence to standard protocols.

Physical activity patterns of children and adolescents with Down syndrome: Using the Fitbit and parental proxy questionnaire

PURPOSE

The purpose of this study was to assess physical activity (PA) levels in children and adolescents with Down syndrome (DS) using a commercially available activity tracker (Fitbit) and a parental proxy questionnaire.

DESIGN AND METHODS

This cross-sectional study included two groups of individuals with DS (school-age children and adolescents) and one parent per child/adolescent. The school-age children and adolescents with DS wore the Fitbit for seven consecutive days. Parents completed the parental proxy questionnaire on the seventh day. Weekday and weekend PA levels for the two groups of individuals with DS were compared. In addition, PA levels obtained with the Fitbit were compared to parental responses.

RESULTS

Complete data sets were available for 32 child-parent dyads. Sedentary time was higher for the adolescent group (p = .022), while light PA time was lower (p = .020). All measured PA patterns, excluding sedentary behavior, decreased on weekends in both groups: steps (p = .002), light PA time (p = .028), and moderate-to-vigorous PA time (p = .004). Parental proxy questionnaires underestimated actual PA levels.

CONCLUSIONS

PA was lower in the adolescent group and during the weekend for both groups.

PRACTICE IMPLICATIONS

Findings from this study suggest a need for tailored programs designed to increase weekend PA levels in school-age children and adolescents with DS in pediatric nursing research. The use of commercial activity trackers, such as the Fitbit, which are user-friendly and relatively affordable, is effective for pediatric nurses to monitor PA levels of children and adolescents with DS in clinical settings.

Compromised femoral and lumbovertebral bone in the Dp(16)1Yey Down syndrome mouse model

Down syndrome (DS), affecting ∼1 in 800 live births, is caused by the triplication of human chromosome 21 (Hsa21). Individuals with DS have skeletal features including craniofacial abnormalities and decreased bone mineral density (BMD). Lowered BMD can lead to increased fracture risk, with common fracture points at the femoral neck and lumbar spine. While the femur has been studied in DS mouse models, there is little research done on the vertebrae despite evidence that humans with DS have affected vertebrae. Additionally, it is important to establish when skeletal deficits occur to find times of potential intervention. The Dp(16)1Yey DS mouse model has all genes triplicated on mouse chromosome 16 orthologous to Hsa21 and displayed deficits in long bone, including trabecular and cortical deficits in male but not female mice, at 12 weeks. We hypothesized that the long bone and lumbovertebral microarchitecture would exhibit sexually dimorphic deficits in Dp(16)1Yey mice compared to control mice and long bone strength would be diminished in Dp(16)1Yey mice at 6 weeks. The trabecular region of the 4th lumbar (L4) vertebra and the trabecular and cortical regions of the femur were analyzed via micro-computed tomography and 3-point bending in 6-week-old male and female Dp(16)1Yey and control mice. Trabecular and cortical deficits were observed in femurs from male Dp(16)1Yey mice, and cortical deficits were seen in femurs of male and female Dp(16)1Yey mice. Male Dp(16)1Yey femurs had more deficits in bone strength at whole bone and tissue-estimate level properties, but female Dp(16)1Yey mice were also affected. Additionally, the L4 of male and female Dp(16)1Yey mice show trabecular deficits, which have not been previously reported in a DS mouse model. Our results indicate that skeletal deficits associated with DS occur early in skeletal development, are dependent on skeletal compartment and site, are sex dependent, and potential interventions should likely begin early in skeletal development of DS mouse models.