Physical activity engagement, memory function, and hippocampal volume in adults with down syndrome

Abstract Background Higher engagement in moderate‐to‐vigorous physical activity (PA) is related to better cognitive functioning in neurotypical adults; however, little is known about the impact of PA on cognitive aging in adults with Down syndrome (DS). Individuals with DS have three copies of the chromosome 21, which includes the gene for the amyloid precursor protein, resulting in an increased risk for/earlier onset of Alzheimer’s disease. The goal of this study was to understand the relationship between moderate PA engagement and memory functioning in non‐demented adults with DS. Method Adults with DS participated in an ancillary Lifestyle study linked to the Alzheimer’s Biomarkers Consortium for Down Syndrome (N = 54). Participants completed the Cued Recall Test (CRT) to measure episodic memory. The total free + cued CRT score was used in analyses. Participants wore a wrist‐worn accelerometer (GT9X) for 7 days to measure PA. Moderate PA was classified using the Freedson cutpoints in ActiLife software and was defined as the daily average minutes. Structural MRI data were acquired within 18 months of actigraphy/cognitive data collection. Hippocampal volume was extracted using Freesurfer v5.3. Associations between moderate PA engagement, memory, and hippocampal volume were evaluated with hierarchical linear regressions controlling for relevant covariates (age, body mass index (BMI), intracranial volume (ICV)). Result Participants were 37.81 years old (SD = 8.15 years) and 55.6% female. They spent ∼10.67% of their time engaged in moderate PA (SD = 7.48%). Participants recalled an average of 32.09 items on the CRT (SD = 6.09, range = 7‐36). After controlling for age and BMI, greater moderate PA engagement was associated with higher total recall score (b = 0.279, p = 0.044). After controlling for age and ICV, moderate PA engagement was not significantly associated with hippocampal volume (p = 0.48). Greater hippocampal volume was associated with higher total recall score after controlling for age and ICV (b = 0.496, p = 0.004). Conclusion A higher proportion of time spent engaging in moderate PA was related to better memory function in adults with DS. While greater hippocampal volume was related to better memory performance, it was not associated with moderate PA engagement. Greater moderate PA engagement may be a promising lifestyle behavior to preserve memory in aging adults with DS.