Department of Psychology, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia.
School of Psychology, Faculty of Science, University of Sydney, Sydney, NSW, Australia.
Sleep. 2021 Jul 9;44(7). doi: 10.1093/sleep/zsab007.
Growing evidence demonstrates pronounced alterations in rest-activity functioning in older adults at-risk for dementia. White matter degeneration, poor cardiometabolic functioning, and depression have also been linked to a greater risk of decline; however, limited studies have examined the white matter in relation to rest-activity functioning in at-risk older adults.
We investigated associations between nonparametric actigraphy measures and white matter microarchitecture using whole-brain fixel-based analysis of diffusion-weighted imaging in older adults (aged 50 years or older) at-risk for cognitive decline and dementia. The fixel-based metrics assessed were fiber density, fiber cross-section, and combined fiber-density, and cross-section. Interactions between rest-activity functioning and known clinical risk factors, specifically body mass index (BMI), vascular risk factors, depressive symptoms and self-reported exercise, and their association with white matter properties were then investigated.
Sixty-seven older adults were included (mean = 65.78 years, SD = 7.89). Lower relative amplitude, poorer 24-h synchronization and earlier onset of the least active 5-h period were associated with reductions in markers of white matter atrophy in widespread regions, including cortico-subcortical and cortical association pathways. Preliminary evidence was also found indicating more pronounced white matter alterations in those with lower amplitude and higher BMI (β = 0.25, 95% CI [0.05, 0.46]), poorer 24-h synchronization and more vascular risk factors (β = 0.17, 95% CI [-0.02, 0.36]) and earlier onset of inactivity and greater depressive symptoms (β = 0.17, 95% CI [0.03, 0.30]).
These findings highlight the complex interplay between rest-activity rhythms, white matter, and clinical risk factors in individuals at-risk for dementia that should be considered in future studies.
越来越多的证据表明，痴呆风险较高的老年人静息-活动功能出现明显改变。白质退化、代谢功能不良和抑郁也与更高的衰退风险有关；然而，有限的研究已经检查了与风险较高的老年人静息-活动功能相关的白质。
我们使用扩散加权成像的全脑固定点分析，研究了认知能力下降和痴呆风险较高的老年人（年龄在 50 岁或以上）的非参数活动计测量值与白质微观结构之间的关联。评估的固定点指标包括纤维密度、纤维横截面积和纤维密度与横截面积的综合。然后研究了静息-活动功能与已知临床危险因素（特别是体重指数 (BMI)、血管危险因素、抑郁症状和自我报告的运动）之间的相互作用及其与白质特性的关联。
纳入了 67 名老年人（平均年龄=65.78 岁，标准差=7.89）。相对振幅较低、24 小时同步性较差和最不活跃的 5 小时期的起始时间较早与广泛区域的白质萎缩标志物减少相关，包括皮质下和皮质联络通路上。初步证据还表明，振幅较低和 BMI 较高（β=0.25，95%CI[0.05，0.46]）、24 小时同步性较差和血管危险因素较多（β=0.17，95%CI[-0.02，0.36]）以及静息期起始时间较早和抑郁症状较重（β=0.17，95%CI[0.03，0.30]）的人，白质改变更为明显。
这些发现强调了痴呆风险较高的个体中静息-活动节律、白质和临床危险因素之间的复杂相互作用，这在未来的研究中应予以考虑。
