Physical activity levels are associated with sleep efficiency and cerebral blood flow in healthy older adults: Prevention (nonpharmacological) / Exercise. (7th December 2020)

• Record Type: Journal Article
• Authors: Fenton, Laura E; Albrecht, Daniel; Isenberg, Lisette; Aslayan, Vahan; Stradford, Joy; Monreal, Teresa; Pa, Judy
• Is Part Of: Alzheimer's & dementia. Volume 16(2020)Supplement 10
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-12-07
• Subjects: Alzheimer's disease -- Periodicals; Alzheimer Disease -- Periodicals; Dementia -- Periodicals; Démence; Maladie d'Alzheimer; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); 616.83
• DOI: 10.1002/alz.044171
• Languages: English
• ISSNs: 1552-5260

Abstract

Abstract: Background: Identifying modifiable risk factors that prevent or delay the onset of dementia remains a priority. While there is evidence that physical activity (PA) can improve cognition (Hillman et al., 2008; Kramer & Colcombe 2018) and prevent cognitive decline (Sofi et al., 2011; Hamer & Chida, 2009), our understanding of the mechanisms through which PA exerts these effects remains unclear. Two recently proposed mechanisms which warrant further investigation are cerebral blood flow (CBF) and sleep efficiency (Stillman et al., 2016). Method: We examined relationships between PA, sleep efficiency, CBF, and performance on neuropsychological assessments (MoCA, Flanker, CVLT) in a sample of non‐demented, older adults (N=43, 67% female, age=66.67+ 6.83). An average of 36.97 days of objective PA and sleep efficiency were recorded using the GENEActiv tri‐axis accelerometer prior to participants' in‐person visits. CBF was quantified using a pseudo‐continuous arterial spin labeling MRI scan. Linear regression analyses adjusting for age, sex, and education were conducted to examine the relationships between PA, sleep efficiency, CBF, and cognition. As an exploratory analysis we examined the moderating effect of APOE4 status. Result: Higher levels of light PA were associated with greater levels of global CBF (p=0.03) which was in turn associated with higher MoCA scores (p=0.03). In APOE4 non‐carriers (n=32), higher levels of vigorous PA were associated with greater sleep efficiency (p=0.03). No significant relationships between PA and cognition or between sleep efficiency and cognition were observed. Additionally, CBF was not a significant mediator of the relationship between PA and cognition. Exploratory analyses revealed a significant moderating effect of APOE4, such that elevated right hippocampal CBF was associated with poorer sleep efficiency in APOE4 carriers only (p<0.01). Conclusion: These results provide evidence that baseline levels of light PA are associated with greater CBF throughout the brain. However, more intense levels of PA are necessary to influence sleep efficiency and differ based on APOE4 status. The lack of relationship between PA and cognition may be due to the fact that participants did not meet a necessary PA threshold to elicit a relationship. Future intervention studies assessing whether increasing levels of PA impacts sleep efficiency, CBF, and cognition are needed.