A population-based prospective study on rest-activity rhythm and mild cognitive impairment among Hong Kong healthy community-dwelling older adults

Background: Relatively few studies investigated the association between rest-activity circadian rhythm and cognitive impairment in population-based study, and the evidence from Asian populations is sparse. We aimed to examine the relationship of actigraphy measured rest-activity circadian rhythm with mild cognitive impairment (MCI) or cognitive impairment in Hong Kong healthy community-dwelling older adults.

Methods: We recruited 174 Hong Kong healthy adults aged ≥65 years (36 male vs. 138 female) during April-September 2018, and followed up them for 12 months. Participants were invited to wear wrist actigraphy for 7 days in both baseline and follow-up study. We used the actigraph data to calculate their midline statistic of rhythm (MESOR), amplitude, acrophase and percent rhythm. Montreal Cognitive Assessment (MoCA) was used to assess their cognitive scores at baseline and follow-up. Multivariate logistic regression model was performed to estimate the association of rest-activity circadian rhythm parameters with MCI; whilst multinomial logistic regression model was used to examine the association between rhythm parameters and changes of cognitive scores (i.e., worsen: <-1, stable: -1 to 1, better cognition: ≥2) after 12-months follow-up respectively.

Results: There was no association between rest-activity circadian rhythm parameters and MCI or cognitive impairment at baseline. Compared to those with an averaged value of acrophase (1:24pm-3:00pm), results of multinominal logistic regression showed that participants with a delayed acrophase (after 3:00pm) were less likely to have better cognition (adjusted odds ratio (AOR) = 0.32, 95% confidence interval (CI) = 0.11-0.88). Upon one year of follow-up, participants who delayed their acrophase for 24 min than their baseline measurements were also less likely to have better cognitive functions (AOR = 0.26, 95%CI = 0.08-0.79).

Conclusions: Results from both the baseline survey and follow-up study consistently confirmed that older adults, especially in light of the majority of participants being the females, with delayed acrophase were less likely to have better cognition in the Asian population.