Contribution of sleep disturbances to cognitive changes in vascular cognitive impairment

Vascular cognitive impairment (VCI) is highly prevalent and is associated with increased disability, mortality, as well as social and economic burden, highlighting the necessities of early monitoring and management. Previous studies suggested that early intervention on modifiable risk factors reduced its prevalence and therefore, it is crucial to identify these factors for efficient management and reduction of these outcomes. Sleep disturbances have been previously linked to onset and progression of stroke, as well as cognitive impairment. However, its contribution to changes in cognition and specific cognitive domains in individuals with cerebrovascular conditions remain unclear. This study aims to determine correlations between sleep disturbances and cognitive impairment in patients with cerebrovascular conditions and identify vulnerable cognitive domains for monitoring and intervention of the disease.

A systematic review was performed on human studies investigating associations between sleep disturbances and cognitive impairment in individuals with cerebrovascular conditions by searching PubMed, Embase, Web of science (WOS), Scopus and Cochrane central databases. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA).

Twelve studies including a total of 5525 samples were included. Breathing-related sleep disorders (BSD), insomnia, excessive daytime sleepiness (EDS) and period limb movement disorders (PLMD) were frequently present following stroke. Sleep disorders such as obstructive sleep apnea (OSA), sleep fragmentation, and changes in sleep quality as well as total sleep time (TST) were associated with general cognition or cognitive domains (such as visuospatial ability, delayed recall, working memory, executive function, attention and verbal fluency) in various types of cerebrovascular conditions (such as cerebral small vessel disease (CSVD), stroke and minor ischemic stroke).

The present systematic review revealed high prevalence of sleep disturbances such as BSD, insomnia, EDS, and PLMD, and associations between OSA, sleep fragmentation, changes in sleep quality as well as TST and impairment in general cognition or cognitive domains such as memory and verbal fluency. These findings provide useful information on exploration of early detection, monitoring and management of this modifiable condition for VCI.