Longer sleep-onset latency, as monitored by wrist actigraphy, predicts long-term declines in global cognitive function, verbal learning, and verbal memory in Hispanic/Latino adults, according to study results published in Alzheimer’s & Dementia.
This observational study included 1035 Hispanic/Latino adults between the ages of 45 to 64 years old who participated in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). Cognitive function was measured at baseline and an average of 7 years after the first visit. Cognitive tests included the 6-Item Screener for mental status, Brief-Spanish English Verbal Learning Test (B-SEVLT) for verbal episodic learning and memory, phonemic verbal fluency test, and the Digit Symbol Subtest for processing speed.
Additionally, participants in this study were also undergoing 7-day wrist actigraphy measurements to monitor sleep patterns in relation to cardiometabolic disease. In this analysis of the HCHS/SOL participants, study researchers specifically examined the changes in cognitive function over the mean 7-year period in association with actigraphy-measured sleep patterns.
At the first visit, the mean age of the population was 55.2 (Standard Deviation [SD], ±2.5) years. The average sleep onset latency in this population was 11.3 (SD, ±11.5) minutes, while that of sleep duration per nap was 49.7 (SD, ±17.5) minutes. The average sleep duration was 6.7 (SD, ±0.5) hours.
Longer mean sleep-onset latency was associated with worse performance on the B-SEVLT- Sum (P <.001), B-SEVLT-Recall (P <.01), Word Fluency (P <.01), and Trail Making Test part B (P <.01). In an analysis adjusted for covariates, greater mean sleep-onset latency inversely correlated with the B-SEVLT-Sum (P <.001), B-SEVLT-Recall (P <.05), and 6-Item Screener (P <.05).
A limitation of this study included the reliance on actigraphy, an incomplete objective assessment of sleep. Additionally, the study did not assess sleep stages. Polysomnography would offer better estimates of sleep-onset latency and duration.
Because of the study’s limitations, the study researchers concluded that additional research “is needed to understand the etiologies that influence prolonged sleep-onset latency, sleep duration, and napping behaviors to identify potential mechanisms of cognitive decline and preserve cognitive function.”
Agudelo C, Tarraf W, Wu B, et al. Actigraphic sleep patterns and cognitive decline in the Hispanic Community Health Study/Study of Latinos. Published online December 22, 2020. Alzheimer’s Dement. doi:10.1002/alz.12250