A longer latency to the onset of sleep, monitored by wrist actigraphy, predicts long-term decline in global cognitive function, verbal learning, and verbal memory in Hispanic / Latin American adults, according to study results published in Alzheimer’s & Dementia.
This observational study enrolled 1,035 Hispanic / Latin American adults between the ages of 45 and 64 who participated in the Hispanic Community Health Study / Study of Latinos (HCHS / SOL). Cognitive function was measured at the start of the study and an average of 7 years after the first visit. The cognitive tests included the 6-point screener for mental status, the Short Spanish-English Test for Verbal Learning (B-SEVLT) for verbal episodic learning and memory, the phonemic test for verbal language proficiency, and the Digit Symbol Subtest for processing speed.
Additionally, participants in this study underwent 7-day wrist actigraphy measurements to monitor sleep patterns related to cardiometabolic disorders. In this analysis of the HCHS / SOL participants, the study researchers specifically examined the changes in cognitive function over the mean period of 7 years in connection with actigraphically measured sleep patterns.
At the first visit, the mean age of the population was 55.2 years (standard deviation) [SD]± 2.5) years. The mean onset of sleep latency in this population was 11.3 (SD, ± 11.5) minutes, while the duration of sleep per nap was 49.7 (SD, ± 17.5) minutes. The mean sleep duration was 6.7 (SD, ± 0.5) hours.
Longer mean latency to sleep was associated with poorer performance on B-SEVLT Sum (P <0.001), B-SEVLT Recall (P <0.01), Word Flow (P <0.01), and Trail Making Test Part B (P <0.01). In an analysis adjusted for covariates, a higher mean latency at sleep correlated inversely with the B-SEVLT total (P <0.001), the B-SEVLT recall (P <0.05) and the 6-item screener (P < ). 05).
One limitation of this study was its reliance on actigraphy, an incomplete objective assessment of sleep. In addition, no sleep stages were assessed in the study. Polysomnography would provide better estimates of the latency and duration of onset of sleep.
Because of the limitations of the study, the researchers concluded that additional research is needed to “understand the etiologies that affect prolonged sleep latency, sleep duration, and nap behavior, in order to identify possible mechanisms of cognitive decline and cognitive decline 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