Abstract
As brain insults, sleep disorders could enhance microglial activation and aggravate neuroinflammation. Soluble triggering receptor expressed on myeloid cells 2 (sTREM2) in cerebrospinal fluid (CSF) serves as a readout for TREM2-associated microglial responses. We aimed to study the association of sleep characteristics with CSF sTREM2 in cognitively normal (CN) older adults. Linear and non-linear regression analyses were conducted in 830 participants with measurements of sleep characteristics and CSF sTREM2, after adjusting for age, sex, education, the Chinese-Modified Mini-Mental State Examination (CM-MMSE) scores, and APOE4 status. These analyses were also performed in amyloid-negative (A -) and amyloid-positive (A +) individuals. Linear relationships between sleep characteristics and CSF sTREM2 were found. In all the participants, sleep efficiency score in Pittsburgh Sleep Quality Index (PSQI) (p = 0.037) showed a positive linear association with CSF sTREM2. In A + individuals, the grade of PSQI total score (p = 0.011) as well as subjective sleep quality score (p = 0.048) and sleep efficiency score (p < 0.001) in PSQI were positively associated with CSF sTREM2. Besides, several U-shaped relationships were revealed of sleep-time measures, such as insufficient or excessive nocturnal sleep duration, with CSF sTREM2 in A + individuals (the optimal model: bedtime 22:21 p.m., time to fall asleep 22:52 p.m., nocturnal sleep duration 7.36 h). In A - individuals, the above relationships were not found. Poor self-reported sleep characteristics and sleep indicators were associated with higher CSF sTREM2, suggesting that sleep might play an important role in the regulation of TREM2-associated microglial activity.