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230 Association Between Chronotype and Subjective Cognitive Functioning: Population-Based Study


 
 
 Increasing research suggests that subjective cognitive decline (SCD) in the absence of objective cognitive dysfunction may be a forerunner of non-normative cognitive decline and eventual progression to dementia. We investigated the association between chronotype and subjective cognitive functioning in the representative sample of the adult population.
 
 
 
 We included subjects who participated in a nationwide cross-sectional survey of sleep and headache in 2018 in the Republic of Korea. A total of 2136 subjects (age 19-92, mean 48.3 ± 16.5 years old, 1062 male) was included in the analysis. To assess subjective cognitive functioning, we adopted the Mail-In Cognitive Function Screening Instrument (MCFSI). The MCSFSI is a brief, self-administered potential outcome measure developed by the Alzheimer’s Disease Cooperative Study (ADCS) to detect early changes in cognitive and functional abilities in individuals without clinical impairment. MCFSI scores ≥5 were considered abnormal for this study. As an indicator of chronotype, we adopted the “midpoint of sleep on free days corrected for sleep extension on free days (MSFsc).” MSFsc was calculated as follows: MSFsc = midpoint of sleep on free days − 0.5 × (sleep duration on free days − [5 × sleep duration on workdays + 2 × sleep duration on free days]/7). Participants whose MSFsc occurred before 04:00 AM, between 04:00 and 04:59 AM, and after 05:00 AM were classified as early, intermediate, and late chronotype, respectively. The associations between chronotype and subjective cognitive functioning were analyzed with logistic regression models adjusted for potential confounders.
 
 
 
 Subjective cognitive functioning was abnormal in 381 subjects (17.8%). A late chronotype was significantly associated with abnormal subjective cognitive functioning compared with an early chronotype independent of age, sex, average sleep duration, alcohol, smoking, regular exercise, anxiety, depression, body mass index (BMI), education years, and income status (OR 1.619, 95% CI 1.03 - 2.55, p=0.038). Abnormal subjective cognitive functioning was significantly associated with older age, female sex, lower education, higher BMI, anxiety, and depression.
 
 
 
 This survey cohort results provide evidence at the population level that late chronotype is associated with abnormal subjective cognitive functioning.
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