title: The relationship between long-term sunlight radiation and cognitive decline in the REGARDS cohort study.
abstract: Sunlight may be related to cognitive function through vitamin D metabolism or circadian rhythm regulation. The analysis presented here sought to test whether ground and satellite measures of solar radiation are associated with cognitive decline. The study used a 15-year residential history merged with satellite and ground monitor data to determine sunlight (solar radiation) and air temperature exposure for a cohort of 19,896 cognitively intact black and white participants aged 45+ from the 48 contiguous United States. Exposures of 15, 10, 5, 2, and 1-year were used to predict cognitive status at the most recent assessment in logistic regression models; 1-year insolation and maximum temperatures were chosen as exposure measures. Solar radiation interacted with temperature, age, and gender in its relationships with incident cognitive impairment. After adjustment for covariates, the odds ratio (OR) of cognitive decline for solar radiation exposure below the median vs above the median in the 3rd tertile of maximum temperatures was 1.88 (95 % CI: 1.24, 2.85), that in the 2nd tertile was 1.33 (95 % CI: 1.09, 1.62), and that in the 1st tertile was 1.22 (95 % CI: 0.92, 1.60). We also found that participants under 60 years old had an OR = 1.63 (95 % CI: 1.20, 2.22), those 60-80 years old had an OR = 1.18 (95 % CI: 1.02, 1.36), and those over 80 years old had an OR = 1.05 (0.80, 1.37). Lastly, we found that males had an OR = 1.43 (95 % CI: 1.22, 1.69), and females had an OR = 1.02 (0.87, 1.20). We found that lower levels of solar radiation were associated with increased odds of incident cognitive impairment.
authors: Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, 1665 University Blvd, Birmingham, AL, USA, shia@uab.edu.
authors: Shia T
authors: ST
authors: Kent
authors: Edmond K
authors: EK
authors: Kabagambe
authors: Virginia G
authors: VG
authors: Wadley
authors: Virginia J
authors: VJ
authors: Howard
authors: William L
authors: WL
authors: Crosson
authors: Mohammad Z
authors: MZ
authors: Al-Hamdan
authors: Suzanne E
authors: SE
authors: Judd
authors: Fredrick
authors: F
authors: Peace
authors: Leslie A
authors: LA
authors: McClure
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D044383:Black People / Q000706:statistics & numerical data*; D002980:Climate; D003072:Cognition Disorders / Q000208:ethnology*; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000453:epidemiology*; D011834:Radiation Monitoring / Q000706:statistics & numerical data; D012307:Risk Factors; D017678:Sex Distribution; D012993:Solar Energy / Q000706:statistics & numerical data*; D013472:Sunlight; D013696:Temperature; D014481:United States / Q000453:epidemiology; D014887:Weather; D044465:White People / Q000706:statistics & numerical data*; D001741:Black or African American