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Table 1 Baseline characteristics of study participants by incident dementia status

From: Time spent in outdoor light is associated with the risk of dementia: a prospective cohort study of 362094 participants

Variables Incident dementia No incident dementia P value
  (N=4149) (N=357945)  
Age at baseline, years, mean (SD) 64.49(4.53) 56.87(8.00) <0.001
Sex, N (%)    <0.001
 Male 2211(53.3%) 159183(44.5%)  
 Female 1938(46.7%) 198762(55.5%)  
Education, N (%)    <0.001
 ≥College or University degree 903(21.8%) 120477(33.7%)  
 <College or University degree 1831(44.1%) 178522(49.9%)  
Skin color, N (%)    <0.001
 White 3302(79.6%) 273585(76.4%)  
 Colored 847(20.4%) 84352(23.6%)  
Use of sun/UV protection, N (%)    <0.001
 No 625(15.1%) 33268(9.3%)  
 Yes 3477(83.8%) 322624(90.1%)  
 Do not go out in sunshine 3 45(1.1%) 2038(5.7%)  
Employment status, N (%)    <0.001
 Yes 753(18.1%) 203004(56.7%)  
 No 3396(81.9%) 154941(43.3%)  
Sleep duration, hours, N (%)    <0.001
 <7 1070(25.8%) 87199(24.4%)  
 7 1246(30.0%) 138878(38.8%)  
 >7 1833(44.2%) 131868(36.8%)  
PM2.5, ug/m3, mean (SD) 10.04(1.05) 9.97(1.05) <0.001
Fracture history, N (%)    0.348
 Yes 414(10.0%) 34184(9.6%)  
 No 3711(90.0%) 322213(90.4%)  
Vitamin D supplement, N (%)    0.092
 Yes 177(4.3%) 13490(3.8%)  
 No 3944(95.7%) 343441(96.2%)  
Hearing loss, N (%)    <0.001
 Yes 1440(36.1%) 90025(26.1%)  
 No 2548(63.9%) 254597(73.9%)  
Smoking status, N (%)    <0.001
 Never 1901 (46.1%) 194259 (54.4%)  
 Previous 1805 (43.7%) 126431 (35.4%)  
 Current 420 (10.2%) 36256 (10.2%)  
Alcohol drinker status, N (%)    <0.001
 Never 280 (6.8%) 14058 (3.9)  
 Previous 295 (7.1%) 12469 (3.5)  
 Current 3566 (86.1%) 331202 (92.6)  
CVD diagnosed by doctor, N (%)    <0.001
 Heart disease a 582(14.1%) 16708(4.7%)  
 Stroke 243(5.9%) 5503(1.5%)  
 Hypertension 1744(42.1%) 98880(27.7%)  
TPA, MET-mins/week, mean (SD) 2423.34 (2875.69) 2449.20 (2746.68) 0.555
BMI, kg/m2, mean (SD) 27.72(4.95) 27.44(4.80) <0.001
Time spent in outdoor light, hours/day, mean (SD)
 Average 2.98(1.51) 2.51(1.45) <0.001
 Summer 3.99(2.05) 3.46(1.97) <0.001
 Winter 1.97(1.46) 1.57(1.31) <0.001
  1. aHeart disease group includes myocardial infarction and angina. Data are n (%) and mean (SD). P values are derived using ether Student’s test, Mann-Whitney U test, or Chi-square test
  2. Abbreviation: SD Standard deviation, UV Ultraviolet radiation, CVD Cardiovascular disease, TPA Total physical activity, BMI Body mass index