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Table 1 Selected characteristics from the analytic study sample (n = 669)

From: Exposure to polychlorinated biphenyls and organochlorine pesticides and risk of dementia, Alzheimer’s disease and cognitive decline in an older population: a prospective analysis from the Canadian Study of Health and Aging

Characteristics Non-demented individuals (n = 513) Incident cases of dementia (n = 156) P-value
Age at study entry, y 80.1 ± 6.12 82.4 ± 6.60 < 0.001
Sex, female, n (%) 304 (59.3) 102 (65.4) 0.17
Education, y 10.1 ± 4.1 9.0 ± 4.1 <  0.01
BMI, kg/m2 25.9 ± 4.6 25.4 ± 5.2 0.30
Total lipids, g/L 6.1 ± 1.7 6.0 ± 2.0 0.63
ApoE4 carrier, n (%) 92 (18.0) 39 (25.2) < 0.05
3MS score at study entry 88 ± 8.4 83 ± 9.8 < 0.001
Residence area, n (% urban) 448 (87.8) 139 (90.3) 0.41
Smoking, n (% yes) a 217 (46.7) 67 (48.6) 0.70
Alcohol drinking, n (% yes)b 176 (37.7) 44 (32.4) 0.26
Vascular score 1.19 ± 0.83 1.26 ± 0.88 0.38
Blood heavy metal concentrations
 Copper, median (IQR), μmol/L 13.0 (12.0–14.0) 13.0 (12.0–14.0) 0.15
 Lead, median (IQR), μmol/L 0.15 (0.11–0.20) 0.14 (0.10–0.20) 0.55
 Mercury, median (IQR), nmol/L 3.3 (1.7–5.9) 2.4 (1.1–4.6) < 0.001
 Zinc, median (IQR), μmol/L 340 (270–460) 345 (270–455) 0.88
  1. Note: BMI body mass index, IQR interquartile range
  2. Study entry was set at the moment of blood collection (n = 112 at CSHA-1 and n = 557 at CSHA-2)
  3. Values are represented as mean ± standard deviation unless mentioned otherwise
  4. P-values were obtained using χ2 test for dichotomous variables and t-tests or non-parametric Wilcoxon rank-sum tests for continuous variables, as applicable
  5. a Indicates ever been smoking regularly (nearly everyday)
  6. b Indicates ever been drinking regularly (once a week)
  7. Information was missing for 35 subjects on BMI (21 for nondemented and 14 for demented subjects); 3 subjects on ApoE4 status (2 for nondemented vs. 1 for demented subjects); 5 subjects on residence area (3 for nondemented vs. 2 for demented subjects); 66 subjects on smoking (48 for nondemented vs. 18 for demented subjects); 66 subjects on alcohol drinking (46 for nondemented vs. 20 for demented subjects); 33 subjects on plasma total lipids (27 for nondemented vs. 6 for demented subjects)