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

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

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

Note: BMI body mass index, IQR interquartile range
Study entry was set at the moment of blood collection (n = 112 at CSHA-1 and n = 557 at CSHA-2)
Values are represented as mean ± standard deviation unless mentioned otherwise
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
^a Indicates ever been smoking regularly (nearly everyday)
^b Indicates ever been drinking regularly (once a week)
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)

ISSN: 1476-069X