A path analysis of multiple neurotoxic chemicals and cognitive functioning in older US adults (NHANES 1999–2002)

Abstract

BackgroundPolychlorinated biphenyls (PCBs) and metals (lead and cadmium) are neurotoxic and affect neurobehavioral performance. Yet little is known about the association between exposure to multiple neurotoxic compounds and cognitive functioning in older adults.MethodsUsing data from two consecutive cycles of the National Health and Nutrition and Examination Survey (1999–2002), path analysis was used to simultaneously evaluate the association between whole blood concentrations of 14 neurotoxic compounds and cognitive functioning measured by the Digit Symbol Coding Test of the Weschler Adult Intelligence Scale, 3rd Edition in participants 60–84 years of age (N = 498). Effect modification was assessed for age (above/below the mean) and sex.ResultsThe final path model fit 5 compounds (i.e. PCB 74, PCB 118, PCB 146, PCB 153, and lead). After controlling for co-exposures and confounders, PCB 146 (β = −0.16, 95% CI: −0.29, −0.02, p = 0.02) and lead (β = −0.10, 95% CI: −0.20, −0.006, p = 0.04) were negatively associated with DSC scores in 60–84 year olds. Whereas, PCB 153 was positively associated with DSC scores (β =0.20, 95% CI: 0.05, 0.35; p = 0.01).ConclusionsThis cross-sectional analysis which controlled for collinear exposure to several neurotoxic compounds demonstrated an association between non-dioxin like polychlorinated biphenyl exposure, specifically PCB 146, and lower cognitive functioning, in older adults. Lead exposure was also weakly associated with lower cognitive functioning. Additional studies are needed to determine the causality of the observed associations.

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

“…Increased concentrations of four PCBs (congeners 118, 153, 156, 163) and two OC pesticides (p,p'-DDT and its metabolite p, p'-DDE) were found to be significantly associated with a lower cognitive function. These findings are somewhat in line with previous studies which reported associations between a lower performance in some cognitive domains and exposure to PCBs [7,11,[38][39][40][41] in population-or community-dwelling older subjects, to p,p'-DDT or/and p,p'-DDE in population-dwelling older subjects (US National Health and Nutrition Examination Survey, 1999-2002) [8,9] and in retired malaria-control Costa-Rican workers [42]. In contrast to our study, neither p,p'-DDT nor p,p'-DDE were significantly associated with a lower cognitive function measured with the Mini-Mental State Examination (MMSE) among occupational OC pesticide exposure Costa Ricans [43].…”

“…Few observational studies have explored the potential association between exposure to organochlorines and risk of all-cause dementia, AD [12][13][14][15], and cognitive impairment [7][8][9][10][11] over the last years among seniors. The present study was designed to evaluate prospectively such associations among Canadians aged 65 and older.…”

“…One systematic review including a meta-analysis reported a positive association between pesticide exposure and AD [4]. Since polychlorinated biphenyls (PCBs) and organochlorine (OCs) pesticides, also known as persistent OC compounds, were reported to induce cognitive, motor and behavioral deficits in animal models through a number of potential modes of action [5,6], growing interest in ascertaining their relationship with cognitive impairment [7][8][9][10][11], allcause dementia and AD [12][13][14][15] and Lewy pathology [16] has been mostly noticed in recent years. These few studies indicate a potential association between OC compound exposure and cognitive impairment and dementia, but the results are still inconsistent.…”

Integrated transcriptomics and metabolomics reveal signatures of lipid metabolism dysregulation in HepaRG liver cells exposed to PCB 126

“…PCB 126 was found at concentrations of 209 and 80.4 ng/kg in the breast milk of Inuit and Caucasian women, respectively, in a survey performed in 1989–1990 (Dewailly et al 1994 ). The analysis of the National Health and Nutrition Examination Survey (NHANES) data (1999–2002) reveals associations between PCB serum levels and adverse cognitive effects in older US adults (Przybyla et al 2017 ). In more recent biomonitoring surveys, PCB 126 was found at a mean concentration of 6.5 μg/L in umbilical cord serum of populations living near waste dump sites in Italy (Grumetto et al 2015 ).…”

Integrated transcriptomics and metabolomics reveal signatures of lipid metabolism dysregulation in HepaRG liver cells exposed to PCB 126

“…PCB 126 was found at concentrations of 209 ng/kg and 80.4 ng/kg in the breastmilk of Inuit women and Caucasian women, respectively, in a survey performed in 1989-1990(Dewailly et al, 1994. The analysis of the National Health and Nutrition Examination Survey (NHANES) data (1999)(2000)(2001)(2002) reveals associations between PCB serum levels and adverse cognitive effects in older US adults (Przybyla et al, 2017). In more recent biomonitoring surveys, PCB 126 was found at a mean concentration of 6.5 μg/L in umbilical cord serum of populations living near waste dump sites in Italy (Grumetto et al, 2015).…”