Elevated serum pesticide levels and risk for Alzheimer disease.
OBJECTIVE
The causes of late-onset Alzheimer disease (AD) are not yet understood but likely include a combination of genetic, environmental, and lifestyle factors. Limited epidemiological studies suggest that occupational pesticide exposures are associated with AD. Previously, we reported that serum levels of dichlorodiphenyldichloroethylene (DDE), the metabolite of the pesticide dichlorodiphenyltrichloroethane (DDT), were elevated in a small number of patients with AD (n=20).


OBJECTIVE
To evaluate the association between serum levels of DDE and AD and whether the apolipoprotein E (APOE) genotype modifies the association.


METHODS
A case-control study consisting of existing samples from patients with AD and control participants from the Emory University Alzheimer's Disease Research Center and the University of Texas Southwestern Medical School's Alzheimer's Disease Center. Serum levels of DDE were measured in 79 control and 86 AD cases.


METHODS
Serum DDE levels, AD diagnosis, severity of AD measured by the Mini-Mental State Examination score, and interaction with APOE4 status.


RESULTS
Levels of DDE were 3.8-fold higher in the serum of those with AD (mean [SEM], 2.64 [0.35] ng/mg cholesterol) when compared with control participants (mean [SEM], 0.69 [0.1] ng/mg cholesterol; P < .001). The highest tertile of DDE levels was associated with an odds ratio of 4.18 for increased risk for AD (95% CI, 2.54-5.82; P < .001) and lower Mini-Mental State Examination scores (-1.605; range, -3.095 to -0.114; P < .0001). The Mini-Mental State Examination scores in the highest tertile of DDE were -1.753 points lower in the subpopulation carrying an APOE ε4 allele compared with those carrying an APOE ε3 allele (P interaction = .04). Serum levels of DDE were highly correlated with brain levels of DDE (ρ = 0.95). Exposure of human neuroblastoma cells to DDT or DDE increased levels of amyloid precursor protein.


CONCLUSIONS
Elevated serum DDE levels are associated with an increased risk for AD and carriers of an APOE4 ε4 allele may be more susceptible to the effects of DDE. Both DDT and DDE increase amyloid precursor protein levels, providing mechanistic plausibility for the association of DDE exposure with AD. Identifying people who have elevated levels of DDE and carry an APOE ε4 allele may lead to early identification of some cases of AD.
Department of Environmental and Occupational Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey2Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, New Jersey.
Jason R
JR
Richardson
Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, New Jersey.
Ananya
A
Roy
Department of Environmental and Occupational Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey2Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, New Jersey.
Stuart L
SL
Shalat
Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, New Jersey.
Richard T
RT
von Stein
Department of Environmental and Occupational Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey2Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, New Jersey.
Muhammad M
MM
Hossain
Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, New Jersey.
Brian
B
Buckley
Department of Pathology, Emory University School of Medicine, Atlanta, Georgia.
Marla
M
Gearing
Department of Neurology and Alzheimer's Disease, Emory University School of Medicine, Atlanta, Georgia.
Allan I
AI
Levey
Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas.
Dwight C
DC
German
D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D000544:Alzheimer Disease / Q000097:blood / Q000139:chemically induced* / Q000235:genetics; D016229:Amyloid beta-Peptides / Q000187:drug effects; D053318:Apolipoprotein E3 / Q000235:genetics; D053327:Apolipoprotein E4 / Q000235:genetics*; D001057:Apolipoproteins E; D016022:Case-Control Studies; D015331:Cohort Studies; D003634:DDT / Q000009:adverse effects; D003633:Dichlorodiphenyl Dichloroethylene / Q000009:adverse effects* / Q000097:blood; D005260:Female; D006801:Humans; D007306:Insecticides / Q000009:adverse effects* / Q000097:blood; D008297:Male; D012306:Risk; D012720:Severity of Illness Index; D014407:Tumor Cells, Cultured / Q000187:drug effects
D016229:Amyloid beta-Peptides; D053318:Apolipoprotein E3; D053327:Apolipoprotein E4; D001057:Apolipoproteins E; D007306:Insecticides; D003633:Dichlorodiphenyl Dichloroethylene; D003634:DDT