Serum IgG Antibody Levels to Periodontal Microbiota Are Associated with Incident Alzheimer Disease.

BACKGROUND:

Periodontitis
and Alzheimer disease (AD) are associated with systemic inflammation.
This research studied serum IgG to periodontal microbiota as possible
predictors of incident AD.

METHODS:

Using a case-cohort study design, 219 subjects (110 incident AD cases and 109
controls without incident cognitive impairment at last follow-up),
matched on race-ethnicity, were drawn from the Washington Heights-Inwood
Columbia Aging Project (WHICAP), a cohort of longitudinally followed
northern Manhattan residents aged >65 years. Mean follow-up was five
years (SD 2.6). In baseline sera, serum IgG levels were determined for
bacteria known to be positively or negatively associated with
periodontitis (Porphyromonas gingivalis, Tannerella forsythia,
Actinobacillus actinomycetemcomitans Y4, Treponema denticola,
Campylobacter rectus, Eubacterium nodatum, and Actinomyces naeslundii
genospecies-2). In all analyses, we used antibody threshold levels shown
to correlate with presence of moderate-severe periodontitis.

RESULTS:

Mean age was 72 years (SD 6.9) for controls, and 79 years (SD 4.6) for cases
(p<0.001). Non-Hispanic Whites comprised 26%, non-Hispanic Blacks
27%, and Hispanics 48% of the sample. In a model adjusting for baseline
age, sex, education, diabetes mellitus, hypertension, smoking, prior
history of stroke, and apolipoprotein E genotype, high anti-A.
naeslundii titer (>640 ng/ml, present in 10% of subjects) was
associated with increased risk of AD (HR = 2.0, 95%CI: 1.1-3.8). This
association was stronger after adjusting for other significant titers
(HR = 3.1, 95%CI: 1.5-6.4). In this model, high anti-E. nodatum IgG
(>1755 ng/ml; 19% of subjects) was associated with lower risk of AD
(HR = 0.5, 95%CI: 0.2-0.9).

CONCLUSIONS:

Serum IgG levels to common periodontal microbiota are associated with risk for developing incident AD.