Different stages of Alzheimer's disease with periodontitis: clinical features and potential mechanisms involving gingipains, neuropathological biomarkers and neurological damage.

BACKGROUND

Alzheimer's disease (AD) and periodontitis are common in older adults aged over 65 years. However, the clinical features and mechanisms at the stages of mild cognitive impairment and dementia due to AD (AD-MCI and AD-D) remain unknown.

METHODS

In 110 patients with AD-MCI and AD-D, oral hygiene, periodontitis status, clinical symptoms and the levels of gingipain, neuropathological biomarkers and neurological damage indicators in cerebrospinal fluid were evaluated.

RESULTS

The frequency of periodontitis was 38.18% in the AD-MCI group and 67.27% in the AD-D group. The AD-MCI with periodontitis group had significantly worse cognition and lower β-amyloid (Aβ) level than those without periodontitis (all p < 0.05). The AD-D with periodontitis group had further impaired cognition and more severe neuropsychiatric symptoms. Gingipain K (K-GP) level was significantly correlated with Aβ, phosphorylated tau 199 and synaptosomal-associated protein 25 levels in the cerebrospinal fluid from AD-D with periodontitis group (all p < 0.05).

CONCLUSION

Periodontitis is more prevalent and severe in AD patients. K-GP plays a significant role in AD with periodontitis, and is associated with AD pathology and impairs cognition at the MCI stage. K-GP contributes to the exacerbation of AD pathology and neurodegeneration, and is potentially involved in the aggravation of symptoms at the dementia stage.