Associations of Dental Health With the Progression of Hippocampal Atrophy in Community-Dwelling Individuals

Abstract

Background and ObjectivesAlthough tooth loss and periodontitis have been considered risk factors for Alzheimer's disease, recent longitudinal researches have not found a significant association with hippocampal atrophy. Therefore, this study aimed to clarify a longitudinal association between the number of teeth present (NTP) and hippocampal atrophy dependent on the severity of periodontitis in a late middle-aged and older adult population.MethodsThis study included community-dwelling individuals aged ≥55 years who had no cognitive decline and had undergone brain magnetic resonance imaging (MRI) and oral and systemic data collection twice at 4-year intervals. Hippocampal volumes were obtained from MRIs by automated region-of-interest analysis. The mean periodontal probing depth (mean PD) was used as a measure of periodontitis. Multiple regression analysis was performed with the annual symmetric percentage change (SPC) of the hippocampal volume as the dependent variable and including an interaction term between NTP and mean PD as the independent variable. The interaction details were examined using the Johnson–Neyman technique and simple slope analysis. The three-way interaction of NTP, mean PD, and time on hippocampal volume was analyzed using a linear mixed-effects model, and the interaction of NTP and time was examined in subgroups divided by the median mean PD. In all models, dropout bias was adjusted by inverse probability weighting.ResultsThe data of 172 participants were analyzed. The qualitative interaction between NTP and mean PD was significant for the annual SPC in the left hippocampus. The regression coefficient of the NTP on annual SPC in the left hippocampus was significantly positive (B=0.038,P=.026) at the low-level mean PD (mean-1SD) and significantly negative (B=-0.054,P=.001) at the high-level mean PD (mean+1SD). Similar results were obtained in the linear mixed-effects model; the interaction of NTP and time was significant in the higher mean PD group.DiscussionIn a late middle-aged and older cohort, fewer teeth were associated with a faster rate of left hippocampal atrophy in patients with mild periodontitis, whereas having more teeth was associated with a faster rate of atrophy in those with severe periodontitis. The importance of keeping teeth healthy is suggested.

Restoring periodontal tissue homoeostasis prevents cognitive decline by reducing the number of Serpina3nhigh astrocytes in the hippocampus

“… 25 Human periodontitis patients with a greater number of teeth have been observed to experience a faster rate of hippocampal atrophy and cognitive decline. 26 However, the exact cells in the hippocampus affected by periodontitis remain to be identified. In the present study, we constructed a comprehensive single-nucleus transcriptomic atlas of the hippocampus using snRNA-seq.…”

Advances in the prevention and treatment of Alzheimer’s disease based on oral bacteria

“…Notably, AD patients exhibit an increased risk of tooth loss and complete edentulism, surpassing the risks observed within the general population ( 21 ). A prospective cohort study has revealed a longitudinal association between the number of teeth present (NTP) and hippocampal atrophy, particularly when considering the severity of periodontitis, and this underscores the potential link between tooth loss and subsequent cognitive decline, which may outweigh the influence of age ( 22 ). Moreover, the loss of functional teeth and impairment of functional occlusal units can further exacerbate cognitive impairments in affected individuals ( 23 ).…”

“…However, a long-term follow-up study was carried out on individuals participating in the National Health and Nutrition Examination Survey III (NHANES III) from 1988 to 2019. The results indicated that the IgG antibody cluster of periodontal microbiota could not serve as a predictor for AD mortality ( 22 ). Additionally, a prospective longitudinal study has indicated that elevated levels of TNF-α in the blood plasma, as well as the presence of antibodies against periodontal pathogens, may be associated with the development or progression of AD, and these factors may contribute to improving the clinical diagnosis of AD ( 50 ).…”

Periodontitis and brain magnetic resonance imaging markers of Alzheimer's disease and cognitive aging

“… 44 To date, there are few reports that analyzed features of periodontitis and brain imaging findings associated with impaired cognition and ADRD. 21 , 45 , 46 , 47 , 48 , 49 , 50 In this study, we examined the association of clinical, microbiological, and serological markers of periodontitis with magnetic resonance imaging (MRI) markers of atrophy and cerebrovascular disease in a tri‐ethnic cohort of individuals over the age of 65 years.…”