Effects of the Co-occurrence of Diabetes Mellitus and Tooth Loss on Cognitive Function

Improving oral hygiene for better cognitive health: Interrelationships of oral hygiene habits, oral health status, and cognitive function in older adults

OBJECTIVES

To explore the interrelationships between oral hygiene habits, oral health status and cognitive function in older adults.

DESIGN

A cross-sectional study.

SETTING AND PARTICIPANTS

A total of 371 participants (age 76.79 [7.99] years) were enrolled from June 2020 to November 2021 in an aged care facility.

METHODS

Cognitive function was screened using the mini-mental state examination (MMSE) with adjusted cut-off points for age and education. Periodontal status (Biofilm-Gingival Interface index based on periodontal probing depth and bleeding on probing), dental status (plaque, calculus, and caries), and tooth loss were assessed through full-mouth examination. Oral hygiene habits were based on self- or informant-reporting.

RESULTS

Poor periodontal status was an associated factor for MCI (OR = 2.89, 95% CI = 1.20-6.95), while multiple tooth loss (OR = 4.90, 95% CI = 1.06 ~ 22.59), brushing teeth less than once a day (OR = 2.88, 95% CI = 1.12 ~ 7.45) and delayed dental visits (OR = 2.45, 95% CI = 1.05 ~ 5.68) were associated factors for cognitive impairment. An indirect effect of brushing teeth ≥2 daily on MMSE score through periodontal status was observed only in older adults without cognitive impairment (Bootstrap-corrected B = 0.17, 95%CI = 0.03 ~ 0.36, SE = 0.08, β = 0.08).

CONCLUSIONS AND IMPLICATIONS

Adequate toothbrushing might prevent cognitive decline indirectly by improving periodontal health only in older adults without cognitive impairment. Multiple tooth loss, infrequent toothbrushing, and delayed dental visits were associated factors for cognitive impairment. Nursing professionals and health care policymakers should advocate for the improvement of basic oral hygiene in older adults, and provide regular professional oral hygiene care for older adults with cognitive impairment.

PATIENT OR PUBLIC CONTRIBUTION

The information on oral health habits of this study was based on an interview with the participants or their caregivers during the study period.

Periodontal health, cognitive decline, and dementia: A systematic review and meta-analysis of longitudinal studies

BACKGROUND

Emerging evidence indicates that poor periodontal health adversely impacts cognition. This review examined the available longitudinal evidence concerning the effect of poor periodontal health on cognitive decline and dementia.

METHODS

Comprehensive literature search was conducted on five electronic databases for relevant studies published until April 2022. Longitudinal studies having periodontal health as exposure and cognitive decline and/or dementia as outcomes were considered. Random effects pooled estimates and 95% confidence intervals were generated (pooled odds ratio for cognitive decline and hazards ratio for dementia) to assess whether poor periodontal health increases the risk of cognitive decline and dementia. Heterogeneity between studies was estimated by I2 and the quality of available evidence was assessed through quality assessment criteria.

RESULTS

Adopted search strategy produced 2132 studies for cognitive decline and 2023 for dementia, from which 47 studies (24 for cognitive decline and 23 for dementia) were included in this review. Poor periodontal health (reflected by having periodontitis, tooth loss, deep periodontal pockets, or alveolar bone loss) was associated with both cognitive decline (OR = 1.23; 1.05-1.44) and dementia (HR = 1.21; 1.07-1.38). Further analysis, based on measures of periodontal assessment, found tooth loss to independently increase the risk of both cognitive decline (OR = 1.23; 1.09-1.39) and dementia (HR = 1.13; 1.04-1.23). Stratified analysis based on the extent of tooth loss indicated partial tooth loss to be important for cognitive decline (OR = 1.50; 1.02-2.23) and complete tooth loss for dementia (HR = 1.23; 1.05-1.45). However, the overall quality of evidence was low, and associations were at least partly due to reverse causality.

CONCLUSIONS

Poor periodontal health and tooth loss appear to increase the risk of both cognitive decline and dementia. However, the available evidence is limited (e.g., highly heterogenous, lacking robust methodology) to draw firm conclusions. Further well-designed studies involving standardized periodontal and cognitive health assessment and addressing reverse causality are highly warranted.