Association Between Oral Health and Cognitive Status: A Systematic Review

Abstract

OBJECTIVES We have carried out a systematic review of longitudinal studies examining the association between oral health and cognitive decline. DESIGN Studies, published 01/1993-03/2013, were identified by search of English language publications in PubMed/Medline using relevant MeSH terms and title/abstract keywords, and from CINAHL using relevant subject headings. After applying eligibility criteria, and adding four studies identified from article references, 56 of the 1412 articles identified remained: 40 were cross-sectional, and 16 longitudinal; 11 of the latter examined the impact of oral health on change in cognitive health or dementia incidence, five examined the reverse. SETTING Sources of information included administrative data, subject evaluations in parent studies, medical and dental records, self-reports, and in-person evaluations. MEASUREMENTS Most studies used subjects whose oral or cognitive status was known, adding the missing piece using standard measures. The oral health information most frequently studied included number of teeth, periodontal and caries problems, and denture use. Cognition was most frequently evaluated using the MMSE, or by determination of dementia. RESULTS Some studies found that oral health measures such as number of teeth and periodontal disease were associated with increased risk of cognitive decline or incident dementia, while others did not find the association. Similarly, cognitive decline was not consistently associated with greater loss of teeth or number of caries. Methodological limitations likely play a major role in explaining the inconsistent findings. CONCLUSION It is unclear how or whether oral health and cognitive status are related. Additional research is needed in which there is greater agreement on how oral health and cognitive states are assessed, in order to better examine the linkages between these two health outcomes.

Systemic inflammatory impact of periodontitis on cognitive impairment

“…Published evidence on the role of periodontitis or tooth loss in dementia has been inconclusive, 8,14,[39][40][41][42][43] and comparisons among studies are hampered by differences in their design, diagnostic criteria, exposure variables and outcome variables. 11 However, most investigations have reported an association of periodontitis or tooth loss with cognitive function or the presence of dementia, suggesting the involvement of peripheral inflammation as a likely causal factor, although this relationship was not addressed in these studies. 12,[22][23][24] A recent study in a broad Taiwanese sample concluded that periodontitis in the older adult was associated with a greater risk of developing dementia (hazard ratio:1.16), 44 but there was no examination of underlying physiopathological mechanisms.…”

“…21 However, the role of peripheral inflammation of periodontal origin has yet to be fully elucidated. 11 Few studies have analysed in depth the involvement in dementia of systemic inflammation and its biomarkers due to periodontal disease, [22][23][24] all based on a limited number of cytokines and partially confirming the role of systemic inflammation of periodontal origin in dementia. However, studies in patients with cardiovascular disease failed to establish positive associations among periodontitis, systemic inflammation and cardiovascular disease.…”

Association of oral health and activities of daily living with cognitive impairment

“…Conversely, a few recent systematic reviews on oral health and cognitive function have reported that more studies on this topic are necessary to address the lack of definitive evidence on the relationship between oral health and cognitive function. 12,13 Therefore, the purpose of this study was to evaluate the associations of oral health and ADL with cognitive impairment.…”

Influence of lack of posterior occlusal support on cognitive decline among 80‐year‐old Japanese people in a 3‐year prospective study

“…Recently, several studies have reported an influence of oral health on cognitive decline. 8 Periodontal disease has previously been discussed in relation to cognitive decline. 9 It has been hypothesized that the mechanism of this association might involve inflammatory molecules, bacteria and bacterial products that enhance neuroinflammation.…”