AUTHOR=Li Liqing , Zhang Qi , Yang Di , Yang Sule , Zhao Yulan , Jiang Min , Wang Xiaofang , Zhao Ling , Liu Qi , Lu Zuxun , Zhou Xiaogang , Gan Yong , Wu Chunmei 

TITLE=Tooth loss and the risk of cognitive decline and dementia: A meta-analysis of cohort studies

JOURNAL=Frontiers in Neurology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1103052

DOI=10.3389/fneur.2023.1103052

ISSN=1664-2295

ABSTRACT=<sec><title>Introduction</title><p>Epidemiological studies have shown that tooth loss may be associated with an increased risk of cognitive decline and dementia. However, some results do not show a significant association. Therefore, we performed a meta-analysis to evaluate this association.</p></sec><sec><title>Methods</title><p>Relevant cohort studies were searched in PubMed, Embase, Web of Science (up to May 2022), and the reference lists of retrieved articles. The pooled relative risk (<italic>RR</italic>) and 95% confidence intervals were computed using a random-effects model (<italic>CI</italic>). Heterogeneity was evaluated using the <italic>I</italic><sup>2</sup> statistic. Publication bias was evaluated using the Begg's and Egger's tests.</p></sec><sec><title>Results</title><p>Eighteen cohort studies met the inclusion criteria. Original studies with 356,297 participants with an average follow-up of 8.6 years (ranging from 2 to 20 years) were included in this study. The pooled <italic>RRs</italic> of tooth loss on dementia and cognitive decline were 1.15 (95% <italic>CI</italic>: 1.10–1.20; <italic>P</italic> &lt; 0.01, <italic>I</italic><sup>2</sup> = 67.4%) and 1.20 (95% <italic>CI</italic>: 1.14–1.26; <italic>P</italic> = 0.04, <italic>I</italic><sup>2</sup> = 42.3%), respectively. The results of the subgroup analysis showed an increased association between tooth loss and Alzheimer's disease (AD) (<italic>RR</italic> = 1.12, 95% <italic>CI</italic>: 1.02–1.23) and vascular dementia (VaD) (<italic>RR</italic> = 1.25, 95% <italic>CI</italic>: 1.06–1.47). The results of the subgroup analysis also showed that pooled RRs varied by geographic location, sex, use of dentures, number of teeth or edentulous status, dental assessment, and follow-up duration. None of the Begg's and Egger's tests or funnel plots showed evidence of publication bias.</p></sec><sec><title>Discussion</title><p>Tooth loss is associated with a significantly increased risk of cognitive decline and dementia, suggesting that adequate natural teeth are important for cognitive function in older adults. The likely mechanisms mostly suggested include nutrition, inflammation, and neural feedback, especially deficiency of several nutrients like vitamin D.</p></sec>