Letter to the editor regarding: Summary of the evidence on modifiable risk factors for cognitive decline and dementia: A population-based perspective

The article entitled “Summary of the evidence on modifiable risk factors for cognitive decline and dementia: A population-based perspective” was published recently by M Baumghart et al. in Alzheimer’s & Dementia on behalf of the Alzheimer’s Association. This article succinctly reviews the evidence for many putative modifiable risk factors of Alzheimer’s disease (AD) and cognitive decline [1] and concludes that there is strong evidence for some risk factors, e.g. diabetes and obesity. However, although the article sampled a broad range of risk factors, it was not comprehensive. Considering the vast implications of this article for practice guidelines and AD research priorities, we suggest attention to another well-studied and modifiable risk for AD—periodontal disease. Periodontal disease is a chronic polymicrobial disease of the tissues supporting the teeth. Others and we have studied the association between AD/cognition and periodontal disease using a variety of exposure indexes, study designs, and outcomes. In one longitudinal study of 597 subjects followed for 32 years, there was an association (1.03, hazard ratio [HR].1.09) between pocket depth, alveolar bone loss, and tooth loss (indices of current and historical periodontal disease) and cognitive decline [2,3]. Another showed that periodontal inflammation predicted cognitive decline in 947 subjects with mild-to-moderate strength (odds ratio [OR] 5 1.57 [95% confidence interval (CI), 1.01–2.45]) [4]. Other studies defining periodontal disease by immunologic parameters [5] also show strong prediction (OR 5 HR 5 3.1; 95% CI, 1.5–6.4) [6]. Because of its convenient assessment, the most prevalent index of periodontal exposure is tooth loss (it is also the ultimate outcome of the untreated periodontal disease), and seven longitudinal studies