High throughput DNA sequencing to detect differences in the subgingival plaque microbiome in elderly subjects with and without dementia

Abstract

BackgroundTo investigate the potential association between oral health and cognitive function, a pilot study was conducted to evaluate high throughput DNA sequencing of the V3 region of the 16S ribosomal RNA gene for determining the relative abundance of bacterial taxa in subgingival plaque from older adults with or without dementia.MethodsSubgingival plaque samples were obtained from ten individuals at least 70 years old who participated in a study to assess oral health and cognitive function. DNA was isolated from the samples and a gene segment from the V3 portion of the 16S bacterial ribosomal RNA gene was amplified and sequenced using an Illumina HiSeq1000 DNA sequencer. Bacterial populations found in the subgingival plaque were identified and assessed with respect to the cognitive status and oral health of the participants who provided the samples.ResultsMore than two million high quality DNA sequences were obtained from each sample. Individuals differed greatly in the mix of phylotypes, but different sites from different subgingival depths in the same subject were usually similar. No consistent differences were observed in this small sample between subjects separated by levels of oral health, sex, or age; however a consistently higher level of Fusobacteriaceae and a generally lower level of Prevotellaceae was seen in subjects without dementia, although the difference did not reach statistical significance, possibly because of the small sample size.ConclusionsThe results from this pilot study provide suggestive evidence that alterations in the subgingival microbiome are associated with changes in cognitive function, and provide support for an expanded analysis of the role of the oral microbiome in dementia.

Aging and Alzheimer’s disease: Comparison and associations from molecular to system level

“…Poor dental status has been linked to AD or early signs of AD (Gatz et al, 2006). An early study found that subgingival microbiome is associated with changes in cognitive function (Cockburn et al, 2012). Please refer to Pistollato et al (2016) and Tremlett, Bauer, Appel‐Cresswell, Finlay, and Waubant (2017) as a starting point.…”

Cross-sectional associations of oral health measures with cognitive function in late middle–aged adults

“…The results of several studies suggest that periodontal infection and increased inflammatory levels in early life could be responsible for later cognitive decline. 6,7,11,14,18–20 …”

“…Although investigators in cross-sectional studies 14,20,21 and a prospective study 19 found that biological markers for periodontal infection were associated with dementia or cognitive impairment, studies in which researchers have investigated these associations by using clinical signs of periodontal disease (for example, pocket depth, gingival bleeding or attachment loss) have shown mixed results. 2,5,7,8,11,18,22,23 Possible reasons for this variability are that many of these studies had small numbers of participants, 7,18 and some studies relied on measures of periodontal disease that are based on partial examinations 8,22 or self-report.…”

Oral biofilms: molecular analysis, challenges, and future prospects in dental diagnostics

“…Other studies have used the Illumina platform to perform taxonomic profiling by 16S rRNA amplicon sequencing,60,61 using different hypervariable regions. This next-generation sequencing platform uses a different chemistry involving a reversible terminator-based method during sequencing by synthesis, resulting in shorter read lengths compared with the 454 pyrosequencing platform, but yields a much higher data output.…”