Bacteria behind gum disease linked to Alzheimer's

Posted on 2019-02-26

The leading cause of death in the UK? Surprisingly to most it is not cancer, nor heart disease, but dementia. Dementia is an umbrella term which describes a collection of symptoms, including impaired cognitive ability, communication difficulties and memory problems. Statistics from the WHO and Dementia Research UK predict an overall global rise in dementia from 50m to 152m in 2050, a 205% increase. Couple that with its disproportionate research investment and the future can look bleak: 2017 saw only 2% of medical research funds go to Dementia research, despite it costing health and social care sectors more than both cancer and heart disease combined in the UK. Multiple forms of Dementia exist, with Alzheimer's being the prominent cause of the disease here in the UK, according to the NHS. Characterised by an accumulation of a number of proteins, predominantly beta-amyloid and Tau, build-up of these proteins form the plaques and tangles which are the recognisable pathological hallmarks of the disease. As for the various types of Dementia, cause and effect has not been previously established, with a distinct inability of previous research to fulfil Koch's postulates.

Hope, however, is on the horizon. New research sheds a light on the elusive cause of Alzheimer's, with researchers from multiple institutions converging on a common culprit: Porphyromonas gingivalis, the bacterium behind common gum disease. Researchers from an American Biotechnology company and numerous institutions across the globe established the pathogen in chronic periodontitis as present in the brains of patients with Alzheimer’s, with levels of its virulence factors correlating with disease protein pathology. P. gingivalis secretes virulence factors known as gingipains; toxic proteases which facilitate the survival and pathogenicity of the bacterium. It is thought the accumulation of proteins commonly seen in the disease is a defensive mechanism against infection and the effects of these proteases.

Importantly, the study appears to show the presence of the bacterial infection within the brain preceding a diagnosis of dementia, with the discovery of gingipain antigens in brains displaying Alzheimer's pathology before any apparent dementia symptoms are observed. This gives more credit to the notion that P.gingivalis may be the causal agent, as opposed to being a result of poor oral hygiene that may accompany the disease in its more established stages. The study goes on to show targeting and inhibition of the bacterial virulence factors by small molecule inhibitors reduced disease pathology and decreased beta-amyloid production, thus providing more evidence for a causal link and presenting possible treatment options to explore.

Whilst the results of this study carry promising implications, it is essential to remember that this research is still within its early stages, with researchers suggesting P.gingivalis could be just one of a number of pathogens contributing to the build-up of tangles and plaques seen in Alzheimer's. For now, however, it is a promising avenue for further study and may provide, at the very least, a way of slowing disease progression.

One thing remains certain; keep brushing and flossing those pearly whites!

Read the full study here .

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