A bacterium seems to cause Alzheimer’s as well as gum disease, hinting that our microbial denizens may be involved in many diseases we thought weren’t infectious
A. Dowsett, Public Health England/Science Photo Library
THE suggestion that a bacterium behind gum disease could be the long-elusive cause of Alzheimer’s is an early contender for most astounding science story of the year. If the implications of a landmark study (see “We may finally know what causes Alzheimer’s – and how to stop it”) are confirmed by future research, the finding will not only point the way towards new treatments, but may also change how we think about disease altogether.
Over the past decade, we have been amazed to discover the wide-ranging roles the microbes in our guts and on our skin play in shaping our health. The delicate balance of species that make up our body’s microbiome has been implicated in everything from allergies to diabetes.
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In some respects, our mouths are the original microbiome. Long before the human microbiome became a flourishing field of study, the knowledge that our mouths are home to a diverse array of bacteria that can, under certain circumstances, lead to tooth decay and gum disease, was commonplace, taught to many of us as schoolchildren.
That such bacteria may also play a role in Alzheimer’s disease is a dramatic swerve from previous thinking, which has focused on the idea that the condition is caused by the misregulation of two particular proteins.
Only further research can tellus the extent to which one of the bacteria behind gum disease – Porphyromonas gingivalis – causes Alzheimer’s. But whatever the long-term significance of this discovery, more studies in coming years are likely to reveal the involvement of the microbiome in a range of diseases we previously thought weren’t infectious.
For now, we can only hope that this latest development will bring us closer to effective treatments for a disease that brings terrible loss even before it kills.
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