A common stomach infection may be increasing the risk of Alzheimer's disease
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Physicians ought to be watching this large area of the role of the intestinal microbiome, those bacteria that are in the intestine having extra-intestinal effects. This is an area of research that's no longer at the beginning but far from the end.
—William Schaffner, MD
Preliminary research suggests there may be an association between H. pylori and dementia. [] MDLinx spoke with three experts who say while the research is interesting, there is not enough definitive evidence at this stage to change clinical practice.
The jury is still out on this one since the studies are not of the highest quality and results are not consistent, according to Julie Parsonnet, MD, an infectious diseases clinician and epidemiologist at Stanford University. Some studies show an association, she says, and others do not.
"Also, H. pylori is an organism that is closely linked to socioeconomic status, starting in childhood," she says. "Because of that, it has been linked to quite a number of things that may actually just reflect living conditions. So the question remains, Is H. pylori really just a marker for something else? It can be very challenging to separate out H. pylori from other exposures in life."
Evidence is lacking
Researchers have hypothesized a number of potential biological mechanisms that could link H. pylori and dementia, but Dr. Parsonnet notes none of them is backed by strong evidence.
“There are numerous mechanisms posited for H. pylori and dementia. None of them are proven. Some speculate that the systemic inflammation caused by H. pylori adversely impacts the brain health or that this inflammation disrupts the blood-brain barrier. Another hypothesis is that H. pylori infection may reduce absorption of B12 and folate and that these are necessary for neurologic health; there is little good data for this. Again, the data for this are not strong,” she says.
Related: 5 tips to stave off dementia as you ageThe role of the gut microbiome
While the research into H. pylori and dementia is not yet definitive, William Schaffner, MD, an infectious disease expert at Vanderbilt University, argues the growing body of research into the gut microbiome is worth following.
“Physicians ought to be watching this large area of the role of the intestinal microbiome, those bacteria that are in the intestine having extra-intestinal effects. This is an area of research that's no longer at the beginning but far from the end,” he says.
Our experts note that more research is needed to change current clinical practices surrounding both H. pylori and dementia. But if the link is proven, experts say there could be significant public health implications.
This research could be very important from a public health perspective because H. pylori is common, often chronic, and treatable, according to Dung Trinh, MD, internist at MemorialCare Medical Group and Chief Medical Officer of Healthy Brain Clinic in Irvine, CA. Even a small increase in dementia risk could matter if the exposure affects a large portion of the world’s population, he explains.
"That said, we cannot yet say that preventing or eradicating H. pylori will prevent dementia. The most promising implication is that chronic infection and inflammation may be part of a broader group of modifiable dementia risk factors. More research is needed to determine whether treating H. pylori can reduce long-term cognitive decline or Alzheimer’s risk,” Dr. Trinh says.
He continues, "Physicians should take notice because the signal is biologically plausible and clinically relevant, especially given how common and treatable H. pylori is. However, it should not yet change dementia care into routine universal H. pylori screening. The right stance is awareness without overreaction.”
Related: Common conditions that raise dementia risk