Study shows the effects of cannabis use on oral microbiome and brain health

Although marijuana’s legalization is increasing in popularity, there is still a lot to learn about the long-term effects of cannabis consumption on the microbes that live in the oral cavity (or oral microbiome). The oral microbiome plays an important role in maintaining dental health, but changes in the environment of the mouth, such as those caused by smoking can upset the balance of microbes making us more vulnerable to diseases.

To find out more, Medical University of South Carolina immunologist Wei Jiang, M.D. who was the leader of a study to explore the effects of cannabis usage on the oral microbiome. Her team looked at saliva from long-term cannabis users. They found an increase in Actinomyces in the mouth, which was associated with the length of cannabis use. An increase in the amount of bacteria can cause problems with your immune system. To determine if high levels of A. meyeri influence the immune system, Jiang’s team gave mice A. meyeri through the mouth and observed a dramatic reduction in global activity as well as an increase in the levels of beta-amyloid in the brain, one of the proteins that are associated with Alzheimer’s disease. These studies indicate that the long-term use of cannabis alters brain health. The findings of the team were published online in EBioMedicine on Nov. 23.

I believe the most exciting aspect of our research is the connection between oral microbiome and brain health. To establish this connection, we went beyond the usual associative studies in humans and conducted a causal study in mice.”

Wei Jiang M.D. Immunologist, Medical University of South Carolina

Cannabis use and the oral microbiome

Microbes have been viewed as foreign invaders that could cause disease. But the truth is much more complex. In the majority of cases we live in harmony with our microbiome, since these microbes in the communal do not cause disease and usually serve vital biological functions.

However, not only does smoking upset the balance of microbes within the oral cavity, smoking cannabis is also known to affect neural functioning, and some of its constituents like tetrahydrocannabinol (THC) can affect the immune system.

Jiang and her colleagues gathered microbiome information from chronic cannabis users. They compared them to non-smokers and tobacco smokers by analyzing their saliva. This was to determine how changes to the oral microbiome can be attributed to smoking cannabis. They found similar changes in several bacteria species between smokers and nonsmokers. However, A. The meyeri gene was distinct in cannabis smokers.

The Actinomyces family of bacteria, of which A. meyeri is a member are common bacteria found in the oral cavity. However, they can also be pathogens that are opportunistic. Smoking can cause damage to the oral mucosa, which could lead to bacteria fragments or even whole bacteria transferring into your circulatory system. This could impact the immune system. Indeed, Jiang found increased levels of antibodies against A. meyeri in plasma of cannabis smokers.

The health of the brain is impacted by the use of cannabis

To better understand the ways in which A. meyeri affects brain health, researchers inoculated mice with A. meyeri. The mice showed reduced activity, increased migration of macrophages into the brain, and increased levels of beta-amyloid. These results suggest that long-term cannabis use alters the health of the brain, specifically the build-up of the toxic beta-amyloid protein which is linked to Alzheimer’s disease and other dementias. The presence of immune cells in brains can cause brain dysfunctional changes. This could be due to ongoing brain inflammation. However, A. stimulated macrophages unexpectedly. While meyeri didn’t trigger an inflammatory response, it did induce macrophages to migrate into the brain.

“That’s a puzzle. In general, people think that if you activate macrophages and they move to the brain, they will release pro-inflammatory signals that cause brain inflammation and eventually brain dysfunction,” said Jiang. “However brain dysfunction could be present without inflammation signals.”

While cannabis usage can cause dementia, it could be beneficial for those suffering from the condition. The paradoxical effects of cannabis could be due to the duration and frequency of cannabis consumption. This is a reason to conduct further research.

These findings underscore the importance of oral health to brain function. Jiang and her team are hoping to continue investigating the mechanisms by which A. meyeri is involved in amyloid protein production within brains and we are developing an inhibitor.

Journal reference:

Luo, Z., and Luo, Z., and. (2021). Oral pathwayobiont enriched by chronic cannabis smoking causes behavioral changes, macrophage inflammation, and increases brain-amyloid protein levels. EBioMedicine.

Content Source:

Gemma Wilson

Gemma is a journalism graduate with keen interest in covering business news – specifically startups. She has as a keen eye for technologies and has predicted quite a few successful startups over the last couple of years.

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