Chronic cannabis use linked to disruptions in healthy oral microbiome that may alter brain health

Increased levels of the bacteria Actinomyces meyeri in the saliva of long-term cannabis users that, when given to mice, was shown to change brain behavior, a recent study found.

The study was led by Wei Jiang, MD, an immunologist at the Medical University of South Carolina. Jiang and her team of researchers analyzed the saliva of chronic cannabis smokers, tobacco smokers, and nonsmokers. While there were many similarities in the oral microbiomes among each group, they found a correlation between increased levels of Actinomyces meyeri and frequency of cannabis use.

To study the effect of increased levels of Actinomyces meyeri, researchers fed it orally to mice. When compared to mice given control bacteria, mice exposed to the Actinomyces meyeri had decreased global activity, increased macrophage infiltration, and increased β-amyloid 42 protein production.

Jiang said their results suggest that chronic cannabis use may affect central nervous system (CNS) function. The study showed a correlation between oral health and CNS functions, findings which may contribute to new treatment and prevention of certain neurological abnormalities.