For nearly eight years, we’ve routinely tested the oral microbiome in our cognitive health patients. Originally, our interest stemmed from emerging evidence linking oral pathogens with cognitive decline, particularly in Alzheimer’s disease. But new research is opening up a wider conversation—one that extends into the realm of mental health and mood.
Lower oral microbial diversity may be associated with higher levels of depressive symptoms.
What a New Study Suggests
A recent study from NYU Rory Meyers College of Nursing, published in BMC Oral Health, analysed data from 15,000+ U.S. adults, comparing depression scores with microbial diversity from saliva samples. Even after adjusting for smoking, alcohol intake, and oral hygiene practices, the association held: people with less diverse oral microbiomes were more likely to report depressive symptoms.
Why Does Oral Microbiome Diversity Matter?
Your mouth is home to an estimated 500 billion to 1 trillion bacteria—making it the second-largest microbial ecosystem in your body after the gut. While most people have heard of the gut–brain axis, far fewer are aware of the oral–brain connection.
The theory is that oral dysbiosis (an imbalance in oral bacteria) can trigger inflammation or immune changes that may impact mood regulation—much as it can contribute to cognitive decline.
Important caveat: the direction of causality isn’t yet clear. Does oral dysbiosis contribute to depression? Does depression (via diet, smoking, reduced oral hygiene) drive the dysbiosis? Or is it a two-way street? Research is ongoing.
What This Means in Functional Medicine
In functional medicine, we look at the whole system. We’ve long known that inflammation, immune dysregulation, and microbial imbalance can drive both cognitive and emotional symptoms. This study strengthens the case for including oral microbiome testing not just in cognitive clinics, but also when assessing mood disorders such as depression.
- Novel diagnostics: oral microbial profiles as potential biomarkers for mental health risk.
- New treatment avenues: targeted oral probiotics, dental hygiene interventions, and (where appropriate) antimicrobial strategies to support wellbeing.
- Personalised prevention: bringing oral health into the conversation on mental health and resilience.
What This Means for You
If you’re dealing with low mood, persistent fatigue, or brain fog, it may be worth exploring less obvious sources of inflammation and imbalance—including what’s going on in your mouth.
At Cogmission, our root-cause approach may include:
- Advanced oral microbiome testing
- Functional stool and nutrient analysis
- Hormonal and neurotransmitter balance assessments
- Supportive natural therapies, dietary adjustments, and targeted supplements
Takeaway: Your mouth isn’t just for smiling—it may be a key window into your brain and mood.
Ready to explore your oral–mood connection?
If you’d like to include oral microbiome testing in your mental wellness or cognitive support plan, we’re here to help.
Enquire or BookFAQs
Is testing invasive?
No—oral microbiome testing typically uses a simple saliva sample collected at home or in-clinic.
Can improving oral health improve mood?
Potentially. While more research is needed, improving oral hygiene, diet, and targeted support may positively influence the oral microbiome and, in turn, overall wellbeing.
Do I need a dentist as well as functional testing?
Often yes. We’re happy to collaborate with your dental team to ensure a coordinated approach.
Research note: Summary adapted from a large cross-sectional analysis published in BMC Oral Health by researchers at NYU Rory Meyers College of Nursing. Associations do not imply causation; personalised assessment is recommended.