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 Good Morning.

New research confirms: untreated sleep apnea may be one of the most preventable drivers of dementia we have.   

A few years ago, a patient came in for a routine crown. Sharp, articulate, a retired school principal. She mentioned offhand that she'd been "a little forgetful lately" — her kids had noticed it too. Her husband snored terribly and never slept well. She assumed her fatigue was just a normal part of aging. Her airway screening told a different story.                                  

She was at high risk for obstructive sleep apnea. She'd never been tested. No one had ever asked.  I think about her often, because the research we now have shows that the window to intervene on cognitive decline doesn't open when memory starts slipping. It opens in the dental chair, years earlier, when we spot the signs that the brain's overnight cleaning system is being slowly shut down.                     

5-minute read👇

The Night Shift Your Brain Depends On 

Every night during deep sleep, your brain runs a process most people have never heard of, and it may be one of the most important things that happens in your body.                  

It's called the glymphatic system: a network of channels that flushes toxic waste proteins, including amyloid-beta and tau, out of brain tissue and into the bloodstream for disposal. Think of it as a nightly pressure wash for the brain. Here's the critical part: this system is almost entirely sleep-dependent. During sleep, the spaces between brain cells expand by up to 60%, allowing cerebrospinal fluid to flow through and carry waste out. When sleep is disrupted, as it is hundreds of times per night, in a patient with untreated OSA, that clearance process is cut short. The waste stays. And it accumulates.                                                                                                                                                                                                              

Research published in Nature Communications has now confirmed this process occurs in humans, not just animal models, and that overnight glymphatic clearance of Alzheimer 's-associated proteins is measurably reduced in people with sleep disruption.                                                                                                   

 The Numbers Are Alarming 

A 2022 meta-analysis in the Journal of Sleep Research, analyzing over 1.3 million patients, found that people with sleep apnea had:                                                                                                                                                             

• 43% higher risk of developing any neurocognitive disorder 

• 28% higher risk of Alzheimer's disease specifically   

• 54% higher risk of Parkinson's disease

• 106% higher risk of Lewy body dementia                                                                                                                                                                                      

A 2025 meta-analysis in GeroScience, covering 76 longitudinal cohort studies, concluded that sleep management is "a pivotal modifiable factor in reducing the risk of all-cause cognitive decline."  And perhaps most sobering: a separate analysis of 33,226 OSA patients found that 36.92% already showed signs of cognitive impairment at the time of assessment.  These are not obscure findings. This is mainstream science, and it's landing in our laps as dental sleep providers.                                                                                                          

 It Hits Women Harder Than We Thought 

 A 2024 study in SLEEP Advances followed 18,815 Americans aged 50 and older for 10 years. The findings on women were striking: women with OSA showed 3.7–4.7% higher cumulative dementia incidence by age 80 compared to non-OSA women, and OSA contributed to over 10% of dementia cases in women in that population.                   

OSA is more commonly diagnosed in men, but its impact on dementia risk appears disproportionately severe in women. That's a patient conversation most of us haven't been having.

The Earlier the Diagnosis, the Higher the stakes. One finding that stood out: patients diagnosed with OSA before age 52 carry the highest risk of all-cause dementia. This isn't a disease of old age. The neurological damage is cumulative and begins early.  

CLINICAL CORNER

Pearl: Oral Appliances Protect the Brain Too

One of the most important takeaways from current research for dental sleep providers:

Mandibular advancement devices (MADs) show cognitive outcomes comparable to CPAP.

Multiple studies confirm that oral appliance therapy improves:

• Neurocognitive function

• Daytime alertness and processing speed

• Blood pressure

• Cardiovascular mortality risk

And here’s the part that actually matters in the real world:

Adherence is higher with oral appliances than with CPAP.

A device worn 7 hours a night will always outperform one that ends up sitting in a drawer.

What This Means for Your Practice

When you present oral appliance therapy, you’re no longer just offering better sleep.

You’re offering a credible, evidence-backed intervention against one of the most feared diseases of aging.

That’s a different conversation, and frankly, a more honest one.

Screening Reminder

Patients with any of the following conditions should be screened using at least the STOP-Bang questionnaire: a receding chin, a high-arched palate, a large tongue with scalloped edges, snoring, and daytime fatigue. Since about 36% of people with obstructive sleep apnea (OSA) have cognitive issues, you might already notice these problems in your patients, even if you haven't mentioned it.

COACH CATHY’S TAKE

By Cathy Bennett, MS, NBCHWC

When I work with patients on lifestyle habits, sleep is always the first conversation.

Not nutrition.
Not exercise.

Because without restorative sleep, none of the other pieces work the way they should.

Start Here: Support the Brain’s Overnight Cleanup

Even before perfecting apnea treatment, patients can begin supporting their brain today.

1. Side Sleeping Matters

The glymphatic system functions more efficiently when sleeping on your side, especially on your left side.

If a patient sleeps on their back and has OSA, they’re taking a double hit:

• Worse apnea events

• Reduced waste clearance

Positional therapy is simple and free.

2. Limit Alcohol at Night

Alcohol:

• Fragments sleep architecture

• Suppresses deep sleep

Even one drink within 3 hours of bedtime measurably impairs sleep quality—and brain detox.

3. Hydration + Movement

The glymphatic system depends on cerebrospinal fluid flow.

That means:

• Adequate hydration

• Daily movement (yes, even just walking)

Not flashy advice, but consistently supported by research.

Bottom Line

The brain can heal and clear itself. But only if we give it the conditions to do so. And that starts with treating the airway.

REFERENCES

Beaudin et al. (2024). Association between sleep microarchitecture and cognition in obstructive sleep apnea. https://academic.oup.com/sleep/article/47/8/zsae141/7693579

Braley et al. (2024). Sex-specific dementia risk in known or suspected obstructive sleep apnea: a 10-year longitudinal population-based study. https://academic.oup.com/sleepadvances/article/5/1/zpae077/7831433

Chen et al. (2025). Prevalence of cognitive impairment among adults with obstructive sleep apnea: a systematic review and meta-analysis. https://link.springer.com/article/10.1007/s11325-025-03509-7

Guay-Gagnon et al. (2022). Sleep apnea and the risk of dementia: A systematic review and meta-analysis. https://onlinelibrary.wiley.com/doi/10.1111/jsr.13589

Steenland et al. (2024). The glymphatic system clears amyloid beta and tau from brain to plasma in humans. https://pmc.ncbi.nlm.nih.gov/articles/PMC12847902/

Ungvári, Zhang, et al. (2024). Sleep disorders increase the risk of dementia, Alzheimer’s disease, and cognitive decline: a meta-analysis. https://link.springer.com/article/10.1007/s11357-024-01173-7

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Until next week,
Dr. Michael & Cathy Bennett
More Than Teeth | A Mission for Generational Health