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Oral health and Alzheimer’s risk

Oral health and Alzheimer’s risk
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January 9, 2023
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Researchers have acknowledged for decades the connection between a healthy body and a healthy mind. Recent research is extending that link to draw a connection between oral health and Alzheimer’s disease and dementia.

To that end, the Alzheimer’s Association is conducting the two-year U.S. Pointer study to look closely at the impact that lifestyle interventions (including physical activity, nutrition, health coaching and intellectual engagement) can have on the risk for cognitive decline among older adults. 

While the links between oral health and dementia are less clear, researchers are learning more about the issue, both in terms of reducing our risk for the onset of dementia as well as important dental care steps for those who are already in the early stages of the disease.

The mouth is home to about 700 species of bacteria, including those that can cause gum disease (gingivitis), which affects up to 90% of the population at any one time. If a person has gum tissues that are red, instead of pink, and are prone to bleeding when flossing, odds are they are at high risk of having gingivitis. The good news is for most people, proper dental hygiene can reverse gingivitis. The research around a link between chronic systemic disease and gingivitis is less clear.  

Dental health experts at Delta Dental of Colorado note that the more serious issue is periodontitis, or periodontal disease. This condition affects up to half of all adults. A recent analysis led by National Institute on Aging (NIA) scientists suggests that the bacteria associated with periodontal disease that causes the chronic inflammation are also associated with the development of Alzheimer’s disease and related dementias, especially vascular dementia. The results were reported in the Journal of Alzheimer’s Disease.

Periodontitis can be characterized by bad biofilm, bad bacteria, attachment loss (when the ligament that connects the soft tissue to the bone that supports the teeth starts to degrade), increased pocket depths (think of that little probe that dentists poke you with and call out measurements), inflammation and bone loss. Bacteria and the inflammation cascade that they cause can travel through the bloodstream to the brain. Previous lab studies have suggested that this is one mechanism influencing the cascade of events that leads to dementia, but large studies with people have not been conducted to confirm this relationship.

The NIA Intramural Research Program team used nationally representative, publicly available data from the National Health and Nutrition Examination Survey (NHANES), a large population study performed by the CDC’s National Center for Health Statistics. The team used restricted data linkages with Medicare records and the National Death Index to examine whether the bacteria associated with periodontal infections were linked to dementia diagnoses and deaths. The team compared different age groups at baseline, with up to 26 years of follow-up, for more than 6,000 participants.

The analysis revealed that older adults with signs of periodontitis at baseline were more likely to develop Alzheimer’s during the study period. A long-term follow-up for this study is needed because the findings suggest that chronic oral inflammation preceded the diagnosis of dementia. It is important to keep in mind that population studies can show association but not causality.

Taking the initiative on oral health
Gum disease (gingivitis) has been linked to a higher risk of heart disease, but a recent study (published Jan. 23, 2019, in Science Advances) says that the bacteria that cause gingivitis also may be connected to Alzheimer's disease. 

Scientists have found that this species of bacteria, called Porphyromonas gingivalis, can move from the mouth to the brain. Once in the brain, the bacteria release enzymes called gingipains that can destroy nerve cells, which in turn can lead to memory loss and eventually Alzheimer's.

In this study, researchers looked for evidence of this process in human brains. They examined the brains of 53 deceased people who had been diagnosed with Alzheimer's and found high levels of gingipain in almost all of them. They also noted that the amount of gingipain tended to rise over time, which suggests there may be a tipping point when dementia symptoms first begin.

The next step is to see if a drug can block these harmful bacterial enzymes and possibly stop Alzheimer's from developing or at least slow its progression. Until then, all patients can do their part in fighting gingivitis with strong oral health habits that include daily flossing, brushing twice a day and staying current on regular dental check-ups.

Prioritizing oral health after a dementia diagnosis
In the early stages of Alzheimer's, dental care focuses on prevention. Getting check-ups and cleaning and flossing teeth regularly can prevent the need for extensive procedures later on, when the person with dementia may be less able to tolerate them. 

During the middle and late stages of Alzheimer's, oral health may become more challenging. The person may forget what to do with toothpaste or how to rinse, and may be resistant to assistance from others. Following are some brushing tips:
  • Provide short, simple instructions. Explain dental care by breaking directions into steps. "Brush your teeth" by itself may be too vague. Instead, walk the person through the process. Say: "Hold your toothbrush." "Put paste on the brush." Then, "brush your teeth."
  • Use a "watch me" technique. Hold a toothbrush and show the person how to brush his or her teeth. Or, put your hand over the person's hand, gently guiding the brush. If the person seems agitated or uncooperative, postpone brushing until later in the day.
  • Keep the teeth and mouth clean. Very gently brush the person’s teeth, gums, tongue and roof of the mouth at least twice a day, with the last brushing after the evening meal and any nighttime liquid medication. Allow plenty of time and find a comfortable position if you must do the brushing yourself. Gently place the toothbrush in the person's mouth at a 45-degree angle so you massage gum tissue as you clean the teeth.
If the person wears dentures, rinse them with plain water after meals and brush them daily to remove food particles. Each night, remove them and soak in a water or an approved cleanser. Then, use a soft toothbrush or moistened gauze pad to clean the gums, tongue and other soft mouth tissues.
  • Use a brush with soft bristles, but experiment with different styles, such as a long-handled or angled brush if you find it easier to use than a standard toothbrush. Be aware that electric dental appliances may confuse a person with Alzheimer's, although a sonic or rotary toothbrush can be helpful of the person is willing.
  • Floss regularly. Most dentists recommend flossing daily. If using floss is distressing to the person with Alzheimer's, try using a "proxabrush" to clean between teeth instead. When caring for a loved one in advanced stages, take care to monitor use of proxabrushes and toothpicks. Dentists also recommend “Stim-U-Dents” (triangular-shaped toothpicks).
  • Sometimes high-dose prescription fluoride toothpastes may be helpful too.  
  • For those who can rinse with full strength Listerine for 30-60 seconds, this can help keep gingivitis risk lower, but watch to ensure they don’t swallow it. Some medications may dry the mouth out and Listerine-type rinses may exacerbate that issue.  
  • Be aware of potential mouth pain. Investigate any signs of mouth discomfort during mealtime. Refusing to eat or strained facial expressions while eating may indicate mouth pain or dentures that don't fit properly.
For more tips, join ALZConnected, an online support community where caregivers share their ideas, or call the Alzheimer’s Association free 24/7 Helpline at 800-272-3900.

Alzheimer's Association

The Alzheimer's Association leads the way to end Alzheimer's and all other dementia — by accelerating global research, driving risk reduction and early detection, and maximizing quality care and support. Our vision is a world without Alzheimer's and all other dementia.™ For more information, visit or call the 24/7 Helpline at 800.272.3900.

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