Links Between Systemic Inflammation, Periodontal Disease and Alzheimer's Disease
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According to the Alzheimer's Association of America, approximately 6.7 million patients are currently diagnosed with Alzheimer's disease. It is the most common form of dementia, as well as the sixth leading cause of death in the country. The chance of being diagnosed with Alzheimer's disease increases with age, although it is not a "normal" part of aging. That said, one in eight people age 65 and older have Alzheime's, and this rises dramatically to nearly half (45%) of those age 85 and beyond.
Naturally, as the population continues to live longer, the prevalence of Alzheimer's disease will grow -- researchers believe that in 50 years time, approximately 14 million people will be diagnosed with Alzheimer's disease, and the annual incidence of Alzheimer's and other dementias is expected to double by 2050.
It is for these reasons that it is important for you to understand every measure that can be taken to reduce your risk of this deadly disease.
The Inflammatory Response
For many years, there have been obvious links between periodontal disease and other types of systemic diseases, such as heart disease. Many scientists now believe that the common thread between diseases of the body and diseases of the mouth can be traced back to one thing: systemic inflammation. Your body instinctively reacts when called upon to fight off different types of infection, heal injuries, and guard against various irritants. Inflammation is the result of your body's own reaction to these "invaders." You will often see swelling and redness, and feel heat and localized pain in an area that is experiencing inflammation.
While your body induces inflammation to heal what is ailing your body, over long periods of time, chronic inflammation may lead to severe problems and health complications, and it can linger silently in your body until disease develops.
Chronic inflammation of tissues in the central nervous system is thought to be one cause for the development of Alzheimer's disease. Research published in Alzheimer's & Dementia shows that people who have high levels of certain systemic inflammatory markers, such as C-reactive protein and pro-inflammatory cytokines, have a higher risk of developing dementia than those people who have lower levels. There are many potential sources of chronic inflammation, including the chronic inflammation associated with periodontal diseases!
Periodontal disease is extremely common. It is estimated that 75% of adults have a mild form of periodontal disease (gingivitis), while around 40% of all adults have a moderate or severe form known as periodontitis.
Scientists believe that the inflammatory response to bacteria in the mouth may be one of the primary causes of the periodontal-systemic health link. Many of the other diseases associated with periodontal disease are also considered systemic inflammatory disorders. This includes heart disease, rheumatoid arthritis, kidney disease, diabetes, and even certain types of cancer, all of which have an inflammatory connection. Practically speaking, this means that even if you may have a family history that increases your risk of developing Alzheimer's, there are various oral health behaviors -- when started early in life -- that may help to deter the onset of Alzheimer's disease. This is actually true whether you have a family history of the disease or not.
Oral health habits introduced early in life have the most potential to help prevent disease, although middle-aged people can also benefit from healthy oral lifestyle changes.
Dr. Susan Karabin, past president of the American Academy of Periodontology (AAP) and a practicing periodontist in New York City, believes that periodontal disease is a perfect textbook example of an inflammatory disorder. In an interview published by perio.org, Dr. Karabin states:
"While plaque accumulation is still a factor in the development and progression of gum disease, researchers now suspect that the more severe symptoms, namely swollen, bleeding gums; recession around the gum line, and loss of the bone that holds the teeth in place, may be caused by the chronic inflammatory response to the bacterial infection, rather than the bacteria itself."
The Mental Connection
The link between poor oral health and Alzheimer's disease is an intense area of research. The idea that inflammation is the link between the mouth and the body has evolved from being a simple idea to becoming a part of mainstream medical thinking.
Your brain contains phagocytes, especially microglia (brain resident macrophages), which function to protect your nervous system by scavenging for any debris, killing microbial pathogens and regulating immune responses throughout the body. Microglia are activated by different environmental stimuli, including the pro-inflammatory cytokines and bacterial lipopolysaccharides, which initiate the neuro-inflammatory process. Recent research suggests that systemic inflammation is associated with the very signals that pass from the blood to the brain via perivascular macrophages and microglia. The resulting neuro-inflammatory responses include the secretion of many different toxic factors that cause cell injury and death throughout your entire central nervous system.
Over time, this severe inflammation in your brain may destroy high numbers of healthy neurons, causing the clinical signs of Alzheimer's disease or dementia. A recent study demonstrated that serum C-reactive protein and pro-inflammatory cytokine levels increase just before the clinical onset of dementia.
Critical Research Data
Scientists examined periodontal disease as a potential risk factor in the development of dementia in what is known as the Nun study. This was a longitudinal study of aging and the incidence of Alzheimer's disease in 144 participants who were between the ages of 75 and 98 years old. The study consisted of 40 years of dental data, along with 12 years of findings from yearly cognitive assessments and brain autopsies.
This was indeed an unparalleled opportunity to study dental health, dementia and neuropathology. The findings conclusively demonstrated the first true association between a history of oral disease and the development of dementia in a longitudinal population-based environment. The participants with the most tooth loss caused by periodontal disease also had the highest risk of prevalence and actual incidence of dementia. These people had an overall risk for developing Alzheimer's disease or dementia that was increased by an overwhelming 120%!
The results from this study seem to suggest that systemic infection, or anything that causes a systemic inflammatory response, contributes to the outcome or the progression of chronic neurodegenerative disease, including Alzheimer's disease. This data provides a solid link between periodontal disease and neuronal injury.
Additionally, dental researchers at NYU have found long-term evidence that periodontal disease can increase the risk of Alzheimer's disease in healthy people, as well as in those people who are already cognitively impaired. This study offers the most recent evidence that gum inflammation can contribute to brain inflammation, neurodegeneration and Alzheimer's disease.
Dr. Angela Kamer, assistant professor of periodontology & implant dentistry, led the research team at NYU. The team examined 20 years of involved data that supports the belief that a link exists between periodontal disease and Alzheimer's disease. The findings were presented by Dr. Kamer the International Association for Dental Research, in Barcelona, Spain.
"The research suggests that cognitively normal subjects with periodontal inflammation are at an increased risk of lower cognitive function compared to cognitively normal subjects with little or no periodontal inflammation," Dr. Kamer said during the meeting.
In addition, Dr. Kamer's study was conducted in collaboration with Dr. Douglas E. Morse, Associate Professor of Epidemiology & Health Promotion at NYU College of Dentistry, and a team of researchers in Denmark. The research builds upon a study conducted by Dr. Kamer that found that the subjects who were diagnosed with Alzheimer's disease each had a much higher level of antibodies and inflammatory molecules associated with periodontal disease present in their plasma as compared to the levels of healthy people.
Home Care
If you want to maintain optimal oral health and in so doing, reduce your risk of Alzheimer's, here are some of the top steps to consider:
Practicing good oral hygiene can help you keep a healthy smile for life.
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Sources:
The Impact of Systemic Inflammation on Alzheimer's Disease Pathology
Neurology
The blood-brain barrier in systemic inflammation
Medical News Today
