Previous research has indicated interesting parallels between periodontal disease and Alzheimer’s. Are they connected? We asked the experts.
You may have read news coverage of research that seemed to indicate a link between periodontal (gum) disease and Alzheimer’s disease. But are they truly linked? What do we know about the link, if there is one?
The answer is yes—but the nature of the link is not simple by any means.
Research has pointed to intriguing connections. “In 2007 an observational study in the Journal of the American Dental Association on 118 nuns concluded those with fewest teeth had the highest risk of prevalence and incidence of dementia,” notes Dr. Leena Palomo, DDS, MSD, Diplomate of the American Board of Periodontology and Associate Professor & Director of DMD Periodontics at the School of Dental Medicine, Case Western Reserve University. “Robust research shows inflammation plays a big role in many diseases of aging.” Among those diseases, Dr. Palomo says, is Alzheimer’s disease.
Gustavo C. Román, MD, Professor of Neurology, Weill Cornell Medical College and Nantz National Alzheimer Center at Houston Methodist Hospital, concurs. “Periodontal disease is an independent risk factor for vascular disease, including both cerebrovascular disease (stroke) and coronary disease (heart attack),” he says. “Vascular disease in the brain is currently the most important preventable factor for Alzheimer’s disease.”
Knowing that there is a link, the question becomes, how are periodontal disease and Alzheimer’s linked? One of the keys to understanding the link is the presence of inflammation. “The bacteria responsible for periodontal disease do not remain immobile in the gum tissues. Using nucleic acid detection techniques, it has been demonstrated that these bacteria are present in the plaques of atheroma [the fatty material that builds in and on the insides of artery walls] in the carotid and coronary arteries,” says Dr. Román. “In addition, inflammation induced by the bacteria is part of the mechanisms of development of narrowing and occlusion of the blood vessels in stroke and heart attack. Moreover, the bacteria-induced inflammation reaches the brain in patients with Alzheimer’s, and amyloid precursor protein has been found in the gum tissue of people with gingivitis.”
Dr. Palomo points to the genetic factors involved, as well. “Genetic differences in the inflammatory response are said to influence the course of these diseases. The IL-1 genetic variations are associated with variation in both the inflammatory response and the clinical appearance of a host of diseases, of which Alzheimer’s disease and periodontitis are two,” she says. “Risk factors for Alzheimer’s disease overlap with vascular disease risk factors. Many of these factors share associations with evidence of systemic inflammation such as that identified in periodontitis.”
A Diabetes Link?
Another point to consider is the complication of diabetes, a rapidly growing health problem among Americans. The American Diabetes Association estimates that approximately one-third of Americans have diabetes or prediabetes, a condition of elevated blood sugar that hasn’t yet reached the point of a diabetes diagnosis. The majority of these cases are diagnosed as type 2 diabetes, which was once referred to as “adult onset diabetes.” That term isn’t as frequently used now because an increasing number of children and adolescents are being diagnosed with type 2.
In type 2 diabetes, the body is unable to produce enough insulin to “unlock” cells so they can use blood sugar for the energy they need, or the cells are resistant to the insulin the body produces. In some cases, both are true. Alzheimer’s has sometimes been referred to as “type 3 diabetes” or “diabetes of the brain” by some in the medical community because of the apparent link between insulin resistance and the health of brain cells.
The exact link between diabetes and Alzheimer’s is still unknown, but the evidence of a strong link continues to stir interest among researchers. Indeed, the presence of diabetes significantly increases the risk of getting Alzheimer’s disease. The connection to periodontal disease? “Gum disease is a risk for diabetes, and diabetes is a risk for gum disease,” says Dr. Palomo.
More Research, Better Oral Care
The need for further research is apparent to both doctors. “I would expect robust future investigation— likely multidisciplinary involving oral health conditions, medicine, nursing, pharmacy and others to elucidate plausible mechanisms linking these conditions,” says Dr. Palomo. “I would hope for clinical treatment studies and translational research to link bench-top findings to bedside and chair-side clinical applications.”
In the meantime, we can all take steps to protect our health overall, beginning with good oral care. “Elevated antibodies to periodontal disease bacteria are present years before cognitive impairment develops and suggests that periodontal disease could potentially contribute to the risk of Alzheimer’s onset/progression,” says Dr. Román. He believes that oral health is a critical factor in preventing stroke, heart attack, and Alzheimer’s disease.
In that vein, Dr. Román sees an immediate need in the way healthcare policies are formulated. “The main problem is that oral health coverage by insurance is seldom sufficient,” he says.
Dr. Román underscores the urgency of lifelong good oral care for everyone. “[We must] identify and treat early in life hypertension, elevated cholesterol, diabetes, smoking, sleep apnea, overweight and sedentary lifestyle, elevated homocysteine from low vitamin B12, and periodontal disease,” he says.
“It is said that the mouth is the mirror of overall health,” says Dr. Palomo. “We can’t pick our parents and change our genetics. We also can’t change certain things in our environment. But preventing and treating gum disease is a relatively simple way to modify our risks for several diseases of aging associated with inflammation, of which Alzheimer’s is one.” ■