A possible link between gum disease and Alzheimer's disease was explored by a group of British researchers (from University of Southampton and King's College London) in a group of 60 people diagnosed with mild-to-moderate dementia due to Alzheimer's disease. These researchers assessed the patients' cognitive abilities and also took blood samples to measure inflammatory markers in the blood. In addition, each patient was assessed by a dental hygienist who was unaware (blinded to the results) of the patient's cognitive abilities. This group of 60 people was divided into two groups; 22 had considerable gum disease while 37 had far less gum disease. Fifty-two of the 59 patients were followed up at 6 months, and all tests (cognitive, blood samples, and gum disease assessment by the dental hygienist) were repeated.
Unfortunately for patients with gum disease (periodontitis or periodontal disease), over the 6-month time span between the initial and final evaluations of cognitive ability, researchers were “surprised” by the rapid decline in cognitive ability in patients with periodontal disease. One researcher, Dr. Mark Ide, considered the measured six-fold decrease in cognitive ability in patients with considerable gum disease as “scary” and suggested that patients with more severe gum disease were giving themselves “mini-injections” of bacteria as they chew their food, thus increasing the presence of bacteria in the bloodstream and triggering inflammatory reactions. Inflammatory reactions have previously been linked to greater rates of cognitive decline in people with Alzheimer's disease.
The senior author, Professor Clive Holmes, suggests that the results are “very interesting” but suggested that the study needs to be carried out again using a larger number of patients. In addition, the cause and/or effect of gum disease on Alzheimer's disease progression has not been proven, according to other scientists. For example, Dr. Doug Brown, Director of research and development at the Alzheimer's Society, suggests that because the study utilized a small number of patients (according to Dr. Ide in the paper's discussion, the patient number was too small to rule out that the relationship is due to chance) so the study needs to be replicated. For example, the study design did not clearly show if gum disease is triggering more rapid cognitive declines or if patients with rapidly declining cognitive functions imply further neglect of personal hygiene that results in more severe gum disease. Nonetheless, another study could be designed to determine cause-and-effect by providing treatment of gum disease in patients with Alzheimer's disease to determine if disease progression can be markedly slowed down by preventing and/or reducing gum disease.
In the UK, approximately 80% of adults 55 and older have gum disease; if the results of this early research are proved to be true, it may be possible to slow or prevent some cases of Alzheimer's by aggressive treatment of gum disease. Alternatively, if gum disease is not proved to cause or to accelerate Alzheimer's disease, advancing gum disease may be found to be a useful marker for clinicians to suspect Alzheimer's disease or its more rapid advancement.
As a physician, I consider this to be an interesting and potentially important finding and it has made me much more aware of potential primary and/or secondary problems of gum disease. I'm anxious to see what findings will be made in future studies on the possible link between gum disease and Alzheimer's disease.
Ide, M., et al, “Periodontitis and cognitive decline in Alzheimer’s disease.” PLoS One 11.3 (2016): pp e0151081.