Cognitive diseases like dementia and Alzheimer’s rob individuals of more than just their memories; they take away their independence, their communication, and their identity. While a cure for these diseases continues to perplex scientists, a recent development may reveal a key contributor to the development of these devastating diseases. Through maintaining hygiene practices and preventing diseases, oral health might be the gateway to a brain armored against dementia. 

A 2023 study by the National Health Insurance Service, an organization providing medical services to 97% of Koreans, revealed interesting trends between oral health and cognitive diseases. Periodontal diseases (gum diseases such as gingivitis, for example) and cavities were associated with an increased risk of all-cause dementia and Alzheimer’s Disease, while strong dental hygiene habits, such as brushing at least twice a day, were associated with lower risks of all-cause dementia, Alzheimer’s, and vascular Dementia. These associations don’t necessarily prove causation between oral health and cognitive decline. Because much of the study’s data on oral hygiene was self-reported (and likely not completely accurate), it is necessary to first understand the connections between the teeth and the brain. 

One potential explanation for this connection may be found in cytokines. Cytokines are proteins made by certain types of white blood cells, primarily lymphocytes and macrophages, that aid in the body's immune defense response. While cytokines are intended to protect the body, pro-inflammatory cytokines contribute to neuroinflammation and can lead to conditions such as Alzheimer’s Disease. Gum diseases often result in the release of cytokines to manage damaged gums. Cytokines may prove to be the link between oral health and neurodegeneration. 

Poor oral health also has more obvious impacts on health; it directly impacts one’s ability to chew. The process of chewing itself may also influence cognitive health, as absurd as it may sound. According to a report published in the Journal of Dental Research, mastication (chewing) has an impact on the development of the central nervous system. In this study, mice were randomly assigned to soft and hard diets before undergoing cognitive exams. The mice were tested on their ability to enter a dark compartment after undergoing an electrical shock; the soft diet mice took longer to complete their task, indicating lower cognitive health. This study supported the idea that soft foods don’t provide enough chewing stimulation to support the brain’s hippocampus, resulting in the mice being unable to remember locations and navigate environments. People whose oral diseases make it harder to chew and receive that same stimulation may also be at risk of cognitive decline, highlighting the value of oral health in preventing brain diseases. 

There are many confounding factors that blur the directional relationship between oral and cognitive health. A 2023 study of data from the National Health and Nutrition Examination Survey reveals that this relationship might in fact be bidirectional. Just like missing teeth might affect hippocampus functions, poor cognitive health may lead to people becoming less attentive about booking their regular checkups or brushing their teeth at night. Common symptoms of Alzheimer's, such as mood swings and memory loss, likely also contribute to cavities, gum disease, and other indicators of poor oral hygiene. 

Despite the remarkable amount of information these studies have revealed about cognitive diseases, a cure-all treatment continues to remain elusive. The role of gums and teeth is often overlooked as an influential factor in one’s health. Just like monitoring blood pressure or cholesterol is considered standard practice in preventative care, so should maintaining overall oral health through at-home hygiene routines and regular dentist appointments.