Can Brushing Your Teeth Impact Dementia? The relationship between oral health and Alzheimer’s

By Gabriella Mouris

Every three seconds, someone in the world develops dementia. While most research has focused on the molecular basis of dementia in the brain, new evidence suggests that risk factors might also originate elsewhere in the body. Oral health, while often not paid as much attention to, is increasingly recognized as one such factor. Mounting research indicates that oral disease may increase the risk of developing Alzheimer’s disease by sustaining low-grade inflammation and circulating microbial by-products throughout the body (Hasturk et al., 2021; Hajishengallis et al., 2022; Ryder, 2020).

Periodontitis is one of the most common chronic inflammatory conditions, affecting roughly one in ten adults worldwide (Hasturk et al., 2021). Beyond damaging gum tissue, it provokes systemic immune activation that alters specific blood and stem cells, producing excess inflammatory cells (Hajishengallis et al., 2022). This process, known as trained innate immunity, can sustain inflammatory signaling even after the initial infection subsides. Persistent inflammation is a known contributor to vascular injury and neuronal vulnerability, linking oral health to brain health.

​Alzheimer’s and periodontitis can be further linked on a molecular basis, focusing on the connection to Porphyromonas gingivalis, a key bacterial species in chronic gum disease. Evidence suggests that enzymes correlated to P. gingivalis, known as gingipains, may travel through the bloodstream to the brain (Ryder, 2020). Recent studies have identified molecular markers of the gum-disease bacterium in brain tissue from individuals who had Alzheimer’s disease, as well as in the cerebrospinal fluid and saliva of people with mild-to-moderate cognitive impairment clinically diagnosed as probable Alzheimer’s (Poole et al., 2013; Dominy et al., 2019).

Recent population-based research has begun to translate these findings into human evidence. A 2024 Columbia University Medical Center study of older adults found that higher colonization of Tannerella forsythia correlated with smaller entorhinal cortex volumes, which is an early imaging marker of Alzheimer’s disease (Rubinstein et al., 2024). Other bacterial species showed distinct associations with white-matter integrity, implying that diverse microbial communities may differentially affect brain aging (Rubinstein et al., 2024). While these studies cannot establish causality, they reveal measurable neurological correlates of oral bacterial exposure.

Social determinants amplify this biological risk. Periodontitis disproportionately affects low-income, Black, and Hispanic adults, who also experience higher rates of dementia (Noble et al., 2019; Kamer et al., 2020; Papapanou et al., 2023). Structural barriers including limited insurance coverage, discrimination, and gaps in health literacy, reduce access to preventive dental care and delay treatment. These inequities mean that inflammation-related cognitive decline may correlate to other chronic diseases. As highlighted in community health research at Columbia and Barnard, addressing oral health disparities is inseparable from advancing health equity (Laidlaw et al., 2023).

Public health initiatives linking oral care and systemic health are beginning to show results. In nursing homes, staff training programs led by dental hygienists have improved residents’ oral hygiene and lowered infection rates (Poole et al., 2013). Community trials that add oral health checks to primary care visits have increased early detection of inflammation and dental service use among older adults (Dominy et al., 2019). Broader policy frameworks now include oral care in “healthy aging” strategies and subsidize preventive supplies for seniors (Rubinstein et al., 2024). These approaches show that small investments in oral care can support overall and cognitive health.

Brushing your teeth may seem like an act of routine hygiene, but it could also be an act of neuroprotection. As we learn more about the oral-systemic connection, the toothbrush may join the ranks of the most powerful tools for brain health. So remember to brush your teeth, or you may forget to later…

References 

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