Tooth loss is a risk factor for cognitive impairment and dementia, and the risk of cognitive decline grows with each tooth lost, according to the New York University (NYU) Rory Meyers College of Nursing. However, the researchers noted, this risk was not significant among older adults with dentures, suggesting that timely treatment with dentures may protect against cognitive decline.
Approximately one in six adults age 65 or older have lost all of their teeth, according to the Centers for Disease Control and Prevention. Also, prior studies have shown a connection between tooth loss and diminished cognitive function, with researchers offering a range of possible explanations for the link.
Missing teeth can lead to difficulty chewing, which may contribute to nutritional deficiencies or promote changes in the brain, NYU said. A growing body of research also points to a connection between gum disease, a leading cause of tooth loss, and cognitive decline, NYU added. Tooth loss may reflect lifelong socioeconomic disadvantages that are risk factors for cognitive decline as well, NYU continued.
“Given the staggering number of people diagnosed with Alzheimer’s disease and dementia each year, and the opportunity to improve oral health across the lifespan, it’s important to gain a deeper understanding of the connection between poor oral health and cognitive decline,” said senior author Bei Wu, PhD, Dean’s Professor in Global Health at the NYU Rory Meyers College of Nursing and codirector of the NYU Aging Incubator.
The researchers conducted a meta-analysis using longitudinal studies of tooth loss and cognitive impairment. The 14 studies included in the analysis involved 34,074 adults and 4,689 cases of people with diminished cognitive function.
According to the study, adults with more tooth loss had a 1.48 times higher risk of developing cognitive impairment and 1.28 times higher risk of being diagnosed with dementia, even after controlling for other factors.
However, adults missing teeth were more likely to have cognitive impairment if they did not have dentures (23.8%) compare to those with dentures (16.9%). Further analysis revealed that the association between tooth loss and cognitive impairment was not significant when participants had dentures.
The researchers also analyzed a subset of eight studies to determine if there was a dose-response association between tooth loss and cognitive impairment, or if a greater number of missing teeth was linked to a higher risk of cognitive decline. Each missing tooth was associated with a 1.4% increased risk of cognitive impairment and 1.1% increased risk of being diagnosed with dementia.
“This dose-response relationship between the number of missing teeth and risk of diminished cognitive function substantially strengthens the evidence linking tooth loss to cognitive impairment and provides some evidence that tooth loss may actually predict cognitive decline,” said Xiang Qi, a doctoral candidate at NYU Meyers.
“Our findings underscore the importance of maintaining good oral health and its role in helping to preserve cognitive function,” said Wu.
The study was published by JAMDA: The Journal of Post-Acute and Long-Term Care Medicine.