A certain number of teeth in the mouth called the main sign of dementia

A new study shows that scientists were missing a major risk factor for dementia that lurks right under our noses. According to the study, poor oral hygiene may be a much larger cause of dementia than previously thought. Although a number of studies have linked oral hygiene to dementia, it has not been included in 14 modifiable risk factors.

The researchers analyzed data from 47,293 adults 65 years and older from the Japan Gerontological Evaluation Study, following them for about nine years, from 2013 to 2022. During this period, 8,247 respondents developed dementia. The researchers wanted to find out how much poor oral health, measured by the number of teeth, is associated with dementia compared to established risk factors for commission, with the exception of LDL cholesterol (low-density lipoproteins) and air pollution, which could not be assessed.

“We used the number of remaining teeth as an indicator of poor oral health, as tooth loss usually reflects an endpoint in the history of oral diseases throughout life, such as advanced caries and severe periodontal disease,” explains researcher Maho Iwata.

Fewer teeth were associated with a significantly higher incidence of dementia. From 1.63 for people with 20 or more teeth, to 2.31 for 10-19 teeth, 2.97 for 1-9 and 4.34 for people without teeth. After adjusting for gender, age and income, the risk of dementia was 14 percent higher in people with 10-19 teeth.

Using proportions related to the population, the researchers calculated that tooth loss could account for 7.2 percent of dementia cases. The rate was the third highest, second only to depression and social isolation. When filtered for men alone, tooth loss was the single largest risk factor (12 percent) and the fourth largest risk factor for women. This suggests that tooth loss may be responsible for a larger proportion of dementia cases than inactivity, smoking, and low education.

“To our knowledge, this is the first study to quantify and compare the effects of poor oral health and a large number of other dementia risk factors within a single population.” In men, the rate associated with tooth loss was significant and comparable to major modifiable risk factors such as depression and social isolation.

Scientists recognize limitations. However, there are several possible ways of communication. So, fewer teeth can affect the ability to chew food, which leads to poor nutrition associated with cognitive decline. In addition, tooth loss is associated with oral inflammation, which can lead to systemic inflammation.

The authors explain that the results show serious public health implications and recommend incorporating oral hygiene into dementia prevention strategies.

“Dental loss contributes significantly to dementia incidence comparable to the main modifiable risk factors identified,” the researchers conclude. These results suggest a need to reassess oral health as a key risk factor for dementia.