Tooth Loss Ranked Third Among 13 Dementia Risk Factors in 9-Year Japanese Study

Edited by Hygienetown staff

Tooth loss accounted for a larger share of dementia cases than most established modifiable risk factors in a nine-year study of more than 47,000 older adults in Japan, ranking third among 13 risk factors overall and first among men, according to research published online Nov. 2 in the Journal of the American Medical Directors Association.

The prospective cohort study followed functionally independent adults age 65 and older in 22 Japanese municipalities who were free of dementia at baseline, from 2013 to 2022. Researchers compared tooth loss with the 12 modifiable risk factors identified by the 2024 Lancet Commission on Dementia Prevention, Intervention, and Care, using models adjusted for sex, age, and income to calculate each factor’s population attributable fraction.

The analysis included 47,293 participants, 46.7% of them men, with a mean age of 73.5 years. Over a median follow-up of 9.0 years, 17.4% developed dementia.

Compared with participants who had 20 or more teeth, dementia risk was higher among those with 10–19 teeth (hazard ratio, 1.14; 95% CI, 1.08–1.21), 1–9 teeth (HR, 1.12; 95% CI, 1.05–1.19), and no teeth (HR, 1.27; 95% CI, 1.18–1.36).

The population attributable fraction for tooth loss was 7.2%, behind depressive symptoms (10.5%) and social isolation (9.4%). Among men, tooth loss ranked first, at 12.0%.

Maho Iwata, Taro Kusama, Ken Osaka, and Kenji Takeuchi of Tohoku University conducted the study with Jun Aida of the Institute of Science Tokyo, Tatsuo Yamamoto of Kanagawa Dental University, and Kokoro Shirai of Osaka University. The authors reported no conflicts of interest.

The authors concluded that tooth loss accounted for a substantial proportion of dementia cases, comparable to major risk factors, and that the findings support including oral health in dementia prevention strategies. The observational design cannot establish that tooth loss causes dementia.

Sources:
Journal of the American Medical Directors Association, “Comparative Population Impact of Oral Health and Established Modifiable Risk Factors for Dementia: A 9-Year Population-Based Cohort Study,” published online Nov. 2, 2026: doi.org/10.1016/j.jamda.2026.106536
National Library of Medicine, PubMed, PMID 42971073: pubmed.ncbi.nlm.nih.gov/42971073