The Association Between Anxiety and Periodontal Disease Among Twins

Objectives: Recently, an association between anxiety and periodontitis has been reported. The aim of this study was to test whether genetic confounding is in part responsible for this finding, by evaluating the relationship between anxiety and periodontal disease in female adult twins.
Methods: This was a cross sectional study using questionnaire data in the TwinsUK registry from 2004 to 2016. Self-reported bleeding gums and tooth mobility were used as the indicators of periodontal disease. The anxiety phenotype was identified by the question “Has a doctor ever told you that you have an anxiety or stress disorder?”
The co-twin control analysis was implemented to identify the odds ratio between anxiety and each periodontal phenotype separately. The genetic confounders in both habits were examined by comparing the odds ratios in all participants with those from monozygotic (MZ) discordant twins only.
Results: Data of women over 20 years old were available for tooth mobility in 4009 individuals (MZ; 2221, dizygotic (DZ); 1788) and for bleeding gums in 4258 individuals (MZ; 2385, DZ; 1873). In the total sample treated as individuals adjusted for age, smoking, obesity and income, anxiety was associated with increased odds of tooth mobility (OR 1.51, CI 1.22-1.88), and bleeding gums (OR 1.38, CI 1.16-1.64). The number of discordant MZ twin individuals for tooth mobility was 408, and that for gum bleeding was 754. Within discordant monozygotic twins, the association was still significant for tooth mobility (OR 1.67, CI 1.02-2.73), and for gum bleeding (OR 1.62, CI 1.06-2.48).
Conclusions: The significant association between anxiety and stress disorders and periodontal phenotypes still held in MZ discordant twins, suggesting that factors shared by MZ twins (genetic / early life environment) do not explain the association between anxiety and periodontal disease among female adults.