Tooth loss is associated with subsequent brain white matter degradation up to over a decade

OBJECTIVES: Tooth loss is linked to cognitive impairment and cognitive decline in older adults. Whether tooth loss is associated with loss of brain structure is unknown, particularly with respect to white matter integrity, which is vulnerable to inflammation and vascular pathology. METHODS: We examined the associations between clinically assessed tooth loss and subsequent changes in brain atrophy and microstructural integrity over an average follow-up of 4.8 (SD=3.6) years in 375 Baltimore Longitudinal Study of Aging participants (mean age=65.5 years, 53.6% women, average tooth loss: 3) using linear mixed-effects models, adjusted for age, sex, race, and scanner site. Brain volumes and microstructural integrity were assessed via 3T MRI volumetric scans and DTI, respectively, over up to 12 years between 2008 and 2020. RESULTS: More tooth loss was cross-sectionally associated with a larger 4th ventricle, smaller brain volumes in temporal areas, greater deep white matter signal abnormalities, and lower white matter integrity in the corpus callosum. Longitudinally, each tooth loss was associated with a faster increase in diffusivity in the corpus callosum and corona radiata (all p < 0.01), suggesting loss of microstructural integrity. Tooth loss was also associated with higher white blood cell counts, neutrophil counts, and erythrocyte sedimentation rate, greater increases in white blood cell and neutrophil counts and greater decrease in albumin over time (all p < 0.05). Adjustment for these markers did not alter the associations with neuroimaging outcomes. CONCLUSION: Tooth loss may indicate subsequent white matter degradation, independent of inflammation markers. Future studies are warranted to elucidate the biological mechanisms driving these associations. CLINICAL SIGNIFICANCE: Within aging, tooth loss may indicate an unfavorable brain structure which overlaps with the Alzheimer's disease signature and indicate long-term degradation of white matter integrity and increased inflammation.