Editorial

 

Tooth loss and dementia: Is there an association between them?

 

Cognitive impairment is a feature frequently found in elderly patients. This problem is characterized by dementia and might originate from vascular disease, as ischemic stroke, or from Alzheimer's disease ¹⁰. Recently, some studies have sought to relate the tooth loss with the impairment of cognition ^1,10.

Three main hypotheses were formulated to explain this. The first hypothesis claims that tooth loss reduces masticatory function, which in turn negatively affects the stimuli to brain activity and may lead to dementia ². The second, associates the systemic inflammation caused by periodontal disease with the brain function and dementia ¹. Other possible pathway would be the influence of tooth loss on the nutrition status, once the absence of some nutrients intake may lead to cognition impairment ^6,7. However, it is not yet certain that tooth loss can cause dementia, and the real cause of cognitive impairment is still uncertain ¹¹.

Some recent clinical studies showed a direct association between tooth loss and the higher risk of develop dementia, including Alzheimer's disease and ischemic stroke ^10,12. However, there are other authors stating that this association is still inconclusive ⁹. The same contradiction can be seen in experimental studies, with some authors linking oral status with dementia ³ and others stating that tooth loss has not a causal effect on cognitive impairment ⁴.

A certainty is that cognitive impairment affects the overall health of the patient, including oral health deterioration ⁵. Once the population, in general, is becoming older, this issue shows the importance of oral health management on the cognitive status of elderly patients. Thus, the role of the general dentist is to avoid tooth loss and promote oral health, in seeking to improve the quality of life of elderly patient.

 

References

1. Harding A, Robinson S, Crean S, Singhrao SK. Can better management of periodontal disease delay the onset and progression of Alzheimer's disease? J Alzheimers Dis. 2017;58(2):337-48.

2. Hirano Y, Obata T, Kashikura K, Nonaka H, Tachibana A, Ikehira H et al. Effects of chewing in working memory processing. Neurosci Lett. 2008;436:189-92.

3. Kushida S, Kimoto K, Hori N, Toyoda M, Karasawa N, Yamamoto T et al. Soft-diet feeding decreases dopamine release and impairs aversion learning in Alzheimer model rats. Neurosci Lett. 2008 Jul 11;439(2):208-11.

4. Oue H, Miyamoto Y, Koretake K, Okada S, Doi K, Jung CG et al. Tooth loss might not alter molecular pathogenesis in an aged transgenic Alzheimer's disease model mouse. Gerodontology. 2016 Sep;33(3):308-14.

5. Ribeiro GR, Costa JL, Ambrosano GM, Garcia RC. Oral health of the elderly with Alzheimer's disease. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012 Sep;114(3):338-43.

6. Sadamori S, Hayashi S, Fujihara I, Abekura H, Hamada T, Akagawa Y. Nutritional status and oral status of the elderly with dementia: a 2-year study. Gerodontology. 2012 Jun;29(2):e756-60.

7. Sheiham A, Steele JG, Marcenes W, Lowe C, Finch S, Bates CJ et al. The relationship among dental status, nutrient intake, and nutritional status in older people. J Dent Res. 2001 Feb;80(2):408-13.

8. Stein PS, Desrosiers M, Donegan SJ, Yepes JF, Kryscio RJ. Tooth loss, dementia and neuropathology in the Nun study. J Am Dent Assoc. 2007 Oct;138(10):1314-22.

9. Stewart R, Stenman U, Hakeberg M, Hägglin C, Gustafson D, Skoog I. Associations between oral health and risk of dementia in a 37-year follow-up study: the prospective population study of women in Gothenburg. J Am Geriatr Soc. 2015 Jan;63(1):100-5.

10. Takeuchi K, Ohara T, Furuta M, Takeshita T, Shibata Y, Hata J et al. Tooth loss and risk of dementia in the community: the Hisayama study. J Am Geriatr Soc. 2017 May;65(5):e95-e100.

11. Tonsekar PP, Jiang SS, Yue G. Periodontal disease, tooth loss and dementia: Is there a link? A systematic review. Gerodontology. 2017 Jun;34(2):151-63.

12. Tsakos G, Watt RG, Rouxel PL, de Oliveira C, Demakakos P. Tooth loss associated with physical and cognitive decline in older adults. J Am Geriatr Soc. 2015 Jan;63(1):91-9.

 

Carlos Rezende
MPhD in Oral Rehabilitation (FOB/USP)