Take care of your teeth, take care of your mind!

This statement rings a bell and brings us back to the popular phrase that we often hear: “A healthy mind, a healthy body!”.

The reality is that recent research has focused on the possible relationship between periodontal disease and Alzheimer’s disease.  As the possibility of an influence between oral health and dementia begins to be widespread, it tends to be easily extrapolated.

Let’s go into the facts:

Periodontal disease is classified as a chronic inflammatory oral disease, characterised by the presence and development of an oral microflora in which pathological microorganisms (i.e. those capable of developing the disease) prevail. Although it is considered multifactorial, the presence of bacterial plaque is necessary for the progression of the disease in susceptible individuals. It is the 6th most prevalent disease worldwide (according to the WHO) and represents the second leading cause of tooth loss worldwide, with an estimated 50% of the general population experiencing it. This percentage is expected to rise over the years due to the increase in average life expectancy and the overall ageing of the population. Although this condition has no statistically significant influence on mortality rates, it can have a considerable effect on morbidity.

Alzheimer’s disease is classified as a neurodegenerative condition, a group of pathologies characterised by the slow and progressive loss of one or more functions of the nervous system. Like periodontal disease, it is a condition whose prevalence/incidence increases with age. In addition, many environmental, epidemiological and risk factors are common to both conditions.

That being said, the true impact that all these factors have on the relation between periodontal disease and Alzheimer’s disease can act as misleading factors, camouflaging the veracity of the facts.

Most of the studies published in this field present results stating that patients with diagnosed Alzheimer’s disease have more tooth loss and edentulism compared to the control group. However, this association must be interpreted with caution, as there are different biological mechanisms that may be responsible for tooth loss.

Below, we’ve highlighted some of the key ideas that could make this relation credible:

• Periodontal disease, being an inflammatory condition, is characterised by a local and possibly systemic increase in inflammatory factors that can have an impact on the central nervous system. In addition, bacteria, that are a mandatory presence in periodontal disease, can migrate to the central nervous system, affecting its normal functioning.
• Masticatory function is ensured by the presence of teeth or their replacement when they are lost. It is directly associated with a good quality of life, as well as proper eating habits based on a healthy and balanced diet. The loss of teeth, and therefore of masticatory function, can reduce the loss of essential nutrients for the central nervous system.
• There are common genetic predisposing factors for periodontal disease and Alzheimer’s disease.
• The presence of teeth in the oral cavity contributes to procioception (a “force management” mechanism associated with the central nervous system).
• Alzheimer’s disease, associated with loss of congenital function, compromises the correct oral hygiene of patients who experience it. This condition increases the risk of developing oral health problems, particularly periodontal disease, which culminates in tooth loss.

These key ideas suggest that periodontal disease may be an indirect risk factor for the progression, exacerbation and form of manifestation of Alzheimer’s disease. It is too early to assume the existence of a correlation. However, the results of the literature suggest the existence of a risk association between the two pathologies. This association is bivalent.

This relation makes dentists aware of the importance of preventing oral diseases that could have an impact on patients’ general health. Not forgetting that the oral cavity has a privileged position in the early diagnosis of some pathologies.

You can also see Dr Hugo Madeira’s opinion on this subject:

References:

Singhrao SK, Harding A, Simmons T, Robinson S, Kesavalu L, Crean S. Oral inflammation, tooth loss, risk factors, and association with progression of Alzheimer’s disease. J Alzheimers Dis. 2014;42(3):723-37. doi: 10.3233/JAD-140387. PMID: 24946875.

Dioguardi M, Gioia GD, Caloro GA, Capocasale G, Zhurakivska K, Troiano G, Russo LL, Muzio LL. The Association between Tooth Loss and Alzheimer’s Disease: a Systematic Review with Meta-Analysis of Case Control Studies. Dent J (Basel). 2019 May 1;7(2):49. doi: 10.3390/dj7020049. PMID: 31052367; PMCID: PMC6630622.

Taslima F, Jung CG, Zhou C, Abdelhamid M, Abdullah M, Goto T, Saito T, Saido TC, Michikawa M. Tooth Loss Induces Memory Impairment and Gliosis in App Knock-In Mouse Models of Alzheimer’s Disease. J Alzheimers Dis. 2021;80(4):1687-1704. doi: 10.3233/JAD-201055. PMID: 33720883.