Tooth Loss and Dementia: A Critical Examination

Abstract

Dementia is a major contributor to dependence and disability in older people, with aging societies characterized by growing numbers of people living with the condition. Dementia rates are highest in those with low education early in life, midlife hypertension, midlife hearing loss, depression, obesity, loneliness, a sedentary lifestyle, or sustained exposure to smoking or diabetes. Tooth loss is a putative risk factor for dementia which has received increasing research attention, but systematic review findings are mixed. Three main mechanisms have been proposed, involving 1) tooth loss leading to compromised nutrition and then leading to poorer central nervous system (CNS) function; 2) tooth loss resulting in fewer interocclusal contacts and so less somatosensory feedback to the CNS, leading to impaired cognition; and (3) chronic periodontitis resulting in tooth loss, but not before the inflammation has affected the CNS, impairing cognition. None of these is supported by compelling empirical evidence. Here, we use the life course approach to propose a plausible, empirically supported explanation for the associations between missing teeth and poorer cognitive function in older people. Evidence from longstanding cohort studies demonstrates that the putative association arises from cognitive function much earlier in life, in childhood. People with better childhood cognitive function have better oral health and access to routine dental care as they go through life, losing fewer teeth along the life course. They are also much more likely to have better cognitive function in old age. Their less cognitively able childhood counterparts will experience higher disease rates and poorer access to care, resulting in greater incremental tooth loss. Comparison of the 2 groups at any age from the mid-20s on will show greater numbers of missing teeth in the group who were less cognitively able in childhood. Those differences will be most pronounced in old age.

Low Tongue Strength and the Number of Teeth Present Are Associated with Cognitive Decline in Older Japanese Dental Outpatients: A Cross-Sectional Study

“…(2) an indirect process via inflammatory mediators; and (3) the induction of the expression of platelet aggregation proteins [46]. One of two recent reviews concluded that chronic periodontitis resulting in tooth loss, but not before the inflammation, has affected the central nervous system by impairing cognition [47]. The other review indicated that the causal relationship between periodontitis and Alzheimer´s disease is unknown [48].…”

Oral Health Status in Older People with Dementia: A Case-Control Study

“…Thomson and Barack [ 40 ] suggested that the possible related mechanisms between tooth loss and cognitive decline in older people are: (1) Tooth loss can compromise nutritional status and this can lead to a weakened nervous system. (2) Tooth loss results in less “interoclusal contacts”, therefore, less somatosensory feedback, leading to a cognitive decline, and (3) chronic periodontitis drives tooth loss, and during this inflammatory process, CNS can be affected, as so can cognition.…”

“…The oral health and hygiene of older people with dementia need to be improved [ 40 , 41 , 42 ]. This could be achieved through caregiver education in oral health, the use of oral disease detection tools, the assistance of dental professionals in adequate oral care and correct treatment planning, behavioral management of dementia patients, and the intervention of multidisciplinary health professional teams [ 4 , 5 , 6 , 7 , 8 ].…”

The Association between Age-Related Changes in Oral Neuromechanics and Alzheimer’s Disease

“…On the other hand, one should also consider the person’s ability to adapt mastication to changes in dental status [ 45 ] and whether this is impaired in AD/ARD. Currently, evidence supporting the association between tooth loss, masticatory performance, and dementia is still lacking [ 46 , 47 ]. (2) AD and oromotor dysfunctions share common risk factors : aging, diet/nutrition, and socio-economic status [ 7 ].…”