Association between tooth loss rate and risk of mild cognitive impairment in older adults: a population-based longitudinal study

Abstract

Mild cognitive impairment (MCI) is a symptomatic predementia phase of the trajectory of cognitive decline, and its prevalence increases with age. Although the relationship between oral health and MCI have been explored previously, it is uncertain whether individuals with different tooth loss rates have altered MCI risks. We hereby conducted a longitudinal study by using data from the Chinese Longitudinal Healthy Longevity Survey to investigate the association. Tooth loss rate was defined as the difference of teeth between two interview waves divided by years of interval; participants were then grouped into four categories: stable, no tooth loss; mild, 0-1 tooth loss; middle, 1-2 tooth loss; and severe, more than 2 tooth loss per year. Cognitive function was assessed by the Chinese version of Mini-Mental State Examination. We used the generalized estimating equation model to estimate the odds ratio (OR) and the 95% confidence intervals (CIs) and applied the restricted cubic spline function to explore the dose-response association. Among 11,862 participants, 3,966 developed MCI in a median follow-up time of 5.93 years. Higher tooth loss rate was associated with an increased risk of MCI in elderly subjects. Compared with subjects with stable tooth, the corresponding ORs (95% CIs) were 0.94 (0.85-1.03), 1.16 (1.04-1.29) and 1.28 (1.17-1.40) for subjects with the mild, middle and severe rate of tooth loss. A nonlinear dose-response relationship was detected ( P non-linearity = 0.0165). Similar results were observed in the subgroup analyses stratified by sex, age at baseline, and number of teeth at baseline. The positive association was only observed among denture nonwearers (OR middle vs stable : 1.19; 1.06-1.35; OR severe vs stable : 1.35; 1.22-1.50), but not among denture wearers. In conclusion, among elderly population in China, higher rate of tooth loss may be associated with an increased risk of MCI, while denture wearers may be less likely to develop MCI.

Periodontal health, cognitive decline, and dementia: A systematic review and meta‐analysis of longitudinal studies

“…Forty seven studies were included in this review: 24 for cognitive decline 8 , 9 , 15 , 16 , 17 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 and 23 for dementia 10 , 11 , 12 , 13 , 14 , 47 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 (Figure 1 ). Characteristics of included studies are summarized in Table S1 .…”

“…Quality assessment of included studies is summarized in Table S2 and Supplementary Text S2 . For cognitive decline, the overall risk of bias was high; 1 study received “moderate” 56 and 23 “low” 8 , 9 , 15 , 16 , 17 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 57 , 58 , 59 , 60 for overall quality. For dementia, overall risk of bias was moderate; 2 studies receiving “good,” 67 , 70 9 “moderate” 10 , 13 , 14 , 64 , 68 , 71 , 72 , 74 , 77 and 12 “low” 11 , 12 , 47 , 61 , 62 , 63 , 65 , 66 , 69 , 73 , 75 , 76 for overall quality.…”

The Impact of Masticatory Function on Cognitive Impairment in Older Patients: A Population-Based Matched Case-Control Study

“…Similar association between tooth loss and cognitive impairment has also been demonstrated by several other epidemiological studies. 10 21 In addition, a recently published retrospective study based on two USA national health surveys reported that edentulism was highly associated with cognitive decline, and that there was a gradient effect between a decreasing number of teeth and an increasing risk of cognitive impairment. 22 Another recent study of national database from Japan reported that older people with fewer teeth were more likely to develop Alzheimer’s disease.…”

The Sedentary Lifestyle and Masticatory Dysfunction: Time to Review the Contribution to Age-Associated Cognitive Decline and Astrocyte Morphotypes in the Dentate Gyrus

“…Highly sedentary humans (≥8 h/day) display reduced hippocampal volumes and increased white matter (WM) hyperintensities [ 3 , 4 ] that are associated with accelerated cognitive, neuropsychiatric and functional decline [ 5 ]. In addition to the changes associated with a sedentary life, it has become clear that oral dysfunction is present in the same individuals and that this group feature is also associated with dementia or mild cognitive decline [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. While it is not clear whether poor oral health predicts dementia, substantial data suggests that oral health declines as cognitive impairment and dementia progresses [ 7 , 12 , 14 , 15 , 16 ].…”

“…Furthermore, it has been demonstrated that masticatory exercise improves cognitive function in older adults [ 17 ] and thus the link between cognitive decline and masticatory dysfunction is now clear [ 8 , 18 , 19 , 20 , 21 , 22 ]. As loss of masticatory activity [ 8 , 11 , 12 , 13 , 18 , 19 , 20 , 21 , 22 ] and sedentary life style [ 23 , 24 ] are risk factors for age-related cognitive decline, there is a need to focus attention on those sub-populations that experience greater oral health deterioration or impairment of the stomatognathic system, and those having living sedentary lives.…”