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

Abstract

To mitigate the impact of dementia, initiating early intervention is important. This study aims to investigate the associations between deterioration in oral function and cognitive decline in older outpatients whose oral health was maintained in the dental clinic. This study included 50 outpatients aged ≥65 years. We used the Japanese version of the Montreal Cognitive Assessment (MoCA-J) to assess cognitive decline. Oral function was evaluated by tongue pressure, masticatory performance, and swallowing ability. A full-mouth periodontal examination was conducted, and the occlusal support and number of teeth were recorded. Odds ratios (ORs) and 95% confidence intervals (CIs) for cognitive decline (MoCA-J score ≤25 points) were calculated using logistic regression models. The age, number of teeth, tongue pressure, and masticatory performance were significantly correlated with cognitive decline (p < 0.05). Logistic regression analyses revealed that cognitive decline was independently associated with age (OR: 1.25; 95% CI: 1.03–1.52; p = 0.024), number of teeth (OR = 0.83; 95% CI: 0.76–1.00; p = 0.047), and lower tongue pressure (OR: 0.87; 95% CI: 0.77–0.98; p = 0.022). Lower tongue pressure and a small number of remaining teeth may be associated with cognitive decline in Japanese outpatients.

Effect of Oral Health Education Using a Mobile App (OHEMA) on the Oral Health and Swallowing-Related Quality of Life in Community-Based Integrated Care of the Elderly: A Randomized Clinical Trial

“…As an indicator of oral frailty, the perceived chewing disability was slightly high in both the intervention (3.40) and control (3.75) groups, while the tongue pressure in the preliminary oral examination was very low in both the intervention (17.75) and control (17.78) groups. This coincides with the high risk of diaphragmatic spasm or aspiration pneumonia at a tongue pressure of 20 kPa in the elderly aged ≥ 65 years [ 45 ]. However, the increase in tongue pressure to 27.24 kPa in the intervention group after the 6-week OHEMA was proof of its positive effect, with a predicted effect of enhancing the SWAL-QoL.…”

“…Oral frailty was assessed based on subjective oral dryness, perceived chewing disability, chewing disability, swallowing difficulty, and inconvenient pronunciation [ 28 , 29 ]; dietary factors (meal types, mealtimes, and daily amount of water); activities of daily living (ADL) [ 30 , 31 , 32 ] and instrumental activities of daily living (IADL) [ 33 ]; mini-mental state examination—Korean version (MMSE-K) [ 34 ]; the multidimensional scale of perceived social support (MSPSS) [ 35 , 36 ]; and oral health-related quality of life (OHRQoL) scales (oral health impact profile (OHIP-14), geriatric oral health assessment index (GOHAI), and SWAL-QoL) [ 37 , 38 , 39 , 40 , 41 , 42 ]. For oral health status, the number of remaining functional teeth, plaque index (PI) [ 43 ], tongue coating index [ 44 ], USFR [ 13 ], and tongue pressure [ 45 ] were measured. For intra- and inter-rater reliability, the authors conducted training before the beginning of the study and confirmed a concordance of > 90%.…”

“…The USFR was assessed by positioning a Schirmer strip (WF41-1850) cut to the size of 1 × 17 cm on the dorsal surface of the tongue and measuring the level of wetness of the strip after 1 min of lightly closing the mouth [ 13 ]. Tongue pressure was assessed as the maximum pressure on the JMS tongue pressure device (JMS Co., Ltd., Hiroshima, Japan) in relation to the mean tongue pressure of 30.0 kPa for individuals aged ≥ 65 years, with a tongue pressure of 20 kPa or below indicating a significantly high risk of diaphragmatic spasm or aspiration pneumonia [ 45 ].…”

Patients with mild cognitive impairment diagnosed at dementia clinic display decreased maximum occlusal force: a cross-sectional study

“…Egashira et al [ 42 ] compared the oral function and environment of participants classified into healthy and MCI groups based on MoCA-J scores. They reported that the participants in the MCI group were significantly older than those in the healthy group and that the MCI group had significantly fewer existing teeth, significantly lower masticatory ability, and significantly lower maximum tongue pressure than the healthy group.…”

Tongue cleaning in the elderly and its role in the respiratory and swallowing functions: Benefits and medical perspectives

“…66 Cognitive decline was independently associated with lower tongue pressure. 67,68 Tongue pressure is an important indicator of tongue function. Tongue pressure was evaluated using a specified tongue pressure measurement device (JMS Co, TPM-01) 69,70 or the Iowa Oral Performance Instrument ® .…”