1
|
Hatakeyama R, Oue H, Yokoi M, Ishida E, Tsuga K. Tooth loss in young mice is associated with cognitive decline and femur-bone mineral density. Odontology 2024:10.1007/s10266-024-01008-x. [PMID: 39365507 DOI: 10.1007/s10266-024-01008-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Accepted: 09/18/2024] [Indexed: 10/05/2024]
Abstract
Osteoporosis is a prevalent disease that is associated with increased hip fractures which cause significant decline in quality of life. Tooth loss affects systemic condition such as cognitive function through various mechanism, but the link between tooth loss and femoral bone mineral density is still uncertain. This study aims to investigate whether tooth loss in young mice affects memory function and femoral bone mineral density. Eight-week-old male C57BL/6 J mice were allocated randomly into the control group with sham operation and the tooth-loss group extracted all maxillary molar. Step-through passive avoidance test as cognitive function test, micro-CT analysis and western blotting analysis were performed after 1- and 2-month observation period. Step-through passive avoidance test revealed that the tooth-loss group in 2-month observation period impaired cognitive function. Additionally, micro-CT analysis revealed a significant decrease in both the length of the mandible and bone mineral density in the femur of the tooth-loss group compared to the control group. Claudin-5 level in the hippocampus, which is one of the tight junction markers in blood-brain-barrier, was significantly decreased in the tooth-loss group. The findings of our present study suggested that tooth loss impair cognitive function accompanied by reduced tight-junction marker, mandibular growth and bone mineral density of femur.
Collapse
Affiliation(s)
- Rie Hatakeyama
- Department of Advanced Prosthodontics, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
| | - Hiroshi Oue
- Department of Advanced Prosthodontics, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan.
| | - Miyuki Yokoi
- Department of Advanced Prosthodontics, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
- Department of Dentistry & Oral-Maxillofacial Surgery, Fujita Health University, Toyoake, Aichi, Japan
| | - Eri Ishida
- Department of Advanced Prosthodontics, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
| | - Kazuhiro Tsuga
- Department of Advanced Prosthodontics, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
| |
Collapse
|
2
|
Oh DJ, Han JW, Kim JS, Kim TH, Kwak KP, Kim BJ, Kim SG, Kim JL, Moon SW, Park JH, Ryu SH, Youn JC, Lee DY, Lee DW, Lee SB, Lee JJ, Jhoo JH, Kim KW. Masticatory Function, Sex, and Risk of Dementia Among Older Adults: A Population-Based Cohort Study. J Korean Med Sci 2024; 39:e246. [PMID: 39315441 PMCID: PMC11419966 DOI: 10.3346/jkms.2024.39.e246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Accepted: 07/14/2024] [Indexed: 09/25/2024] Open
Abstract
BACKGROUND A decline in masticatory function may indicate brain dysfunction related to dementia, but the relationship between masticatory function and dementia risk remains unclear. This study aimed to investigate whether masticatory function is associated with the risk of cognitive decline and dementia. METHODS Data were obtained from the nationwide prospective cohort study of randomly sampled community-dwelling Koreans aged ≥ 60 years. The 5,064 non-demented participants, whose number of chewing cycles per bite was assessed by clinical interview, were followed for 8 years with biennial assessments of cognitive performance and clinical diagnoses of all-cause dementia and Alzheimer's disease (AD). Structural brain magnetic resonance imaging was collected from a subset of cohort participants and their spouses for imaging analyses. RESULTS Males who chewed ≥ 30 cycles/bite had faster decline in global cognition and memory function and were at higher risk for incident all-cause dementia (hazard ratio [HR], 2.91; 95% confidence interval [CI], 1.18-7.18) and AD (HR, 3.22; 95% CI, 1.14-9.11) compared to males with less than 10 cycles/bite. Additionally, increased chewing cycles in males were associated with reduced brain volume, particularly in regions involved in compensatory cognitive control of mastication. There was no significant association between chewing cycles and the risk of dementia or brain volume in females. CONCLUSION Older men who frequently chew their meals could be considered a notable population at risk for dementia who should be carefully assessed for their cognitive trajectories.
Collapse
Affiliation(s)
- Dae Jong Oh
- Workplace Mental Health Institute, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ji Won Han
- Department of Neuropsychiatry, Seoul National University Bundang Hospital, Seongnam, Korea
- Department of Psychiatry, Seoul National University College of Medicine, Seoul, Korea
| | - Jun Sung Kim
- Department of Neuropsychiatry, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Tae Hui Kim
- Department of Psychiatry, Yonsei University Wonju Severance Christian Hospital, Wonju, Korea
| | - Kyung Phil Kwak
- Department of Psychiatry, Dongguk University Gyeongju Hospital, Gyeongju, Korea
| | - Bong Jo Kim
- Department of Psychiatry, Gyeongsang National University School of Medicine, Jinju, Korea
| | - Shin Gyeom Kim
- Department of Neuropsychiatry, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Jeong Lan Kim
- Department of Psychiatry, College of Medicine, Chungnam National University, Daejeon, Korea
| | - Seok Woo Moon
- Department of Psychiatry, Konkuk University Chungju Hospital, School of Medicine, Konkuk University, Chungju, Korea
| | - Joon Hyuk Park
- Department of Neuropsychiatry, Jeju National University Hospital, Jeju, Korea
| | - Seung-Ho Ryu
- Department of Psychiatry, Konkuk University Medical Center, School of Medicine, Konkuk University, Seoul, Korea
| | - Jong Chul Youn
- Department of Neuropsychiatry, Kyunggi Provincial Hospital for the Elderly, Yongin, Korea
| | - Dong Young Lee
- Department of Psychiatry, Seoul National University College of Medicine, Seoul, Korea
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Korea
| | - Dong Woo Lee
- Department of Psychiatry, Inje University Sanggye Paik Hospital, Seoul, Korea
| | - Seok Bum Lee
- Department of Psychiatry, Dankook University Hospital, Cheonan, Korea
| | - Jung Jae Lee
- Department of Psychiatry, Dankook University Hospital, Cheonan, Korea
| | - Jin Hyeong Jhoo
- Department of Psychiatry, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Ki Woong Kim
- Department of Neuropsychiatry, Seoul National University Bundang Hospital, Seongnam, Korea
- Department of Psychiatry, Seoul National University College of Medicine, Seoul, Korea
- Department of Brain and Cognitive Science, Seoul National University College of Natural Sciences, Seoul, Korea
- Institute of Human Behavioral Medicine, Seoul National University Medical Research Center, Seoul, Korea.
| |
Collapse
|
3
|
Wang Q, Zhen W, Hu R, Wang Z, Sun Y, Sun W, Huang C, Xu J, Zhang H. Occlusion dysfunction and Alzheimer's disease: Mendelian randomization study. Front Aging Neurosci 2024; 16:1423322. [PMID: 39035234 PMCID: PMC11258003 DOI: 10.3389/fnagi.2024.1423322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Accepted: 06/20/2024] [Indexed: 07/23/2024] Open
Abstract
Aim Occlusion dysfunction (OD) is increasingly linked to Alzheimer's disease (AD). This study aimed to elucidate the causal relationship between OD and AD using Mendelian randomization (MR) analysis. Materials and methods Genome-wide association study (GWAS) meta-analysis data obtained from FinnGen, IEU Open GWAS, and UK Biobank (UKBB) was represented as instrumental variables. We validated the causal relationship between periodontal disease (PD), loose teeth (PD & occlusion dysfunction), dentures restoration (occlusion recovery), and AD. Results According to the MR analysis, PD and AD have no direct causal relationship (P = 0.395, IVW). However, loose teeth significantly increased the risk of AD progression (P = 0.017, IVW, OR = 187.3567, 95%CI = 2.54E+00-1.38E+04). These findings were further supported by the negative causal relationship between dentures restoration and AD (P = 0.015, IVW, OR = 0.0234, 95%CI = 1.13E-03-0.485). Conclusion The occlusion dysfunction can ultimately induce Alzheimer's disease. Occlusion function was a potentially protective factor for maintaining neurological health.
Collapse
Affiliation(s)
- Qing Wang
- Key Laboratory of Oral Diseases Research of Anhui Province, College and Hospital of Stomatology, Anhui Medical University, Hefei, China
| | - Wenyu Zhen
- Key Laboratory of Oral Diseases Research of Anhui Province, College and Hospital of Stomatology, Anhui Medical University, Hefei, China
| | - Rui Hu
- Department of Anesthesiology and Perioperative Medicine, The Second Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Zifei Wang
- Key Laboratory of Oral Diseases Research of Anhui Province, College and Hospital of Stomatology, Anhui Medical University, Hefei, China
| | - Yuqiang Sun
- Key Laboratory of Oral Diseases Research of Anhui Province, College and Hospital of Stomatology, Anhui Medical University, Hefei, China
| | - Wansu Sun
- Department of Stomatology, Anhui Public Health Clinical Center, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Chunxia Huang
- Department of Anesthesiology and Perioperative Medicine, The Second Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Jianguang Xu
- Key Laboratory of Oral Diseases Research of Anhui Province, College and Hospital of Stomatology, Anhui Medical University, Hefei, China
| | - Hengguo Zhang
- Key Laboratory of Oral Diseases Research of Anhui Province, College and Hospital of Stomatology, Anhui Medical University, Hefei, China
| |
Collapse
|
4
|
Esmaeili A, Ebrahimpour S, Hefshejani KF, Esmaeili A. Molecular mechanisms underlying the effect of tooth shortening on memory dysfunction in Wistar male rat. Arch Oral Biol 2024; 159:105878. [PMID: 38171058 DOI: 10.1016/j.archoralbio.2023.105878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 12/15/2023] [Accepted: 12/27/2023] [Indexed: 01/05/2024]
Abstract
OBJECTIVE We investigated the effects of molar tooth shortening on the mRNA expression of the AβPP/BACE1, BDNF/TrkB, and Bax/Bcl-2 signaling pathways in the Wistar male rat hippocampal regions. DESIGN Four groups (n = 5 per group) of male Wistar rats (control, SRM (shortened right molar), SLM (shortened left molar), and SBM (shortened bilateral molar)) were used. RNA was isolated from the hippocampus and transformed into cDNA. Real-time quantitative PCR was used to evaluate the mRNA expression levels of AβPP, BACE1, Bax, Bcl-2, BDNF, and TrkB. RESULTS Differential mRNA expression was observed in rat groups. SBM significantly upregulated the AβPP, BACE1, and Bax mRNA expressions, whereas the expression levels of Bcl-2, BDNF, and TrkB were decreased. SRM and SLM approximately had the same effect on the expression enhancement of AβPP, BACE1, and Bax; however, SRM was more effective than SLM in increasing the expression of these genes. CONCLUSIONS Symmetrical molar teeth shortening affected the mRNA expression of AβPP and BACE1, which is related to learning and memory dysfunction.
Collapse
Affiliation(s)
- Ali Esmaeili
- Dental Materials Research Center, Dental Research Institute, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Shiva Ebrahimpour
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran
| | | | - Abolghasem Esmaeili
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran.
| |
Collapse
|
5
|
Ishida E, Furusho H, Renn TY, Shiba F, Chang HM, Oue H, Terayama R, Ago Y, Tsuga K, Miyauchi M. Mouse maternal odontogenic infection with Porphyromonas gingivalis induces cognitive decline in offspring. Front Pediatr 2023; 11:1203894. [PMID: 37635786 PMCID: PMC10450928 DOI: 10.3389/fped.2023.1203894] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 07/24/2023] [Indexed: 08/29/2023] Open
Abstract
Introduction Porphyromonas gingivalis (P. gingivalis), a major periodontal pathogen, causes intrauterine infection/inflammation. Offspring exposed to intrauterine infection/inflammation have an increased risk of neurological disorders, regardless of gestational age. However, the relationship between maternal periodontitis and offspring functional/histological changes in the brain has not yet been elucidated. Methods In this study, we used a gestational mouse model to investigate the effects of maternal odontogenic infection of P. gingivalis on offspring behavior and brain tissue. Results The step-through passive avoidance test showed that the latency of the acquisition trial was significantly shorter in the P. gingivalis group (p < 0.05), but no difference in spontaneous motor/exploratory parameters by open-field test. P. gingivalis was diffusely distributed throughout the brain, especially in the hippocampus. In the hippocampus and amygdala, the numbers of neuron cells and cyclic adenosine monophosphate response element binding protein-positive cells were significantly reduced (p < 0.05), whereas the number of ionized calcium binding adapter protein 1-positive microglia was significantly increased (p < 0.05). In the hippocampus, the number of glial fibrillary acidic protein-positive astrocytes was also significantly increased (p < 0.05). Discussion The offspring of P. gingivalis-infected mothers have reduced cognitive function. Neurodegeneration/neuroinflammation in the hippocampus and amygdala may be caused by P. gingivalis infection, which is maternally transmitted. The importance of eliminating maternal P. gingivalis-odontogenic infection before or during gestation in maintenance healthy brain function in offspring should be addressed in near future.
Collapse
Affiliation(s)
- Eri Ishida
- Department of Advanced Prosthodontics, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Hisako Furusho
- Department of Oral and Maxillofacial Pathobiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Ting-Yi Renn
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Fumie Shiba
- Department of Oral and Maxillofacial Pathobiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Hung-Ming Chang
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Hiroshi Oue
- Department of Advanced Prosthodontics, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Ryuji Terayama
- Department of Maxillofacial Anatomy and Neuroscience, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Yukio Ago
- Department of Cellular and Molecular Pharmacology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Kazuhiro Tsuga
- Department of Advanced Prosthodontics, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Mutsumi Miyauchi
- Department of Oral and Maxillofacial Pathobiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| |
Collapse
|
6
|
Furukawa M, Tada H, Raju R, Wang J, Yokoi H, Ikuyo Y, Yamada M, Shikama Y, Matsushita K. Long-Term Capsaicin Administration Ameliorates the Dysfunction and Astrogliosis of the Brain in Aged Mice with Missing Maxillary Molars. Nutrients 2023; 15:nu15112471. [PMID: 37299434 DOI: 10.3390/nu15112471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 05/13/2023] [Accepted: 05/22/2023] [Indexed: 06/12/2023] Open
Abstract
Tooth loss and decreased masticatory function reportedly affect cognitive function; tooth loss allegedly induces astrogliosis and aging of astrocytes in the hippocampus and hypothalamus, which is a response specific to the central nervous system owing to homeostasis in different brain regions. Capsaicin, a component of red peppers, has positive effects on brain disorders in mice. Decreased expression of transient receptor potential vanilloid 1, a receptor of capsaicin, is associated with the development of dementia. In this study, we investigated the effect of capsaicin administration in aged mice (C57BL/6N mice) with reduced masticatory function owing to the extraction of maxillary molars to investigate preventive/therapeutic methods for cognitive decline attributed to age-related masticatory function loss. The results demonstrated that mice with impaired masticatory function showed decreased motor and cognitive function at the behavioral level. At the genetic level, neuroinflammation, microglial activity, and astrogliosis, such as increased glial fibrillary acidic protein levels, were observed in the mouse brain. The mice with extracted molars fed on a diet containing capsaicin for 3 months demonstrated improved behavioral levels and astrogliosis, which suggest that capsaicin is useful in maintaining brain function in cases of poor oral function and prosthetic difficulties.
Collapse
Affiliation(s)
- Masae Furukawa
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Hirobumi Tada
- Department of Nutrition, Faculty of Wellness, Shigakkan University, Obu 474-8651, Japan
- Department of Integrative Physiology, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Resmi Raju
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Jingshu Wang
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Haruna Yokoi
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Yoriko Ikuyo
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Mitsuyoshi Yamada
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
- Department of Operative Dentistry, School of Dentistry, Aichi Gakuin University, Nagoya 464-8651, Japan
| | - Yosuke Shikama
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| | - Kenji Matsushita
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan
| |
Collapse
|
7
|
Ebrahimpour S, Esmaeili A, Esmaeili A, Sattari K, Forouzandeh Hafshejani K. Molar tooth shortening induces learning and memory impairment in Wistar rat. Oral Dis 2023; 29:1356-1366. [PMID: 34862999 DOI: 10.1111/odi.14093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 10/26/2021] [Accepted: 11/28/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVE This study aimed to investigate the relationship between different patterns of molar crown loss and the association between symmetrical and asymmetrical shortening molar teeth with memory impairment. MATERIALS AND METHODS Male Wistar rats were divided into four groups (n = 10) including control, SLM (shortened left molar), SRM (shortened right molar), and SBM (shortened bilateral molar) groups. Morris water maze (MWM) and passive avoidance test (PAT) were performed to assess spatial and fear memory, respectively. Besides, histological assessment of hippocampus and gingival tissues was done. RESULTS In the MWM test, SBM and SLM groups had higher escape latency over training trials and spent less time in the target quadrant in the probe trial (p < 0.01). In the PAT, step-through latency was significantly reduced in three groups, and time spent in the dark compartment increased in SBM (p < 0.01) and SLM (p < 0.05) groups. In addition, each teeth shortening group indicated a reduction in density (p < 0.01) and thickness layer (p < 0.05) of pyramidal cells. Gingival was normal after shortening of the molar crown. CONCLUSIONS Different patterns of molar teeth shortening induced learning and memory impairment; however, symmetrical molar teeth shortening has more effects on memory impairment.
Collapse
Affiliation(s)
- Shiva Ebrahimpour
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran
| | - Abolghasem Esmaeili
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran
| | - Ali Esmaeili
- School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Kimiya Sattari
- School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran
| | | |
Collapse
|
8
|
Al-Manei K, Jia L, Al-Manei KK, Ndanshau EL, Grigoriadis A, Kumar A. Food Hardness Modulates Behavior, Cognition, and Brain Activation: A Systematic Review of Animal and Human Studies. Nutrients 2023; 15:nu15051168. [PMID: 36904167 PMCID: PMC10005610 DOI: 10.3390/nu15051168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/22/2023] [Accepted: 02/23/2023] [Indexed: 03/02/2023] Open
Abstract
Food hardness is one of the dietary features that may impact brain functions. We performed a systematic review to evaluate the effect of food hardness (hard food versus soft food diet) on behavior, cognition, and brain activation in animals and humans (PROSPERO ID: CRD42021254204). The search was conducted on 29 June 2022 using Medline (Ovid), Embase, and Web of Science databases. Data were extracted, tabulated by food hardness as an intervention, and summarized by qualitative synthesis. The SYRCLE and JBI tools were used to assess the risk of bias (RoB) of individual studies. Of the 5427 studies identified, 18 animal studies and 6 human studies met the inclusion criteria and were included. The RoB assessment indicated that 61% of animal studies had unclear risks, 11% had moderate risks, and 28% had low risks. All human studies were deemed to have a low risk of bias. The majority (48%) of the animal studies showed that a hard food diet improved behavioral task performance compared to soft food diets (8%). However, 44% of studies also showed no differential effects of food hardness on behavioral tests. It was also evident that certain regions of the brain were activated in response to changes in food hardness in humans, with a positive association between chewing hard food, cognition performance, and brain function. However, variations in the methodologies of the included studies hindered the meta-analysis execution. In conclusion, our findings highlight the beneficial effects of dietary food hardness on behavior, cognition, and brain function in both animals and humans, however, this effect may depend on several factors that require further understanding of the causality.
Collapse
Affiliation(s)
- Khaled Al-Manei
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, 141 04 Huddinge, Sweden
- Division of Endodontics, Department of Restorative Dental Science, College of Dentistry, King Saud University, Riyadh 11545, Saudi Arabia
| | - Leming Jia
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, 141 04 Huddinge, Sweden
| | - Kholod Khalil Al-Manei
- Division of Endodontics, Department of Restorative Dental Science, College of Dentistry, King Saud University, Riyadh 11545, Saudi Arabia
| | | | - Anastasios Grigoriadis
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, 141 04 Huddinge, Sweden
| | - Abhishek Kumar
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, 141 04 Huddinge, Sweden
- Academic Center for Geriatric Dentistry, 112 19 Stockholm, Sweden
- Correspondence:
| |
Collapse
|
9
|
Wei T, Du Y, Hou T, Zhai C, Li Y, Xiao W, Liu K. Association between adverse oral conditions and cognitive impairment: A literature review. Front Public Health 2023; 11:1147026. [PMID: 37089515 PMCID: PMC10117837 DOI: 10.3389/fpubh.2023.1147026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/02/2023] [Indexed: 04/25/2023] Open
Abstract
Oral environment deterioration results from a lack of self-cleaning ability in patients with cognitive dysfunction but is also a risk factor for cognitive dysfunction. Adverse oral conditions can be alleviated and improved through a self-management and medical examination. In this review, the epidemiological evidence of previous studies is integrated to highlight the relationship between periodontitis, tooth loss, oral flora, oral dysfunction and cognitive dysfunction, emphasizing the importance of oral health for cognition. The results show that poor oral condition is associated with cognitive impairment. Although many previous studies have been conducted, there is a lack of higher-level research evidence, different judgment criteria, and conflicting research results. There is a bidirectional relationship between oral health and cognitive dysfunction. A comprehensive analysis of the relationship between oral health and cognitive dysfunction that explores the relationship and takes measures to prevent cognitive dysfunction and control the progression of such diseases is warranted in the future.
Collapse
Affiliation(s)
- Tianhao Wei
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
| | - Yifeng Du
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Neurology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Tingting Hou
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Neurology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Chunjuan Zhai
- Department of Cardiology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Yuqi Li
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
| | - Wei Xiao
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Neurology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Keke Liu
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Department of Neurology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
- Department of Infection Control, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
| |
Collapse
|
10
|
de Siqueira Mendes FDCC, de Almeida MNF, Falsoni M, Andrade MLF, Felício APG, da Paixão LTVB, Júnior FLDA, Anthony DC, Brites D, Diniz CWP, Sosthenes MCK. The Sedentary Lifestyle and Masticatory Dysfunction: Time to Review the Contribution to Age-Associated Cognitive Decline and Astrocyte Morphotypes in the Dentate Gyrus. Int J Mol Sci 2022; 23:ijms23116342. [PMID: 35683023 PMCID: PMC9180988 DOI: 10.3390/ijms23116342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/15/2022] [Accepted: 05/16/2022] [Indexed: 02/01/2023] Open
Abstract
As aging and cognitive decline progresses, the impact of a sedentary lifestyle on the appearance of environment-dependent cellular morphologies in the brain becomes more apparent. Sedentary living is also associated with poor oral health, which is known to correlate with the rate of cognitive decline. Here, we will review the evidence for the interplay between mastication and environmental enrichment and assess the impact of each on the structure of the brain. In previous studies, we explored the relationship between behavior and the morphological features of dentate gyrus glial fibrillary acidic protein (GFAP)-positive astrocytes during aging in contrasting environments and in the context of induced masticatory dysfunction. Hierarchical cluster and discriminant analysis of GFAP-positive astrocytes from the dentate gyrus molecular layer revealed that the proportion of AST1 (astrocyte arbors with greater complexity phenotype) and AST2 (lower complexity) are differentially affected by environment, aging and masticatory dysfunction, but the relationship is not straightforward. Here we re-evaluated our previous reconstructions by comparing dorsal and ventral astrocyte morphologies in the dentate gyrus, and we found that morphological complexity was the variable that contributed most to cluster formation across the experimental groups. In general, reducing masticatory activity increases astrocyte morphological complexity, and the effect is most marked in the ventral dentate gyrus, whereas the effect of environment was more marked in the dorsal dentate gyrus. All morphotypes retained their basic structural organization in intact tissue, suggesting that they are subtypes with a non-proliferative astrocyte profile. In summary, the increased complexity of astrocytes in situations where neuronal loss and behavioral deficits are present is counterintuitive, but highlights the need to better understand the role of the astrocyte in these conditions.
Collapse
Affiliation(s)
- Fabíola de Carvalho Chaves de Siqueira Mendes
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém 66073-005, PA, Brazil; (F.d.C.C.d.S.M.); (M.N.F.d.A.); (M.F.); (M.L.F.A.); (A.P.G.F.); (L.T.V.B.d.P.); (F.L.d.A.J.); (C.W.P.D.)
- Curso de Medicina, Centro Universitário do Estado do Pará, Belém 66613-903, PA, Brazil
| | - Marina Negrão Frota de Almeida
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém 66073-005, PA, Brazil; (F.d.C.C.d.S.M.); (M.N.F.d.A.); (M.F.); (M.L.F.A.); (A.P.G.F.); (L.T.V.B.d.P.); (F.L.d.A.J.); (C.W.P.D.)
| | - Manoela Falsoni
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém 66073-005, PA, Brazil; (F.d.C.C.d.S.M.); (M.N.F.d.A.); (M.F.); (M.L.F.A.); (A.P.G.F.); (L.T.V.B.d.P.); (F.L.d.A.J.); (C.W.P.D.)
| | - Marcia Lorena Ferreira Andrade
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém 66073-005, PA, Brazil; (F.d.C.C.d.S.M.); (M.N.F.d.A.); (M.F.); (M.L.F.A.); (A.P.G.F.); (L.T.V.B.d.P.); (F.L.d.A.J.); (C.W.P.D.)
| | - André Pinheiro Gurgel Felício
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém 66073-005, PA, Brazil; (F.d.C.C.d.S.M.); (M.N.F.d.A.); (M.F.); (M.L.F.A.); (A.P.G.F.); (L.T.V.B.d.P.); (F.L.d.A.J.); (C.W.P.D.)
| | - Luisa Taynah Vasconcelos Barbosa da Paixão
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém 66073-005, PA, Brazil; (F.d.C.C.d.S.M.); (M.N.F.d.A.); (M.F.); (M.L.F.A.); (A.P.G.F.); (L.T.V.B.d.P.); (F.L.d.A.J.); (C.W.P.D.)
| | - Fábio Leite do Amaral Júnior
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém 66073-005, PA, Brazil; (F.d.C.C.d.S.M.); (M.N.F.d.A.); (M.F.); (M.L.F.A.); (A.P.G.F.); (L.T.V.B.d.P.); (F.L.d.A.J.); (C.W.P.D.)
| | - Daniel Clive Anthony
- Laboratory of Experimental Neuropathology, Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK;
| | - Dora Brites
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-004 Lisbon, Portugal;
- Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, 1649-004 Lisbon, Portugal
| | - Cristovam Wanderley Picanço Diniz
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém 66073-005, PA, Brazil; (F.d.C.C.d.S.M.); (M.N.F.d.A.); (M.F.); (M.L.F.A.); (A.P.G.F.); (L.T.V.B.d.P.); (F.L.d.A.J.); (C.W.P.D.)
| | - Marcia Consentino Kronka Sosthenes
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém 66073-005, PA, Brazil; (F.d.C.C.d.S.M.); (M.N.F.d.A.); (M.F.); (M.L.F.A.); (A.P.G.F.); (L.T.V.B.d.P.); (F.L.d.A.J.); (C.W.P.D.)
- Correspondence:
| |
Collapse
|
11
|
Furukawa M, Tada H, Wang J, Yamada M, Kurosawa M, Satoh A, Ogiso N, Shikama Y, Matsushita K. Molar loss induces hypothalamic and hippocampal astrogliosis in aged mice. Sci Rep 2022; 12:6409. [PMID: 35437315 PMCID: PMC9016068 DOI: 10.1038/s41598-022-10321-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 04/05/2022] [Indexed: 11/09/2022] Open
Abstract
Age-related tooth loss impedes mastication. Epidemiological and physiological studies have reported that poor oral hygiene and occlusion are associated with cognitive decline. In the present study, we analyzed the mechanism by which decreased occlusal support following bilateral extraction of the maxillary first molars affects cognitive functions in young and aged mice and examined the expression of brain-function-related genes in the hippocampus and hypothalamus. We observed decreased working memory, enhanced restlessness, and increased nocturnal activity in aged mice with molar extraction compared with that in mice with intact molars. Furthermore, in the hypothalamus and hippocampus of molar-extracted aged mice, the transcript-level expression of Bdnf, Rbfox3, and Fos decreased, while that of Cdkn2a and Aif1 increased. Thus, decreased occlusal support after maxillary first molar extraction may affect cognitive function and activity in mice by influencing aging, neural activity, and neuroinflammation in the hippocampus and hypothalamus.
Collapse
Affiliation(s)
- Masae Furukawa
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan.
| | - Hirobumi Tada
- Department of Nutrition, Faculty of Wellness, Shigakkan University, Obu, Japan.,Department of Inflammation and Immunosenescence, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Jingshu Wang
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Mitsuyoshi Yamada
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan.,Department of Operative Dentistry, School of Dentistry, Aichi Gakuin University, Nagoya, Japan
| | - Mie Kurosawa
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Akiko Satoh
- Department of Integrative Physiology, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan.,Department of Integrative Physiology, Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan
| | - Noboru Ogiso
- Department of Laboratory of Experimental Animals, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Yosuke Shikama
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Kenji Matsushita
- Department of Oral Disease Research, Geroscience Research Center, National Center for Geriatrics and Gerontology, Obu, Japan.
| |
Collapse
|
12
|
Wang X, Hu J, Jiang Q. Tooth Loss-Associated Mechanisms That Negatively Affect Cognitive Function: A Systematic Review of Animal Experiments Based on Occlusal Support Loss and Cognitive Impairment. Front Neurosci 2022; 16:811335. [PMID: 35221901 PMCID: PMC8866659 DOI: 10.3389/fnins.2022.811335] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/18/2022] [Indexed: 12/15/2022] Open
Abstract
BackgroundThere is a dose-response relationship between tooth loss and cognitive impairment, while tooth loss can be an independent risk factor for Alzheimer's disease (AD) and vascular dementia (VaD). Tooth loss can also accelerate nerve damage and neurodegeneration. However, the associated mechanisms remain poorly understood.ObjectiveTo conduct a systematic review of animal experiments on cognitive decline caused by the loss of occlusal support performed over the past 10 years and summarize the possible underlying mechanisms.Methods“Tooth Loss,” “Edentulous,” “Tooth Extraction and Memory Loss,” “Cognition Impairment,” and “Dementia” were used as keywords to search PubMed, Embase, SCI, ScienceDirect, and OpenGrey. A total of 1,317 related articles from 2010 to 2021 were retrieved, 26 of which were included in the review after screening according to predetermined inclusion and exclusion criteria. Comprehensiveness was evaluated using ARRIVE guidelines and the risk of bias was assessed using SYCLE'S risk of bias tool.ResultsThe putative mechanisms underlying the cognitive impairment resulting from the loss of occlusal support are as follows: (1) The mechanical pathway, whereby tooth loss leads to masticatory motor system functional disorders. Masticatory organ activity and cerebral blood flow decrease. With reduced afferent stimulation of peripheral receptors (such as in the periodontal membrane) the strength of the connections between neural pathways is decreased, and the corresponding brain regions degenerate; (2) the aggravation pathway, in which tooth loss aggravates existing neurodegenerative changes. Tooth loss can accelerates nerve damage through apoptosis and mitochondrial autophagy, increases amyloid deposition in the brain; and (3) the long-term inflammatory stress pathway, which involves metabolic disorders, microbial-gut-brain axis, the activation of microglia and astrocytes, and inflammatory cascade effect in central nervous system.ConclusionThe loss of occlusal support may lead to cognitive dysfunction through the reduction of chewing-related stimuli, aggravation of nerve damage, and long-term inflammatory stress.
Collapse
|
13
|
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; 80:1687-1704. [PMID: 33720883 DOI: 10.3233/jad-201055] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND Epidemiological studies have shown that tooth loss is associated with Alzheimer's disease (AD) and dementia. However, the molecular and cellular mechanisms by which tooth loss causes AD remain unclear. OBJECTIVE We investigated the effects of tooth loss on memory impairment and AD pathogenesis in AppNL-G-F mice. METHODS Maxillary molar teeth on both sides were extracted from 2-month-old AppNL-G-F mice, and the mice were reared for 2 months. The short- and long-term memory functions were evaluated using a novel object recognition test and a passive avoidance test. Amyloid plaques, amyloid-β (Aβ) levels, glial activity, and neuronal activity were evaluated by immunohistochemistry, Aβ ELISA, immunofluorescence staining, and western blotting. The mRNA expression levels of neuroinflammatory cytokines were determined by qRT-PCR analysis. RESULTS Tooth loss induced memory impairment via an amyloid-cascade-independent pathway, and decreased the neuronal activity, presynaptic and postsynaptic protein levels in both the cortex and hippocampus. Interestingly, we found that tooth loss induced glial activation, which in turn leads to the upregulation of the mRNA expression levels of the neuroinflammation cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β in the hippocampus. We also found that tooth loss activated a stress-activated protein kinase, c-Jun N-terminal kinase (JNK), and increased heat shock protein 90 (HSP90) levels in the hippocampus, which may lead to a glial activation. CONCLUSION Our findings suggest that taking care of teeth is very important to preserve a healthy oral environment, which may reduce the risk of cognitive dysfunction.
Collapse
Affiliation(s)
- Ferdous Taslima
- Department of Biochemistry, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Cha-Gyun Jung
- Department of Biochemistry, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Chunyu Zhou
- Department of Biochemistry, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Mona Abdelhamid
- Department of Biochemistry, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Mohammad Abdullah
- Department of Biochemistry, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Tetsuya Goto
- Department of Oral Anatomy & Cell Biology, Graduate School of Medical and Dental Science, Kagoshima University, Kagoshima, Japan
| | - Takashi Saito
- Department of Neurocognitive Science, Institute of Brain Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Takaomi C Saido
- Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science, Wako, Japan
| | - Makoto Michikawa
- Department of Biochemistry, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| |
Collapse
|
14
|
Tramonti Fantozzi MP, Lazzarini G, De Cicco V, Briganti A, Argento S, De Cicco D, Barresi M, Cataldo E, Bruschini L, d'Ascanio P, Pirone A, Lenzi C, Vannozzi I, Miragliotta V, Faraguna U, Manzoni D. The path from trigeminal asymmetry to cognitive impairment: a behavioral and molecular study. Sci Rep 2021; 11:4744. [PMID: 33637775 PMCID: PMC7910455 DOI: 10.1038/s41598-021-82265-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 01/15/2021] [Indexed: 01/02/2023] Open
Abstract
Trigeminal input exerts acute and chronic effects on the brain, modulating cognitive functions. Here, new data from humans and animals suggest that these effects are caused by trigeminal influences on the Locus Coeruleus (LC). In humans subjects clenching with masseter asymmetric activity, occlusal correction improved cognition, alongside with reductions in pupil size and anisocoria, proxies of LC activity and asymmetry, respectively. Notably, reductions in pupil size at rest on the hypertonic side predicted cognitive improvements. In adult rats, a distal unilateral section of the trigeminal mandibular branch reduced, on the contralateral side, the expression of c-Fos (brainstem) and BDNF (brainstem, hippocampus, frontal cortex). This counterintuitive finding can be explained by the following model: teeth contact perception loss on the lesioned side results in an increased occlusal effort, which enhances afferent inputs from muscle spindles and posterior periodontal receptors, spared by the distal lesion. Such effort leads to a reduced engagement of the intact side, with a corresponding reduction in the afferent inputs to the LC and in c-Fos and BDNF gene expression. In conclusion, acute effects of malocclusion on performance seem mediated by the LC, which could also contribute to the chronic trophic dysfunction induced by loss of trigeminal input.
Collapse
Affiliation(s)
- Maria Paola Tramonti Fantozzi
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Via San Zeno 31, 56127, Pisa, Italy
| | - Giulia Lazzarini
- Department of Veterinary Sciences, University of Pisa, Pisa, Italy
| | - Vincenzo De Cicco
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Via San Zeno 31, 56127, Pisa, Italy
| | - Angela Briganti
- Department of Veterinary Sciences, University of Pisa, Pisa, Italy
| | - Serena Argento
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Via San Zeno 31, 56127, Pisa, Italy
| | - Davide De Cicco
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples "Federico II", Naples, Italy
| | - Massimo Barresi
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Via San Zeno 31, 56127, Pisa, Italy
| | | | - Luca Bruschini
- Department of Surgical, Medical, Molecular Pathology and CriticalCare Medicine, University of Pisa, Pisa, Italy
| | - Paola d'Ascanio
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Via San Zeno 31, 56127, Pisa, Italy
| | - Andrea Pirone
- Department of Veterinary Sciences, University of Pisa, Pisa, Italy
| | - Carla Lenzi
- Department of Veterinary Sciences, University of Pisa, Pisa, Italy
| | - Iacopo Vannozzi
- Department of Veterinary Sciences, University of Pisa, Pisa, Italy
| | | | - Ugo Faraguna
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Via San Zeno 31, 56127, Pisa, Italy
- Department of Developmental Neuroscience, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Diego Manzoni
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Via San Zeno 31, 56127, Pisa, Italy.
| |
Collapse
|
15
|
Egashira R, Umezaki Y, Mizutani S, Obata T, Yamaguchi M, Tamai K, Yoshida M, Makino M, Naito T. Relationship between cerebral atrophy and number of present teeth in elderly individuals with cognitive decline. Exp Gerontol 2020; 144:111189. [PMID: 33285222 DOI: 10.1016/j.exger.2020.111189] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 11/30/2020] [Accepted: 12/02/2020] [Indexed: 12/21/2022]
Abstract
BACKGROUND AND AIM Recent shifts in the distribution of Japan's population towards older ages, have meant that the chance of encountering patients with dementia in dental clinics is increasing. Many studies have shown that the brain volume decreases along with the progression of dementia. Although previous studies have reported a relationship between tooth loss or periodontitis and the onset of dementia, the pathological mechanisms underlying this association have not been elucidated. In this study, we aimed to examine the relationship between the oral condition and brain atrophy and to discuss how to adequately deal with patients with dementia. PARTICIPANTS AND METHODS This cross-sectional study included 15 participants who underwent brain magnetic resonance imaging (MRI). The participants were 60 years or older and presented with cognitive decline, including Alzheimer's disease (AD) and mild cognitive impairment (MCI), diagnosed by a neurologist. We obtained information on the oral condition, lifestyle, cognitive function, and brain atrophy. Cognitive function was assessed using the Mini-Mental State Examination (MMSE). MR images of each patient were analyzed using the voxel-based specific regional analysis system for Alzheimer's disease (VSRAD) to provide a quantitative measure of the degree of brain atrophy. RESULTS The study population included 4 male and 11 female patients. The mean age and mean number of present teeth were 75.9 years (SD 6.7) and 15.0 (SD 11.1), respectively. The median MMSE score was 25.6 (SD 3.7). The degree of atrophy of the whole brain was significantly correlated with the number of present teeth (ρ = -0.72, p < 0.05) and the presence of a daily exercise habit (ρ = -0.66, p < 0.05). CONCLUSION This study demonstrated that the number of present teeth could be an indicator of the progress of dementia. Preserving the teeth as well as the acquisition of a regular exercise habit might be important for preventing progression of dementia. Further research examining a larger study population and analyzing a greater number of factors is warranted.
Collapse
Affiliation(s)
- Rui Egashira
- Section of Geriatric Dentistry, Department of General Dentistry, Fukuoka Dental College, Fukuoka, Japan
| | - Yojiro Umezaki
- Section of Geriatric Dentistry, Department of General Dentistry, Fukuoka Dental College, Fukuoka, Japan.
| | - Shinsuke Mizutani
- Section of Geriatric Dentistry and Perioperative Medicine in Dentistry, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyusyu University, Fukuoka, Japan; OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | | | - Masahiro Yamaguchi
- Section of Geriatric Dentistry, Department of General Dentistry, Fukuoka Dental College, Fukuoka, Japan
| | - Keiko Tamai
- Section of Geriatric Dentistry, Department of General Dentistry, Fukuoka Dental College, Fukuoka, Japan
| | - Mizuki Yoshida
- Section of Geriatric Dentistry, Department of General Dentistry, Fukuoka Dental College, Fukuoka, Japan
| | - Michiko Makino
- The Center for Visiting Dental Service, Fukuoka Dental College, Fukuoka, Japan
| | - Toru Naito
- Section of Geriatric Dentistry, Department of General Dentistry, Fukuoka Dental College, Fukuoka, Japan
| |
Collapse
|
16
|
Lopez-Chaichio L, Padial-Molina M, O'Valle F, Gil-Montoya JA, Catena A, Galindo-Moreno P. Oral health and healthy chewing for healthy cognitive ageing: A comprehensive narrative review. Gerodontology 2020; 38:126-135. [PMID: 33179281 DOI: 10.1111/ger.12510] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 09/11/2020] [Accepted: 10/24/2020] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Ageing leads to physiological cognitive decline that it is worsened in people with neurodegenerative diseases such as Alzheimer's disease. Despite the ongoing search for a solution to this cognitive decline, no effective remedies have been established. It has been determined that modifiable external factors, such as oral health and occlusal function, prevent cognitive decline. OBJECTIVE To analyse the primary interactions between occlusal function and cognitive functions. MAIN FINDINGS Masticatory function is related to cognitive functions. In particular, current evidence, from both animal and human studies, suggests that the activation of masticatory muscles and proper mastication, with natural teeth or dental prosthesis, induces the release of several mediators and the activation of specific brain areas. Together, they result in higher neuronal activity, neurotrophic support, blood flow and the prevention of amyloid-beta plaque formation. Thus, all the components of the masticatory system must work together in order to preserve cognitive function. CONCLUSIONS Available evidence suggests that oral and cognitive health are more interconnected than previously thought. Therefore, maintenance and adequate restoration of the whole masticatory system are important for the prevention of cognitive decline. In summary, oral and chewing health lead to healthy cognitive ageing.
Collapse
Affiliation(s)
- Lucia Lopez-Chaichio
- Department of Oral Surgery and Implant Dentistry, School of Dentistry, University of Granada, Granada, Spain
| | - Miguel Padial-Molina
- Department of Oral Surgery and Implant Dentistry, School of Dentistry, University of Granada, Granada, Spain
| | - Francisco O'Valle
- Department of Pathology and IBIMER, School of Medicine, University of Granada, Granada, Spain.,Biosanitary Institute of Granada (ibs.Granada), University of Granada, Granada, Spain
| | - Jose Antonio Gil-Montoya
- Biosanitary Institute of Granada (ibs.Granada), University of Granada, Granada, Spain.,Department of Gerodontology, School of Dentistry, University of Granada, Granada, Spain
| | - Andres Catena
- Mind, Brain and Behavior Research Center, University of Granada, Granada, Spain
| | - Pablo Galindo-Moreno
- Department of Oral Surgery and Implant Dentistry, School of Dentistry, University of Granada, Granada, Spain
| |
Collapse
|
17
|
Nakamura T, Zou K, Shibuya Y, Michikawa M. Oral dysfunctions and cognitive impairment/dementia. J Neurosci Res 2020; 99:518-528. [PMID: 33164225 DOI: 10.1002/jnr.24745] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 10/01/2020] [Accepted: 10/04/2020] [Indexed: 01/11/2023]
Abstract
With global increases in the aging population, the number of patients with dementia is greatly increasing, which has become a big social problem. Many studies have shown strong associations between oral disorders and systemic disorders, such as diabetes, arthritis, sepsis, aspiration pneumonia, arteriosclerosis, bacterial endocarditis, and other cardiovascular diseases. Similarly, numerous cross-sectional studies showed that patients with dementia usually have poor oral conditions and tooth loss. These have long been considered as a result of difficulty with oral care due to impaired cognitive function, memory, and physical ability in patients with dementia. Indeed, even in patients with mild cognitive impairment, oral care becomes insufficient owing to decreases in spontaneity of grooming and finger dexterity. However, recent studies have shown that tooth loss and occlusal dysfunction may affect brain function and trigger the onset of dementia found in neurodegenerative diseases including Alzheimer's disease. In this review, we highlight the relationships among aging, oral dysfunction, and the development of dementia. Increasing evidence suggests that oral dysfunction is not only a result of dementia in the elderly people, but could also be a causative factor for the onset of dementia.
Collapse
Affiliation(s)
- Tomohisa Nakamura
- Department of Biochemistry, Nagoya City University, Graduate School of Medical Sciences, Nagoya, Japan.,Maxillofacial Surgery, Nagoya City University, Graduate School of Medical Sciences, Nagoya, Japan
| | - Kun Zou
- Department of Biochemistry, Nagoya City University, Graduate School of Medical Sciences, Nagoya, Japan
| | - Yasuyuki Shibuya
- Maxillofacial Surgery, Nagoya City University, Graduate School of Medical Sciences, Nagoya, Japan
| | - Makoto Michikawa
- Department of Biochemistry, Nagoya City University, Graduate School of Medical Sciences, Nagoya, Japan
| |
Collapse
|
18
|
Piancino MG, Tortarolo A, Polimeni A, Bramanti E, Bramanti P. Altered mastication adversely impacts morpho-functional features of the hippocampus: A systematic review on animal studies in three different experimental conditions involving the masticatory function. PLoS One 2020; 15:e0237872. [PMID: 32817680 PMCID: PMC7446800 DOI: 10.1371/journal.pone.0237872] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Accepted: 08/04/2020] [Indexed: 02/06/2023] Open
Abstract
Recent results have established that masticatory function plays a role not only in the balance of the stomatognathic system and in the central motor control, but also in the trophism of the hippocampus and in the cognitive activity. These implications have been shown in clinical studies and in animal researches as well, by means of histological, biochemical and behavioural techniques. This systematic review describes the effects of three forms of experimentally altered mastication, namely soft-diet feeding, molar extraction and bite-raising, on the trophism and function of the hippocampus in animal models. Through a systematic search of PubMed, Embase, Web of Science, Scopus, OpenGray and GrayMatters, 645 articles were identified, 33 full text articles were assessed for eligibility and 28 articles were included in the review process. The comprehensiveness of reporting was evaluated with the ARRIVE guidelines and the risk of bias with the SYRCLE RoB tool. The literature reviewed agrees that a disturbed mastication is significantly associated with a reduced number of hippocampal pyramidal neurons in Cornu Ammonis (CA)1 and CA3, downregulation of Brain Derived Neurotrophic Factor (BDNF), reduced synaptic activity, reduced neurogenesis in the Dentate Gyrus (DG), glial proliferation, and reduced performances in behavioural tests, indicating memory impairment and reduced spatial orientation. Moreover, while the bite-raised condition, characterized by occlusal instability, is known to be a source of stress, soft-diet feeding and molar extractions were not consistently associated with a stress response. More research is needed to clarify this topic. The emerging role of chewing in the preservation of hippocampal trophism, neurogenesis and synaptic activity is worthy of interest and may contribute to the study of neurodegenerative diseases in new and potentially relevant ways.
Collapse
Affiliation(s)
- Maria Grazia Piancino
- Department of Surgical Sciences, Dental School, University of Turin, Turin, Italy
- * E-mail:
| | - Alessandro Tortarolo
- Department of Surgical Sciences, Dental School, University of Turin, Turin, Italy
| | - Antonella Polimeni
- Department of Oral and Maxillo-Facial Science, Sapienza University of Rome, Rome, Italy
| | - Ennio Bramanti
- Department of Biomedical and Dental Sciences, Morphological and Functional Images, University of Messina, Messina, Italy
| | | |
Collapse
|
19
|
Katano M, Kajimoto K, Iinuma M, Azuma K, Kubo KY. Tooth loss early in life induces hippocampal morphology remodeling in senescence-accelerated mouse prone 8 (SAMP8) mice. Int J Med Sci 2020; 17:517-524. [PMID: 32174782 PMCID: PMC7053313 DOI: 10.7150/ijms.40241] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 01/15/2020] [Indexed: 11/05/2022] Open
Abstract
Long-term tooth loss is associated with the suppression of hippocampal neurogenesis and impairment of hippocampus-dependent cognition with aging. The morphologic basis of the hippocampal alterations, however, remains unclear. In the present study, we investigated whether tooth loss early in life affects the hippocampal ultrastructure in senescence-accelerated mouse prone 8 (SAMP8) mice, using transmission electron microscopy. Male SAMP8 mice were randomized into control or tooth-loss groups. All maxillary molar teeth were removed at 1 month of age. Hippocampal morphologic alterations were evaluated at 9 months of age. Tooth loss early in life induced mitochondrial damage and lipofuscin accumulation in the hippocampal neurons. A thinner myelin sheath and decreased postsynaptic density length were also observed. Our results revealed that tooth loss early in life may lead to hippocampal ultrastructure remodeling and subsequent hippocampus-dependent cognitive impairment in SAMP8 mice with aging.
Collapse
Affiliation(s)
- Masahisa Katano
- Department of Pediatric Dentistry, Asahi University School of Dentistry, 1851 Hozumi, Mizuho, Gifu, 501-0296, Japan
| | - Kyoko Kajimoto
- Department of Pediatric Dentistry, Asahi University School of Dentistry, 1851 Hozumi, Mizuho, Gifu, 501-0296, Japan
| | - Mitsuo Iinuma
- Department of Pediatric Dentistry, Asahi University School of Dentistry, 1851 Hozumi, Mizuho, Gifu, 501-0296, Japan
| | - Kagaku Azuma
- Department of Anatomy, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, Fukuoka, 807-8555, Japan
| | - Kin-Ya Kubo
- Graduate School of Human Life Science, Nagoya Women's University, 3-40 Shioji-cho, Mizuho-ku, Nagoya, Aichi, 467-8610, Japan
| |
Collapse
|
20
|
Systemic inflammation linking chronic periodontitis to cognitive decline. Brain Behav Immun 2019; 81:63-73. [PMID: 31279681 DOI: 10.1016/j.bbi.2019.07.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 07/03/2019] [Accepted: 07/03/2019] [Indexed: 12/25/2022] Open
Abstract
Persistent inflammation in the systemic immune system can impose detrimental effects on the central nervous system (CNS). Neuroinflammation might be a result of this to accelerate the progressive deterioration of neuronal functions during aging. In this regard, controlling inflammation through delaying and/or preventing chronic inflammatory diseases may be a potential strategy to prevent or modify the progression of Alzheimer's Disease (AD). Periodontitis is a chronic inflammatory disease of the oral cavity that is common among the elderly, especially for those who have decline in cognitive functions. While epidemiological findings support the association of chronic periodontitis and cognitive decline, whether they have causal relationship remains unclear. Nonetheless, the possibility that periodontopathogens, systemic immune cells and inflammatory cytokines could reach the CNS should not be overlooked. The impacts of periodontitis on CNS homeostasis and inflammation as a pathophysiological factor concerning the association between periodontitis and AD will be discussed in this review. Future work should elucidate the pathological pathways involved in periodontitis-induced cerebral infections and inflammation, and define the role of the latter in AD progression.
Collapse
|
21
|
Tooth loss causes spatial cognitive impairment in rats through decreased cerebral blood flow and increased glutamate. Arch Oral Biol 2019; 102:225-230. [PMID: 31079020 DOI: 10.1016/j.archoralbio.2019.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 05/02/2019] [Accepted: 05/05/2019] [Indexed: 12/31/2022]
Abstract
OBJECTIVE The loss of teeth not only causes damage to oral function but also is associated with cognitive impairment. Previous studies have reported that chewing can increase CBF, and CBF plays an important role in cognitive function. Whether the loss of teeth can lead to cognitive impairment by reducing CBF is unclear. This study aimed to investigate the changes in CBF, glutamate concentration, the expression of neuronal apoptosis-relatedBax/Bcl-2 and Caspase-3 mRNA and pyramidal cells in the hippocampus, as well as behavioral changes after tooth loss in rats. DESIGN Twelve weeks after the extraction of all maxillary molars in rats, their spatial learning and memory were tested by the Morris water maze, the CBF was detected by ASL-MRI and glutamate concentration was detected by HPLC; the expression of neuronal apoptosis-related Bax/Bcl-2 and Caspase-3 mRNA and the number of pyramidal cells in the CA1 region were also measured. RESULTS Rats with tooth loss exhibited spatial cognitive impairment in the Morris water maze, decreased CBF, increased glutamate levels andBax/Bcl-2 and Caspase-3 mRNA expression in the hippocampus; the number of pyramidal cells in the CA1 region were also reduced. CONCLUSIONS These findings suggest that the loss of teeth causes spatial cognitive impairment in rats and that the underlying mechanism might be associated with a decrease in CBF and an increase in the glutamate level in the hippocampus.
Collapse
|
22
|
de Siqueira Mendes FDCC, da Paixão LTVB, Diniz CWP, Sosthenes MCK. Environmental Impoverishment, Aging, and Reduction in Mastication Affect Mouse Innate Repertoire to Explore Novel Environments and to Assess Risk. Front Neurosci 2019; 13:107. [PMID: 30930726 PMCID: PMC6427831 DOI: 10.3389/fnins.2019.00107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 01/29/2019] [Indexed: 12/20/2022] Open
Abstract
Studies indicate that inhibition of adequate masticatory function, due to soft diet, occlusal disharmony, or molar losses affects the cognitive behavior of rodents. However, no study has tested the effects on new environments exploration and risk assessment coupled with a combination of masticatory function rehabilitation and environmental enrichment. In the present report, we tested the hypothesis that age, environment, and masticatory changes may interact and alter exploratory patterns of locomotor activity and mice preferences in an open field (OF) arena. As OF arenas are widely used to measure anxiety-like behavior in rats and mice. We examined in an open arena, the exploratory and locomotor activities of mature (6-month-old; 6M), late mature (12-month-old; 12M), and aged (18-month-old; 18M) mice, subjected to distinct masticatory regimens and environments. Three different regimens of masticatory activity were used: continuous normal mastication with hard pellets (HD); normal mastication followed by reduced mastication with equal periods of pellets followed by soft powder – HD/SD; or rehabilitated masticatory activity with equal periods of HD, followed by powder, followed by pellets – HD/SD/HD). Under each diet regimen, half of the individuals were raised in standard cages [impoverished environment (IE)] and the other half in enriched cages [enriched environment (EE)]. Animals behavior on the open field (OF) task were recorded by webcam and analyzed with Any Maze software (Stöelting). The locomotor and exploratory activities in OF task declined with age, and this was particularly evident in 18M HD EE mice. Although all groups kept their preference by the peripheral zone, the outcomes were significantly influenced by interactions between environment, age, and diet. Independent of diet regime, 6M young mice maintained in an EE where voluntary exercise apparatus is available, revealed significant less body weight than all other groups. Although body weight differences were minimized as age progressed, 18M EE group revealed intragroup significant influence of diet regimens. We suggest that long life environmental enrichment reduces the tendency to avoid open/lit spaces (OF) and this is particularly influenced by masticatory activity. These measurements may be useful in discussions of anxiety-related tasks.
Collapse
Affiliation(s)
- Fabíola de Carvalho Chaves de Siqueira Mendes
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil.,Curso de Medicina, Centro Universitário do Estado do Pará, Belém, Brazil
| | - Luisa Taynah Vasconcelos Barbosa da Paixão
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| | - Cristovam Wanderley Picanço Diniz
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| | - Marcia Consentino Kronka Sosthenes
- Laboratório de Investigações em Neurodegeneração e Infecção, Instituto de Ciências Biológicas, Hospital Universitário João de Barros Barreto, Universidade Federal do Pará, Belém, Brazil
| |
Collapse
|
23
|
Leon M, Woo C. Environmental Enrichment and Successful Aging. Front Behav Neurosci 2018; 12:155. [PMID: 30083097 PMCID: PMC6065351 DOI: 10.3389/fnbeh.2018.00155] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 07/04/2018] [Indexed: 12/18/2022] Open
Abstract
The human brain sustains a slow but progressive decline in function as it ages and these changes are particularly profound in cognitive processing. A potential contributor to this deterioration is the gradual decline in the functioning of multiple sensory systems and the effects they have on areas of the brain that mediate cognitive function. In older adults, diminished capacity is typically observed in the visual, auditory, masticatory, olfactory, and motor systems, and these age-related declines are associated with both a decline in cognitive proficiency, and a loss of neurons in regions of the brain. We will review how the loss of hearing, vision, mastication skills, olfactory impairment, and motoric decline accompany cognitive loss, and how improved functioning of these systems may aid in the restoration of the cognitive abilities in older adults. The human brain appears to require a great deal of stimulation to maintain its cognitive efficacy as people age and environmental enrichment may aid in its maintenance and recovery.
Collapse
Affiliation(s)
- Michael Leon
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Cynthia Woo
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| |
Collapse
|
24
|
Lin CS. Revisiting the link between cognitive decline and masticatory dysfunction. BMC Geriatr 2018; 18:5. [PMID: 29304748 PMCID: PMC5756393 DOI: 10.1186/s12877-017-0693-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 12/18/2017] [Indexed: 12/17/2022] Open
Abstract
Age-related decline in cognitive functions and dementia are major challenges in geriatric healthcare. Accumulating evidence from clinical, epidemiological and animal research suggests that tooth loss may be a risk factor for the decline of cognitive functions. This issue highlights the role of the brain-stomatognathic axis in geriatric medicine. Whether input from the stomatognathic apparatus can affect the brain remains an open debate. By revisiting the evidence published in the past five years, we argue that the hypothesis regarding the association between cognitive decline and masticatory dysfunction should be carefully interpreted. Most of the available clinical and epidemiological studies present only cross-sectional data. With respect to the prospective studies, important confounding factors, such as nutritional and physical conditions, were not fully controlled for. Animal research has revealed that hippocampal deficits may play key roles in the observed cognitive decline. However, experimental intervention and outcome assessments may not capture the condition of human subjects. Brain neuroimaging research may be suitable for bridging the gap between clinical and animal research, potentially contributing to (a) the clarification of the brain network associated with mastication, (b) the identification of brain imaging markers for exploring the mechanisms underlying long-term changes in masticatory functions, and (c) the elucidation of interactions between mastication and other cognitive-affective processing systems. Three potential models of the brain-stomatognathic axis and relevant hypotheses are summarized, focusing on the sensory feedback mechanisms, the compensation of motor control, and cerebellar deficits. Finally, we highlight four critical aspects of study and experimental design that should be considered in future research: (a) the refinement of the considered behavioral assessments, (b) the inclusion of baseline changes in mental and physical conditions,
Collapse
Affiliation(s)
- Chia-Shu Lin
- Department of Dentistry, School of Dentistry, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei, 11221, Taiwan.
| |
Collapse
|
25
|
Mutoh T, Sasaki K, Tatewaki Y, Kunitoki K, Takano Y, Taki Y. Preceding functional tooth loss delays recovery from acute cerebral hypoxia and locomotor hypoactivity after murine subarachnoid haemorrhage. Clin Exp Pharmacol Physiol 2017; 45:344-348. [PMID: 29044603 DOI: 10.1111/1440-1681.12874] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 09/30/2017] [Accepted: 10/03/2017] [Indexed: 01/04/2023]
Abstract
Tooth loss and related changes in the functionality may lead to worse outcome of stroke patients, but the effect on hemorrhagic stroke remains unclear. This study aimed to determine the impact of impaired masticatory function on acute cerebral oxygenation and locomotor activity after experimental subarachnoid haemorrhage (SAH). Twenty C57BL/6 mice with (MC-treated group) or without (control group) prior treatment of cutting off the upper molars were subjected to SAH by endovascular perforation. Grading of SAH and acute cerebral infarction were assessed by MR images. Brain tissue oxygen saturation (SbtO2 ) by photoacoustic imaging and parameters related to locomotor activity by open-field test were analyzed serially after SAH. In all mice, global SbtO2 depression was notable immediately after SAH induction (P <.001), which recovered close to the baseline levels until day 3. However, MC-treated mice demonstrated a prolonged relative cerebral hypoxia (<40% of the baseline SbtO2) as compared to the control (3 ± 1 vs 1 ± 1 days; P <.05). The average distance travelled on day 7 and the ratio of central-area distance/total travelled distance by open-field test between days 7 and 14 were significantly lower in MC-treated mice than in the control mice (P <.05), although the occurrences of new infarction were not statistically different (P >.05). These data suggest a possible link between preceding masticatory impairment and early brain injury to deteriorate neurobehavioural function in patients after SAH.
Collapse
Affiliation(s)
- Tatsushi Mutoh
- Institute of Development, Aging and Cancer (IDAC), Tohoku University, Sendai, Japan
| | - Kazumasu Sasaki
- Institute of Development, Aging and Cancer (IDAC), Tohoku University, Sendai, Japan
| | - Yasuko Tatewaki
- Institute of Development, Aging and Cancer (IDAC), Tohoku University, Sendai, Japan
| | - Keiko Kunitoki
- Institute of Development, Aging and Cancer (IDAC), Tohoku University, Sendai, Japan
| | - Yumi Takano
- Institute of Development, Aging and Cancer (IDAC), Tohoku University, Sendai, Japan
| | - Yasuyuki Taki
- Institute of Development, Aging and Cancer (IDAC), Tohoku University, Sendai, Japan
| |
Collapse
|