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Igeta Y, Hemmi I, Yuyama K, Ouchi Y. Odor identification score as an alternative method for early identification of amyloidogenesis in Alzheimer's disease. Sci Rep 2024; 14:4658. [PMID: 38409432 PMCID: PMC10897211 DOI: 10.1038/s41598-024-54322-3] [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: 08/13/2023] [Accepted: 02/11/2024] [Indexed: 02/28/2024] Open
Abstract
A simple screening test to identify the early stages of Alzheimer's disease (AD) is urgently needed. We investigated whether odor identification impairment can be used to differentiate between stages of the A/T/N classification (amyloid, tau, neurodegeneration) in individuals with amnestic mild cognitive impairment or AD and in healthy controls. We collected data from 132 Japanese participants visiting the Toranomon Hospital dementia outpatient clinic. The odor identification scores correlated significantly with major neuropsychological scores, regardless of apolipoprotein E4 status, and with effective cerebrospinal fluid (CSF) biomarkers [amyloid β 42 (Aβ42) and the Aβ42/40 and phosphorylated Tau (p-Tau)/Aβ42 ratios] but not with ineffective biomarkers [Aβ40 and the p-Tau/total Tau ratio]. A weak positive correlation was observed between the corrected odor identification score (adjusted for age, sex, ApoE4 and MMSE), CSF Aβ42, and the Aβ42/40 ratio. The odor identification score demonstrated excellent discriminative power for the amyloidogenesis stage , according to the A/T/N classification, but was unsuitable for differentiating between the p-Tau accumulation and the neurodegeneration stages. After twelve odor species were analyzed, a version of the score comprising only four odors-India ink, wood, curry, and sweaty socks-proved highly effective in identifying AD amyloidogenesis, showing promise for the screening of preclinical AD.
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Affiliation(s)
- Yukifusa Igeta
- Department of Dementia, Dementia Center, Federation of National Public Service Personnel Mutual Aid Associations, Toranomon Hospital, 2-2-2 Toranomon, Minato-ku, Tokyo, 105-8470, Japan.
- Division of Dementia Research, Okinaka Memorial Institute for Medical Research, 2-2-2 Toranomon, Minato-ku, Tokyo, 105-8470, Japan.
| | - Isao Hemmi
- Japanese Red Cross College of Nursing, 4-1-3 Hiroo, Shibuya-ku, Tokyo, 150-0012, Japan
| | - Kohei Yuyama
- Lipid Biofunction Section, Faculty of Advanced Life Science, Hokkaido University, Kita-21, Nishi-11, Kita-ku, Sapporo, 001-0021, Japan
| | - Yasuyoshi Ouchi
- Department of Dementia, Dementia Center, Federation of National Public Service Personnel Mutual Aid Associations, Toranomon Hospital, 2-2-2 Toranomon, Minato-ku, Tokyo, 105-8470, Japan
- Division of Dementia Research, Okinaka Memorial Institute for Medical Research, 2-2-2 Toranomon, Minato-ku, Tokyo, 105-8470, Japan
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Tian S, Jiang J, Wang J, Zhang Z, Miao Y, Ji X, Bi Y. Comparison on cognitive outcomes of antidiabetic agents for type 2 diabetes: A systematic review and network meta-analysis. Diabetes Metab Res Rev 2023; 39:e3673. [PMID: 37302139 DOI: 10.1002/dmrr.3673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 03/02/2023] [Accepted: 04/25/2023] [Indexed: 06/13/2023]
Abstract
We aimed to summarise current evidence on different antidiabetic drugs to delay cognitive impairment, including mild cognitive impairment, dementia, Alzheimer's disease (AD) and vascular dementia, among subjects with type 2 diabetes mellitus (T2DM). Medline, Cochrane and Embase databases were searched from inception to 31 July 2022. Two investigators independently reviewed and screened trials comparing antidiabetic drugs with no antidiabetic drugs, placebo, or other active antidiabetic drugs on cognitive outcomes in T2DM. Data were analysed using meta-analysis and network meta-analysis. Twenty-seven studies met the inclusion criteria, including 3 randomised controlled trials, 19 cohort studies and 5 case-control studies. Compared with non-user, SGLT-2i (OR 0.41 [95% CI 0.22-0.76]), GLP-1RA (OR 0.34 [95% CI 0.14-0.85]), thiazolidinedione (OR 0.60 [95% CI 0.51-0.69]), and DPP-4i (OR 0.78 [95% CI 0.61-0.99]) users had a decreased risk of dementia, whereas sulfonylurea (OR 1.43 [95% CI 1.11-1.82]) increased dementia risk. Network meta-analysis showed that SGLT-2i was most likely to rank best (SUCRA = 94.4%), GLP-1 RA second best (SUCRA = 92.7%), thiazolidinedione third best (SUCRA = 74.7%) and DPP-4i fourth best (SUCRA = 54.9%), while sulfonylurea second worst (SUCRA = 20.0%) for decreasing dementia outcomes, by synthesising evidence from direct and indirect comparisons of multiple intervention. Evidence suggests the effects of SGLT-2i ≈ GLP-1 RAs > thiazolidinedione > DPP-4i for delaying cognitive impairment, dementia and AD outcomes, whereas sulfonylurea was associated with the highest risk. These findings provide evidence for evaluating the optional treatment for clinical practice. PROSPERO REGISTRATION: Registration no. CRD42022347280.
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Affiliation(s)
- Sai Tian
- Department of Endocrinology, Endocrine and Metabolic Disease Medical Center, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Branch of National Clinical Research Centre for Metabolic Diseases, Nanjing, China
| | - Jiaxuan Jiang
- Department of Endocrinology, Endocrine and Metabolic Disease Medical Center, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Branch of National Clinical Research Centre for Metabolic Diseases, Nanjing, China
| | - Jin Wang
- Department of Endocrinology, Endocrine and Metabolic Disease Medical Center, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Branch of National Clinical Research Centre for Metabolic Diseases, Nanjing, China
| | - Zhou Zhang
- Department of Endocrinology, Endocrine and Metabolic Disease Medical Center, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Branch of National Clinical Research Centre for Metabolic Diseases, Nanjing, China
| | - Yingwen Miao
- Department of Endocrinology, Endocrine and Metabolic Disease Medical Center, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Branch of National Clinical Research Centre for Metabolic Diseases, Nanjing, China
| | - Xinlu Ji
- Department of Endocrinology, Endocrine and Metabolic Disease Medical Center, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Branch of National Clinical Research Centre for Metabolic Diseases, Nanjing, China
| | - Yan Bi
- Department of Endocrinology, Endocrine and Metabolic Disease Medical Center, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Branch of National Clinical Research Centre for Metabolic Diseases, Nanjing, China
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Fukuda S, Ohi K, Fujikane D, Takai K, Kuramitsu A, Fujita K, Muto Y, Sugiyama S, Shioiri T. Olfactory identification ability among schizophrenia patients, their first-degree relatives and healthy subjects. Aust N Z J Psychiatry 2023; 57:1367-1374. [PMID: 36967530 DOI: 10.1177/00048674231164568] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
OBJECTIVE Olfactory impairments, including identification, have been reported in patients with schizophrenia, while few studies have examined the olfactory function of unaffected first-degree relatives of patients with schizophrenia, and the sample sizes of first-degree relatives were relatively small. Here, we investigated olfactory identification ability among patients with schizophrenia, first-degree relatives and healthy controls (HCs) using relatively large sample sizes at a single institute. METHODS To assess olfactory identification ability, the open essence odorant identification test was administered to 172 schizophrenia patients, 75 first-degree relatives and 158 healthy controls. Differences in olfactory identification and correlations between olfactory ability and clinical variables were examined among these participants. RESULTS We found a significant difference in olfactory identification ability among the diagnostic groups (p = 7.65 × 10-16). Schizophrenia patients displayed lower olfactory identification ability than first-degree relatives (Cohen's d = -0.57, p = 3.13 × 10-6) and healthy controls (d = -1.00, p = 2.19 × 10-16). Furthermore, first-degree relatives had lower olfactory identification ability than healthy controls (d = -0.29, p = 0.039). Olfactory identification ability moderately and negatively correlated with the duration of illness (r = -0.41, p = 1.88 × 10-8) and negative symptoms (r = -0.28, p = 1.99 × 10-4) in schizophrenia patients, although the correlation with the duration of illness was affected by aging (r = -0.24). CONCLUSIONS Our results demonstrated that schizophrenia patients have impaired olfactory identification ability compared with first-degree relatives and healthy controls, and the impaired olfactory identification ability of first-degree relatives was intermediate between those in schizophrenia patients and healthy controls. Olfactory identification ability was relatively independent of clinical variables. Therefore, olfactory identification ability might be an intermediate phenotype for schizophrenia.
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Affiliation(s)
| | - Kazutaka Ohi
- Department of Psychiatry, Gifu University Graduate School of Medicine, Gifu, Japan
- Department of General Internal Medicine, Kanazawa Medical University, Ishikawa, Japan
| | - Daisuke Fujikane
- Department of Psychiatry, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Kentaro Takai
- Department of Psychiatry, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Ayumi Kuramitsu
- Department of Psychiatry, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Koji Fujita
- Department of Psychiatry, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Yukimasa Muto
- Department of Psychiatry, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Shunsuke Sugiyama
- Department of Psychiatry, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Toshiki Shioiri
- Department of Psychiatry, Gifu University Graduate School of Medicine, Gifu, Japan
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Park SY, Kim KS, Min HJ. Gustatory dysfunction perceptions versus objective gustatory dysfunction among older adults. BMC Geriatr 2023; 23:56. [PMID: 36721099 PMCID: PMC9887822 DOI: 10.1186/s12877-023-03781-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/29/2023] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Research on gustatory dysfunction among older adults has been scarce relative to research on olfactory dysfunction, and the relationship between subjective and objective gustatory dysfunction has not been studied in detail. We aimed to evaluate whether subjective recognition of gustatory dysfunction correlates with objective diagnosis of gustatory dysfunction among older adults. METHODS In this retrospective, cross-sectional study, we reviewed the medical records of 138 patients of ages ≥ 60 years for whom data were available on self-reported and objectively measured gustatory and olfactory function from January 2018 through April 2021 at a specialized smell/taste center of a single institution. We reviewed self-reported and measured outcomes of gustatory and olfactory function using patient data including clinical characteristics, including age, sex, smoking history, and medical history. RESULTS We found that the subjective recognition of gustatory dysfunction does not correlate with the objective diagnosis of gustatory dysfunction based on the measured results of gustatory function tests. Subjective gustatory dysfunction, however, was correlated with subjective olfactory dysfunction. Among clinical and demographic characteristics, age and sex were significantly associated with measured gustatory function outcomes. CONCLUSION We suggest that subjective gustatory dysfunction underestimates objective dysfunction and recommend that older men with diminished olfactory function undergo gustatory function testing regardless of their self-reported gustatory function status.
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Affiliation(s)
- Seung Yong Park
- grid.254224.70000 0001 0789 9563Department of Otorhinolaryngology-Head and Neck Surgery, Chung-Ang University College of Medicine, 102, Heukseok-ro, Dongjak-gu, Seoul, 156-755 South Korea
| | - Kyung Soo Kim
- grid.254224.70000 0001 0789 9563Department of Otorhinolaryngology-Head and Neck Surgery, Chung-Ang University College of Medicine, 102, Heukseok-ro, Dongjak-gu, Seoul, 156-755 South Korea
| | - Hyun Jin Min
- grid.254224.70000 0001 0789 9563Department of Otorhinolaryngology-Head and Neck Surgery, Chung-Ang University College of Medicine, 102, Heukseok-ro, Dongjak-gu, Seoul, 156-755 South Korea
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Sato S, Imaeda T, Mugikura S, Mori N, Takanashi M, Hayakawa K, Saito T, Taira M, Narita A, Kogure M, Chiba I, Hatanaka R, Nakaya K, Kanno I, Ishiwata R, Nakamura T, Motoike IN, Nakaya N, Koshiba S, Kinoshita K, Kuriyama S, Ogishima S, Nagami F, Fuse N, Hozawa A. Association Between Olfactory Test Data with Multiple Levels of Odor Intensity and Suspected Cognitive Impairment: A Cross-Sectional Study. J Alzheimers Dis 2023; 95:1469-1480. [PMID: 37718802 DOI: 10.3233/jad-230318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
BACKGROUND Olfactory function decline has recently been reported to be associated with a risk of cognitive impairment. Few population-based studies have included younger adults when examining the association between olfactory test data with multiple odor intensities and suspected cognitive impairment. OBJECTIVE We investigated the association between high-resolution olfactory test data with fewer odors and suspected cognitive impairments. We also examined the differences between older and younger adults in this association. METHODS The Japanese version of the Montreal Cognitive Assessment (MoCA-J) was administered to 1,450 participants, with three odor-intensity-level olfactometry using six different odors. Logistic regressions to discriminate suspected cognitive impairment were conducted to examine the association, adjusted for age, sex, education duration, and smoking history. Data were collected from the Program by Tohoku University Tohoku Medical Megabank Organization, with an additional olfactory test conducted between 2019 and 2021. RESULTS We generally observed that the lower the limit of distinguishable odor intensity was, the higher the MoCA-J score was. The combination of spearmint and stuffy socks contributed most to the distinction between suspected and unsuspected cognitive impairment. Furthermore, the association was significant in women aged 60-74 years (adjusted odds ratio 0.881, 95% confidence interval [0.790, 0.983], p = 0.024). CONCLUSIONS The results indicate an association between the limit of distinguishable odor intensity and cognitive function. The olfactory test with multiple odor intensity levels using fewer odors may be applicable for the early detection of mild cognitive impairment, especially in older women aged 60-74 years.
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Affiliation(s)
- Shuichi Sato
- Toyota Central Research and Development Laboratories, Inc., Nagakute, Japan
| | - Takao Imaeda
- Toyota Central Research and Development Laboratories, Inc., Nagakute, Japan
| | - Shunji Mugikura
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- The Advanced Research Center for Innovations in Next-Generation Medicine, Tohoku University, Sendai, Japan
- Tohoku University Hospital, Sendai, Japan
- Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Naoko Mori
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- Akita University Graduate School of Medicine, Akita, Japan
| | - Masaki Takanashi
- Toyota Central Research and Development Laboratories, Inc., Nagakute, Japan
| | - Kazumi Hayakawa
- Toyota Central Research and Development Laboratories, Inc., Nagakute, Japan
| | - Tomo Saito
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
| | - Makiko Taira
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- Tohoku University Hospital, Sendai, Japan
- Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Akira Narita
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
| | - Mana Kogure
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Ippei Chiba
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Rieko Hatanaka
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Kumi Nakaya
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Ikumi Kanno
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Ryosuke Ishiwata
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
| | - Tomohiro Nakamura
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
| | - Ikuko N Motoike
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
| | - Naoki Nakaya
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Seizo Koshiba
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- The Advanced Research Center for Innovations in Next-Generation Medicine, Tohoku University, Sendai, Japan
| | - Kengo Kinoshita
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- The Advanced Research Center for Innovations in Next-Generation Medicine, Tohoku University, Sendai, Japan
- Tohoku University Graduate School of Information Sciences, Sendai, Japan
- Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan
| | - Shinichi Kuriyama
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- Tohoku University Graduate School of Medicine, Sendai, Japan
- International Research Institute of Disaster Science, Tohoku University, Sendai, Japan
| | - Soichi Ogishima
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- The Advanced Research Center for Innovations in Next-Generation Medicine, Tohoku University, Sendai, Japan
| | - Fuji Nagami
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- The Advanced Research Center for Innovations in Next-Generation Medicine, Tohoku University, Sendai, Japan
| | - Nobuo Fuse
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- The Advanced Research Center for Innovations in Next-Generation Medicine, Tohoku University, Sendai, Japan
- Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Atsushi Hozawa
- Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
- Tohoku University Graduate School of Medicine, Sendai, Japan
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Jiménez A, Herrera-González A, Organista-Juárez D, Estudillo E, Velasco I, Guerrero-Vargas NN, Guzmán-Ruíz MA, Guevara-Guzmán R. Diabetes Induces Permanent Deleterious Effects in the Olfactory Bulb Associated with Increased Tyrosine Hydroxylase Expression and ERK1/2 Phosphorylation. ACS Chem Neurosci 2022; 13:2821-2828. [PMID: 36122168 DOI: 10.1021/acschemneuro.2c00319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Diabetes mellitus type 2 (T2D) complications include brain damage which increases the risk of neurodegenerative diseases and dementia. An early manifestation of neurodegeneration is olfactory dysfunction (OD), which is also presented in diabetic patients. Previously, we demonstrated that OD correlates with IL-1β and miR-146a overexpression in the olfactory bulb (OB) on a T2D rodent model, suggesting the participation of inflammation on OD. Here, we found that OD persists on a long-term T2D condition after the downregulation of IL-1β. Remarkably, OD was associated with the increased expression of the dopaminergic neuronal marker tyrosine hydroxylase, ERK1/2 phosphorylation, and reduced neuronal activation on the OB of diabetic rats, suggesting the participation of the dopaminergic tone on the OD derived from T2D. Dopaminergic neurons are susceptible in neurodegenerative diseases such as Parkinson's disease; therefore further studies must be performed to completely elucidate the participation of these neurons and ERK1/2 signaling on olfactory impairment.
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Affiliation(s)
- Adriana Jiménez
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México 04510, México.,División de Investigación, Hospital Juárez de México, Ciudad de México 07760, México
| | - Amor Herrera-González
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
| | - Diana Organista-Juárez
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
| | - Enrique Estudillo
- Laboratorio de Reprogramación Celular, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez, Ciudad de México 14269, México
| | - Iván Velasco
- Laboratorio de Reprogramación Celular, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez, Ciudad de México 14269, México.,Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
| | - Natalí N Guerrero-Vargas
- Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
| | - Mara A Guzmán-Ruíz
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
| | - Rosalinda Guevara-Guzmán
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
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Faour M, Magnan C, Gurden H, Martin C. Olfaction in the context of obesity and diabetes: Insights from animal models to humans. Neuropharmacology 2021; 206:108923. [PMID: 34919903 DOI: 10.1016/j.neuropharm.2021.108923] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 12/07/2021] [Accepted: 12/10/2021] [Indexed: 12/12/2022]
Abstract
The olfactory system is at the crossroad between sensory processing and metabolic sensing. In addition to being the center of detection and identification of food odors, it is a sensor for most of the hormones and nutrients responsible for feeding behavior regulation. The consequences of modifications in body homeostasis, nutrient overload and alteration of this brain network in the pathological condition of food-induced obesity and type 2 diabetes are still not elucidated. The aim of this review was first to use both humans and animal studies to report on the current knowledge of the consequences of obesity and type 2 diabetes on odorant threshold and olfactory perception including identification discrimination and memory. We then discuss how olfactory processing can be modified by an alteration of the metabolic homeostasis of the organism and available elements on pharmacological treatments that regulate olfaction. We focus on data within the olfactory system but also on the interactions between the olfactory system and other brain networks impacted by metabolic diseases.
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Affiliation(s)
- Maya Faour
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | | | - Hirac Gurden
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | - Claire Martin
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France.
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Gouveri E, Papanas N. Olfactory Dysfunction: A Complication of Diabetes or a Factor That Complicates Glucose Metabolism? A Narrative Review. J Clin Med 2021; 10:jcm10235637. [PMID: 34884338 PMCID: PMC8658580 DOI: 10.3390/jcm10235637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 11/21/2021] [Accepted: 11/28/2021] [Indexed: 11/16/2022] Open
Abstract
The present narrative review presents emerging data regarding the association between diabetes mellitus and olfactory dysfunction and discusses the role of olfactory dysfunction in glucose metabolism. We searched relevant published articles in PubMed and Google Scholar until October 2021. Main key words included “olfactory dysfunction”, “diabetes mellitus”, and “glucose metabolism”. Olfactory dysfunction has been associated with diabetes mellitus. Furthermore, it has been proposed to be a diabetic complication, given that it has been linked with microvascular complications, such as diabetic peripheral neuropathy. Interestingly, it has been suggested that olfactory dysfunction is a manifestation of central neuropathy in diabetes, a hypothesis based on the observation that diabetes, olfactory dysfunction, and cognitive decline often coexist. However, evidence is limited and inconsistent. More importantly, olfactory and endocrine systems are closely linked, and olfactory dysfunction plays a significant role in glucose metabolism and obesity. Indeed, food behaviour and energy balance are influenced by olfaction status.
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Affiliation(s)
| | - Nikolaos Papanas
- Diabetes Centre, Second Department of Internal Medicine, Democritus University of Thrace, 68132 Alexandroupolis, Greece
- Correspondence: ; Fax: +30-25-5135-1723
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9
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Machine Learning Refutes Loss of Smell as a Risk Indicator of Diabetes Mellitus. J Clin Med 2021; 10:jcm10214971. [PMID: 34768493 PMCID: PMC8584618 DOI: 10.3390/jcm10214971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/19/2021] [Accepted: 10/21/2021] [Indexed: 12/02/2022] Open
Abstract
Because it is associated with central nervous changes, and olfactory dysfunction has been reported with increased prevalence among persons with diabetes, this study addressed the question of whether the risk of developing diabetes in the next 10 years is reflected in olfactory symptoms. In a cross-sectional study, in 164 individuals seeking medical consulting for possible diabetes, olfactory function was evaluated using a standardized clinical test assessing olfactory threshold, odor discrimination, and odor identification. Metabolomics parameters were assessed via blood concentrations. The individual diabetes risk was quantified according to the validated German version of the “FINDRISK” diabetes risk score. Machine learning algorithms trained with metabolomics patterns predicted low or high diabetes risk with a balanced accuracy of 63–75%. Similarly, olfactory subtest results predicted the olfactory dysfunction category with a balanced accuracy of 85–94%, occasionally reaching 100%. However, olfactory subtest results failed to improve the prediction of diabetes risk based on metabolomics data, and metabolomics data did not improve the prediction of the olfactory dysfunction category based on olfactory subtest results. Results of the present study suggest that olfactory function is not a useful predictor of diabetes.
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