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Zhang X, Zhu Y, Lu J, Chen Q, Chen F, Long C, Xu X, Ge D, Bai Y, Liu D, Du S, Zhu Z, Mai X, Yang QX, Zhang B. Altered functional connectivity of primary olfactory cortex-hippocampus-frontal cortex in subjective cognitive decline during odor stimulation. Hum Brain Mapp 2024; 45:e26814. [PMID: 39163575 PMCID: PMC11335137 DOI: 10.1002/hbm.26814] [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: 01/28/2024] [Revised: 07/08/2024] [Accepted: 07/29/2024] [Indexed: 08/22/2024] Open
Abstract
Subjective cognitive decline (SCD) is a high-risk population in the preclinical stage of Alzheimer's disease (AD), and olfactory dysfunction is a risk factor for dementia progression. The present study aimed to explore the patterns of functional connectivity (FC) changes in the olfactory neural circuits during olfactory stimulation in SCD subjects. A total of 56 SCD subjects and 56 normal controls (NCs) were included. All subjects were assessed with a cognitive scale, an olfactory behavior test, and olfactory task-based functional magnetic resonance imaging scanning. The FC differences in olfactory neural circuits between the two groups were analyzed by the generalized psychophysiological interaction. Additionally, we calculated and compared the activation of brain regions within the olfactory neural circuits during odor stimulation, the volumetric differences in brain regions showing FC differences between groups, and the correlations between neuroimaging indicators and olfactory behavioral and cognitive scale scores. During odor stimulation, the FC between the bilateral primary olfactory cortex (bPOC) and the right hippocampus in the SCD group was significantly reduced; while the FC between the right hippocampus and the right frontal cortex was significantly increased in the SCD group. The bPOC of all subjects showed significant activation, but no significant difference in activation between groups was found. No significant differences were observed in the volume of the brain regions within the olfactory neural circuits or in olfactory behavior between groups. The volume of the bPOC and right frontal cortex was significantly positively correlated with olfactory identification, and the volume of the right frontal cortex and right hippocampus was significantly correlated with cognitive functions. Furthermore, a significant correlation between the activation of bPOC and the olfactory threshold was found in the whole cohort. These results suggested that while the structure of the olfactory neural circuits and olfactory behavior in SCD subjects remained stable, there were significant changes observed in the FC of the olfactory neural circuits (specifically, the POC-hippocampus-frontal cortex neural circuits) during odor stimulation. These findings highlight the potential of FC alterations as sensitive imaging markers for identifying high-risk individuals in the early stage of AD.
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Affiliation(s)
- Xin Zhang
- Department of RadiologyNanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese MedicineNanjingChina
| | - Yajing Zhu
- Department of RadiologyNanjing Drum Tower Hospital Clinical College of Nanjing Medical UniversityNanjingChina
| | - Jiaming Lu
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical SchoolNanjing UniversityNanjingChina
| | - Qian Chen
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical SchoolNanjing UniversityNanjingChina
| | - Futao Chen
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical SchoolNanjing UniversityNanjingChina
| | - Cong Long
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical SchoolNanjing UniversityNanjingChina
| | - Xinru Xu
- Department of RadiologyNanjing Drum Tower Hospital Clinical College of Nanjing Medical UniversityNanjingChina
| | - Danni Ge
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical SchoolNanjing UniversityNanjingChina
| | - Yijun Bai
- Department of PsychologyNanjing UniversityNanjingChina
| | - Dongming Liu
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical SchoolNanjing UniversityNanjingChina
| | - Shunshun Du
- Department of PsychologyNanjing UniversityNanjingChina
| | - Zhengyang Zhu
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical SchoolNanjing UniversityNanjingChina
| | - Xiaoli Mai
- Department of RadiologyNanjing Drum Tower Hospital Clinical College of Nanjing Medical UniversityNanjingChina
| | - Qing X. Yang
- Department of RadiologyThe Pennsylvania State University College of MedicineHersheyPennsylvaniaUSA
| | - Bing Zhang
- Department of RadiologyNanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese MedicineNanjingChina
- Department of RadiologyNanjing Drum Tower Hospital Clinical College of Nanjing Medical UniversityNanjingChina
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical SchoolNanjing UniversityNanjingChina
- Department of PsychologyNanjing UniversityNanjingChina
- Institute of Medical Imaging and Artificial IntelligenceNanjing UniversityNanjingChina
- Medical Imaging Center, Affiliated Drum Tower HospitalMedical School of Nanjing UniversityNanjingChina
- Jiangsu Key Laboratory of Molecular MedicineNanjingChina
- Institute of Brain ScienceNanjing UniversityNanjingChina
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Huang X, Wu J, Zhang N, Teng J, Yang Q, Zhang Y, Yin T, Zhou W, Fan D, Ye S. Smell loss is associated with cognitive impairment in amyotrophic lateral sclerosis patients. CNS Neurosci Ther 2024; 30:e14851. [PMID: 38978196 PMCID: PMC11230928 DOI: 10.1111/cns.14851] [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: 04/09/2024] [Revised: 06/20/2024] [Accepted: 06/28/2024] [Indexed: 07/10/2024] Open
Abstract
BACKGROUND Smell loss significantly impacts the quality of life in patients. However, there is limited research on smell loss in individuals with amyotrophic lateral sclerosis (ALS), and the correlation between smell loss and cognitive impairment is unclear. This study aimed to investigate the correlation between smell loss and cognition impairment in ALS patients. METHODS The study included 216 ALS patients. The Edinburgh Cognitive and Behavioural ALS Screen (ECAS) and smell identification test specifically for the Chinese population (CSIT) were administered to evaluate participants' cognitive and olfactory function, respectively. RESULTS After covarying for age, sex, BMI, education level, degree of hunger, dietary bias, eagerness for food, stress, smoking status, alcohol consumption, and upper respiratory tract infection (URTI) or rhinitis, CSIT scores were significantly correlated with ECAS scores (r = 0.162, p = 0.028), especially the ALS-specific scores (r = 0.158, p = 0.031). Even after excluding patients with URTI or rhinitis, the results were similar. CSIT scores were significantly correlated with ECAS scores (r = 0.224, p = 0.011), especially the ALS-specific scores (r = 0.205, p = 0.019). CONCLUSION In patients with ALS, smell loss is significantly correlated with cognitive impairment, particularly frontotemporal dysfunction. Cognitive dysfunction may lead to worse olfactory performance in ALS patients.
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Affiliation(s)
- Xin Huang
- Department of Neurology, Peking University Third Hospital, Beijing, China
| | - Jieying Wu
- Department of Neurology, Peking University Third Hospital, Beijing, China
| | - Nan Zhang
- Department of Neurology, Peking University Third Hospital, Beijing, China
| | - Jinghong Teng
- Department of Neurology, Peking University Third Hospital, Beijing, China
| | - Qiong Yang
- Department of Neurology, Peking University Third Hospital, Beijing, China
- Beijing Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China
- Key Laboratory for Neuroscience, National Health Commission/Ministry of Education, Peking University, Beijing, China
| | - Yingshuang Zhang
- Department of Neurology, Peking University Third Hospital, Beijing, China
| | - Tielun Yin
- Department of Neurology, Peking University Third Hospital, Beijing, China
| | - Wen Zhou
- State Key Laboratory of Brain and Cognitive Science, Chinese Academy of Sciences, Beijing, China
- Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Dongsheng Fan
- Department of Neurology, Peking University Third Hospital, Beijing, China
- Beijing Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China
- Key Laboratory for Neuroscience, National Health Commission/Ministry of Education, Peking University, Beijing, China
| | - Shan Ye
- Department of Neurology, Peking University Third Hospital, Beijing, China
- Beijing Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China
- Key Laboratory for Neuroscience, National Health Commission/Ministry of Education, Peking University, Beijing, China
- Department of Neurology, Yan'an Hospital of Traditional Chinese Medicine, Yan'an, China
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Liu D, Lu J, Wei L, Yao M, Yang H, Lv P, Wang H, Zhu Y, Zhu Z, Zhang X, Chen J, Yang QX, Zhang B. Olfactory deficit: a potential functional marker across the Alzheimer's disease continuum. Front Neurosci 2024; 18:1309482. [PMID: 38435057 PMCID: PMC10907997 DOI: 10.3389/fnins.2024.1309482] [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: 10/08/2023] [Accepted: 02/02/2024] [Indexed: 03/05/2024] Open
Abstract
Alzheimer's disease (AD) is a prevalent form of dementia that affects an estimated 32 million individuals globally. Identifying early indicators is vital for screening at-risk populations and implementing timely interventions. At present, there is an urgent need for early and sensitive biomarkers to screen individuals at risk of AD. Among all sensory biomarkers, olfaction is currently one of the most promising indicators for AD. Olfactory dysfunction signifies a decline in the ability to detect, identify, or remember odors. Within the spectrum of AD, impairment in olfactory identification precedes detectable cognitive impairments, including mild cognitive impairment (MCI) and even the stage of subjective cognitive decline (SCD), by several years. Olfactory impairment is closely linked to the clinical symptoms and neuropathological biomarkers of AD, accompanied by significant structural and functional abnormalities in the brain. Olfactory behavior examination can subjectively evaluate the abilities of olfactory identification, threshold, and discrimination. Olfactory functional magnetic resonance imaging (fMRI) can provide a relatively objective assessment of olfactory capabilities, with the potential to become a promising tool for exploring the neural mechanisms of olfactory damage in AD. Here, we provide a timely review of recent literature on the characteristics, neuropathology, and examination of olfactory dysfunction in the AD continuum. We focus on the early changes in olfactory indicators detected by behavioral and fMRI assessments and discuss the potential of these techniques in MCI and preclinical AD. Despite the challenges and limitations of existing research, olfactory dysfunction has demonstrated its value in assessing neurodegenerative diseases and may serve as an early indicator of AD in the future.
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Affiliation(s)
- Dongming Liu
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Institute of Medical Imaging and Artificial Intelligence, Nanjing University, Nanjing, China
- Medical Imaging Center, The Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Jiaming Lu
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Institute of Medical Imaging and Artificial Intelligence, Nanjing University, Nanjing, China
- Medical Imaging Center, The Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Liangpeng Wei
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Institute of Medical Imaging and Artificial Intelligence, Nanjing University, Nanjing, China
- Medical Imaging Center, The Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Mei Yao
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Institute of Medical Imaging and Artificial Intelligence, Nanjing University, Nanjing, China
- Medical Imaging Center, The Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Huiquan Yang
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Institute of Medical Imaging and Artificial Intelligence, Nanjing University, Nanjing, China
- Medical Imaging Center, The Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Pin Lv
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Institute of Medical Imaging and Artificial Intelligence, Nanjing University, Nanjing, China
- Medical Imaging Center, The Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Haoyao Wang
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Institute of Medical Imaging and Artificial Intelligence, Nanjing University, Nanjing, China
- Medical Imaging Center, The Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Yajing Zhu
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Zhengyang Zhu
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Xin Zhang
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Institute of Medical Imaging and Artificial Intelligence, Nanjing University, Nanjing, China
- Medical Imaging Center, The Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Jiu Chen
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Institute of Medical Imaging and Artificial Intelligence, Nanjing University, Nanjing, China
- Medical Imaging Center, The Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Qing X. Yang
- Department of Radiology, Center for NMR Research, Penn State University College of Medicine, Hershey, PA, United States
| | - Bing Zhang
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Institute of Medical Imaging and Artificial Intelligence, Nanjing University, Nanjing, China
- Medical Imaging Center, The Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, China
- Jiangsu Key Laboratory of Molecular Medicine, Nanjing, China
- Institute of Brain Science, Nanjing University, Nanjing, China
- Jiangsu Provincial Medical Key Discipline (Laboratory), Nanjing, China
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Novel diagnostic tools for identifying cognitive impairment using olfactory-stimulated functional near-infrared spectroscopy: patient-level, single-group, diagnostic trial. Alzheimers Res Ther 2022; 14:39. [PMID: 35260170 PMCID: PMC8905807 DOI: 10.1186/s13195-022-00978-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/08/2022] [Indexed: 11/17/2022]
Abstract
Introduction Basic studies suggest that olfactory dysfunction and functional near-infrared spectroscopy (fNIRS) can be used as tools for the diagnosis of mild cognitive impairment (MCI); however, real-world evidence is lacking. We investigated the potential diagnostic efficacy of olfactory-stimulated fNIRS for early detection of MCI and/or Alzheimer disease (AD). Methods We conducted a patient-level, single-group, diagnostic interventional trial involving elderly volunteers (age >60 years) suspected of declining cognitive function. Patients received open-label olfactory-stimulated fNIRS for measurement of oxygenation difference in the orbitofrontal cortex. All participants underwent amyloid PET, MRI, Mini-Mental State Examination (MMSE), and Seoul Neuropsychological Screening Battery (SNSB). Results Of 97 subjects, 28 (28.9%) were cognitively normal, 32 (33.0%) had preclinical AD, 21 (21.6%) had MCI, and 16 (16.5%) had AD. Olfactory-stimulated oxygenation differences in the orbitofrontal cortex were associated with cognitive impairment; the association was more pronounced with cognitive severity. Olfactory-stimulated oxygenation difference was associated with MMSE (adjusted β [aβ] 1.001; 95% CI 0.540−1.463), SNSB language and related function (aβ, 1.218; 95% CI, 0.020−2.417), SNSB memory (aβ, 1.963; 95% CI, 0.841−3.084), SNSB frontal/executive function (aβ, 1.715; 95% CI, 0.401−3.029) scores, standard uptake value ratio from amyloid PET (aβ, −10.083; 95% CI, −19.063 to −1.103), and hippocampal volume from MRI (aβ, 0.002; 95% CI, 0.001−0.004). Olfactory-stimulated oxygenation difference in the orbitofrontal cortex was superior in diagnosing MCI and AD (AUC, 0.909; 95% CI, 0.848−0.971), compared to amyloid PET (AUC, 0.793; 95% CI, 0.694−0.893) or MRI (AUC, 0.758; 95% CI, 0.644−0.871). Discussion Our trial showed that olfactory-stimulated oxygenation differences in the orbitofrontal cortex detected by fNIRS were associated with cognitive impairment and cognitive-related objectives. This novel approach may be a potential diagnostic tool for patients with MCI and/or AD. Trial registration CRIS number, KCT0006197. Supplementary Information The online version contains supplementary material available at 10.1186/s13195-022-00978-w.
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Kim S, Nam Y, Kim HS, Jung H, Jeon SG, Hong SB, Moon M. Alteration of Neural Pathways and Its Implications in Alzheimer’s Disease. Biomedicines 2022; 10:biomedicines10040845. [PMID: 35453595 PMCID: PMC9025507 DOI: 10.3390/biomedicines10040845] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/29/2022] [Accepted: 03/31/2022] [Indexed: 02/01/2023] Open
Abstract
Alzheimer’s disease (AD) is a neurodegenerative disease accompanied by cognitive and behavioral symptoms. These AD-related manifestations result from the alteration of neural circuitry by aggregated forms of amyloid-β (Aβ) and hyperphosphorylated tau, which are neurotoxic. From a neuroscience perspective, identifying neural circuits that integrate various inputs and outputs to determine behaviors can provide insight into the principles of behavior. Therefore, it is crucial to understand the alterations in the neural circuits associated with AD-related behavioral and psychological symptoms. Interestingly, it is well known that the alteration of neural circuitry is prominent in the brains of patients with AD. Here, we selected specific regions in the AD brain that are associated with AD-related behavioral and psychological symptoms, and reviewed studies of healthy and altered efferent pathways to the target regions. Moreover, we propose that specific neural circuits that are altered in the AD brain can be potential targets for AD treatment. Furthermore, we provide therapeutic implications for targeting neuronal circuits through various therapeutic approaches and the appropriate timing of treatment for AD.
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Affiliation(s)
- Sujin Kim
- Department of Biochemistry, College of Medicine, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Korea; (S.K.); (Y.N.); (H.s.K.); (H.J.); (S.G.J.); (S.B.H.)
- Research Institute for Dementia Science, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Korea
| | - Yunkwon Nam
- Department of Biochemistry, College of Medicine, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Korea; (S.K.); (Y.N.); (H.s.K.); (H.J.); (S.G.J.); (S.B.H.)
| | - Hyeon soo Kim
- Department of Biochemistry, College of Medicine, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Korea; (S.K.); (Y.N.); (H.s.K.); (H.J.); (S.G.J.); (S.B.H.)
| | - Haram Jung
- Department of Biochemistry, College of Medicine, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Korea; (S.K.); (Y.N.); (H.s.K.); (H.J.); (S.G.J.); (S.B.H.)
| | - Seong Gak Jeon
- Department of Biochemistry, College of Medicine, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Korea; (S.K.); (Y.N.); (H.s.K.); (H.J.); (S.G.J.); (S.B.H.)
| | - Sang Bum Hong
- Department of Biochemistry, College of Medicine, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Korea; (S.K.); (Y.N.); (H.s.K.); (H.J.); (S.G.J.); (S.B.H.)
| | - Minho Moon
- Department of Biochemistry, College of Medicine, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Korea; (S.K.); (Y.N.); (H.s.K.); (H.J.); (S.G.J.); (S.B.H.)
- Research Institute for Dementia Science, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Korea
- Correspondence:
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Kamath V, Senjem ML, Spychalla AJ, Chen H, Palta P, Mosley TH, Windham BG, Griswold M, Knopman DS, Gottesman RF, Jack CR, Sharrett AR, Schneider AL. The Neuroanatomic Correlates of Olfactory Identification Impairment in Healthy Older Adults and in Persons with Mild Cognitive Impairment. J Alzheimers Dis 2022; 89:233-245. [PMID: 35871337 PMCID: PMC10134400 DOI: 10.3233/jad-220228] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
BACKGROUND Olfactory identification (OI) impairment appears early in the course of Alzheimer's disease dementia (AD), prior to detectable cognitive impairment. However, the neuroanatomical correlates of impaired OI in cognitively normal older adults (CN) and persons with mild cognitive impairment (MCI) are not fully understood. OBJECTIVE We examined the neuroanatomic correlates of OI impairment in older adults from the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS). METHODS Our sample included 1,600 older adults without dementia who completed clinical assessment and structural brain imaging from 2011 to 2013. We characterized OI impairment using the 12-item Sniffin' Sticks odor identification test (score ≤6). We used voxel-based morphometry (VBM) and region of interest (ROI) analyses to examine the neuroanatomic correlates of impaired OI in CN and MCI, after adjusting for potential confounders. Analyses were also separately stratified by race and sex. RESULTS In CN, OI impairment was associated with smaller amygdala gray matter (GM) volume (p < 0.05). In MCI, OI impairment was associated with smaller GM volumes of the olfactory cortex, amygdala, entorhinal cortex, hippocampus, and insula (ps < 0.05). Differential associations were observed by sex in MCI; OI impairment was associated with lower insular GM volumes among men but not among women (p-interaction = 0.04). There were no meaningful interactions by race. CONCLUSION The brain regions associated with OI impairment in individuals without dementia are specifically those regions known to be the primary targets of AD pathogenic processes. These findings highlight the potential utility of olfactory assessment in the identification and stratification of older adults at risk for AD.
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Affiliation(s)
- Vidyulata Kamath
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Matthew L. Senjem
- Department of Radiology, Mayo Clinic, Rochester, MN
- Department of Information Technology, Mayo Clinic, Rochester, MN
| | | | - Honglei Chen
- Department of Epidemiology and Biostatistics, Michigan State University, East Lansing, MI
| | - Priya Palta
- Division of General Medicine, Department of Medicine, Columbia University Irving Medical Center, New York, NY
| | - Thomas H. Mosley
- The MIND Center, Department of Medicine, The University of Mississippi School of Medicine, Jackson, MI
| | - B. Gwen Windham
- The MIND Center, Department of Medicine, The University of Mississippi School of Medicine, Jackson, MI
| | - Michael Griswold
- The MIND Center, Department of Medicine, The University of Mississippi School of Medicine, Jackson, MI
| | | | - Rebecca F. Gottesman
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | | | - A. Richey Sharrett
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health; Baltimore, MD
| | - Andrea L.C. Schneider
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
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Torske A, Koch K, Eickhoff S, Freiherr J. Localizing the human brain response to olfactory stimulation: A meta-analytic approach. Neurosci Biobehav Rev 2021; 134:104512. [PMID: 34968523 DOI: 10.1016/j.neubiorev.2021.12.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/18/2021] [Accepted: 12/20/2021] [Indexed: 11/28/2022]
Abstract
The human sense of smell and the ability to detect and distinguish odors allows for the extraction of valuable information from the environment, thereby driving human behavior. Not only can the sense of smell help to monitor the safety of inhaled air, but it can also help to evaluate the edibility of food. Therefore, in an effort to further our understanding of the human sense of smell, the aim of this meta-analysis was to provide the scientific community with activation probability maps of the functional anatomy of the olfactory system, in addition to separate activation maps for specific odor categories (pleasant, food, and aversive odors). The activation likelihood estimation (ALE) method was utilized to quantify all relevant and available data to perform a formal statistical analysis on the inter-study concordance of various odor categories. A total of 81 studies (108 contrasts, 1053 foci) fulfilled our inclusion criteria. Significant ALE peaks were observed in all odor categories in brain areas typically associated with the functional neuroanatomy of olfaction including the piriform cortex, amygdala, insula, and orbitofrontal cortex, amongst others. Additional contrast analyses indicate clear differences in neural activation patterns between odor categories.
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Affiliation(s)
- A Torske
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Technical University of Munich, Germany; Neuroimaging Center (TUM-NIC), Klinikum rechts der Isar, Technical University of Munich, Munich, Germany; Graduate School of Systemic Neurosciences, Ludwig Maximilians Universität München, Martinsried, Germany
| | - K Koch
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Technical University of Munich, Germany; Neuroimaging Center (TUM-NIC), Klinikum rechts der Isar, Technical University of Munich, Munich, Germany; Graduate School of Systemic Neurosciences, Ludwig Maximilians Universität München, Martinsried, Germany
| | - S Eickhoff
- Institute of Systems Neuroscience, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute of Neuroscience and Medicine, Brain & Behaviour (INM-7), Research Centre Jülich, Jülich, Germany
| | - J Freiherr
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany; Institute for Process Engineering and Packaging IVV, Sensory Analytics and Technologies, Fraunhofer Freising, Germany.
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Olfactory adaptation: recordings from the human olfactory epithelium. Eur Arch Otorhinolaryngol 2021; 279:3503-3510. [PMID: 34921612 PMCID: PMC9130158 DOI: 10.1007/s00405-021-07170-0] [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: 08/19/2021] [Accepted: 11/02/2021] [Indexed: 11/04/2022]
Abstract
Purpose Olfactory adaptation is a peripheral (at the epithelium level) or a central (at the brain level) mechanism resulting from repeated or prolonged odorous exposure that can induce a perceptual decrease. The aim of this study was to assess whether a peripheral adaptation occurs when an odor is repeated ten times. Moreover, the specificity of the peripheral adaptation to the nature of the odorant was investigated. Methods Four odorants (eugenol, manzanate, ISO E Super and phenylethanol) were presented using precisely controlled air-dilution olfactometry. They differed in terms of their physicochemical properties. Electrophysiological recordings were made at the level of the olfactory mucosa, the so-called electro-olfactogram (EOG). Thirty-five right-handed participants were recruited. Results Sixty-nine percent of the participants presented at least one EOG, whatever the odor condition. The EOG amplitude did not significantly decrease over 10 repeated exposures to any odorant. The intensity ratings tended to decrease over stimulations for manzanate, PEA, and eugenol. No correlation was found between the mean EOG amplitudes and the mean intensity ratings. However, the presence of EOG amplitude decreases over stimulations for few subjects suggests that peripheral adaptation might exist. Conclusion Overall, our results did not establish a clear peripheral adaptation measured with EOG but indicate the eventuality of such an effect. Supplementary Information The online version contains supplementary material available at 10.1007/s00405-021-07170-0.
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Chen B, Wang Q, Zhong X, Mai N, Zhang M, Zhou H, Haehner A, Chen X, Wu Z, Auber LA, Rao D, Liu W, Zheng J, Lin L, Li N, Chen S, Chen B, Hummel T, Ning Y. Structural and Functional Abnormalities of Olfactory-Related Regions in Subjective Cognitive Decline, Mild Cognitive Impairment, and Alzheimer's Disease. Int J Neuropsychopharmacol 2021; 25:361-374. [PMID: 34893841 PMCID: PMC9154279 DOI: 10.1093/ijnp/pyab091] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 11/11/2021] [Accepted: 12/09/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Odor identification (OI) dysfunction is an early marker of Alzheimer's disease (AD), but it remains unclear how olfactory-related regions change from stages of subjective cognitive decline (SCD) and mild cognitive impairment (MCI) to AD dementia. METHODS Two hundred and sixty-nine individuals were recruited in the present study. The olfactory-related regions were defined as the regions of interest, and the grey matter volume (GMV), low-frequency fluctuation, regional homogeneity (ReHo), and functional connectivity (FC) were compared for exploring the changing pattern of structural and functional abnormalities across AD, MCI, SCD, and normal controls. RESULTS From the SCD, MCI to AD groups, the reduced GMV, increased low-frequency fluctuation, increased ReHo, and reduced FC of olfactory-related regions became increasingly severe, and only the degree of reduced GMV of hippocampus and caudate nucleus clearly distinguished the 3 groups. SCD participants exhibited reduced GMV (hippocampus, etc.), increased ReHo (caudate nucleus), and reduced FC (hippocampus-hippocampus and hippocampus-parahippocampus) in olfactory-related regions compared with normal controls. Additionally, reduced GMV of the bilateral hippocampus and increased ReHo of the right caudate nucleus were associated with OI dysfunction and global cognitive impairment, and they exhibited partially mediated effects on the relationships between OI and global cognition across all participants. CONCLUSION Structural and functional abnormalities of olfactory-related regions present early with SCD and deepen with disease severity in the AD spectrum. The hippocampus and caudate nucleus may be the hub joining OI and cognitive function in the AD spectrum.
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Affiliation(s)
| | | | | | - Naikeng Mai
- Memory Clinic, Department of Geriatric Psychiatry, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, Guangdong Province, China
| | - Min Zhang
- Memory Clinic, Department of Geriatric Psychiatry, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, Guangdong Province, China
| | - Huarong Zhou
- Memory Clinic, Department of Geriatric Psychiatry, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, Guangdong Province, China
| | - Antje Haehner
- Smell and Taste Clinic, Department of Otorhinolaryngology, Technische Universität Dresden, Dresden, Germany
| | - Xinru Chen
- Memory Clinic, Department of Geriatric Psychiatry, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, Guangdong Province, China
| | - Zhangying Wu
- Memory Clinic, Department of Geriatric Psychiatry, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, Guangdong Province, China
| | - Lavinia Alberi Auber
- Department of Medicine, University of Fribourg, Fribourg, Switzerland,Swiss Integrative Center of Human Health, Fribourg, Switzerland
| | - Dongping Rao
- Memory Clinic, Department of Geriatric Psychiatry, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, Guangdong Province, China
| | - Wentao Liu
- Memory Clinic, Department of Geriatric Psychiatry, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, Guangdong Province, China
| | - Jinhong Zheng
- Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Lijing Lin
- Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Nanxi Li
- Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Sihao Chen
- Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Bingxin Chen
- Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Thomas Hummel
- Smell and Taste Clinic, Department of Otorhinolaryngology, Technische Universität Dresden, Dresden, Germany
| | - Yuping Ning
- Correspondence: Yuping Ning, PhD, No. 13, Mingxin Road, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, Guangdong Province, China ()
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10
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Feng Q, Liu H, Zhang H, Liu Y, Zhang H, Zhou Y, Liu G, Han T. Objective Assessment of Hyposmia in Alzheimer's Disease From Image and Behavior by Combining Pleasant Odor With Unpleasant Odor. Front Neurol 2021; 12:697487. [PMID: 34566843 PMCID: PMC8459611 DOI: 10.3389/fneur.2021.697487] [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: 04/19/2021] [Accepted: 07/22/2021] [Indexed: 11/15/2022] Open
Abstract
Background: Olfactory functional magnetic resonance imaging (fMRI) of responses to a pleasant odor (PO) (lavender) can objectively evaluate olfactory dysfunction in Alzheimer's disease (AD) patients. The brain responses to a PO and unpleasant odor (UPO) were shown to differ in normal young people. Whether AD patients with olfactory dysfunction have the same brain response is not yet known. Objective: Our aim was to explore whether olfactory fMRI with both a PO and UPO can provide more information regarding olfactory impairment in AD than a PO alone. Methods: Twenty-five normal controls (NC), 26 individuals with mild cognitive impairment (MCI), and 22 AD patients underwent olfactory fMRI with lavender and pyridine odorants at three concentrations (0.10, 0.33, and 1.00%) with a 3.0-T MRI scanner. Results: There were no differences in the number of activated voxels in the primary olfactory cortex (POC) between PO and UPO conditions in the NC, MCI, and AD groups (SPM, paired t-test, uncorrected p < 0.001, extent threshold = 70). In the right inferior frontal gyrus, orbital part (F3O), the number of activated voxels was greater with the UPO than with the PO in the NC group (SPM, paired t-test, uncorrected p < 0.001, extent threshold = 70), but there were no differences in the MCI and AD groups. Regardless of PO or UPO conditions, there were significant differences in the number of activated voxels in the POC among the NC, MCI, and AD groups. With increasing odor concentration, the number of activated voxels in the POC decreased in the NC group but increased in the AD group. When 0.10% UPO was presented, the NC group (21/25) showed a lower breathing amplitude and shorter inhalation time, whereas the AD patients (0/22) did not show such changes in breathing. Conclusions: After PO and UPO inhalation, brain activation and respiratory behavior in AD patients were significantly different than in NC patients. Therefore, olfactory fMRI using both PO and UPO stimulation, compared with PO stimulation only, can provide more objective information regarding hyposmia associated with AD based on imaging and behavior.
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Affiliation(s)
- Quanzhi Feng
- Department of Radiology, Tianjin Huanhu Hospital, Tianjin University, Tianjin, China.,Tianjin Key Laboratory of Cerebral Vascular and Neurodegenerative Diseases, Tianjin, China
| | - Hui Liu
- Department of Radiology, Tianjin Huanhu Hospital, Tianjin University, Tianjin, China
| | - Hui Zhang
- Department of Radiology, First Teaching Hospital of Tianjin University of Traditional Chinese, Tianjin, China
| | - Yi Liu
- Department of Ultrasound, Tianjin Huanhu Hospital, Tianjin, China
| | - Huihong Zhang
- Department of Neurology, Tianjin Huanhu Hospital, Tianjin, China
| | - Yuying Zhou
- Department of Neurology, Tianjin Huanhu Hospital, Tianjin, China
| | - Gang Liu
- Department of Otolaryngology, Tianjin Huanhu Hospital, Tianjin, China
| | - Tong Han
- Department of Radiology, Tianjin Huanhu Hospital, Tianjin University, Tianjin, China.,Tianjin Key Laboratory of Cerebral Vascular and Neurodegenerative Diseases, Tianjin, China
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11
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Dan X, Wechter N, Gray S, Mohanty JG, Croteau DL, Bohr VA. Olfactory dysfunction in aging and neurodegenerative diseases. Ageing Res Rev 2021; 70:101416. [PMID: 34325072 PMCID: PMC8373788 DOI: 10.1016/j.arr.2021.101416] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 12/15/2022]
Abstract
Alterations in olfactory functions are proposed to be early biomarkers for neurodegeneration. Many neurodegenerative diseases are age-related, including two of the most common, Parkinson's disease (PD) and Alzheimer's disease (AD). The establishment of biomarkers that promote early risk identification is critical for the implementation of early treatment to postpone or avert pathological development. Olfactory dysfunction (OD) is seen in 90% of early-stage PD patients and 85% of patients with early-stage AD, which makes it an attractive biomarker for early diagnosis of these diseases. Here, we systematically review widely applied smelling tests available for humans as well as olfaction assessments performed in some animal models and the relationships between OD and normal aging, PD, AD, and other conditions. The utility of OD as a biomarker for neurodegenerative disease diagnosis and future research directions are also discussed.
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Affiliation(s)
- Xiuli Dan
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Noah Wechter
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Samuel Gray
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Joy G Mohanty
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Deborah L Croteau
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Vilhelm A Bohr
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA; Danish Center for Healthy Aging, University of Copenhagen, 2200 Copenhagen, Denmark.
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12
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Kjelvik G, Evensmoen HR, Hummel T, Engedal K, Selbæk G, Saltvedt I, Håberg AK. The Human Brain Representation of Odor Identification in Amnestic Mild Cognitive Impairment and Alzheimer's Dementia of Mild Degree. Front Neurol 2021; 11:607566. [PMID: 33519686 PMCID: PMC7838677 DOI: 10.3389/fneur.2020.607566] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/02/2020] [Indexed: 11/13/2022] Open
Abstract
Background: Odor identification (OI) ability is a suggested early biomarker of Alzheimer's disease. In this study, we investigated brain activity within the brain's olfactory network associated with OI in patients with amnestic mild cognitive impairment (aMCI) and mild Alzheimer's dementia (mAD) to uncover the neuronal basis of this impairment. Materials and Methods: Patients with aMCI (n = 11) or mAD (n = 6) and 28 healthy older adults underwent OI functional MRI (fMRI) at 3T, OI, odor discrimination, and cognitive tests and apolipoprotein-e4 (APOE4) genotyping. Eleven patients had cerebrospinal fluid (CSF) analyzed. Those with aMCI were followed for 2 years to examine conversion to dementia. Results: The aMCI/mAD group performed significantly worse on all OI tests and the odor discrimination test compared to controls. The aMCI/mAD group had reduced activation in the right anterior piriform cortex compared to the controls during OI fMRI [Gaussian random field (GRF) corrected cluster threshold, p < 0.05]. This group difference remained after correcting for age, sex education, and brain parenchymal fraction. This difference in piriform activity was driven primarily by differences in odor discrimination ability and to a lesser extent by OI ability. There was no group by odor discrimination/identification score interaction on brain activity. Across both groups, only odor discrimination score was significantly associated with brain activity located to the right piriform cortex. Brain activity during OI was not associated with Mini Mental Status Examination scores. At the group level, the aMCI/mAD group activated only the anterior insula, while the control group had significant activation within all regions of the olfactory network during OI fMRI. There was no association between brain activity during OI fMRI and total beta-amyloid levels in the CSF in the aMCI/mAD group. Conclusion: The OI impairment in aMCI/mAD patients is associated with significantly reduced activity in the piriform cortex compared to controls. Activation of downstream regions within the olfactory network is also significantly affected in the aMCI/mAD group, except the anterior insula, which is impinged late in the course of Alzheimer's disease. OI tests thus reflect Alzheimer's disease pathology in olfactory brain structures.
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Affiliation(s)
- Grete Kjelvik
- Norwegian National Advisory Unit on Ageing and Health (Ageing and Health), Tønsberg, Norway.,Department of Radiology and Nuclear Medicine, St. Olavs Hospital (Norwegian National Advisory Unit for Functional Magnetic Resonance Imaging), University Hospital of Trondheim, Trondheim, Norway
| | - Hallvard R Evensmoen
- Department of Radiology and Nuclear Medicine, St. Olavs Hospital (Norwegian National Advisory Unit for Functional Magnetic Resonance Imaging), University Hospital of Trondheim, Trondheim, Norway.,Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Thomas Hummel
- Smell and Taste Clinic, Department of Otorhinolaryngology, Technische Universität Dresden, Dresden, Germany
| | - Knut Engedal
- Norwegian National Advisory Unit on Ageing and Health (Ageing and Health), Tønsberg, Norway
| | - Geir Selbæk
- Norwegian National Advisory Unit on Ageing and Health (Ageing and Health), Tønsberg, Norway.,Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Department of Geriatric Medicine, Oslo University Hospital, Oslo, Norway
| | - Ingvild Saltvedt
- Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway.,Department of Geriatrics, Clinic of Medicine, St. Olavs Hospital, University Hospital of Trondheim, Trondheim, Norway
| | - Asta K Håberg
- Department of Radiology and Nuclear Medicine, St. Olavs Hospital (Norwegian National Advisory Unit for Functional Magnetic Resonance Imaging), University Hospital of Trondheim, Trondheim, Norway.,Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
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13
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Abbasi NI, Bezerianos A, Hamano J, Chaudhury A, Thakor NV, Dragomir A. Evoked Brain Responses in Odor Stimuli Evaluation - an EEG Event Related Potential Study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:2861-2864. [PMID: 33018603 DOI: 10.1109/embc44109.2020.9175650] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Decoding olfactory cognition has been generating significant interest in recent years due to a wide range of applications, from diagnosing neurodegenerative disorders to consumer research and traditional medicine. In this study, we have investigated whether changes in odor stimuli evaluation across repeated stimuli presentation can be attributed to changes in brain perception of the stimuli. Epoch intervals representing olfactory sensory perception were extracted from electroencephalography (EEG) signals using minimum variance distortionless response (MVDR)-based single trial event related potential (ERP) approach to understand the evoked response to high pleasantness and low pleasantness stimuli. We found statistically significant changes in self reported stimuli evaluation between initial and final trials (p < 0.05) for both stimuli categories. However, the changes in ERP amplitude were found to be statistically significant only for the high pleasantness stimuli. This implies that olfactory stimuli of higher hedonic value recruit high-order cognitive processing that may be responsible for initial increased ERP response, as well as for rapid subsequent adaptation in processing the stimuli.
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