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Paitel ER, Nielson KA. Inhibitory P300 subprocesses and neural compensation in genetic risk for Alzheimer's disease: The case for temporal-spatial principal component analysis. Psychophysiology 2024:e14693. [PMID: 39344966 DOI: 10.1111/psyp.14693] [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: 04/17/2024] [Revised: 08/21/2024] [Accepted: 09/16/2024] [Indexed: 10/01/2024]
Abstract
The P300 event-related potential (ERP) is widely investigated in cognitive neuroscience, including related to aging, with smaller amplitudes and delayed latency consistently reported in Alzheimer's disease (AD). Given that AD-related neurological changes begin years before symptom onset, ERPs in asymptomatic elders with AD risk may characterize early changes. ERPs are seldom studied in this population. Yet, healthy carriers of apolipoprotein-E (APOE) ε4 have evidenced delayed P300 latencies, while P300 amplitude differences are seldom found. However, despite its frequent study, the specific cognitive processes reflected by P300 remain unclear. We propose that these challenges are due to the relatively long P300 window, which likely encompasses multiple underlying subprocesses that overlap in time. Temporal-spatial principal component analysis (tsPCA) maintains the high temporal resolution of EEG and is better suited to isolate processes that overlap in time. Thus, we interrogated APOE ε4 differences in P300 activity during successful stop-signal inhibitory control in healthy, cognitively intact older adults (25 ε4-, 20 ε4+), using both conventional ERP metrics (i.e., mean and peak amplitude) and P300 tsPCA factors. P300 amplitudes did not differ by ε4 using conventional metrics. tsPCA revealed two P300 factors in each ε4 group: first, a Posterior P300 (attention allocation) factor, and second, a relatively Anterior P300 (performance monitoring, evaluating, and updating) factor. tsPCA uniquely revealed greater activity in ε4+ vs. ε4- in Anterior P300. ε4 groups had comparable task performance, suggesting that greater P300 activity in ε4+ likely reflects neural compensation for ε4-related deficits, thereby enabling the maintenance of good task performance.
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Affiliation(s)
- Elizabeth R Paitel
- Department of Psychology, Marquette University, Milwaukee, Wisconsin, USA
| | - Kristy A Nielson
- Department of Psychology, Marquette University, Milwaukee, Wisconsin, USA
- Department of Neurology and the Center for Imaging Research, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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Kucikova L, Xiong X, Reinecke P, Madden J, Jackson E, Tappin O, Huang W, Dounavi ME, Su L. The effects of APOEe4 allele on cerebral structure, function, and related interactions with cognition in young adults. Ageing Res Rev 2024; 101:102510. [PMID: 39326705 DOI: 10.1016/j.arr.2024.102510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 09/11/2024] [Accepted: 09/16/2024] [Indexed: 09/28/2024]
Abstract
In the last decade, extensive research has emerged into understanding the impact of risk factors for Alzheimer's Disease (AD) on brain in pre-symptomatic stages. We investigated the neuroimaging correlates of the APOEe4 genetic risk factor for AD in young adulthood, its relationship with cognition, and potential effects of other variables on the findings. While conventional volumetric analyses revealed no consistent differences, more sophisticated analyses identified subtle structural differences between APOEe4 carriers and non-carriers. Findings from diffusion studies were limited, but functional studies demonstrated consistent alterations in connectivity and activity. The complex relationship between APOE genotype, neuroimaging variables, and cognition revealed no consensus on the directionality of findings. Methodological choices, including analytical approaches, sample size, and the influence of other genes, gender, and ethnicity, varied across studies, impacting comparability and generalizability. Recommendations for future research include multimodal and longitudinal imaging, standardisation of pipelines, advanced analytical techniques, and collaborative data pooling.
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Affiliation(s)
- Ludmila Kucikova
- Neuroscience Institute, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom; Insigneo Institute for In Silico Medicine, University of Sheffield, Sheffield, United Kingdom
| | - Xiong Xiong
- Neuroscience Institute, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom; School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing, China
| | - Patricia Reinecke
- Academic Unit of Medical Education, Medical School, University of Sheffield, Sheffield, United Kingdom
| | - Jessica Madden
- Academic Unit of Medical Education, Medical School, University of Sheffield, Sheffield, United Kingdom
| | - Elizabeth Jackson
- Academic Unit of Medical Education, Medical School, University of Sheffield, Sheffield, United Kingdom
| | - Oliver Tappin
- Academic Unit of Medical Education, Medical School, University of Sheffield, Sheffield, United Kingdom
| | - Weijie Huang
- Neuroscience Institute, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom; State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China; Department of Psychiatry, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Maria-Eleni Dounavi
- Department of Psychiatry, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Li Su
- Neuroscience Institute, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom; Insigneo Institute for In Silico Medicine, University of Sheffield, Sheffield, United Kingdom; Department of Psychiatry, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom.
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Liao W, Wang Y, Wang L, Li J, Huang D, Cheng W, Luan P. The current status and challenges of olfactory dysfunction study in Alzheimer's Disease. Ageing Res Rev 2024; 100:102453. [PMID: 39127444 DOI: 10.1016/j.arr.2024.102453] [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: 06/26/2024] [Accepted: 08/07/2024] [Indexed: 08/12/2024]
Abstract
Olfactory functioning involves multiple cognitive processes and the coordinated actions of various neural systems. Any disruption at any stage of this process may result in olfactory dysfunction, which is consequently widely used to predict the onset and progression of diseases, such as Alzheimer's Disease (AD). Although the underlying mechanisms have not yet been fully unraveled, apparent changes were observed in olfactory brain areas form patients who suffer from AD by means of medical imaging and electroencephalography (EEG). Olfactory dysfunction holds significant promise in detecting AD during the preclinical stage preceding mild cognitive impairment (MCI). Owing to the strong specificity, olfactory tests are prevalently applied for screening in community cohorts. And combining olfactory tests with other biomarkers may further establish an optimal model for AD prediction in studies of specific olfactory dysfunctions and improve the sensitivity and specificity of early AD diagnosis.
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Affiliation(s)
- Wanchen Liao
- Department of Alzheimer's Disease Clinical Research Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China
| | - Yulin Wang
- Department of Alzheimer's Disease Clinical Research Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China
| | - Lei Wang
- Department of Alzheimer's Disease Clinical Research Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China
| | - Jun Li
- Department of Alzheimer's Disease Clinical Research Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China
| | - Dongqing Huang
- Department of Alzheimer's Disease Clinical Research Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China
| | - Weibin Cheng
- Department of Alzheimer's Disease Clinical Research Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China.
| | - Ping Luan
- Department of Alzheimer's Disease Clinical Research Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China.
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Pedroso RV, Fraga FJ, Pavarini SCI, Nascimento CMC, Ayán C, Cominetti MR. A Systematic Review of Altered P300 Event-Related Potential in Apolipoprotein E4 ( APOE4) Carriers. Clin EEG Neurosci 2021; 52:193-200. [PMID: 32945192 DOI: 10.1177/1550059420959966] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Apolipoprotein ε4 allele (APOE4) is the strongest genetic risk factor for Alzheimer's disease and seems to be related to cognitive decline and damaged event-related potential P300, which is a sensitive measure to assess cognitive processing. OBJECTIVE This research aims to critically review the existing scientific evidence regarding the association between APOE4 and P300. METHODS A systematic review was carried out up to January 2020 on the following databases: Web of Science, Scopus and Medline/PubMed. Articles were considered for inclusion if they are original research that provided information regarding the association between APOE4 and P300, available in English, Spanish, or Portuguese, and available in full text. The methodological quality of the studies selected was evaluated using the quality assessment tool for observational cohort and cross-sectional studies recommended by Cochrane. RESULTS Out of 993 studies, 14 met the inclusion criteria. The results obtained showed that APOE4 is related to a longer P300 latency. However, the data supplied do not allow us to confirm if this relationship also occurs in amplitude measures. Moreover, it was observed that APOE genotype may influence P300 in different ages, from younger individuals to demented older people. CONCLUSION Evidence shows that APOE4 negatively influences cortical activities related to cognitive functions, as indicated by P300.
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Affiliation(s)
- Renata Valle Pedroso
- Department of Gerontology, 67828Federal University of São Carlos, São Carlos, SP, Brazil
| | - Francisco José Fraga
- Engineering, Modelling and Applied Social Sciences Center (CECS), 488580Federal University of the ABC (UFABC), Santo André, SP, Brazil
| | | | | | - Carlos Ayán
- Well-Move Research Group, Department of Special Didactics, 16784University of Vigo, Vigo, Spain.,IIS Galicia Sur, Vigo, Spain
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Olofsson JK. Olfaction and Aging: A Review of the Current State of Research and Future Directions. Iperception 2021; 12:20416695211020331. [PMID: 34249327 PMCID: PMC8239976 DOI: 10.1177/20416695211020331] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/21/2021] [Indexed: 11/16/2022] Open
Abstract
Olfaction, the sense of smell, is characterized by a notable age-dependency such that aging individuals are more likely to have poor olfactory abilities. These impairments are considered to be mostly irreversible and as having potentially profound effects on quality of life and food behavior, as well as constituting warning signs of mortality, cognitive dysfunction, and dementia. Here, we review the current state of research on aging and olfaction, focusing on five topics which we regard to be of particular relevance for the field: nutrition and health, cognition and dementia, mortality, environment and genetics, and training-based enhancement. Under each of these headlines, we provide a state-of-the-art overview and discuss gaps in our knowledge which might be filled by further research. Understanding how olfactory abilities are diminished in aging, and how they may be alleviated or recovered, involves a set of challenging tasks for researchers in the years to come.
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Affiliation(s)
- Jonas K. Olofsson
- Gösta Ekman Laboratory, Stockholm University, Stockholm, Sweden; Department of Psychology, Stockholm University, Stockholm, Sweden
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Cintra MTG, Ávila RT, Soares TO, Cunha LCM, Silveira KD, de Moraes EN, Simas KR, Fernandes RB, Gonçalves DU, de Rezende NA, Bicalho MAC. Increased N200 and P300 latencies in cognitively impaired elderly carrying ApoE ε-4 allele. Int J Geriatr Psychiatry 2018; 33:e221-e227. [PMID: 28833437 DOI: 10.1002/gps.4773] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 07/12/2017] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To compare the results of neuropsychological tests, evoked potentials N200 and P300 and polymorphisms of ApoE and BDNF rs6265 between patients with normal cognition and those with mild cognitive impairment (MCI) and Alzheimer's dementia (AD). METHODS This is a cross-sectional study of elderly individuals with normal cognition and those with MCI and AD, who were submitted to evoked potential tests (N200 and P300) by means of hearing stimuli based on the auditory oddball paradigm. Genotyping was obtained by using the real-time PCR technique. RESULTS Sixty-five patients were evaluated as follows: 14 controls, 34 with MCI and 17 with AD. N200 latency and P300 latency and amplitude were not associated with MCI and AD diagnosis. Patients with cognitive impairment (MCI or AD) showed increase in the latencies of P300 and N200. BNDF gene was not associated with cognitive impairment. CONCLUSION Latencies of N200 and P300 increased in cognitively impaired patients with the presence of ApoE ε-4 allele.
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Affiliation(s)
| | - Rafaela Teixeira Ávila
- Neuropsychologist of Clinical Hospital of Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Thayana Oliveira Soares
- Molecular Medicine Postgraduate Program of Universidade Federal de Mina Gerais, Belo Horizonte, Brazil
| | | | - Katia Daniela Silveira
- Department of Biochemistry and Immunology of Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Edgar Nunes de Moraes
- Department of Medical Clinic of Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Kaique Roger Simas
- Medicine Student of Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Denise Utsch Gonçalves
- Department of Ophthalmology and Otorhinolaryngology of Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Nilton Alves de Rezende
- Department of Medical Clinic of Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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Olfactory disturbances in ageing with and without dementia: towards new diagnostic tools. The Journal of Laryngology & Otology 2017; 131:572-579. [PMID: 28424103 DOI: 10.1017/s0022215117000858] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Olfactory disorders increase with age and often affect elderly people who have pre-dementia or dementia. Despite the frequent occurrence of olfactory changes at the early stages of neurodegenerative disorders such as Alzheimer's disease, olfactory disorders are rarely assessed in daily clinical practice, mainly due to a lack of standardised assessment tools. The aims of this review were to (1) summarise the existing literature on olfactory disorders in ageing populations and patients with neurodegenerative disorders; (2) present the strengths and weaknesses of current olfactory disorder assessment tools; and (3) discuss the benefits of developing specific olfactory tests for neurodegenerative diseases. METHODS A systematic review was performed of literature published between 2000 and 2015 addressing olfactory disorders in elderly people with or without Alzheimer's disease or other related disorders to identify the main tools currently used for olfactory disorder assessment. RESULTS Olfactory disorder assessment is a promising method for improving both the early and differential diagnosis of Alzheimer's disease. However, the current lack of consensus on which tests should be used does not permit the consistent integration of olfactory disorder assessment into clinical settings. CONCLUSION Otolaryngologists are encouraged to use olfactory tests in older adults to help predict the development of neurodegenerative diseases. Olfactory tests should be specifically adapted to assess olfactory disorders in Alzheimer's disease patients.
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Peng KY, Mathews PM, Levy E, Wilson DA. Apolipoprotein E4 causes early olfactory network abnormalities and short-term olfactory memory impairments. Neuroscience 2016; 343:364-371. [PMID: 28003161 DOI: 10.1016/j.neuroscience.2016.12.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 11/30/2016] [Accepted: 12/02/2016] [Indexed: 02/08/2023]
Abstract
While apolipoprotein (Apo) E4 is linked to increased incidence of Alzheimer's disease (AD), there is growing evidence that it plays a role in functional brain irregularities that are independent of AD pathology. However, ApoE4-driven functional differences within olfactory processing regions have yet to be examined. Utilizing knock-in mice humanized to ApoE4 versus the more common ApoE3, we examined a simple olfactory perceptual memory that relies on the transfer of information from the olfactory bulb (OB) to the piriform cortex (PCX), the primary cortical region involved in higher order olfaction. In addition, we have recorded in vivo resting and odor-evoked local field potentials (LPF) from both brain regions and measured corresponding odor response magnitudes in anesthetized young (6-month-old) and middle-aged (12-month-old) ApoE mice. Young ApoE4 compared to ApoE3 mice exhibited a behavioral olfactory deficit coinciding with hyperactive odor-evoked response magnitudes within the OB that were not observed in older ApoE4 mice. Meanwhile, middle-aged ApoE4 compared to ApoE3 mice exhibited heightened response magnitudes in the PCX without a corresponding olfactory deficit, suggesting a shift with aging in ApoE4-driven effects from OB to PCX. Interestingly, the increased ApoE4-specific response in the PCX at middle-age was primarily due to a dampening of baseline spontaneous activity rather than an increase in evoked response power. Our findings indicate that early ApoE4-driven olfactory memory impairments and OB network abnormalities may be a precursor to later network dysfunction in the PCX, a region that not only is targeted early in AD, but may be selectively vulnerable to ApoE4 genotype.
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Affiliation(s)
- Katherine Y Peng
- Department of Neuroscience & Physiology, New York University Langone Medical Center, 560 1st Avenue, 10016 New York, NY, USA; Department of Biochemistry & Molecular Pharmacology, New York University Langone Medical Center, 560 1st Avenue, 10016 New York, NY, USA.
| | - Paul M Mathews
- Department of Psychiatry, New York University Langone Medical Center, 560 1st Avenue, 10016 New York, NY, USA; Center for Dementia Research, Nathan S. Kline Institute, 140 Old Orangeburg Road, Orangeburg, 10962 New York, USA.
| | - Efrat Levy
- Department of Biochemistry & Molecular Pharmacology, New York University Langone Medical Center, 560 1st Avenue, 10016 New York, NY, USA; Department of Psychiatry, New York University Langone Medical Center, 560 1st Avenue, 10016 New York, NY, USA; Center for Dementia Research, Nathan S. Kline Institute, 140 Old Orangeburg Road, Orangeburg, 10962 New York, USA.
| | - Donald A Wilson
- Department of Neuroscience & Physiology, New York University Langone Medical Center, 560 1st Avenue, 10016 New York, NY, USA; Department of Child & Adolescent Psychiatry, New York University Langone Medical Center, 560 1st Avenue, 10016 New York, NY, USA; Emotional Brain Institute, Nathan S. Kline Institute, 140 Old Orangeburg Road, Orangeburg, 10962 New York, USA.
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Raju HB, Tsinoremas NF, Capobianco E. Emerging Putative Associations between Non-Coding RNAs and Protein-Coding Genes in Neuropathic Pain: Added Value from Reusing Microarray Data. Front Neurol 2016; 7:168. [PMID: 27803687 PMCID: PMC5067702 DOI: 10.3389/fneur.2016.00168] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 09/20/2016] [Indexed: 12/28/2022] Open
Abstract
Regeneration of injured nerves is likely occurring in the peripheral nervous system, but not in the central nervous system. Although protein-coding gene expression has been assessed during nerve regeneration, little is currently known about the role of non-coding RNAs (ncRNAs). This leaves open questions about the potential effects of ncRNAs at transcriptome level. Due to the limited availability of human neuropathic pain (NP) data, we have identified the most comprehensive time-course gene expression profile referred to sciatic nerve (SN) injury and studied in a rat model using two neuronal tissues, namely dorsal root ganglion (DRG) and SN. We have developed a methodology to identify differentially expressed bioentities starting from microarray probes and repurposing them to annotate ncRNAs, while analyzing the expression profiles of protein-coding genes. The approach is designed to reuse microarray data and perform first profiling and then meta-analysis through three main steps. First, we used contextual analysis to identify what we considered putative or potential protein-coding targets for selected ncRNAs. Relevance was therefore assigned to differential expression of neighbor protein-coding genes, with neighborhood defined by a fixed genomic distance from long or antisense ncRNA loci, and of parental genes associated with pseudogenes. Second, connectivity among putative targets was used to build networks, in turn useful to conduct inference at interactomic scale. Last, network paths were annotated to assess relevance to NP. We found significant differential expression in long-intergenic ncRNAs (32 lincRNAs in SN and 8 in DRG), antisense RNA (31 asRNA in SN and 12 in DRG), and pseudogenes (456 in SN and 56 in DRG). In particular, contextual analysis centered on pseudogenes revealed some targets with known association to neurodegeneration and/or neurogenesis processes. While modules of the olfactory receptors were clearly identified in protein-protein interaction networks, other connectivity paths were identified between proteins already investigated in studies on disorders, such as Parkinson, Down syndrome, Huntington disease, and Alzheimer. Our findings suggest the importance of reusing gene expression data by meta-analysis approaches.
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Affiliation(s)
- Hemalatha B Raju
- Center for Computational Science, University of Miami Miller School of Medicine, Miami, FL, USA; Human Genetics and Genomic Graduate Program, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Nicholas F Tsinoremas
- Center for Computational Science, University of Miami Miller School of Medicine, Miami, FL, USA; Human Genetics and Genomic Graduate Program, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Enrico Capobianco
- Center for Computational Science, University of Miami Miller School of Medicine , Miami, FL , USA
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Grashow R, Sparrow D, Hu H, Weisskopf MG. Cumulative lead exposure is associated with reduced olfactory recognition performance in elderly men: The Normative Aging Study. Neurotoxicology 2015; 49:158-64. [PMID: 26121922 DOI: 10.1016/j.neuro.2015.06.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 06/05/2015] [Accepted: 06/23/2015] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Olfactory dysfunction has been identified as an early warning sign for Alzheimer's disease, Parkinson's disease, dementia and more. A few occupational and environmental exposures have also been associated with reduced olfactory function, although the effects of long term environmental exposure to lead on olfactory dysfunction have not been explored. Here we performed olfactory recognition testing in elderly men in a community-dwelling cohort and examined the association with cumulative lead exposure, as assessed by lead in tibial and patellar bone. METHODS Olfactory recognition was measured in 165 men from the Normative Aging Study (NAS) who had previously taken part in bone lead measurements using K-X-ray fluorescence (KXRF). Olfactory recognition was measured using the University of Pennsylvania Smell Identification Test (UPSIT). Associations between olfactory recognition, global cognition and cumulative lead exposure were estimated using linear regression, with additional adjustment for age, smoking, and functional polymorphism status for hemochromatosis (HFE), transferrin (TfC2), glutathione-s-transferase Pi1 (GSTP1) and apolipoprotein E (APOE) genotypes. Sensitivity analyses explored olfactory recognition in men with high global cognitive function as measured using the Mini-Mental Status Exam (MMSE). RESULTS The average age of the NAS participants at the time of olfactory recognition testing was 80.3 (standard deviation or SD=5.7) years. Mean tibia lead was 16.3 (SD=12.0) μg/g bone, mean patella lead was 22.4 (SD=14.4)μg/g bone, and mean UPSIT score was 26.9 out of 40 (SD=7.0). Consistent with previous findings, age at olfaction testing was negatively associated with UPSIT score. Tibia (but not patella) bone lead was negatively associated with olfaction recognition (per 15 μg/g tibia lead: β=-1.57; 95% CI: -2.93, -0.22; p=0.02) in models adjusted for smoking and age. Additional adjustment for education did not significantly change results. Of all the genes explored, only the presence of one or more HFE variant alleles was significantly associated with olfaction recognition (HFE β=2.26; 95% CI: 0.09, 4.43; p=0.04). In a model containing the HFE term and a lead term, the tibia lead parameter estimate dropped by 21% (per 15 μg/g tibia lead: β=-1.25; 95% CI: -2.64, 0.14; p=0.08) while the HFE term dropped 15% (β=1.91; 95% CI: -0.28, 4.10; p=0.09). None of the other gene terms were associated with olfactory recognition in this cohort, nor were any gene-lead interaction terms significant. Additional sensitivity analysis in men with MMSE scores of 25 or higher (n=149) showed a similar but slightly attenuated association between lead and olfactory recognition (per 15 μg/g tibia lead β=-1.39; 95% CI: -3.00, 0.22; p=0.09). CONCLUSION Cumulative exposure to lead is associated with reduced olfactory recognition in a cohort of elderly men. The association was similar but not significant in men with better cognitive function as measured by the MMSE. Iron metabolism gene status may also affect olfactory function.
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Affiliation(s)
- Rachel Grashow
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Department of Civil and Environmental Engineering, Northeastern University, Boston, MA, USA.
| | - David Sparrow
- VA Boston Healthcare System, Boston University Schools of Public Health and Medicine, Boston, MA, USA; Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Howard Hu
- Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada
| | - Marc G Weisskopf
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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Naudin M, Atanasova B. Olfactory markers of depression and Alzheimer's disease. Neurosci Biobehav Rev 2014; 45:262-70. [DOI: 10.1016/j.neubiorev.2014.06.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 05/23/2014] [Accepted: 06/27/2014] [Indexed: 10/25/2022]
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