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Tropitzsch A, Schade-Mann T, Gamerdinger P, Dofek S, Schulte B, Schulze M, Fehr S, Biskup S, Haack TB, Stöbe P, Heyd A, Harre J, Lesinski-Schiedat A, Büchner A, Lenarz T, Warnecke A, Müller M, Vona B, Dahlhoff E, Löwenheim H, Holderried M. Variability in Cochlear Implantation Outcomes in a Large German Cohort With a Genetic Etiology of Hearing Loss. Ear Hear 2023; 44:1464-1484. [PMID: 37438890 PMCID: PMC10583923 DOI: 10.1097/aud.0000000000001386] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 04/04/2023] [Indexed: 07/14/2023]
Abstract
OBJECTIVES The variability in outcomes of cochlear implantation is largely unexplained, and clinical factors are not sufficient for predicting performance. Genetic factors have been suggested to impact outcomes, but the clinical and genetic heterogeneity of hereditary hearing loss makes it difficult to determine and interpret postoperative performance. It is hypothesized that genetic mutations that affect the neuronal components of the cochlea and auditory pathway, targeted by the cochlear implant (CI), may lead to poor performance. A large cohort of CI recipients was studied to verify this hypothesis. DESIGN This study included a large German cohort of CI recipients (n = 123 implanted ears; n = 76 probands) with a definitive genetic etiology of hearing loss according to the American College of Medical Genetics (ACMG)/Association for Molecular Pathology (AMP) guidelines and documented postoperative audiological outcomes. All patients underwent preoperative clinical and audiological examinations. Postoperative CI outcome measures were based on at least 1 year of postoperative audiological follow-up for patients with postlingual hearing loss onset (>6 years) and 5 years for children with congenital or pre/perilingual hearing loss onset (≤6 years). Genetic analysis was performed based on three different methods that included single-gene screening, custom-designed hearing loss gene panel sequencing, targeting known syndromic and nonsyndromic hearing loss genes, and whole-genome sequencing. RESULTS The genetic diagnosis of the 76 probands in the genetic cohort involved 35 genes and 61 different clinically relevant (pathogenic, likely pathogenic) variants. With regard to implanted ears (n = 123), the six most frequently affected genes affecting nearly one-half of implanted ears were GJB2 (21%; n = 26), TMPRSS3 (7%; n = 9), MYO15A (7%; n = 8), SLC26A4 (5%; n = 6), and LOXHD1 and USH2A (each 4%; n = 5). CI recipients with pathogenic variants that influence the sensory nonneural structures performed at or above the median level of speech performance of all ears at 70% [monosyllable word recognition score in quiet at 65 decibels sound pressure level (SPL)]. When gene expression categories were compared to demographic and clinical categories (total number of compared categories: n = 30), mutations in genes expressed in the spiral ganglion emerged as a significant factor more negatively affecting cochlear implantation outcomes than all clinical parameters. An ANOVA of a reduced set of genetic and clinical categories (n = 10) identified five detrimental factors leading to poorer performance with highly significant effects ( p < 0.001), accounting for a total of 11.8% of the observed variance. The single strongest category was neural gene expression accounting for 3.1% of the variance. CONCLUSIONS The analysis of the relationship between the molecular genetic diagnoses of a hereditary etiology of hearing loss and cochlear implantation outcomes in a large German cohort of CI recipients revealed significant variabilities. Poor performance was observed with genetic mutations that affected the neural components of the cochlea, supporting the "spiral ganglion hypothesis."
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Affiliation(s)
- Anke Tropitzsch
- Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
- Hearing Center, Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
- Center for Rare Hearing Disorders, Centre for Rare Diseases, University of Tübingen, Tübingen, Germany
- Neurosensory Center, Departments of Otolaryngology—Head & Neck Surgery and Ophthalmology, University of Tübingen Medical Center, Tübingen, Germany
| | - Thore Schade-Mann
- Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
- Hearing Center, Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
| | - Philipp Gamerdinger
- Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
- Hearing Center, Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
| | - Saskia Dofek
- Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
| | - Björn Schulte
- CeGaT GmbH und Praxis für Humangenetik Tübingen, Tübingen, Germany
| | - Martin Schulze
- CeGaT GmbH und Praxis für Humangenetik Tübingen, Tübingen, Germany
| | - Sarah Fehr
- CeGaT GmbH und Praxis für Humangenetik Tübingen, Tübingen, Germany
| | - Saskia Biskup
- CeGaT GmbH und Praxis für Humangenetik Tübingen, Tübingen, Germany
| | - Tobias B. Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Petra Stöbe
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Andreas Heyd
- Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
| | - Jennifer Harre
- Department of Otorhinolaryngology—Head & Neck Surgery, Hannover Medical School, Hannover, Germany
- Cluster of Excellence “Hearing4all” of the German Research Foundation, Hannover, Germany
| | - Anke Lesinski-Schiedat
- Department of Otorhinolaryngology—Head & Neck Surgery, Hannover Medical School, Hannover, Germany
- Cluster of Excellence “Hearing4all” of the German Research Foundation, Hannover, Germany
| | - Andreas Büchner
- Department of Otorhinolaryngology—Head & Neck Surgery, Hannover Medical School, Hannover, Germany
- Cluster of Excellence “Hearing4all” of the German Research Foundation, Hannover, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology—Head & Neck Surgery, Hannover Medical School, Hannover, Germany
- Cluster of Excellence “Hearing4all” of the German Research Foundation, Hannover, Germany
| | - Athanasia Warnecke
- Department of Otorhinolaryngology—Head & Neck Surgery, Hannover Medical School, Hannover, Germany
- Cluster of Excellence “Hearing4all” of the German Research Foundation, Hannover, Germany
| | - Marcus Müller
- Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
- Neurosensory Center, Departments of Otolaryngology—Head & Neck Surgery and Ophthalmology, University of Tübingen Medical Center, Tübingen, Germany
| | - Barbara Vona
- Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
- Neurosensory Center, Departments of Otolaryngology—Head & Neck Surgery and Ophthalmology, University of Tübingen Medical Center, Tübingen, Germany
| | - Ernst Dahlhoff
- Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
- Neurosensory Center, Departments of Otolaryngology—Head & Neck Surgery and Ophthalmology, University of Tübingen Medical Center, Tübingen, Germany
| | - Hubert Löwenheim
- Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
- Neurosensory Center, Departments of Otolaryngology—Head & Neck Surgery and Ophthalmology, University of Tübingen Medical Center, Tübingen, Germany
| | - Martin Holderried
- Department of Otolaryngology—Head & Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
- Department of Medical Development and Quality Management, University Hospital Tübingen, Tübingen, Germany
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2
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Yang Z, Ni J, Teng Y, Su M, Wei M, Li T, Fan D, Lu T, Xie H, Zhang W, Shi J, Tian J. Effect of hearing aids on cognitive functions in middle-aged and older adults with hearing loss: A systematic review and meta-analysis. Front Aging Neurosci 2022; 14:1017882. [PMID: 36452439 PMCID: PMC9704725 DOI: 10.3389/fnagi.2022.1017882] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 10/13/2022] [Indexed: 09/23/2023] Open
Abstract
OBJECTIVE The study aimed to examine the effects of hearing aids on cognitive function in middle-aged and older adults with hearing loss. DATA SOURCES AND STUDY SELECTION PubMed, Cochrane Library, and Embase were searched for studies published before 30 March 2022. Randomized controlled trials (RCTs) and non-randomized studies of interventions (NRSIs) were included in the search. Restriction was set on neither types, severity, or the time of onset of hearing impairment nor cognitive or psychiatric statuses. DATA EXTRACTION AND SYNTHESIS Two independent reviewers extracted data and assessed the study quality of RCTs. Cognitive function outcomes were descriptively summarized and converted to standardized mean difference (SMD) in the meta-analysis. Meta-analysis was conducted in RCTs. Sub-group analyses were conducted by cognitive statuses, psychiatric disorders, and cognitive domains. RESULTS A total of 15 studies met the inclusion criteria, including five RCTs (n = 339) and 10 NRSIs (n = 507). Groups were classified as subjects without dementia or with normal global cognition, subjects with AD or dementia, and subjects with depressive symptoms. For subjects without dementia, improvements were found in global cognition, executive function, and episodic memory. For subjects with depressive symptoms, improvements were found in immediate memory, global cognition, and executive function. No improvement was found in subjects with AD or dementia. In total, four RCTs were included in the meta-analysis. For subjects without dementia (SMD = 0.11, 95% confidence interval [CI]: -0.15-0.37) and those with AD, no significant effect was found (SMD = -0.19, 95% CI: -0.65-0.28). For subjects without dementia, no significant effect was found in language (SMD = 0.14, 95% CI: -0.30-0.59) or general executive function (SMD = -0.04, 95% CI: -0.46-0.38). Further sub-group analysis found no significant effect in executive function (SMD = -0.27, 95% CI: -0.72-0.18) or processing speed (SMD = -0.02, 95% CI: -0.49-0.44). CONCLUSION Hearing aids might improve cognitive performance in domains such as executive function in subjects without dementia. The effects on subjects with depressive symptoms remained unclear. No improvement was found in subjects with AD or dementia. Long-term RCTs and well-matched comparison-group studies with large sample sizes are warranted. SYSTEMATIC REVIEW REGISTRATION https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022349057.
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Affiliation(s)
- Zhizhong Yang
- Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Jingnian Ni
- Department of Neurology, Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Yuou Teng
- Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Mingwan Su
- Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Mingqing Wei
- Department of Neurology, Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Ting Li
- Department of Neurology, Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Dongsheng Fan
- Department of Neurology, Peking University Third Hospital, Beijing, China
| | - Tao Lu
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing, China
| | - Hengge Xie
- Department of Neurology, Chinese PLA General Hospital, Beijing, China
| | - Wei Zhang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jing Shi
- Department of Neurology, Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Jinzhou Tian
- Department of Neurology, Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
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3
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Wu YQ, Wang YN, Zhang LJ, Liu LQ, Pan YC, Su T, Liao XL, Shu HY, Kang M, Ying P, Xu SH, Shao Y. Regional Homogeneity in Patients With Mild Cognitive Impairment: A Resting-State Functional Magnetic Resonance Imaging Study. Front Aging Neurosci 2022; 14:877281. [PMID: 35493938 PMCID: PMC9050296 DOI: 10.3389/fnagi.2022.877281] [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: 02/16/2022] [Accepted: 03/22/2022] [Indexed: 12/31/2022] Open
Abstract
Objective To analyze the potential changes in brain neural networks in resting state functional magnetic resonance imaging (rs-fMRI) scans by regional homogeneity (ReHo) in patients with mild cognitive impairment (MCI). Methods We recruited and selected 24 volunteers, including 12 patients (6 men and 6 women) with MCI and 12 healthy controls matched by age, sex, and lifestyle. All subjects were examined with rs-fMRI to evaluate changes in neural network connectivity, and the data were analyzed by ReHo method. Correlation analysis was used to investigate the relationship between ReHo values and clinical features in different brain regions of MCI patients. The severity of MCI was determined by the Mini-Mental State Examination (MMSE) scale. Results The signals of the right cerebellum areas 4 and 5, left superior temporal, right superior temporal, left fusiform, and left orbital middle frontal gyri in the patient group were significantly higher than those in the normal group (P < 0.01 by t-test of paired samples). The signal intensity of the right inferior temporal and left inferior temporal gyri was significantly lower than that of the normal group (P < 0.01). The ReHO value for the left inferior temporal gyrus correlated negatively with disease duration, and the value for the right inferior temporal gyrus correlated positively with MMSE scores. Conclusion Mild cognitive impairment in patients with pre- Alzheimer's disease may be related to the excitation and inhibition of neural networks in these regions. This may have a certain guiding significance for clinical diagnosis.
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Affiliation(s)
- Yu-Qian Wu
- Department of Ophthalmology and Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yi-Ning Wang
- Department of Ophthalmology and Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Li-Juan Zhang
- Department of Ophthalmology and Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Li-Qi Liu
- Department of Ophthalmology and Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yi-Cong Pan
- Department of Ophthalmology and Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Ting Su
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
| | - Xu-Lin Liao
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Sha Tin, Hong Kong SAR, China
| | - Hui-Ye Shu
- Department of Ophthalmology and Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Min Kang
- Department of Ophthalmology and Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Ping Ying
- Department of Ophthalmology and Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - San-Hua Xu
- Department of Ophthalmology and Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yi Shao
- Department of Ophthalmology and Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China,*Correspondence: Yi Shao,
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4
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Powell DS, Oh ES, Reed NS, Lin FR, Deal JA. Hearing Loss and Cognition: What We Know and Where We Need to Go. Front Aging Neurosci 2022; 13:769405. [PMID: 35295208 PMCID: PMC8920093 DOI: 10.3389/fnagi.2021.769405] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 10/29/2021] [Indexed: 12/29/2022] Open
Abstract
Although a causal association remains to be determined, epidemiologic evidence suggests an association between hearing loss and increased risk of dementia. If we determine the association is causal, opportunity for targeted intervention for hearing loss may play a fundamental role in dementia prevention. In this discussion, we summarize current research on the association between hearing loss and dementia and review potential casual mechanisms behind the association (e.g., sensory-deprivation hypothesis, information-degradation hypothesis, common cause). We emphasize key areas of research which might best inform our investigation of this potential casual association. These selected research priorities include examination of the causal mechanism, measurement of co-existing hearing loss and cognitive impairment and determination of any bias in testing, potential for managing hearing loss for prevention of dementia and cognitive decline, or the potential to reduce dementia-related symptoms through the management of hearing loss. Addressing these research gaps and how results are then translated for clinical use may prove paramount for dementia prevention, management, and overall health of older adults.
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Affiliation(s)
- Danielle S Powell
- Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Cochlear Center for Hearing and Public Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Esther S Oh
- Cochlear Center for Hearing and Public Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Nicholas S Reed
- Cochlear Center for Hearing and Public Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Frank R Lin
- Cochlear Center for Hearing and Public Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Jennifer A Deal
- Cochlear Center for Hearing and Public Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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5
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Carrasquilla GD, García-Ureña M, Fall T, Sørensen TIA, Kilpeläinen T. Mendelian randomization suggests a bidirectional, causal relationship between physical inactivity and adiposity. eLife 2022; 11:70386. [PMID: 35254260 PMCID: PMC8975550 DOI: 10.7554/elife.70386] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 02/28/2022] [Indexed: 11/17/2022] Open
Abstract
Physical inactivity and increased sedentary time are associated with excess weight gain in observational studies. However, some longitudinal studies indicate reverse causality where weight gain leads to physical inactivity and increased sedentary time. As observational studies suffer from reverse causality, it is challenging to assess the true causal directions. Here, we assess the bidirectional causality between physical inactivity, sedentary time, and adiposity by bidirectional Mendelian randomization analysis. We used results from genome-wide association studies for accelerometer-based physical activity and sedentary time in 91,105 individuals and for body mass index (BMI) in 806,834 individuals. We implemented Mendelian randomization using CAUSE method that accounts for pleiotropy and sample overlap using full genome-wide data. We also applied inverse variance-weighted, MR-Egger, weighted median, and weighted mode methods using genome-wide significant variants only. We found evidence of bidirectional causality between sedentary time and BMI: longer sedentary time was causal for higher BMI [beta (95% CI) from CAUSE method: 0.11 (0.02, 0.2), p = 0.02], and higher BMI was causal for longer sedentary time (0.13 (0.08, 0.17), p = 6.3 x 10-4). Our analyses suggest that higher moderate and vigorous physical activity are causal for lower BMI (moderate: –0.18 (-0.3,–0.05), p = 0.006; vigorous: –0.16 (-0.24,–0.08), p = 3.8 × 10-4), but indicate that the association between higher BMI and lower levels of physical activity is due to horizontal pleiotropy. The bidirectional, causal relationship between sedentary time and BMI suggests that decreasing sedentary time is beneficial for weight management, but also that targeting adiposity may lead to additional health benefits by reducing sedentary time.
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Affiliation(s)
| | | | - Tove Fall
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
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6
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Oluwole OG, James K, Yalcouye A, Wonkam A. Hearing loss and brain disorders: A review of multiple pathologies. Open Med (Wars) 2021; 17:61-69. [PMID: 34993346 PMCID: PMC8678477 DOI: 10.1515/med-2021-0402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/22/2021] [Accepted: 11/05/2021] [Indexed: 11/29/2022] Open
Abstract
Several causative factors are associated with hearing loss (HL) and brain disorders. However, there are many unidentified disease modifiers in these conditions. Our study summarised the most common brain disorders associated with HL and highlighted mechanisms of pathologies. We searched the literature for published articles on HL and brain disorders. Alzheimer's disease/dementia, Parkinson's disease, cognitive impairment, autism spectrum disorder, ataxia, epilepsy, stroke, and hypoxic-ischaemic encephalopathy majorly co-interact with HL. The estimated incidence rate was 113 per 10,000 person-years. Genetic, epigenetic, early life/neonatal stress, hypoxia, inflammation, nitric oxide infiltration, endoplasmic reticulum stress, and excess glutamate were the distinguished modifiers identified. Various mechanisms like adhesion molecules, transport proteins, hair cell apoptosis, and neurodegeneration have been implicated in these conditions and are serving as potential targets for therapies. To improve the quality of life of patients, these understandings will improve clinical diagnoses and management of HL and brain disorders.
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Affiliation(s)
- Oluwafemi Gabriel Oluwole
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, 3.14 Wernher & Beit North Building, P.O Box 7925, Cape Town, South Africa
| | - Kili James
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, 3.14 Wernher & Beit North Building, P.O Box 7925, Cape Town, South Africa
| | - Abdoulaye Yalcouye
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, 3.14 Wernher & Beit North Building, P.O Box 7925, Cape Town, South Africa
| | - Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, 3.14 Wernher & Beit North Building, P.O Box 7925, Cape Town, South Africa
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7
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Hearing difficulty is linked to Alzheimer's disease by common genetic vulnerability, not shared genetic architecture. NPJ Aging Mech Dis 2021; 7:17. [PMID: 34294723 PMCID: PMC8298411 DOI: 10.1038/s41514-021-00069-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 04/02/2021] [Indexed: 02/07/2023] Open
Abstract
Age-related hearing loss was recently established as the largest modifiable risk factor for Alzheimer's disease (AD), however, the reasons for this link remain unclear. We investigate shared underlying genetic associations using results from recent large genome-wide association studies (GWAS) on adult hearing difficulty and AD. Genetic correlation and Mendelian randomization (MR) analysis do not support a genetic correlation between the disorders, but suggest a direct causal link from AD genetic risk to hearing difficulty, driven by APOE. Systematic MR analyses on the effect of other traits revealed shared effects of glutamine, gamma-glutamylglutamine, and citrate levels on reduced risk of both hearing difficulty and AD. In addition, pathway analysis on GWAS risk variants suggests shared function in neuronal signalling pathways as well as etiology of diabetes and cardiovascular disease. However, after multiple testing corrections, neither analysis led to statistically significant associations. Altogether, our genetic-driven analysis suggests hearing difficulty and AD are linked by a shared vulnerability in molecular pathways rather than by a shared genetic architecture.
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8
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Powell DS, Oh ES, Lin FR, Deal JA. Hearing Impairment and Cognition in an Aging World. J Assoc Res Otolaryngol 2021; 22:387-403. [PMID: 34008037 PMCID: PMC8329135 DOI: 10.1007/s10162-021-00799-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 03/24/2021] [Indexed: 12/18/2022] Open
Abstract
With the increasing number of older adults around the world, the overall number of dementia cases is expected to rise dramatically in the next 40 years. In 2020, nearly 6 million individuals in the USA were living with Alzheimer's disease, the most common type of dementia, with anticipated growth to nearly 14 million by year 2050. This increasing prevalence, coupled with high societal burden, makes prevention and intervention of dementia a medical and public health priority. As clinicians and researchers, we will continue to see more individuals with hearing loss with other comorbidities including dementia. Epidemiologic evidence suggests an association between hearing loss and increased risk of dementia, presenting opportunity for targeted intervention for hearing loss to play a fundamental role in dementia prevention. In this discussion, we summarize current research on the association between hearing loss and dementia and review potential casual mechanisms behind the association (e.g., sensory-deprivation hypothesis, information-degradation hypothesis, common cause). We emphasize key areas of research which might best inform our investigation of this potential casual association. These selected research priorities include examination of the causal mechanism, measurement of co-existing hearing loss and cognitive impairment, and potential of aural rehabilitation. Addressing these research gaps and how results are then translated for clinical use is paramount for dementia prevention and overall health of older adults.
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Affiliation(s)
- Danielle S Powell
- Department, of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
- Center on Aging and Health, Johns Hopkins University, Baltimore, MD, USA.
- Cochlear Center for Hearing and Public Health, Health, Johns Hopkins Bloomberg School of Public, Baltimore, MD, USA.
| | - Esther S Oh
- Cochlear Center for Hearing and Public Health, Health, Johns Hopkins Bloomberg School of Public, Baltimore, MD, USA
- Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Frank R Lin
- Department, of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
- Center on Aging and Health, Johns Hopkins University, Baltimore, MD, USA
- Cochlear Center for Hearing and Public Health, Health, Johns Hopkins Bloomberg School of Public, Baltimore, MD, USA
- Department of Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jennifer A Deal
- Department, of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
- Cochlear Center for Hearing and Public Health, Health, Johns Hopkins Bloomberg School of Public, Baltimore, MD, USA
- Department of Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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