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Does hearing loss lead to dementia? A review of the literature
Yosra Nadhimi, Daniel A Llano. Hearing research, 2020-07-30
Topic: Disease mechanisms in lab and animal studies
Recent studies have revealed a correlation between aging-related hearing loss and the likelihood of developing Alzheimer Disease. However, it is not yet known if the correlation simply reflects the fact that these two disorders share common risk factors or whether there is a causal link between them. The answer to this question carries therapeutic implications. Unfortunately, it is not possible to study the question of causality between aging-related hearing loss and dementia in human subjects. Here, we evaluate the research surrounding induced-hearing loss in animal models on non-auditory cognition to help infer if there is any causal evidence linking hearing loss and a more general dementia. We find ample evidence that induction of hearing loss in animals produces cognitive decline, particularly hippocampal dysfunction. The data suggest that noise-exposure produces a toxic milieu in the hippocampus consisting of a spike in glucocorticoid levels, elevations of mediators of oxidative stress and excitotoxicity, which as a consequence induce cessation of neurogenesis, synaptic loss and tau hyperphosphorylation. These data suggest that hearing loss can lead to pathological hallmarks similar to those seen in Alzheimer's Disease and other dementias. However, the rodent data do not establish that hearing loss on its own can induce a progressive degenerative dementing illness. Therefore, we conclude that an additional "hit", such as aging, APOE genotype, microvascular disease or others, may be necessary to trigger an ongoing degenerative process such as Alzheimer Disease.
Key findings
- Recent studies have revealed a correlation between aging-related hearing loss and the likelihood of developing Alzheimer Disease.
- The data suggest that noise-exposure produces a toxic milieu in the hippocampus consisting of a spike in glucocorticoid levels, elevations of mediators of oxidative stress and excitotoxicity, which as a consequence induce cessation of neurogenesis, synaptic loss and tau hyperphosphorylation.
- These data suggest that hearing loss can lead to pathological hallmarks similar to those seen in Alzheimer's Disease and other dementias.
- Therefore, we conclude that an additional "hit", such as aging, APOE genotype, microvascular disease or others, may be necessary to trigger an ongoing degenerative process such as Alzheimer Disease.
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Study details
- Evidence strengthLow
How this study scored 41/100
Published in a peer-reviewed journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record, multi-centre collaboration and free to read, so those were left out: it earned 23 of the 56 points we could judge it on, which is 41 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Hearing research) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 3 / 5 | 2021 — within 6 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 32814645) |
| Free to read | — / 2 | Access not recorded — left out of this score |
| Points | 23 / 56 | Scored on 10 of 20 parts. We have no data for the rest, so they are left out: 23 of the 56 points we could judge it on is 41 out of 100. |
| Total | 41 / 100 | — |
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APA 7th
Nadhimi, Y., & Llano, D. A. (2021). Does hearing loss lead to dementia? A review of the literature. Hearing research. https://doi.org/10.1016/j.heares.2020.108038
Vancouver
Nadhimi Y, Llano DA. Does hearing loss lead to dementia? A review of the literature. Hearing research. 2021. doi:10.1016/j.heares.2020.108038. PMID: 32814645.
BibTeX
@article{nadhimi2021-32814645,
author = {Nadhimi, Yosra and Llano, Daniel A},
title = {{Does hearing loss lead to dementia? A review of the literature}},
journal = {Hearing research},
year = {2021},
doi = {10.1016/j.heares.2020.108038},
pmid = {32814645},
url = {https://doi.org/10.1016/j.heares.2020.108038}
}