Chronic Noise Exposure and Risk of Dementia: A Systematic Review and Dose-Response Meta-Analysis

Life course socioeconomic position and cognitive aging in later life: A scoping review

BACKGROUND AND OBJECTIVES

Low socioeconomic position (SEP) throughout the life course is related to poorer cognitive health in later life, but debate ensues on the life course models for this association. To advance inquiry on the topic, we conducted a scoping review.

RESEARCH DESIGN AND METHODS

We examined the association between life course SEP and cognitive function in later life in observational studies-considering cognition both as a cross-sectional level and as a longitudinal trajectory across cognitive domains-and assessed whether the empirical evidence supported life course models. We focused on studies in the general population with cognition measured in the second half of life (45 +). Forty-two studies (21 datasets) were included representing 595,276 participants (201,375 across unique datasets) from 46 countries.

RESULTS

For cognitive level, studies consistently found associations between SEP at various stages of the life course, both in overall cognition and across specific cognitive domains. These associations were generally robust to confounding and mediating factors. For cognitive trajectory, studies showed inconclusive associations with SEP across life course and across cognitive domains. Results supported the sensitive period, pathway, and accumulation models, but not the critical period model. Results supported that education acts as a pathway (and potential mediator) in the association between early-life SEP and later-life cognition.

DISCUSSION AND IMPLICATIONS

SEP throughout the life course has a robust association with later-life cognitive level, but not decline. Early-life cognitive enrichment for young people raised in socioeconomically disadvantaged households may reduce the SEP gap in cognitive functioning during later life.

Residential exposure to road and railway traffic noise and incidence of dementia: The UK Biobank cohort study

BACKGROUND

Evidence linking noise pollution and brain health, particularly at mid-to-late life, remains scarce. We investigated the associations between long-term exposure to road and railway traffic noise and incident dementia in the UK Biobank cohort.

METHODS

Participants with available data for dementia incidence and linked traffic noise exposure during follow-up were included. Residential road traffic noise from both minor and major roads were calculated in accordance with CNOSSOS-EU framework; railway noise estimates were created by Extrium, with the raster datasets representing noise contributions from major railway corridors. Cox regression was used to quantify the associations between transport noise and incident dementia (incl. its subtypes), adjusting for potential confounders, air pollution and greenness.

RESULTS

Of the full cohort (n = 502,416), 7668 participants had incident dementia during a median follow-up period of 9.67 years. No associations were found between all cause dementia incidence and road or railway noise. However, a 10-dB (dB) higher exposure in annual mean road traffic noise (Lden) was significantly associated with incident Alzheimer's disease (HR:1.150, 95 % CI: 1.022-1.294). The effect estimate was slightly higher when participants were exposed to night-time road noise above 45 dB (HR:1.188, 95 % CI:1.012-1.394) and this was mediated by the cardiovascular health profile. Railway noise (Lden) was significantly associated with incident Parkinson's disease related dementia (HR:1.042, 95 % CI:1.005-1.081), however, the effect estimate was slightly reduced after further adjustment of air pollution and residential greenness (HR:1.037, 95 % CI:0.998-1.077).

CONCLUSION

Distinct associations between different traffic noise exposures and incident dementia subtypes were found in this large UK prospective cohort study.

Environmental risk factors for all-cause dementia, Alzheimer's disease dementia, vascular dementia, and mild cognitive impairment: An umbrella review and meta-analysis

BACKGROUND

Mitigation of environmental risk factors for neurocognitive disorders could reduce the number of incident cases. We sought to synthesize the literature on environmental risk factors for dementia and mild cognitive impairment.

METHODS

We conducted an umbrella review and meta-analysis. Multiple databases were systematically searched to identify systematic reviews and meta-analyses of longitudinal studies examining environmental risk factors for dementia or mild cognitive impairment. We used random effects multi-level, meta-analytic models to synthesize risk ratios for each risk factor while accounting for overlap in the studies within reviews. As a secondary objective, we examined risk factors for two common phenotypes of dementia: Alzheimer's disease dementia and vascular dementia.

RESULTS

A total of 19 reviews containing 37 meta-analyses were included umbrella review. We found 9 factors where exposure was associated with higher risks of all-cause dementia: fine particulate matter, particulate matter, nitrogen dioxide, nitrogen oxides, carbon monoxide, shift work, night shift work, chronic noise, and extremely-low frequency magnetic fields. Neighbourhood greenness was associated with a lower risk of all-cause dementia. In a narrative review, we found that exposure to sulfur dioxide, proximity to roadways, ionizing radiation, aluminum, solvents, pesticides, and environmental tobacco smoke were also associated with dementia. We also found that fine particulate matter, extremely-low frequency magnetic fields, sulfur dioxide, chronic noise, and pesticides were related to Alzheimer's disease dementia. Fine particulate matter, particulate matter, and chronic noise were related to vascular dementia. No systematic review reported on mild cognitive impairment.

CONCLUSION

Achieving stronger air quality targets has the potential to reduce population-level dementia risk. Neighbourhood (i.e., greenness and chronic noise) and occupational (i.e., shift work) characteristics are associated with dementia and are viable public health intervention points. Additional research should examine the relationship between other environmental risk factors and mild cognitive impairment and specific types of dementia.

Tinnitus, noise exposure and the risk of dementia: a prospective cohort study based on UK biobank

BACKGROUND

The burden of dementia is increasing dramatically with the population aging. Tinnitus and chronic noise exposure are associated with neuropsychiatric diseases and cognitive decline, but relationships between tinnitus and noise exposure and incident dementia remain unclear.

METHODS

160 032 participants from the UK Biobank were included. Information on tinnitus, tinnitus severity, noise exposure (loud music and noisy workplace) was collected at baseline. Cox proportional hazards models were used to assess the associations of tinnitus, tinnitus severity and noise exposure with the risk of incident dementia. Logistic regression models were used to assess the associations between noise exposure and tinnitus.

RESULTS

During a median follow-up of 12.8 years, 2219 incident dementias were recorded. Compared with participants without tinnitus, those with tinnitus had a 10% increased risk of dementia (hazard ratios [HR]: 1.10, 95% CI: 1.00-1.20). Among the participants with tinnitus, compared with those with the lowest tinnitus severity, those with slight and moderate or severe tinnitus had 23% (95%CI: 1.03-1.46) and 64% (95%CI: 1.35-2.00) increased risks of dementia, respectively. Furthermore, compared with participants without exposure to noise, those with exposure to noise for more than 5 years had a 12% increased risk of dementia (HR: 1.12, 95%CI: 1.00-1.26). In addition, the longer time the participants exposed to noise, the higher the odds of having tinnitus (P for linear trend <.001).

CONCLUSIONS

Tinnitus, tinnitus severity and long-term noise exposure were associated with incident dementia, and long-term noise exposure were related to tinnitus. Tinnitus and noise exposure are public health issues vital for dementia prevention.

Community impacts of aviation noise: a pilot survey

BACKGROUND

Aviation noise policy in the United States is decades old and has not kept up with the science on the adverse effects of chronic noise exposure. New aviation noise policies are needed for the 21st century, respecting the lived experience of affected communities. Existing surveys have reported adverse impacts from aviation noise but more information is needed to understand the factors that contribute to those impacts.

OBJECTIVE

To evaluate the impacts of current aircraft noise exposure on impacted communities and their determinants.

METHODS

A 10-question online community pilot survey was distributed in May 2022 to an email list of groups and individuals in aviation-impacted communities. The survey was open for two weeks. Information on geographic location, frequency of exposure, and type of aircraft exposure were collected. Seven questions focused on the type and magnitude of health impacts, perceptions, and concerns.

RESULTS

A total of 1452 surveys were completed within the 2-week period. Respondents report experiencing loud, repetitive, low-altitude aircraft noise - day and night - causing stress and negative effects on mental and physical health. For many, "annoyance" did not adequately describe their experience. Strong, consistent exposure-response patterns for weekly flight frequency (<100 to >1000 flights) were found for most health impacts, perceptions, and concerns. The likelihood of adverse impacts and heightened perceptions and concerns was greatest in respondents exposed mainly to military aircraft.

SIGNIFICANCE

Current aviation noise policy is based on annoyance, and relies on a metric that exceeds safe levels and does not meaningfully convey community impact. Aviation-impacted communities are experiencing mental and physical health impacts that extend beyond annoyance. The magnitude of impact is influenced by flight frequency and aircraft type. Aviation noise policy should be updated to account for those factors and focus on reducing public health impacts and their human and economic costs.

IMPACT STATEMENT

Aviation noise policy in the United States is decades old and is based solely on the concept of annoyance without sufficient regard to the harms caused to health and well-being of people living in aviation-impacted communities. Efforts to amend the policy must be informed by the scientific evidence on the adverse effects of noise and health and by metrics that properly represent the lived experiences of communities. The results of this pilot survey highlight the importance of incorporating these aspects into policy for preventing and mitigating harms caused by aviation noise, especially as the industry grows.

Longitudinal associations between air pollution and incident dementia as mediated by MRI-measured brain volumes in the UK Biobank

BACKGROUND

Although there is increasing evidence that environmental exposures are associated with the risk of neurodegenerative conditions, there is still limited mechanistic evidence evaluating potential mediators in human populations.

METHODS

UK Biobank is a large long-term study of 500,000 adults enrolled from 2006 to 2010 age 40-69 years. ICD-10 classified reports of dementia cases up to 2022 (Alzheimer's disease, vascular dementia, dementia in other classified diseases, and unspecified dementia) were identified from health record linkage. Estimates of residential air pollution, traffic noise, and greenspace exposure have been modelled. Structural brain MRI was conducted from 2014 to 2022, with brain volumes relevant to dementia identified a priori. Associations between environmental exposures, brain volumes, and dementia cases (diagnosed post-MRI) were tested using linear and logistic regression and adjusted for age, sex, household income, ethnicity, education, smoking, and area-level deprivation. Mediation of exposure-outcome associations by plausible brain volumes (those associated with both environmental exposure and dementia outcomes) were modelled using the quasi-Bayesian Monte Carlo method (N = 34,817-39,772).

RESULTS

Small but significant mediating effects (2%-8% of relationships mediated) were observed between PM2.5abs exposure and dementia risk by reduced total brain volume, NOx and Alzheimer's disease risk by reduced peripheral cortical grey matter, PM2.5abs and vascular dementia risk by reduced peripheral cortical grey matter, PM2.5abs and other dementia risk by reduced total grey matter, and PM10 and other dementia risk by reduced total grey matter. Greenspace and noise were not associated with dementia outcomes in the subset of the cohort providing brain imaging data.

CONCLUSIONS

This study adds to existing evidence of associations between environmental exposures and dementia outcomes. Our findings provide novel evidence that differences in brain volume may mediate these relationships. Future research is required to prove this mechanism and establish the other mechanisms through which exposure to air pollution might increase dementia risk.

Light at night exposure and risk of dementia conversion from mild cognitive impairment in a Northern Italy population

BACKGROUND

A few studies have suggested that light at night (LAN) exposure, i.e. lighting during night hours, may increase dementia risk. We evaluated such association in a cohort of subjects diagnosed with mild cognitive impairment (MCI).

METHODS

We recruited study participants between 2008 and 2014 at the Cognitive Neurology Clinic of Modena Hospital, Northern Italy and followed them for conversion to dementia up to 2021. We collected their residential history and we assessed outdoor artificial LAN exposure at subjects' residences using satellite imagery data available from the Visible Infrared Imaging Radiometer Suite (VIIRS) for the period 2014-2022. We assessed the relation between LAN exposure and cerebrospinal fluid biomarkers. We used a Cox-proportional hazards model to compute the hazard ratio (HR) of dementia with 95% confidence interval (CI) according to increasing LAN exposure through linear, categorical, and non-linear restricted-cubic spline models, adjusting by relevant confounders.

RESULTS

Out of 53 recruited subjects, 34 converted to dementia of any type and 26 converted to Alzheimer's dementia. Higher levels of LAN were positively associated with biomarkers of tau pathology, as well as with lower concentrations of amyloid β1-42 assessed at baseline. LAN exposure was positively associated with dementia conversion using linear regression model (HR 1.04, 95% CI 1.01-1.07 for 1-unit increase). Using as reference the lowest tertile, subjects at both intermediate and highest tertiles of LAN exposure showed increased risk of dementia conversion (HRs 2.53, 95% CI 0.99-6.50, and 3.61, 95% CI 1.34-9.74). In spline regression analysis, the risk linearly increased for conversion to both any dementia and Alzheimer's dementia above 30 nW/cm2/sr of LAN exposure. Adding potential confounders including traffic-related particulate matter, smoking status, chronic diseases, and apolipoprotein E status to the multivariable model, or removing cases with dementia onset within the first year of follow-up did not substantially alter the results.

CONCLUSION

Our findings suggest that outdoor artificial LAN may increase dementia conversion, especially above 30 nW/cm2/sr, although the limited sample size suggests caution in the interpretation of the results, to be confirmed in larger investigations.

Noise Exposure Promotes Alzheimer's Disease-Like Lesions and DNA Damage

OBJECTIVE

This study aimed to explore the mechanism by which noise contributes to the development of Alzheimer's disease (AD)-like lesions.

METHOD

Male Wistar rats (24 months) were allocated into two groups (n = 6 per groups): a noise group exposed to 98 dB sound pressure-level white noise for 4 hours daily from 8:00 to 12:00 for 30 days, and a control group without noise exposure. The cognitive functions of the rats were assessed using new-object recognition and Morris water maze tests. Then, hippocampal tissues were collected, and the levels of amyloid β 1-42 (Aβ1-42), Aβ1-40, brain-derived neurotrophic factor (BDNF), and tropomyosin receptor kinase B (TrkB) were measured using enzyme-linked immunosorbent assay (ELISA). Protein expression was evaluated through Western blot.

RESULTS

Noise exposure significantly impaired cognitive and recognition abilities, increased the escape latency, and decreased the number of crossings through the platform quadrant intersection and the time spent in the target quadrant (P < 0.01). The new-object exploration and recognition index of the rats in the noise group markedly decreased (P < 0.01). ELISA results indicated increases in Aβ1-40 and Aβ1-42 levels and decreases in BDNF and TrkB levels in the rat hippocampus in the noise group (P < 0.01). Western blot analyses revealed that beta-site amyloid precursor protein (APP) cleaving enzyme 1, phosphorylated tau protein, gamma-H2A histone family, member X, checkpoint kinase 2, p53, and p21 were remarkably elevated in the noise group (P < 0.01).

CONCLUSION

Chronic noise exposure can cause hippocampal genetic damage in aged rats, leading to cognitive disorders and the development of lesions similar to those observed in AD. Thus, noise is a potential risk factor for neurodegenerative disorders.

Association between the Dietary Inflammatory Index and fracture risk in older adults: a systematic review and meta-analysis

OBJECTIVE

We explored correlations between the Dietary Inflammatory Index (DII) and fracture risk in older adults.

METHODS

We systematically searched MEDLINE, PubMed, Science Direct, Scopus, and CNKI for all relevant epidemiological studies published through October 16, 2023. Because observational studies were included in the meta-analysis, we used a random-effects model to pool the study-specific effect sizes and 95% confidence intervals (CIs). We assessed study quality using the Newcastle-Ottawa scale. This meta-analysis was registered in PROSPERO.

RESULTS

Eight studies with 462,986 participants were included, with five cohort studies, two cross-sectional studies, and one case-control study. An analysis of heterogeneity among the eight included studies resulted in I2 = 87.1%, indicating significant between-study heterogeneity; hence, the random-effects model was adopted to generate the combined effect size. We found that the DII was positively associated with fracture (relative risk: 1.188, 95% CI: 1.043-1.354). This result was further confirmed in leave-one-out sensitivity analysis.

CONCLUSIONS

Our study provides evidence suggesting that diets high in pro-inflammatory components might increase the fracture risk among older people. Decreased consumption of pro-inflammatory foods and increased consumption of anti-inflammatory foods are suggested to prevent adverse fracture outcomes. More prospective studies involving both sexes are warranted to verify the results.

Use of headphones for the delivery of music programs for people with dementia in long-term care homes: a scoping review protocol

INTRODUCTION

Dementia affects the quality of life. Excessive noise in care environments can exacerbate stress and related symptoms. Headphone-based music interventions may help improve the quality of life for people with dementia in long-term care homes. This review aims to explore and synthesise research on headphone-based music interventions for people with dementia in long-term care homes, focusing on enablers and barriers to implementing headphone-based music interventions.

METHODS AND ANALYSIS

Joanna Briggs Institute guidance for scoping review and Preferred Reporting Items for Scoping Reviews and Meta-analyses extension for Scoping Reviews will guide the review and report process. CINAHL, MEDLINE, Embase, Web of Science, Scopus, AgeLine, PsycINFO and ProQuest databases will be searched for relevant literature from June 2010 to January 2024, supplemented by hand searches and Google for grey literature. Two research assistants will independently screen citations, followed by a full-text review. Data will be extracted using a data extraction tool. We will present the data in a table with narratives that answer the questions of the scoping review.

ETHICS AND DISSEMINATION

This scoping review does not require ethics approval and participation consent, as all data will be publicly available. The scoping review results will be disseminated through conference presentations and an open-access publication in a peer-reviewed journal. The findings will provide practical insights into the adoption and efficacy of headphone-based music programmes for dementia in long-term care homes, contributing to education, practice, policy and future research.

Staffing and Antipsychotic Medication Use in Nursing Homes and Neighborhood Deprivation

Importance

Inappropriate use of antipsychotic medications in nursing homes is a growing public health concern. Residents exposed to higher levels of socioeconomic deprivation in the area around a nursing home may be currently exposed, or have a long history of exposure, to more noise pollution, higher crime rates, and have less opportunities to safely go outside the facility, which may contribute to psychological stress and increased risk of receiving antipsychotic medications inappropriately. However, it is unclear whether neighborhood deprivation is associated with use of inappropriate antipsychotic medications and whether this outcome is different by facility staffing levels.

Objective

To evaluate whether reported inappropriate antipsychotic medication use differs in severely and less severely deprived neighborhoods, and whether these differences are modified by higher levels of total nurse staffing.

Design, Setting, and Participants

This was a cross-sectional analysis of a national sample of nursing homes that linked across 3 national large-scale data sets for the year 2019. Analyses were conducted between April and June 2023.

Exposure

Neighborhood deprivation status (severe vs less severe) and total staffing hours (registered nurse, licensed practical nurse, certified nursing assistant).

Main Outcome and Measures

This study estimated the association between neighborhood deprivation and the percentage of long-stay residents who received an antipsychotic medication inappropriately in the nursing home at least once in the past week and how this varied by nursing home staffing through generalized estimating equations. Analyses were conducted on the facility level and adjusted for state fixed effects.

Results

This study included 10 966 nursing homes (1867 [17.0%] in severely deprived neighborhoods and 9099 [83.0%] in less deprived neighborhoods). Unadjusted inappropriate antipsychotic medication use was greater in nursing homes located in severely deprived neighborhoods (mean [SD], 15.9% [10.7%] of residents) than in those in less deprived neighborhoods (mean [SD], 14.2% [8.8%] of residents). In adjusted models, inappropriate antipsychotic medication use was higher in severely deprived neighborhoods vs less deprived neighborhoods (19.2% vs 17.1%; adjusted mean difference, 2.0 [95% CI, 0.35 to 3.71] percentage points) in nursing homes that fell below critical levels of staffing (less than 3 hours of nurse staffing per resident-day).

Conclusions and Relevance

These findings suggest that levels of staffing modify disparities seen in inappropriate antipsychotic medication use among nursing homes located in severely deprived neighborhoods compared with nursing homes in less deprived neighborhoods. These findings may have important implications for improving staffing in more severely deprived neighborhoods.

Relationship Between Work-Related Noise Exposure and Cognitive Impairment: A Cross-Sectional Study in China

Background

Noise exposure and the risk of cognitive impairment are currently major public health issues.

Objective

This study aimed to analyze the relationship between noise exposure and early impairment of cognitive function from the perspective of occupational epidemiology and to provide evidence for the long-term prevention and treatment of dementia in the context of aging.

Methods

This study was conducted in China between May and August 2021. The independent variables were the type of hazardous factors, duration of noise exposure, perceived noise intensity, and cumulative noise exposure (CNE). The dependent variable was cognitive function, which was measured using the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Multiple linear and logistic regression were used to analyze the relationship between noise exposure and cognitive function and to establish an effect curve.

Results

The detection rates of cognitive dysfunction using the MMSE and MoCA were 1.1% and 36.2%, respectively. The predicted MMSE and MoCA scores showed a downward trend within the CNE value ranging from 90-140 dB.time. Each unit increase in CNE decreased cognitive function scores by 0.025 (0.037, 0.013) and 0.020 (0.037, 0.003) points,respectively.

Conclusions

From the perspective of occupational epidemiology, these findings reveal a potential link between long-term noise exposure and early cognitive impairment.

Outdoor artificial light at night and risk of early-onset dementia: A case-control study in the Modena population, Northern Italy

Background

Dementia is a neurological syndrome characterized by severe cognitive impairment with functional impact on everyday life. It can be classified as young onset dementia (EOD) in case of symptom onset before 65, and late onset dementia (LOD). The purpose of this study is to assess the risk of dementia due to light pollution, and specifically outdoor artificial light at night (LAN).

Methods

Using a case-control design, we enrolled dementia patients newly-diagnosed in the province of Modena in the period 2017-2019 and a referent population from their caregivers. We geo-referenced the address of residence on the date of recruitment, provided it was stable for the previous five years. We assessed LAN exposure through 2015 nighttime luminance satellite images from the Visible Infrared Imaging Radiometer Suite (VIIRS). Using a logistic regression model adjusted for age, sex, and education, we calculated the risk of dementia associated with increasing LAN exposure, namely using <10 nW/cm²/sr as reference and considering ≥10-<40 nW/cm²/sr intermediate and ≥40 nW/cm²/sr high exposure, respectively We also implemented non-linear assessment using a spline regression model.

Results

We recruited 58 EOD cases, 34 LOD cases and 54 controls. Average LAN exposure levels overlapped for EOD cases and controls, while LOD cases showed higher levels. Compared with the lowest exposure, the risk of EOD associated with LAN was higher in the intermediate exposure (OR = 1.36, 95% CI 0.54-3.39), but not in the high exposure category (OR = 1.04, 95% CI 0.32-3.34). In contrast, the risk of LOD was positively associated with LAN exposure, with ORs of 2.58 (95% CI 0.26-25.97) and 3.50 (95% CI 0.32-38.87) in the intermediate and high exposure categories, respectively. The spline regression analysis showed substantial lack of association between LAN and EOD, while almost linear although highly imprecise association emerged for LOD.

Conclusions

Although the precision of the estimates was affected by the limited sample size and the study design did not allow us to exclude the presence of residual confounding, these results suggest a possible role of LAN in the etiology of dementia, particularly of its late-onset form.

Noise-induced auditory damage affects hippocampus causing memory deficits in a model of early age-related hearing loss

Several studies identified noise-induced hearing loss (NIHL) as a risk factor for sensory aging and cognitive decline processes, including neurodegenerative diseases, such as dementia and age-related hearing loss (ARHL). Although the association between noise- and age-induced hearing impairment has been widely documented by epidemiological and experimental studies, the molecular mechanisms underlying this association are not fully understood as it is not known how these risk factors (aging and noise) can interact, affecting memory processes. We recently found that early noise exposure in an established animal model of ARHL (C57BL/6 mice) accelerates the onset of age-related cochlear dysfunctions. Here, we extended our previous data by investigating what happens in central brain structures (auditory cortex and hippocampus), to assess the relationship between hearing and memory impairment and the possible combined effect of noise and sensory aging on the cognitive domain. To this aim, we exposed juvenile C57BL/6 mice of 2 months of age to repeated noise sessions (60 min/day, pure tone of 100 dB SPL, 10 kHz, 10 consecutive days) and we monitored auditory threshold by measuring auditory brainstem responses (ABR), spatial working memory, by using the Y-maze test, and basal synaptic transmission by using ex vivo electrophysiological recordings, at different time points (1, 4 and 7 months after the onset of noise exposure, corresponding to 3, 6 and 9 months of age). We found that hearing loss, along with accelerated presbycusis onset, can induce persistent synaptic alterations in the auditory cortex. This was associated with decreased memory performance and oxidative-inflammatory injury in the hippocampus, the extra-auditory structure involved in memory processes. Collectively, our data confirm the critical relationship between auditory and memory circuits, suggesting that the combined detrimental effect of noise and sensory aging on hearing function can be considered a high-risk factor for both sensory and cognitive degenerative processes, given that early noise exposure accelerates presbycusis phenotype and induces hippocampal-dependent memory dysfunctions.