Midlife sensory and motor functions improve long-term predictions of cognitive decline and incidence of cognitive impairment

INTRODUCTION

We aimed to assess whether midlife sensory and motor functions improve risk prediction of 10-year cognitive decline and impairment when added to risk prediction models using the Cardiovascular Risk Factors, Aging, and Incidence of Dementia Score (CAIDE) and Framingham Risk Score (FRS).

METHODS

Longitudinal data of N = 1529 (mean age 49 years; 54% women) Beaver Dam Offspring Study (BOSS) participants from baseline, 5 and 10-year follow-up were included. We tested whether including baseline sensory (hearing, vision, olfactory) impairment and motor function improves CAIDE or FRS risk predictions of 10-year cognitive decline or cognitive impairment incidence using logistic regressions.

RESULTS

Adding sensory and motor measures to CAIDE-only and FRS-only models significantly improved areas under the curve for cognitive decline and impairment models.

DISCUSSION

Including midlife sensory and motor function improved risk predictions of long-term cognitive decline and impairment in middle-aged to older adults. Sensory and motor assessments could contribute to cost-effective and non-invasive screening tools that identify high-risk individuals earlier to target intervention and prevention strategies.

Highlights

Sensory and motor measures improve risk prediction models of cognitive decline.Sensory and motor measures improve risk prediction models of cognitive impairment.Prediction improvements were strongest in midlife (adults < 55 years of age).Sensory and motor changes may help identify high-risk individuals early.

Midlife sensory and motor functions improve prediction of blood-based measures of neurodegeneration and Alzheimer's disease in late middle-age

INTRODUCTION

We assessed whether midlife sensory and motor functions added to prediction models using the Cardiovascular Risk Factors, Aging, and Incidence of Dementia Score (CAIDE) and Framingham Risk Score (FRS) improve risk predictions of 10-year changes in biomarkers of neurodegeneration and Alzheimer's disease.

METHODS

Longitudinal data of N = 1529 (mean age 49years) Beaver Dam Offspring Study participants from baseline, 5-year, and 10-year follow-up were included. We tested whether including baseline sensory (hearing, vision, olfactory) impairment and motor function measures improves CAIDE or FRS risk predictions of 10-year incidence of biomarker positivity of serum-based neurofilament light chain (NfL) and amyloid beta (Aβ)42/Aβ40 using logistic regression.

RESULTS

Adding sensory and motor measures to CAIDE-only and FRS-only models significantly improved NfL and Aβ42/Aβ40 positivity predictions in adults above the age of 55.

DISCUSSION

Including midlife sensory and motor function improved long-term biomarker positivity predictions. Non-invasive sensory and motor assessments could contribute to cost-effective screening tools that identify individuals at risk for neurodegeneration early to target interventions and preventions.

Highlights

Sensory and motor measures improve risk prediction models of neurodegenerative biomarkersSensory and motor measures improve risk prediction models of AD biomarkersPrediction improvements were strongest in late midlife (adults >55 years of age)Sensory and motor assessments may help identify high-risk individuals early.

Effect of Neurotoxin Exposure on Blood Biomarkers of Neurodegeneration and Alzheimer Disease

AIM

To determine whether exposure to neurotoxins in midlife is associated with changes in blood-based biomarkers of neurodegeneration and Alzheimer disease pathology.

METHODS

Blood cadmium, lead, neurofilament light (NfL) chain, total tau (TTau), and amyloid beta (Aβ) 40 and Aβ42 concentrations were measured in 1516 participants in the Beaver Dam Offspring Study. Linear mixed-effect models were used to determine associations between baseline cadmium and lead levels and baseline NfL, TTau, and Aβ42/Aβ40, and 10-year change in concentrations using repeated measures of these biomarkers as the outcome.

RESULTS

In women, higher cadmium and lead levels were associated with higher baseline TTau concentrations. A higher baseline cadmium level was associated with lower baseline Aβ42/Aβ40 in both men and women. In age-sex-adjusted models, a doubling in baseline cadmium level was associated with a 0.2% (95% CI: 0.0, 0.3) higher increase per year in NfL concentrations. In men, a doubling of baseline lead level was associated with a 0.9% (95% CI: 0.1, 1.7) higher increase per year in TTau concentration.

CONCLUSIONS

Participants with relatively higher levels of cadmium and lead had blood biomarker concentrations consistent with more neuronal damage and Alzheimer disease pathology. Environmental exposure to neurotoxins may contribute to neurodegeneration.

Associations of Hearing Loss and Hearing Aid Use With Cognition, Health-Related Quality of Life, and Depressive Symptoms

ObjectivesDetermine associations of hearing loss (HL) and hearing aid (HA) use with cognition, health-related quality of life (HRQoL), and depressive symptoms. Methods: Participants were from the Epidemiology of Hearing Loss Study or Beaver Dam Offspring Study. HL was defined as pure-tone average (.5-4.0 kHz) > 25 dB. A principal component analysis of 5 cognitive tasks measured cognition. The SF-12 measured mental and physical HRQoL. The Centers for Epidemiological Studies Depression Scale measured depressive symptoms (score ≥ 16). Regression models returned beta (B) coefficients or odds ratios (OR) with 95% confidence intervals. Results: This study included 3574 participants. HL (vs. none) was associated with poorer cognition (B-.12 [-.18, -.06]), mental (B-.99 [-1.65, -.33]) and physical (B-.76 [-1.50, -.03]) HRQoL, and increased odds of depressive symptoms (OR 1.49 [1.16, 1.91]). HA users had better cognition than non-users. Discussion: HL likely impacts cognition and well-being. HA use may have cognitive benefits.

Association of Central Retinal Arteriolar and Venular Equivalents with Brain-aging and Macular Ganglion Cell-inner Plexiform Layer Thickness

INTRODUCTION

Neurodegeneration and cognitive decline in aging are growing public health concerns. This study investigates associations between central retinal arteriolar and venular equivalents (CRAE, CRVE) and brain-aging, a sensory and cognitive test composite measure, and macular ganglion cell-inner plexiform layer (mGCIPL) thickness, a biomarker of neurodegeneration.

METHODS

Beaver Dam Offspring Study (BOSS) participants are adult children (baseline (2005-2008) age 21-84 years) of the population-based Epidemiology of Hearing Loss Study participants. Follow-up occurred every 5 years. In 2010-2013, fundus photographs were used to measure retinal vessels. A brain-aging score was constructed by principal component analysis using sensorineural and cognitive data. Associations between incident brain-aging and vessel measures were investigated using logistic regression. Associations between CRAE and CRVE and mGCIPL thickness, measured in 2015-2017, were also investigated.

RESULTS

Participants (N = 2381; mean age: 53.9 years (SD = 9.8); 54% women) had a mean CRAE and CRVE of 148.8 µm (SD = 14.5) and 221.7 µm (SD = 20.7), respectively. Among those without ocular conditions, wider CRAE was associated with decreased 5-year brain-aging risk (33% per SD CRAE increase). Both vessel measures were independently associated with mGCIPL thickness. The mGCIPL thickness increased by approximately 1.7 µm and 2.0 µm per SD increase in CRAE and CRVE, respectively.

DISCUSSION

The association of CRAE with incident brain-aging indicates its potential use as a screening tool among those without eye disease. The associations between CRAE and CRVE and mGCIPL thickness indicate narrower vasculature could affect neuronal health. These associations point to potential usefulness of retinal vessel measurements to identify people at higher risk of sensorineural declines and neurodegeneration.

Inflammation, metabolic dysregulation and environmental neurotoxins and risk of cognitive decline and impairment in midlife

BACKGROUND

Age-related declines in cognitive function may begin in midlife.

PURPOSE

To determine whether blood-based biomarkers of inflammation, metabolic dysregulation and neurotoxins are associated with risk of cognitive decline and impairment.

METHODS

Baseline blood samples from the longitudinal Beaver Dam Offspring Study (2005-2008) were assayed for markers of inflammation, metabolic dysregulation, and environmental neurotoxins. Cognitive function was measured at baseline, 5-year (2010-2013) and 10-year (2015-2017) examinations. Participants without cognitive impairment at baseline and with cognitive data from at least one follow-up were included. Cox proportional hazards models were used to evaluate associations between baseline blood biomarkers and the 10-year cumulative incidence of cognitive impairment. Poisson models were used to estimate the relative risk (RR) of 5-year decline in cognitive function by baseline blood biomarkers. Models were adjusted for age, sex, education, and cardiovascular related risk factors.

RESULTS

Participants (N = 2421) were a mean age of 49 years and 55% were women. Soluble vascular cell adhesion molecule-1 (sVCAM-1Tertile(T)3 vs T1-2 hazard ratio (HR) = 1.72, 95% confidence interval (CI) = 1.05,2.82) and hemoglobin A1C (HR = 1.75, 95% CI = 1.18,2.59, per 1% in women) were associated with the 10-year cumulative incidence of cognitive impairment. sVCAM-1 (RRT3 vs T1-2 = 1.45, 95% CI = 1.06,1.99) and white blood cell count (RR = 1.10, 95% CI = 1.02,1.19, per 103/μL) were associated with 5-year cognitive decline.

CONCLUSIONS

Biomarkers related to inflammation and metabolic dysregulation were associated with an increased risk of developing cognitive decline and impairment. These results extend previous research in cognitive aging to early markers of cognitive decline in midlife, a time when intervention methods may be more efficacious.

Associations of Midlife Lifestyle and Health Factors with Long-Term Changes in Blood-Based Biomarkers of Alzheimer's Disease and Neurodegeneration

BACKGROUND

Pathological biomarkers of Alzheimer's disease (AD) and other dementias can change decades before clinical symptoms. Lifestyle and health factors might be relevant modifiable risk factors for dementia. Many previous studies have been focusing on associations of lifestyle and health-related factors with clinical outcomes later in life.

OBJECTIVE

We aimed to determine to what extent midlife factors of lifestyle, inflammation, vascular, and metabolic health were associated with long-term changes in blood-based biomarkers of AD (amyloid beta (Aβ)) and neurodegeneration (neurofilament light chain (NfL); total tau(TTau)).

METHODS

In 1,529 Beaver Dam Offspring Study (BOSS) participants (mean age 49 years, standard deviation (SD) = 9; 54% were women), we applied mixed-effects models with baseline risk factors as determinants and 10-year serum biomarker change as outcomes.

RESULTS

We found that education and inflammatory markers were associated with levels and/or change over time across all three markers of AD and neurodegeneration in the blood. There were baseline associations of measures of cardiovascular health with lower Aβ42/Aβ40. TTau changed little over time and was higher in individuals with diabetes. Individuals with lower risk in a number of cardiovascular and metabolic risk factors, including diabetes, hypertension, and atherosclerosis had slower accumulation of neurodegeneration over time, as determined by NfL levels.

CONCLUSION

Various lifestyle and health factors, including education and inflammation, were associated with longitudinal changes of neurodegenerative and AD biomarker levels in midlife. If confirmed, these findings could have important implications for developing early lifestyle and health interventions that could potentially slow processes of neurodegeneration and AD.

Associations of sensory and motor function with blood-based biomarkers of neurodegeneration and Alzheimer's disease in midlife

Pathological biomarkers of dementia and Alzheimer's disease (AD) change decades before clinical symptoms. Common sensory and motor changes in aging adults may be early markers of neurodegeneration. We investigated if midlife sensory and motor functions in Beaver Dam Offspring Study (BOSS) participants (N = 1529) were associated with longitudinal changes in blood-based biomarkers of neurodegeneration (neurofilament light chain (NfL); total tau (TTau)) and AD (amyloid beta (Aβ)). Mixed-effects models with baseline sensory and motor function as determinants and 10-year biomarker change as outcome were used. Participants with hearing impairment and worse motor function (among women) showed faster increases in NfL level over time (0.8% per year; 0.3% per year, respectively). There were no significant associations with TTau or Aβ. We found consistent relationships between worse baseline hearing and motor function with a faster increase in neurodegeneration, specifically serum NfL level. Future studies with longer follow-up should determine if sensory and motor changes are more reflective of general neurodegeneration than AD-specific pathology and whether sensory and motor tests may be useful screening tools for neurodegeneration risk.

Better cognitive function in younger generations - Insights from two cohort studies of middle-aged to older adults in Wisconsin

BACKGROUND

Understanding generational trends in dementia and cognitive decline is essential to quantify future healthcare needs and may help identify interventions and preventions. We aimed to determine whether individuals from more recent generations showed better neurocognitive function.

METHODS

This cross-sectional study combined data from 4439 participants (mean age 64 years (SD = 13); 57% were women) from the Epidemiology of Hearing Loss Study and Beaver Dam Offspring Study. We assessed participants' birth cohort (1901-1924, Greatest Generation; 1925-1945, Silent Generation; 1946-1964, Baby Boom Generation; 1965-1984, Generation X) and neurocognition (Trail-Making Tests A and B, Digit Symbol Substitution Test, Auditory Verbal Learning Test, Verbal Fluency Test). Multivariable linear regression models were utilized.

RESULTS

Adjusted for age, sex, education, and known risk factors for cognitive decline, more recent generations showed better processing speed, executive function, attention, and verbal fluency than the Greatest Generation. Largest benefits were found in the Baby Boom Generation. Compared with the Greatest Generation, individuals from the Baby Boom Generation performed better on Trail-Making Tests A (-0.21 ln(time in s); 95% confidence interval (CI) -0.29, -0.13) and B (-0.31 ln(time in s); 95% CI -0.40, -0.22), Digit Symbol Substitution Test (6.07 numbers correct; 95% CI 3.61, 8.52) and Verbal Fluency Test (8.75 numbers correct; 95% CI 5.07, 12.42 in women; 5.28 numbers correct; 95% CI 0.79, 9.78 in men), with effect sizes similar to effects of 11-15 years of less aging.

CONCLUSIONS

This indicates that some benefits of younger generations might be related to yet unknown and potentially modifiable environmental, health-related or lifestyle factors and motivates research of such underlying factors to promote healthy cognitive aging.

Effect of Long-Term Storage on the Reliability of Blood Biomarkers for Alzheimer's Disease and Neurodegeneration

BACKGROUND

Stored blood samples from longitudinal cohort studies may be useful for studying biomarkers of preclinical Alzheimer's disease.

OBJECTIVE

This study aimed to determine the reliability of amyloid-β 40 and amyloid-β 42 (Aβ 40, Aβ 42), total tau (TTau), and neurofilament light (NfL) concentrations measured in blood samples stored long-term at -80°C.

METHODS

Aβ 40, Aβ 42, TTau, and NfL were measured in serum and plasma samples from two longitudinal cohort studies. Serum samples had been stored at -80°C for 5 (n = 24), 14 (n = 24), and 20 years (N = 78) and plasma samples had been stored for 16 years (N = 78). Biomarker concentrations were measured in duplicate using a single molecule array assay (Simoa; Quanterix, Billerica, MA). Replicate samples for each sample type and storage length were included.

RESULTS

The concentrations of Aβ 40, Aβ 42, TTau, and NfL were within expected ranges. Some serum TTau concentrations were below the limit of detection. The average intra-assay coefficients of variation (CV) for duplicate measures were 2-7% for all assays except for serum TTau, which were higher (CVs 13% and 17%). Mean differences in original replicate pair Aβ 40, Aβ 42, and NfL concentrations were slightly greater in samples stored for longer versus shorter time periods.

CONCLUSION

Aβ 40, Aβ 42, TTau, and NfL can be measured in serum and plasma samples that have been stored up to 20 years at -80°C. Long-term storage may be associated with small increases in the variability of concentrations in samples stored 14 or more years.

The Association of Psychological Well-Being With Sensory and Cognitive Function and Neuronal Health in Aging Adults

OBJECTIVES

Psychological well-being (PWB) may be a potential modifiable risk factor of age-related diseases. We aimed to determine associations of PWB with sensorineural and cognitive function and neuronal health in middle-aged adults.

METHODS

This study included 2039 Beaver Dam Offspring Study participants. We assessed PWB, hearing, visual acuity, contrast sensitivity impairment, olfactory impairment, cognition, and retinal (macular ganglion cell inner-plexiform layer, mGCIPL) thickness. Age-sex-education-adjusted multivariable linear, logistic regression, and generalized estimating equation models were used and then further adjusted for health-related confounders.

RESULTS

Individuals with higher PWB had better hearing functions, visual acuity, and thicker mGCIPL and reduced odds for hearing, contrast sensitivity and olfactory impairment in age-sex-education-adjusted models. Effects on mGCIPL and visual and olfactory measures decreased with adjustment. Higher PWB was associated with better cognition, better combined sensorineural-cognitive function, and decreased cognitive impairment.

DISCUSSION

Psychological well-being was associated with sensorineural-cognitive health indicating a potential of PWB interventions for healthy aging.

Exposure to Cadmium, Lead, and Tobacco Smoke and the 10-Year Cumulative Incidence of Olfactory Impairment: The Beaver Dam Offspring Study

Importance

Olfactory impairment is common in older adults. Identification of modifiable risk factors for olfactory impairment at midlife has the potential to reduce the burden of olfactory impairment at older ages.

Objective

To determine the 10-year cumulative incidence of olfactory impairment and evaluate potentially modifiable risk factors for impairment including exposure to cadmium, lead, and tobacco smoke.

Design, Setting, and Participants

Data from the Beaver Dam Offspring Study, a longitudinal cohort study of sensory health and aging in a general population, were available from examinations at baseline (2005-2008), 5 years (2010-2013), and 10 (2015-2017) years. A total of 2312 participants without olfactory impairment at baseline and with olfaction data available at the 5- and/or 10-year examination were included. The present study was conducted from April 28, 2020, to January 8, 2021.

Main Outcomes and Measures

Olfactory impairment was measured by the San Diego Odor Identification Test. Cox discrete-time proportional hazards analyses were used to model associations between baseline covariates, including blood cadmium and lead levels and tobacco smoke exposure, and the 10-year cumulative incidence of olfactory impairment.

Results

Of the 2312 participants, 1269 (54.9%) were women; mean age was 49 years (range, 22-84 years) at baseline. The 10-year cumulative incidence of olfactory impairment was 4.6% (95% CI, 3.7%-5.6%) and increased with age. Because of high collinearity, cadmium and tobacco smoke exposure were modeled separately. In a multivariable adjusted model, higher blood cadmium level (hazard ratio [HR], 1.70; 95% CI, 1.05-2.74) was associated with the 10-year cumulative incidence of olfactory impairment. Substituting tobacco smoke exposure for cadmium in the model, high exposure to tobacco smoke as a current smoker (HR, 2.94; 95% CI, 1.63-5.29, smoker vs no exposure) or from environmental tobacco smoke (HR, 2.65; 95% CI, 1.24-5.63, high vs no exposure) was also associated with an increased risk for developing olfactory impairment. Blood lead levels were not associated with olfactory impairment.

Conclusions and Relevance

Results of this longitudinal cohort study suggest that modifiable environmental exposures may contribute to olfactory impairment that occurs with aging. Identification of modifiable risk factors for olfactory impairment may lead to prevention strategies that have the potential to reduce the burden of olfactory impairment at older ages.

Incidence of Hearing Impairment and Changes in Pure-Tone Average Across Generations

Importance

Age-adjusted prevalence of hearing impairment (HI) decreased across generations in the 20th century, suggesting that HI is partially preventable. It is not known whether HI incidence differs by generation.

Objectives

To examine whether HI incidence and change in pure-tone average (PTA) differ by generation and identify factors underlying these differences.

Design, Setting, and Participants

This cohort study used data from the Epidemiology of Hearing Loss Study (EHLS) and Beaver Dam Offspring Study (BOSS), a pair of studies of adults in Beaver Dam, Wisconsin. Baseline examinations occurred from 1993 to 1995 in the EHLS and 2005 to 2008 in BOSS, with two 5-year follow-up examinations in each cohort. This longitudinal cohort study assessed 3651 participants without HI at baseline who had follow-up data.

Main Outcomes and Measures

The primary outcome was incident HI measured by pure-tone audiometry, defined as PTA greater than 25-dB hearing level (dB HL) in either ear. Associations of 5-year incidence were estimated by relative risks (RRs) and 10-year cumulative incidence with generation, as categorized by commonly used sociodemographic descriptors of year of birth, by hazard ratios (HRs). The 10-year change in PTA was investigated using a generation × time interaction term in generalized estimating equation models.

Results

Among the 3651 participants (mean [SD] age at baseline 53.1 [10.6] years; 2255 [61.8%] female; and 3567 [97.7%] non-Hispanic White), the 5-year HI incidence was 14.1% (95% CI, 13.0%-15.3%) and the 10-year cumulative incidence was 26.0% (95% CI, 24.6%-27.6%). The incidence increased with age. The risk of 5-year incident HI decreased by generation (RR, 0.80; 95% CI, 0.66-0.97) when adjusting for multiple covariates. The decreased risk was similar in the 10-year period (HR, 0.86; 95% CI, 0.73-1.01). The PTA change rate (per 5 years of follow-up) decreased by generation, with the Greatest Generation (born 1901-1924) experiencing the highest rate (7.03 dB HL). The rates were all significantly lower for the other generations (Silent Generation [born 1925-1945], 3.30 dB HL; Baby Boom Generation [born 1946-1964], 3.36 dB HL; and Generation X [born 1965-1984], 2.33 dB HL).

Conclusions and Relevance

This study suggests that the risk of HI and rate of PTA change is lower for the Silent Generation and Baby Boom Generation compared with the Greatest Generation. Part of this lower risk is likely associated with changes in modifiable factors. A potential continued benefit may exist for Generation X. Combined with the reduced risk of HI for the Silent Generation and Baby Boom Generation, this finding implies that the future HI burden may be lower than current estimates suggest.

Factors Associated with the Macular Ganglion Cell-Inner Plexiform Layer Thickness in a Cohort of Middle-aged U.S. Adults

SIGNIFICANCE

The macular ganglion cell-inner plexiform layer (mGCIPL) may serve as a quick and easily obtained measure of generalized neurodegeneration. Investigating factors associated with this thickness could help to understand neurodegenerative processes.

PURPOSE

This study aimed to characterize and identify associated factors of the mGCIPL thickness in a Beaver Dam Offspring Study cohort of middle-aged U.S. adults.

METHODS

Baseline examinations occurred from 2005 to 2008, with follow-up examinations every 5 years. Included participants had baseline data and measured mGCIPL at 10-year follow-up (N = 1848). The mGCIPL was measured using the Cirrus 5000 HD-OCT Macular Cube Scan. Associations between mean mGCIPL thickness and thin mGCIPL, defined as 1 standard deviation (SD) below the population mean, and baseline risk factors were investigated using generalized estimating equations.

RESULTS

Participants (mean [SD] baseline age, 48.9 [9.3] years; 54.4% women) had mean (SD) mGCIPL thicknesses of 78.4 (8.1) μm in the right eye and 78.1 (8.5) μm in the left (correlation coefficient = 0.76). In multivariable models, age (-1.07 μm per 5 years; 95% confidence interval [CI], -1.28 to -0.86 μm), high alcohol consumption (-1.44 μm; 95% CI, -2.72 to -0.16 μm), higher interleukin 6 levels (50% increase in level: -0.23 μm; 95% CI, -0.45 to 0.00 μm), myopia (-2.55 μm; 95% CI, -3.17 to -1.94 μm), and glaucoma (-1.74 μm; 95% CI, -2.77 to -0.70 μm) were associated with thinner mGCIPL. Age (per 5 years: odds ratio [OR], 1.38; 95% CI, 1.24 to 1.53), diabetes (OR, 1.89, 95% CI, 1.09 to 3.27), myopia (OR, 2.11; 95% CI, 1.63 to 2.73), and increasing and long-term high C-reactive protein (ORs, 1.46 [95% CI, 1.01 to 2.11] and 1.74 [95% CI, 1.14 to 2.65], respectively) were associated with increased odds of thin mGCIPL.

CONCLUSIONS

Factors associated cross-sectionally with mGCIPL thickness, older age, high alcohol consumption, inflammation, diabetes, myopia, and glaucoma may be important to neural retina structure and health and neuronal health system-wide.

Longitudinal Decline on the Dichotic Digits Test

Purpose The dichotic digits test (DDT) is commonly administered in clinical and research settings, but it is not well understood how performance changes in aging. The purpose of this study is to determine the 5-year change on the free recall task and right ear advantage (REA) in a population-based cohort and factors associated with change. Method Participants in the population-based Epidemiology of Hearing Loss Study, who completed the DDT during the fourth (2009-2010) and fifth (2013-2016) examination periods were included (n = 865, M _age = 72.8 years at baseline). Free recall DDT was administered using 25 sets of triple-digit pairs presented at 70 dB HL. The REA was calculated by subtracting the score in the left ear from the score in the right ear. Results In 5 years, most participants (62.4%) declined on free recall performance (mean decline = 3.0% [4.5 digits], p < .01). In age-sex-adjusted models, higher baseline scores, hearing impairment, and lower education were significantly associated with increased risk of decline. An REA at baseline (76.8%) and follow-up (77.9%) was common. Half of participants (50.6%) had a 5-year REA widening (M = 1.9% [1.4 digits], p = .01). Older age, but not hearing impairment, was associated with increased risk of REA widening. Conclusions The 5-year decline on free recall recognition performance was not associated with age but was associated with hearing impairment, whereas the 5-year widening of REA was associated with age but not hearing impairment. These results indicate that the REA may be a more sensitive measure of aging of the central auditory system than free recall performance.

Macular Ganglion Cell-Inner Plexiform Layer as a Marker of Cognitive and Sensory Function in Midlife

BACKGROUND

Neurodegenerative diseases are public health challenges in aging populations. Early identification of people at risk for neurodegeneration might improve targeted treatment. Noninvasive, inexpensive screening tools are lacking but are of great potential. Optical coherence tomography (OCT) measures the thickness of nerve cell layers in the retina, which is an anatomical extension of the brain and might be indicative of common underlying neurodegeneration. We aimed to determine the association of macular ganglion cell-inner plexiform layer (mGCIPL) thickness with cognitive and sensorineural function in midlife.

METHOD

This cross-sectional study included 1,880 Beaver Dam Offspring Study participants (aged 27-93 years, mean 58) who participated in the 10-year follow-up examination. We assessed cognitive function and impairment, hearing sensitivity thresholds and impairment, central auditory processing, visual impairment, and olfactory impairment. We measured mGCIPL using the Cirrus 5000 HD-OCT Macular Cube Scan. Multivariable linear and logistic regression models adjusted for potential confounders were used to determine associations between mGCIPL thickness and cognitive and sensorineural functions, as well as for comparing participants with a thin mGCIPL (1 SD below average) to the remainder in those functions.

RESULTS

Thinner mGCIPL was associated with worse cognitive function, worse central auditory function, and visual impairment. We found an association of mGCIPL thickness with hearing sensitivity in women only and no association with impairment in hearing, olfaction, and cognition. Results on the thin group comparisons were consistent.

CONCLUSIONS

mGCIPL thickness is associated with cognitive and sensorineural function and has the potential as a marker for neurodegeneration in middle-aged adults.

Generational Differences in the 10-year Incidence of Impaired Contrast Sensitivity

PURPOSE

To determine if incidence of contrast sensitivity (CS) impairment differs by generation and identify factors to explain these differences.

METHODS

The Beaver Dam Eye Study (BDES) and Beaver Dam Offspring Study (BOSS) are cohort studies of aging adults in Beaver Dam, Wisconsin. Baseline examinations occurred from 1993 to 1995 (BDES) and 2005-2008 (BOSS). Follow-up examinations occurred in five-year intervals. CS testing was conducted with Pelli-Robson letter sensitivity charts; Incident impairment was a log CS score <1.55 in either eye at follow-up. Associations of incidence with generation were investigated using estimated hazard ratios (HR) with 95% confidence intervals (CI).

RESULTS

Participants (N = 3185) had a mean age of 51.9 years at baseline (standard deviation = 9.9) and 51.9% were female. Ten-year cumulative incidence of CS impairment was 40.1%, was higher among women (41.7%) than men (38.8%), and increased by age group. The risk of incident CS impairment decreased by 39% per generation. In multivariable models, the Baby Boom Generation (HR = 0.42, 95%CI = 0.31, 0.58) and Generation X (HR = 0.56, 95%CI = 0.34, 0.91) had a significantly decreased risk of CS impairment compared to the Greatest Generation. Results were similar in sensitivity analyses excluding those with cataract, age-related macular degeneration, or visual acuity impairment.

CONCLUSION

The risk of incident CS impairment decreased by birth cohort, with the greatest reduction in the Baby Boom Generation. The difference in risk suggests that there are unknown modifiable risk factors that may help to further explain the etiology of CS impairment and provide potential pathways for prevention in the future.

Sensorineural Impairments, Cardiovascular Risk Factors, and 10-Year Incidence of Cognitive Impairment and Decline in Midlife: The Beaver Dam Offspring Study

BACKGROUND

Sensorineural impairments and cardiovascular risk factors (CVRF) and disease (CVD) in midlife may be important predictors of future cognitive health, but longitudinal studies that include multiple sensorineural measures in middle-aged adults are lacking.

METHODS

Hearing, vision, and olfaction, and CVRF and CVD were measured at the Beaver Dam Offspring Study baseline (2005-2008) examination. The Mini-Mental State Examination and Trail Making Tests A and B were administered at all phases and additional cognitive function measures were obtained at 5 (2010-2013) and 10 years (2015-2017). Cox proportional hazards models were used to evaluate associations between baseline sensorineural impairments, CVRF, CVD, and 10-year cumulative incidence of cognitive impairment and decline.

RESULTS

There were 2,556 participants (22-84 years) without cognitive impairment at baseline and data from at least one follow-up. In a multivariable model including age, sex, education, and head injury, visual impairment (hazard ratio = 2.59, 95% confidence interval = 1.34, 5.02), olfactory impairment (hazard ratio = 3.18, 95% confidence interval = 1.53, 6.59), CVD (hazard ratio = 2.37, 95% confidence interval = 1.24, 4.52), and not consuming alcohol in the past year (hazard ratio = 2.21, 95% confidence interval = 1.16, 4.19) were associated with the 10-year cumulative incidence of cognitive impairment. Current smoking and diabetes were associated with increased risk, and exercise with decreased risk, of 10-year decline in cognitive function.

CONCLUSIONS

Visual and olfactory impairments, CVRF, and CVD were associated with the 10-year cumulative incidence of cognitive impairment and decline in middle-aged adults. Identifying modifiable factors associated with cognitive decline and impairment in midlife may provide opportunities for prevention or treatment and improve cognitive health later in life.

Cadmium, obesity, and education, and the 10-year incidence of hearing impairment: The beaver dam offspring study

OBJECTIVES/HYPOTHESIS

To determine the 10-year incidence of hearing impairment (HI) and associated risk factors in the Beaver Dam Offspring Study (BOSS; 2004-present), a large middle-aged cohort followed for 10 years.

STUDY DESIGN

Prospective cohort study.

METHODS

Hearing thresholds were measured at baseline (2005-2008) and 5- (2010-2013) and 10-year (2015-2017) follow-up examinations. HI was defined as a pure-tone average >25 dB HL in either ear. BOSS participants free of HI at baseline with at least one follow-up examination (N = 2,065) were included. Potential risk factors evaluated included cardiovascular measures, health history, lifestyle factors, inflammatory markers, vitamins D and B12, lead, and cadmium.

RESULTS

Participants were 21 to 79 years (mean age = 47.9 years) at baseline. The 10-year cumulative HI incidence was 17.4% (95% confidence interval [CI]: 15.7-19.2) and was twice as likely in men (24.4%, 95% CI: 21.5-27.7) than in women (12.2%, 95% CI: 10.3-14.3). In a multivariable adjusted model, age (hazard ratio [HR] = 1.48, 95% CI: 1.38-1.59, per 5 years), male sex (HR = 2.47, 95% CI: 1.91-3.18), less than a college education (HR = 1.35, 95% CI: 1.02-1.79), body mass index (HR = 1.03, 95% CI: 1.01-1.05, per kg/m2 ), and higher cadmium levels (HR = 1.42, 95% CI: 1.05-1.92, quintile 5 vs. quintiles 1-4) were associated with the 10-year cumulative incidence of HI. There was no association between high lead levels, vitamins D or B12, and 10-year incidence of HI.

CONCLUSIONS

In addition to age and sex, obesity, education, and blood cadmium levels were associated with increased incidence of HI. These prospective results add to evidence that age-related HI is a multifactorial preventable disorder.

LEVEL OF EVIDENCE

2b Laryngoscope, 130:1396-1401, 2020.

The Post-illumination Pupil Response (PIPR) Is Associated With Cognitive Function in an Epidemiologic Cohort Study

We conducted a cross-sectional study on 403 participants in the 10-year follow-up examination of the Beaver Dam Offspring Study. The participants included 172 male and 231 female, with age ranging from 33 to 81 years (mean ± SD, 60.7 ± 9.3). The post-illumination pupil response (PIPR) was recorded using binocular infrared pupillometer (Neur-Optics, Inc., Irvine, CA). Cognitive testing consisted of Trail Making Test (TMT) Parts A and B, Rey Auditory Verbal Learning Test (AVLT), Digit Symbol Substitution Test (DSST), and Verbal Fluency Test (VFT) (F, A, and S). Principal component analysis (PCA) was used to calculate an overall cognitive function score. There was a significant reduction in the mean baseline pupil diameter by 0.21 mm for every 5-year increase in age (95% CI: -0.25, -0.17). There was also a significant increase in the PCA cognitive score by 0.20 (linear regression, 95% CI: 0.08, 0.32) for every 0.1 unit increase in the PIPR. The association remained significant after adjusting for age, sex, education, medications, systemic and ocular disease, and short form-12 physical and mental component score. The results of this study demonstrated a modest association between the PIPR and cognitive function, warranting longitudinal studies to evaluate the role of the PIPR in predicting cognitive function in the middle-aged and older adults.

Neuroprotective factors and incident hearing impairment in the epidemiology of hearing loss study

OBJECTIVE

Hearing impairment (HI) is common in aging adults. Aldosterone, insulin-like growth factor (IGF1), and brain-derived neurotrophic factor (BDNF) have been identified as potentially protective of hearing. The present study aims to investigate these relationships.

METHODS

The Epidemiology of Hearing Loss Study is a longitudinal population-based study of aging in Beaver Dam, Wisconsin, that began in 1993. Baseline for the present investigation is the 1998 to 2000 phase. Follow-up exams occurred approximately every 5 years, with the most recent occurring from 2013 to 2016. Hearing was measured by pure-tone audiometry. HI was defined as a pure tone average (PTA) > 25 decibels hearing level in either ear. Change in PTA was the difference between follow-up examinations and baseline. Baseline serum samples were used to measure biomarkers in 2017. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated to assess the effect of biomarker levels in the lowest quintile (Q1) versus the highest (Q5) on incident HI and PTA change.

RESULTS

There were 1,088 participants (69.3% women) at risk of HI included in analyses. The mean baseline age was 63.8 years (standard deviation = 7.0). The 16-year incidence of HI was 54.9% and was higher in men (61.1%) than women (52.1%). In age- and sex-adjusted models, aldosterone (HR = 1.06, 95% CI = 0.82-1.37), IGF1 (HR = 0.92, 95% CI = 0.71-1.19), and BDNF (HR = 0.86, 95% CI = 0.66-1.12) levels were not associated with risk of HI. PTA change was similarly not affected by biomarker levels.

CONCLUSION

Aldosterone, IGF1, and BDNF were not associated with decreased risk of age-related hearing loss in this study.

LEVEL OF EVIDENCE

2b Laryngoscope, 129:2178-2183, 2019.

Association of Cadmium and Lead Exposure With the Incidence of Contrast Sensitivity Impairment Among Middle-aged Adults

Importance

Contrast sensitivity (CS) is an important indicator of visual function that affects daily life, including mobility, visually intensive tasks, safety, and autonomy. Understanding the risk factors for CS impairment could prevent decreases in visual function.

Objective

To determine the incidence of and factors associated with CS impairment in a large cohort.

Design, Setting, and Participants

The Beaver Dam Offspring Study is an ongoing longitudinal cohort study of aging involving adults in Beaver Dam, Wisconsin. Participants who were free of CS impairment in both eyes at baseline were included (N = 1983). Baseline data collection occurred from June 8, 2005, through August 4, 2008, when the participants ranged from 21 to 84 years of age. Two follow-up examinations occurred at 5-year intervals: one was conducted between July 12, 2010, and March 21, 2013, and the other between July 1, 2015, and November 13, 2017. Data analysis was performed from November 27, 2017, to February 27, 2018.

Main Outcomes and Measures

Contrast sensitivity testing was conducted with Pelli-Robson letter sensitivity charts, and incident impairment was defined as a log CS score less than 1.55 in either eye at any follow-up examination. Cadmium and lead levels were measured in whole blood with inductively coupled plasma mass spectrometry. Associations between baseline characteristics and CS impairment incidence were examined using Cox proportional hazard models and quantified as hazard ratios (HRs) with 95% CI.

Results

Of the 1983 participants included, 1028 (51.8%) were female and 955 (48.2%) were male, with a mean (SD) age of 48 (9.3) years. The 10-year cumulative incidence of CS impairment was 24.8% (95% CI, 22.9-26.8), similar in women (24.9%) and men (24.6%), and highest in the oldest age group (65-84 years) at 66.3%. In multivariable models, cadmium level in the highest quintile (HR, 1.35; 95% CI, 1.02-1.78), older age (HR, 1.36; 95% CI, 1.25-1.47), larger waist circumference (HR, 1.06; 95% CI, 1.01-1.11), and more plaque sites (1-3 sites: HR, 1.43; 95% CI, 1.07-1.92; 4-6 sites: HR, 2.75; 95% CI, 1.26-6.05) were among the factors associated with increased risk, while male sex (HR, 0.77; 95% CI, 0.60-0.98) and any alcohol consumption (HR, 0.61; 95% CI, 0.43-0.88) were associated with decreased risk. Results were similar when smoking status replaced cadmium exposure in the models. Lead level was not associated with increased risk.

Conclusions and Relevance

This study's findings suggest that incident CS impairment was common in the 10-year follow-up, with cadmium, but not lead, exposure associated with increased risk. The associations of diminished CS with other modifiable risk factors found appear to imply that changes in behavior may reduce future incidence of CS impairment.

Association Between Cystatin C and 20-Year Cumulative Incidence of Hearing Impairment in the Epidemiology of Hearing Loss Study

Importance

Hearing impairment (HI) is one of the most common conditions affecting older adults. Identification of factors associated with the development of HI may lead to ways to reduce the incidence of this condition.

Objective

To investigate the association between cystatin C, both as an independent biomarker and as a marker of kidney function, and the 20-year incidence of HI.

Design, Setting, and Participants

Data were obtained from the Epidemiology of Hearing Loss Study (EHLS), a longitudinal, population-based study in Beaver Dam, Wisconsin. Baseline examinations began in 1993 and continued through 1995, and participants were examined approximately every 5 years, with the most recent examination phase completed in 2015. The EHLS participants with serum cystatin C concentration data and without HI at the baseline examination were included in this study.

Main Outcomes and Measures

Participants without HI were followed up for incident HI (pure-tone average of hearing thresholds at 0.5, 1, 2, and 4 kHz >25 dB hearing level in either ear) for 20 years. Cystatin C was analyzed as a biomarker (concentration) and used to determine estimated glomerular filtration rate (eGFRCysC). Discrete-time Cox proportional hazards regression models were used to analyze the association between cystatin C concentration and eGFRCysC and the 20-year cumulative incidence of HI.

Results

There were 863 participants aged 48 to 86 years with cystatin C data and without HI at baseline. Of these, 599 (69.4%) were women. In models adjusted for age and sex, cystatin C was associated with an increased risk of developing HI (hazard ratio [HR], 1.20; 95% CI, 1.07-1.34 per 0.2-mg/L increase in cystatin C concentration), but the estimate was attenuated after further adjusting for educational level, current smoking, waist circumference, and glycated hemoglobin (HR, 1.11; 95% CI, 0.98-1.27 per 0.2-mg/L increase in cystatin C concentration). Low eGFRCysC was significantly associated with the 20-year cumulative incidence of HI in both the age- and sex-adjusted model (HR, 1.70; 95% CI, 1.16-2.48; <60 vs ≥60 mL/min/1.73 m2) and the multivariable-adjusted model (HR, 1.50; 95% CI, 1.02-2.22; <60 vs ≥60 mL/min/1.73 m2).

Conclusions and Relevance

Reduced kidney function as estimated using cystatin C, but not cystatin C alone, was associated with the 20-year cumulative incidence of HI, suggesting that some age-related HI may occur in conjunction with or as the result of reduced kidney function.

An Epidemiologic Study of the Association between Free Recall Dichotic Digits Test Performance and Vascular Health

BACKGROUND

Associations between vascular health-related factors and hearing loss defined using audiometric pure-tone thresholds have been found. Studies have not focused on a potential relationship between vascular health-related factors and central auditory processing.

PURPOSE

The aim of this study was to evaluate, on a population level, the relationship of vascular health-related factors with central auditory function.

RESEARCH DESIGN

A cross-sectional, population study.

STUDY SAMPLE

Subjects were participants in the Epidemiology of Hearing Loss Study (EHLS) or the Beaver Dam Offspring Study (BOSS)-prospective studies of aging and sensory loss. BOSS participants were the adult offspring of participants in the EHLS. Participants who completed the Dichotic Digits Test (DDT) during the fourth examination period of the EHLS (2008-2010) or the second examination period of the BOSS (2010-2013) were included (n = 3,655, mean age = 61.1 years).

DATA COLLECTION AND ANALYSIS

The DDT-free recall test was conducted using 25 sets of triple-digit pairs at a 70 dB HL presentation level. The total number of correctly repeated digits from the right and left ears was converted to a percentage correct and used as an outcome. The percentage correct in the left ear was subtracted from the percentage correct in the right ear and used as an outcome. Vascular health-related measures obtained during the examination included blood pressure, mean carotid intima-media thickness, femoral pulse wave velocity (PWV), hemoglobin A1C, and non-high-density lipoprotein (HDL) cholesterol, and, in the EHLS participants, C-reactive protein and interleukin-6. Information on vascular health-related history and behaviors was self-reported. General linear modeling produced estimates of the age- and sex-adjusted least squares means for each vascular factor, and multiple linear regression was used for multivariable modeling of each outcome.

RESULTS

After multivariable adjustment, participants with diabetes had a significantly lower (worse) mean DDT-free recall total score (-2.08 percentage points, p < 0.001) than those without diabetes. Participants who exercised at least once per week had a significantly higher (better) mean DDT-free recall total score (+1.07 percentage points, p < 0.01) than those who did not exercise at least once per week. Alcohol consumption was associated with a higher DDT-free recall total score (+0.15 percentage points per +25 g ethanol, p < 0.01). In multivariable modeling of the right-left ear difference in DDT-free recall scores, participants with a history of cardiovascular disease (CVD) or higher PWV demonstrated significantly larger differences (CVD: +3.11 percentage points, p = 0.02; PWV: +0.36 percentage points per 1 m/sec, p < 0.01). Higher levels of non-HDL cholesterol were associated with smaller right-left ear differences (-0.22 percentage points per 10 mg/dL, p = 0.01). Adjustment for handedness did not affect the results.

CONCLUSIONS

Vascular health-related factors may play a role in central auditory function.

A longitudinal population study of the impact of cataract extraction on sleep quality

PURPOSE

To investigate the longitudinal effects of cataract extraction on sleep quality in two discrete population cohorts.

METHODS

301 participants who had senile cataract in both eyes at the baseline examination were selected from two large longitudinal epidemiologic studies of age-related eye disease, hearing, olfaction, and cognition. The participants were divided into two groups: one had cataract surgery (CS) in both eyes, and the other had no cataract surgery (NCS) in either eye by the follow up examination. Cataract was graded from photos or digital images using a standardized protocol. The quality of sleep was assessed using a modified Wisconsin Sleep Cohort Study Questionnaire. The NCS and CS groups were compared as to the change in the number of sleep problems reported from the baseline to the follow-up examination. Systemic co-morbidity data were included as potential confounders, including diabetes mellitus, obesity, hypertension, cerebrovascular disease, thyroid disease, tobacco and alcohol use, and the SF-12 physical component and mental component summary scores.

RESULTS

The average (mean±SD) age was 71.0±8.8 years in the NCS (n=237) group and 73.4±9.1 years (n=64) in the CS group. There was no statistically significant difference in the change in the number of sleep problems reported between the NCS and CS groups (mean: -0.068 for NCS and 0.016 for CS, p=0.57). The multivariable linear regression models, when adjusted for confounders, yielded similar results.

CONCLUSION

In this longitudinal, community-based population study, we found no significant impact of cataract extraction on sleep quality. Studies of the effect of cataract extraction on sleep should allow a longer follow up to demonstrate sustainability.

Dry eye in the beaver dam offspring study: prevalence, risk factors, and health-related quality of life

PURPOSE

To estimate dry eye prevalence in the Beaver Dam Offspring Study (BOSS), including a young adult population, and investigate associated risk factors and impact on health-related quality of life.

DESIGN

Cohort study.

METHODS

The BOSS (2005-2008) is a study of aging in the adult offspring of the population-based Epidemiology of Hearing Loss Study cohort. Questionnaire data on health history, medication use, risk factors, and quality of life were available for 3275 participants. Dry eye was determined by self-report of frequency of symptoms and the intensity of those symptoms. Associations between dry eye and risk factors were analyzed using logistic regression.

RESULTS

The prevalence of dry eye in the BOSS was 14.5%: 17.9% of women and 10.5% of men. In a multivariate model, statistically significant associations were found with female sex (odds ratio [OR], 1.68; 95% confidence interval [CI], 1.33-2.11), current contact lens use (OR, 2.01; 95% CI, 1.53-2.64), allergies (OR, 1.59; 95% CI, 1.22-2.08), arthritis (OR, 1.44; 95% CI, 1.12-1.85), thyroid disease (OR, 1.43; 95% CI, 1.02-1.99), antihistamine use (OR, 1.54; 95% CI, 1.18-2.02), and steroid use (OR, 1.54; 95% CI, 1.16-2.06). Dry eye was also associated with lower scores on the Medical Outcomes Study Short Form 36 (β = -3.9, P < .0001) as well as on the National Eye Institute 25-Item Visual Function Questionnaire (NEI VFQ-25) (β = -3.4, P < .0001) when controlling for age, sex, and comorbid conditions.

CONCLUSIONS

The prevalence of dry eye and its associated risk factors in the BOSS were similar to previous studies. In this study, dry eye was associated with lower quality of life on a health-related quality-of-life instrument and the vision-specific NEI VFQ-25.