Prevalence of Retinal Signs and Association With Cognitive Status: The ARIC Neurocognitive Study

Atherosclerotic burden and cerebral small vessel disease: exploring the link through microvascular aging and cerebral microhemorrhages

Cerebral microhemorrhages (CMHs, also known as cerebral microbleeds) are a critical but frequently underestimated aspect of cerebral small vessel disease (CSVD), bearing substantial clinical consequences. Detectable through sensitive neuroimaging techniques, CMHs reveal an extensive pathological landscape. They are prevalent in the aging population, with multiple CMHs often being observed in a given individual. CMHs are closely associated with accelerated cognitive decline and are increasingly recognized as key contributors to the pathogenesis of vascular cognitive impairment and dementia (VCID) and Alzheimer's disease (AD). This review paper delves into the hypothesis that atherosclerosis, a prevalent age-related large vessel disease, extends its pathological influence into the cerebral microcirculation, thereby contributing to the development and progression of CSVD, with a specific focus on CMHs. We explore the concept of vascular aging as a continuum, bridging macrovascular pathologies like atherosclerosis with microvascular abnormalities characteristic of CSVD. We posit that the same risk factors precipitating accelerated aging in large vessels (i.e., atherogenesis), primarily through oxidative stress and inflammatory pathways, similarly instigate accelerated microvascular aging. Accelerated microvascular aging leads to increased microvascular fragility, which in turn predisposes to the formation of CMHs. The presence of hypertension and amyloid pathology further intensifies this process. We comprehensively overview the current body of evidence supporting this interconnected vascular hypothesis. Our review includes an examination of epidemiological data, which provides insights into the prevalence and impact of CMHs in the context of atherosclerosis and CSVD. Furthermore, we explore the shared mechanisms between large vessel aging, atherogenesis, microvascular aging, and CSVD, particularly focusing on how these intertwined processes contribute to the genesis of CMHs. By highlighting the role of vascular aging in the pathophysiology of CMHs, this review seeks to enhance the understanding of CSVD and its links to systemic vascular disorders. Our aim is to provide insights that could inform future therapeutic approaches and research directions in the realm of neurovascular health.

Standardization and clinical applications of retinal imaging biomarkers for cardiovascular disease: a Roadmap from an NHLBI workshop

The accessibility of the retina with the use of non-invasive and relatively low-cost ophthalmic imaging techniques and analytics provides a unique opportunity to improve the detection, diagnosis and monitoring of systemic diseases. The National Heart, Lung, and Blood Institute conducted a workshop in October 2022 to examine this concept. On the basis of the discussions at that workshop, this Roadmap describes current knowledge gaps and new research opportunities to evaluate the relationships between the eye (in particular, retinal biomarkers) and the risk of cardiovascular diseases, including coronary artery disease, heart failure, stroke, hypertension and vascular dementia. Identified gaps include the need to simplify and standardize the capture of high-quality images of the eye by non-ophthalmic health workers and to conduct longitudinal studies using multidisciplinary networks of diverse at-risk populations with improved implementation and methods to protect participant and dataset privacy. Other gaps include improving the measurement of structural and functional retinal biomarkers, determining the relationship between microvascular and macrovascular risk factors, improving multimodal imaging 'pipelines', and integrating advanced imaging with 'omics', lifestyle factors, primary care data and radiological reports, by using artificial intelligence technology to improve the identification of individual-level risk. Future research on retinal microvascular disease and retinal biomarkers might additionally provide insights into the temporal development of microvascular disease across other systemic vascular beds.

Association between retinal microvascular abnormalities and late-life brain amyloid-β deposition: the ARIC-PET study

BACKGROUND

Retinal microvascular signs are accessible measures of early alterations in microvascular dysregulation and have been associated with dementia; it is unclear if they are associated with AD (Alzheimer's disease) pathogenesis as a potential mechanistic link. This study aimed to test the association of retinal microvascular abnormalities in mid and late life and late life cerebral amyloid.

METHODS

Participants from the ARIC-PET (Atherosclerosis Risk in Communities-Positron Emission Tomography) study with a valid retinal measure (N = 285) were included. The associations of mid- and late-life retinal signs with late-life amyloid-β (Aβ) by florbetapir PET were tested. Two different measures of Aβ burden were included: (1) elevated amyloid (SUVR > 1.2) and (2) continuous amyloid SUVR. The retinal measures' association with Aβ burden was assessed using logistic and robust linear regression models. A newly created retinal score, incorporating multiple markers of retinal abnormalities, was also evaluated in association with greater Aβ burden.

RESULTS

Retinopathy in midlife (OR (95% CI) = 0.36 (0.08, 1.40)) was not significantly associated with elevated amyloid burden. In late life, retinopathy was associated with increased continuous amyloid standardized value uptake ratio (SUVR) (β (95%CI) = 0.16 (0.02, 0.32)) but not elevated amyloid burden (OR (95%CI) = 2.37 (0.66, 9.88)) when accounting for demographic, genetic and clinical risk factors. A high retinal score in late life, indicating a higher burden of retinal abnormalities, was also significantly associated with increased continuous amyloid SUVR (β (95% CI) = 0.16 (0.04, 0.32)) independent of vascular risk factors.

CONCLUSIONS

Retinopathy in late life may be an easily obtainable marker to help evaluate the mechanistic vascular pathway between retinal measures and dementia, perhaps acting via AD pathogenesis. Well-powered future studies with a greater number of retinal features and other microvascular signs are needed to test these findings.

Retinal microvasculature and incident dementia over 10 years: The Three-City-Alienor cohort

Introduction

We explored the longitudinal relationship between retinal vascular features and dementia incidence over 10 years.

Methods

Among 584 participants from the Three-City-Alienor (3C-Alienor) population-based cohort, quantitative retinal vascular features (caliber, tortuosity, fractal dimension) were measured using semi-automated software. Dementia was actively diagnosed over the follow-up period.

Results

One hundred twenty-eight participants (21.9%) developed dementia over a median of 7.1 years. In Cox proportional hazards models adjusted for sociodemographic characteristics, apolipoprotein E (APOE) ε4, and vascular factors, increased retinal arteriolar tortuosity was associated with all-cause dementia (hazard ratio per standard deviation increase, 1.21; 95% confidence interval: 1.02-1.44). Wider retinal calibers and a higher venular tortuosity were associated with mixed/vascular dementia, but not Alzheimer's disease. Fractal dimensions were not associated with dementia.

Discussion

Changes in the retinal microvasculature were associated with dementia risk. More studies are needed to replicate these findings and determine which features might help identify persons at risk at an early stage.

HIGHLIGHTS

The retinal microvasculature might reflect the brain microvasculatureWe explored the association between retinal vascular features and incident dementia584 participants from the Three-City-Alienor cohort were followed-up over 10 yearsIncreased arteriolar tortuosity and venular calibers were associated with dementia riskRetinal imaging might help identify persons at risk of future dementia.

Retinopathy is associated with impaired cognition in patients undergoing peritoneal dialysis

Objective: Previous studies have shown a relationship between retinopathy and cognition including population with and without chronic kidney disease (CKD) but data regarding peritoneal dialysis (PD) are limited. This study aims to investigate the relationship between retinopathy and cognitive impairment in patients undergoing peritoneal dialysis (PD). Methods: In this observational study, we recruited a total of 107 participants undergoing PD, consisting of 48 men and 59 women, ages ranging from 21 to 78 years. The study followed a cross-sectional design. Retinal microvascular characteristics, such as geometric changes in retinal vascular including tortuosity, fractal dimension (FD), and calibers, were assessed. Retinopathy (such as retinal hemorrhage or microaneurysms) was evaluated using digitized photographs. The Modified Mini-Mental State Examination (3MS) was performed to assess global cognitive function. Results: The prevalence rates of retinal hemorrhage, microaneurysms, and retinopathy were 25%, 30%, and 43%, respectively. The mean arteriolar and venular calibers were 63.2 and 78.5 µm, respectively, and the corresponding mean tortuosity was 37.7 ± 3.6 and 37.2 ± 3.0 mm-1. The mean FD was 1.49. After adjusting for age, sex, education, mean arterial pressure, and Charlson index, a negative association was revealed between retinopathy and 3MS scores (regression coefficient: -3.71, 95% confidence interval: -7.09 to -0.33, p = 0.03). Conclusions: Retinopathy, a condition common in patients undergoing PD, was associated with global cognitive impairment. These findings highlight retinopathy, can serve as a valuable primary screening tool for assessing the risk of cognitive decline.

Corresponding risk factors between cognitive impairment and type 1 diabetes mellitus: a narrative review

Type 1 diabetes mellitus (T1DM) is a type of diabetes caused by the destruction of pancreatic β cells and the absolute lack of insulin secretion. T1DM usually starts in adolescence or develops directly as a severe disease state of ketoacidosis. T1DM and its complications make many people suffer and have psychological problems, which make us have to pay more attention to the prevention and early control of T1DM. Cognitive impairment (CI) is one of the major complications of T1DM. It can further develop into Alzheimer's disease, which can seriously affect the quality of life of the elderly. Furthermore, the relationship between T1DM and CI is unclear. Hence, we conducted a narrative review of the existing literature through a PubMed search. We summarized some risk factors that may be associated with the cognitive changes in T1DM patients, including onset age and duration, education and gender, glycemic states, microvascular complications, glycemic control, neuropsychology and emotion, intestinal flora, dyslipidemia, sleep quality. We aimed to provide some content related to CI in T1DM, and hoped that it could play a role in early prediction and treatment to reduce the prevalence.

•

Corresponding risk factors between cognitive impairment and type 1 diabetes mellitus.

•

Duration and age; Education and gender and Glycemic states.

•

Diabetic ketoacidosis; Microvascular complications and Glycemic control–HbA1c.

•

Neuropsychology and emotion; Intestinal flora; Dyslipidemia and Sleep Quality.

Retinal biomarkers of Cerebral Small Vessel Disease: A systematic review

INTRODUCTION

Cerebral Small Vessel Disease (CSVD), a progressive degenerative disorder of small caliber cerebral vessels, represents a major contributor to stroke and vascular dementia incidence worldwide. We sought to conduct a systematic review of the role of retinal biomarkers in diagnosis and characterization of CSVD.

METHODS

We conducted a systematic review of MEDLINE, PubMed, Scopus, the Cochrane Library Database, and Web of Science. We identified studies of sporadic CSVD (including CSVD not otherwise specified, Cerebral Amyloid Angiopathy, and Hypertensive Arteriopathy) and the most common familial CSVD disorders (including CADASIL, Fabry disease, and MELAS). Included studies used one or more of the following tools: visual fields assessment, fundus photography, Optical Coherence Tomography and OCT Angiography, Fluorescein Angiography, Electroretinography, and Visual Evoked Potentials.

RESULTS

We identified 48 studies of retinal biomarkers in CSVD, including 9147 cases and 12276 controls. Abnormalities in retinal vessel diameter (11 reports, n = 11391 participants), increased retinal vessel tortuosity (11 reports, n = 617 participants), decreased vessel fractal dimension (5 reports, n = 1597 participants) and decreased retinal nerve fiber layer thickness (5 reports, n = 4509 participants) were the biomarkers most frequently associated with CSVD. We identified no reports conducting longitudinal retinal evaluations of CSVD, or systematically evaluating diagnostic performance.

CONCLUSION

Multiple retinal biomarkers were associated with CSVD or its validated neuroimaging biomarkers. However, existing evidence is limited by several shortcomings, chiefly small sample size and unstandardized approaches to both biomarkers' capture and CSVD characterization. Additional larger studies will be required to definitively determine whether retinal biomarkers could be successfully incorporated in future research efforts and clinical practice.

Association of different severity of diabetic retinopathy and hearing loss in type 2 diabetes mellitus

PURPOSE

Microvascular involvement in patients with diabetes mellitus is one of the causes of retinopathy, nephropathy, and neuropathy. The same pathologic processes may occur in the inner ear structures. This case-control study aimed to evaluate the hearing thresholds in type 2 diabetic patients with different severity of diabetic retinopathy (DR) and to compare these findings with controls.

MATERIALS AND METHODS

We evaluated the hearing threshold in four groups of eligible subjects aged 20-70 years. These groups were controls, diabetic patients with no-DR, with mild-moderate non-proliferative DR (NPDR), and with severe NPDR/proliferative DR (PDR). Each group consisted of 105 subjects. Speech-frequency and high-frequency hearing levels (SFHL and HFHL, respectively) were measured and log-transformed. Analysis of covariance was used. The prevalence rate of moderate or more hearing loss in the groups was estimated.

RESULTS

In total, 194 men and 226 women participated. The ratio of means of SFHL and HFHL between PDR and controls was 0.18 and 0.20, respectively. Hearing loss was prevalent in severe NPDR/PDR (adjusted prevalence ratio 3.36 for SFHL and 1.51 for HFHL) compared to controls. Also, the prevalence of high-frequency hearing loss was more in mild-moderate NPDR (adjusted prevalence ratio 1.33).

CONCLUSIONS

The magnitude of the increase in hearing impairment prevalence between the severe NPDR/PDR patients and controls was about 24% for both SFHL and HFHL. We recommend hearing assessment in the screening of the DR patients.

Cognitive decline in older adults: What can we learn from optical coherence tomography (OCT)-based retinal vascular imaging?

INTRODUCTION

Accumulated vascular damage contributes to the onset and progression of vascular dementia and possibly to Alzheimer's disease. Here we evaluate the feasibility and utility of using retinal imaging of microvascular markers to identify older adults at risk of cognitive disease.

METHODS

The "Eye Determinants of Cognition" (EyeDOC) study recruited a biracial, population-based sample of participants from two sites: Jackson, MS, and Washington Co, MD. Optical coherence tomographic angiography (OCTA) was used to capture vessel density (VD) from a 6 × 6 mm scan of the macula in several vascular layers from 2017 to 2019. The foveal avascular zone (FAZ) area was also estimated. Image quality was assessed by trained graders at a reading center. A neurocognitive battery of 10 tests was administered at three time points from 2011 to 2019 and incident mild cognitive impairement (MCI)/dementia cases were ascertained. Linear mixed-effects models were used to evaluate associations of retinal vascular markers with cognitive factor score change over time.

RESULTS

Nine-hundred and seventy-six older adults (mean age of 78.7 (± 4.4) years, 44% black) were imaged. Gradable images were obtained in 55% (535/976), with low signal strength (66%) and motion artifact (22%) being the largest contributors to poor quality. Among the 297 participants with both high-quality images and no clinically significant retinal pathology, the average decline in global cognitive function factor score was -0.03 standard deviations per year. In adjusted analyses, no associations of VD or FAZ with longitudinal changes in either global cognitive function or with incident MCI/dementia were found.

CONCLUSIONS

In this large biracial community sample of older adults representative of the target population for retinal screening of cognitive risk, we found that obtaining high-quality OCTA scans was infeasible in a nearly half of older adults. Among the select sample of healthier older adults with scans, OCTA markers were not predictive of cognitive impairment.

Ophthalmic conditions associated with dementia risk: The Cardiovascular Health Study

INTRODUCTION

Ophthalmic conditions and dementia appear to overlap and may share common pathways, but research has not differentiated dementia subtypes.

METHODS

Diagnoses of cataracts, age-related macular degeneration (AMD), diabetic retinopathy (DR), and glaucoma were based on medical histories and International Classification of Diseases, Ninth Revision (ICD-9) codes for 3375 participants from the Cardiovascular Health Study. Dementia, including Alzheimer's disease (AD) and vascular dementia (VaD), was classified using standardized research criteria.

RESULTS

Cataracts were associated with AD (hazard ratio [HR] = 1.34; 95% confidence interval [CI] = 1.01-1.80) and VaD/mixed dementia (HR = 1.41; 95% CI = 1.02-1.95). AMD was associated with AD only (HR = 1.87; 95% CI = 1.13-3.09), whereas DR was associated with VaD/mixed dementia only (HR = 2.63; 95% CI = 1.10-6.27).

DISCUSSION

Differential associations between specific ophthalmic conditions and dementia subtypes may elucidate pathophysiologic pathways. Lack of association between glaucoma and dementia was most surprising from these analyses.

Retinal biomarkers in Alzheimer's disease and mild cognitive impairment: A systematic review and meta-analysis

BACKGROUND

Retinal changes may reflect the pathophysiological processes in the central nervous system and can be assessed by imaging modalities non-invasively. We aim to localize candidate retinal biomarkers in Alzheimer's disease (AD), mild cognitive impairment (MCI), and preclinical AD.

METHODS

We systematically searched PubMed, EMBASE, Scopus, and Web of Science from inception to January 2021 for observational studies that investigated retinal imaging and electrophysiological markers in AD, MCI, and preclinical AD. Between-groups standardized mean differences (SMDs) with 95 % confidence intervals were computed using random-effects models.

RESULTS

Of 19,727 citations identified, 126 articles were eligible for inclusion. Compared with healthy controls, the thickness of peripapillary retinal nerve fiber layer (pRNFL; SMD = -0.723, p < 0.001), total macular (SMD = -0.612, p < 0.001), and subfoveal choroid (SMD = -0.888, p < 0.001) were significantly reduced in patients with AD. Compared with healthy controls, patients with MCI also had lower thickness of pRNFL (SMD = -0.324, p < 0.001), total macular (SMD = -0.302, p < 0.001), and subfoveal choroid (SMD = -0.462, p = 0.020). Other candidate biomarkers included the optic nerve head morphology, retinal amyloid deposition, microvascular morphology and densities, blood flow, and electrophysiological markers.

CONCLUSIONS

Retinal structural, vascular, and electrophysiological biomarkers hold great potential for the diagnosis, prognosis and risk assessment of AD and MCI. These biomarkers warrant further development in the future, especially in diagnostic test accuracy and longitudinal studies.

Association Between Microvascular Retinal Signs and Age-Related Hearing Loss in the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS)

Importance

Given that age-related hearing loss is highly prevalent and treatable, understanding its causes may have implications for disease prevention.

Objective

To investigate whether microvascular retinal signs are associated with age-related hearing loss attributable to a hypothesized underlying shared pathologic entity involving microvascular disease.

Design, Setting, and Participants

The Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS) is a community-based prospective cohort study of 15 792 men and women aged 45 to 64 years at baseline. The ARIC-NCS participants returned for a fifth clinic visit in 2011-2013 and a sixth clinic visit in 2016-2017. Participants were recruited from 4 US communities (Washington County, Maryland; Forsyth County, North Carolina; Jackson, Mississippi; and Minneapolis suburbs, Minnesota). Participants included a subset of the ARIC-NCS cohort with complete covariate data who underwent retinal fundus photography at visit 5 (2011-2013) and completed hearing assessment at visit 6 (2016-2017) (N = 1458). Overall, 453 participants had diabetes; of those, 68 had retinopathy. Of 1005 participants without diabetes, 42 had retinopathy.

Exposures

Microvascular retinal signs included retinopathy, arteriovenous (AV) nicking, and generalized arteriolar narrowing measured using the central retinal arteriolar equivalent (CRAE).

Main Outcomes and Measures

Hearing was measured using the better-hearing ear pure-tone average (PTA) of air conduction speech thresholds (0.5, 1, 2, and 4 kHz). Multivariable-adjusted linear and ordered logistic regression was used to estimate the association between microvascular retinal signs and age-related hearing loss to describe the precision of the estimates and provide a plausible range for the true association.

Results

After full adjustment among 1458 individuals in the analytic cohort (mean [SD] age, 76.1 [5.0] years [age range, 67-90 years]; 825 women [56.6%]; 285 black [19.5%]), the difference in PTA per dB hearing level in persons with and without retinopathy was 2.21 (95% CI, -0.22 to 4.63), suggesting that retinopathy is associated with poorer hearing, although the width of the 95% CI prevents definitive conclusions about the strength of the observed association. Restricting the analysis to participants without diabetes, the difference in PTA associated with retinopathy was even greater (4.14; 95% CI, 0.10-8.17 dB hearing level), but the large width of the 95% CI prevents definitive conclusions about the association. In analyses quantifying the mean differences in hearing thresholds at individual frequencies by retinopathy status, the estimates trended toward retinopathy being associated, contrary to expectation, with better high-frequency hearing. At 8 kHz, the estimated difference in hearing thresholds in persons with retinopathy vs those without was -4.24 (95% CI, -7.39 to -1.09).

Conclusions and Relevance

In this population-based study, an association between the presence of microvascular retinal signs and hearing loss was observed, suggesting that retinopathy may have the potential to identify risk for hearing loss in persons without diabetes. The precision of these estimates is low; therefore, additional epidemiologic studies are needed to better define the degree of microvascular contributions to age-related hearing loss.

Why Miss the Chance? Incidental Findings while Telescreening for Diabetic Retinopathy

PURPOSE

To report on incidental pathological findings met while screening for Diabetic Retinopathy (DR) in Diabetes Clinics (DC) by ophthalmologist-graded digital fundus imaging.

METHODS

At the DC of Pescara (central Italy), for 3,859 eyes of 1,930 consecutive patients having not undergone fundus examination in the last year, two mydriatic fundus digital images, taken with a CenterVue DRS Digital Retinal Camera, were sent along with Best Corrected Visual Acuity, on a "store-and-forward" basis, to an ophthalmologist trained in DR screening, and graded according to the UK Diabetic Eye Screening Programme. Incidental fundus abnormalities other than DR were reported.

RESULTS

No adverse event to mydriasis was reported. One hundred and eighty eyes (4.66%) were ungradable. Among the 3,679 gradable ones, 1,105 (30.04%) showed different degrees of DR (R1 to R3), and 126 (3.42%) maculopathy (M1). Any Age-Related Macular Degeneration was present in 387 eyes (10.52%), any optic disc and parapapillary area features suspect for glaucoma in 562 eyes (15.27%), any hypertensive retinopathy in 1,263 eyes (34.33%), vitreoretinal interface disease in 252 eyes (6.84%), myopic choroidopathy in 92 eyes (2.50%), disc pallor in 31 eyes (0.84%). Mean time was 5 min for screening, 2 min for grading.

CONCLUSION

Teleretinography is a well-established, cost-effective procedure in DR screening. Along with increased attendance, locating a digital camera in a DC with a retina-specialist grader results in finding fundus pathologies also beyond DR, very similarly to fundus examination in an outpatient ophthalmic setting.