Associations between recent and established ophthalmic conditions and risk of Alzheimer's disease

Genetic and Epigenetic Biomarkers Linking Alzheimer's Disease and Age-Related Macular Degeneration

Alzheimer's disease (AD) represents a prominent neurodegenerative disorder (NDD), accounting for the majority of dementia cases worldwide. In addition to memory deficits, individuals with AD also experience alterations in the visual system. As the retina is an extension of the central nervous system (CNS), the loss in retinal ganglion cells manifests clinically as decreased visual acuity, narrowed visual field, and reduced contrast sensitivity. Among the extensively studied retinal disorders, age-related macular degeneration (AMD) shares numerous aging processes and risk factors with NDDs such as cognitive impairment that occurs in AD. Histopathological investigations have revealed similarities in pathological deposits found in the retina and brain of patients with AD and AMD. Cellular aging processes demonstrate similar associations with organelles and signaling pathways in retinal and brain tissues. Despite these similarities, there are distinct genetic backgrounds underlying these diseases. This review comprehensively explores the genetic similarities and differences between AMD and AD. The purpose of this review is to discuss the parallels and differences between AMD and AD in terms of pathophysiology, genetics, and epigenetics.

Deep Learning Models for the Screening of Cognitive Impairment Using Multimodal Fundus Images

OBJECTIVE

We aimed to develop a deep learning system capable of identifying subjects with cognitive impairment quickly and easily based on multimodal ocular images.

DESIGN

Cross sectional study.

SUBJECTS

Participants of Beijing Eye Study 2011 and patients attending Beijing Tongren Eye Center and Beijing Tongren Hospital Physical Examination Center.

METHODS

We trained and validated a deep learning algorithm to assess cognitive impairment using retrospectively collected data from the Beijing Eye Study 2011. Cognitive impairment was defined as a Mini-Mental State Examination score < 24. Based on fundus photographs and OCT images, we developed 5 models based on the following sets of images: macula-centered fundus photographs, optic disc-centered fundus photographs, fundus photographs of both fields, OCT images, and fundus photographs of both fields with OCT (multimodal). The performance of the models was evaluated and compared in an external validation data set, which was collected from patients attending Beijing Tongren Eye Center and Beijing Tongren Hospital Physical Examination Center.

MAIN OUTCOME MEASURES

Area under the curve (AUC).

RESULTS

A total of 9424 retinal photographs and 4712 OCT images were used to develop the model. The external validation sets from each center included 1180 fundus photographs and 590 OCT images. Model comparison revealed that the multimodal performed best, achieving an AUC of 0.820 in the internal validation set, 0.786 in external validation set 1, and 0.784 in external validation set 2. We evaluated the performance of the multi-model in different sexes and different age groups; there were no significant differences. The heatmap analysis showed that signals around the optic disc in fundus photographs and the retina and choroid around the macular and optic disc regions in OCT images were used by the multimodal to identify participants with cognitive impairment.

CONCLUSIONS

Fundus photographs and OCT can provide valuable information on cognitive function. Multimodal models provide richer information compared with single-mode models. Deep learning algorithms based on multimodal retinal images may be capable of screening cognitive impairment. This technique has potential value for broader implementation in community-based screening or clinic settings.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Amyloid-beta and tau protein beyond Alzheimer's disease

ABSTRACT

The aggregation of amyloid-beta peptide and tau protein dysregulation are implicated to play key roles in Alzheimer's disease pathogenesis and are considered the main pathological hallmarks of this devastating disease. Physiologically, these two proteins are produced and expressed within the normal human body. However, under pathological conditions, abnormal expression, post-translational modifications, conformational changes, and truncation can make these proteins prone to aggregation, triggering specific disease-related cascades. Recent studies have indicated associations between aberrant behavior of amyloid-beta and tau proteins and various neurological diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as retinal neurodegenerative diseases like Glaucoma and age-related macular degeneration. Additionally, these proteins have been linked to cardiovascular disease, cancer, traumatic brain injury, and diabetes, which are all leading causes of morbidity and mortality. In this comprehensive review, we provide an overview of the connections between amyloid-beta and tau proteins and a spectrum of disorders.

Age-related macular degeneration and neurodegenerative disorders: Shared pathways in complex interactions

Age-related macular degeneration (AMD) is a leading cause of irreversible blindness in the elderly, and neurodegenerative disorders such as Alzheimer disease and Parkinson disease are debilitating conditions that affect millions worldwide. Despite the different clinical manifestations of these diseases, growing evidence suggests that they share common pathways in their pathogenesis including inflammation, oxidative stress, and impaired autophagy. In this review, we explore the complex interactions between AMD and neurodegenerative disorders, focusing on their shared mechanisms and potential therapeutic targets. We also discuss the current opportunities and challenges for developing effective treatments that can target these pathways to prevent or slow down disease progression in AMD. Some of the promising strategies that we explore include modulating the immune response, reducing oxidative stress, enhancing autophagy and lysosomal function, and targeting specific protein aggregates or pathways. Ultimately, a better understanding of the shared pathways between AMD and neurodegenerative disorders may pave the way for novel and more efficacious treatments.

Outer Retinal Thickness Is Associated With Cognitive Function in Normal Aging to Intermediate Age-Related Macular Degeneration

Purpose

Research on Alzheimer's disease (AD) and precursor states demonstrates a thinner retinal nerve fiber layer (NFL) compared to age-similar controls. Because AD and age-related macular degeneration (AMD) both impact older adults and share risk factors, we asked if retinal layer thicknesses, including NFL, are associated with cognition in AMD.

Methods

Adults ≥ 70 years with normal retinal aging, early AMD, or intermediate AMD per Age-Related Eye Disease Study (AREDS) nine-step grading of color fundus photography were enrolled in a cross-sectional study. Optical coherence tomography (OCT) volumes underwent 11-line segmentation and adjustments by a trained operator. Evaluated thicknesses reflect the vertical organization of retinal neurons and two vascular watersheds: NFL, ganglion cell layer-inner plexiform layer complex (GCL-IPL), inner retina, outer retina (including retinal pigment epithelium-Bruch's membrane), and total retina. Thicknesses were area weighted to achieve mean thickness across the 6-mm-diameter Early Treatment of Diabetic Retinopathy Study (ETDRS) grid. Cognitive status was assessed by the National Institutes of Health Toolbox cognitive battery for fluid and crystallized cognition. Correlations estimated associations between cognition and thicknesses, adjusting for age.

Results

Based on 63 subjects (21 per group), thinning of the outer retina was significantly correlated with lower cognition scores (P < 0.05). No other retinal thickness variables were associated with cognition.

Conclusions

Only the outer retina (photoreceptors, supporting glia, retinal pigment epithelium, Bruch's membrane) is associated with cognition in aging to intermediate AMD; NFL was not associated with cognition, contrary to AD-associated condition reports. Early and intermediate AMD constitute a retinal disease whose earliest, primary impact is in the outer retina. Our findings hint at a unique impact on the brain from the outer retina in persons with AMD.

Associations of cataract, cataract surgery with dementia risk: A systematic review and meta-analysis of 448,140 participants

BACKGROUND

Cataract is the leading cause of blindness around the world. Previous investigations have assessed the relationship between cataract, cataract surgery and dementia risk, but their results remain controversial. Herein, we conducted a meta-analysis to evaluate the associations between cataract, cataract surgery and the risk of dementia.

METHODS

We systemically screened the literature from three electronic databases PubMed, EMBASE and CENTRAL until April 2023. The data were collected by two independent researchers. The hazard ratios (HRs) or odds ratios (ORs) from eligible studies with 95% confidence intervals (CIs) were adjusted into the risk ratios (RRs), which were pooled using the random-effects model.

RESULTS

A total of nine studies with 448,140 participants reported the associations between cataract or cataract surgery and the risk of dementia were included in this meta-analysis. The outcomes of our pooled analysis indicated that cataract was associated with an increased risk of all-cause dementia (RR = 1.24, 95% CI, 1.14-1.35, p < .00001), Alzheimer's disease (RR = 1.22, 95% CI, 1.10-1.35, p = .0002) and vascular dementia (RR = 1.29, 95% CI, 1.01-1.66, p = .04). Cataract surgery is associated with a reduction of the dementia risk (RR = 0.74, 95% CI, 0.67-0.81, p < .00001).

CONCLUSIONS

Current evidence from the existing studies supports that cataract is associated with an increased risk of dementia, and cataract surgery may be instrumental in reducing the risk of dementia in patients with cataract.

The risk of dementia or cognitive impairment in patients with cataracts: a systematic review and meta-analysis

OBJECTIVES

The aim of this study was to investigate whether cataract disease is associated with the risk of developing dementia or cognitive impairment.

METHODS

A systematic search of the literature in PubMed, the Extracts Database (Embase), the Cochrane Library and the Web of Science databases was performed from the inception data of each database until 1 September 2022. Sensitivity analyses were performed to assess the robustness and reliability of the overall findings. All extracted data were statistically analyzed using Stata software v.16.0. Publication bias was assessed using funnel plots and the Egger test.

RESULTS

There were 11 publications included in this study, which consisted of 489,211participants, spanning 10 countries from 2012 to 2022. Aggregation suggested that cataracts were associated with cognitive impairment (odds ratio [OR] = 1.32; 95% CI: 1.21-1.43; I 2 = 45.4.%; p = 0.000). The presence of cataracts is significantly associated with an increased risk of developing all-cause dementia (relative risk [RR] = 1.17; 95% CI: 1.08-1.26; I2 = 0.0%; p = 0.000). In subgroup analyses, having cataracts may increase the risk of Alzheimer's disease (hazard ratio [HR] = 1.28; 95% CI: 1.13-1.45; I2 = 0.0%; p = 0.000) and vascular dementia (HR = 1.35; 95% CI = 1.06-1.73; I2 = 0.0%, p = 0.015). The data from the Egger's test showed no significant evidence of publication bias.

CONCLUSIONS

Cataracts are associated with the risk of cognitive impairment and dementia, including Alzheimer's disease, and vascular dementia.

How Generalizable Are Findings from a Community-Based Prospective Cohort Study? Extending Estimates from the Adult Changes in Thought Study to Its Source Population

Background

The Adult Changes in Thought (ACT) study is a cohort of Kaiser Permanente Washington members ages 65+ that began in 1994.

Objective

We wanted to know how well ACT participants represented all older adults in the region, and how well ACT findings on eye disease and its relationship with Alzheimer's disease generalized to all older adults in the Seattle Metropolitan Region.

Methods

We used participation weights derived from pooling ACT and Behavioral Risk Factor Surveillance System (BRFSS) data to estimate prevalences of common eye diseases and their associations with Alzheimer's disease incidence. Cox proportional hazards models accounted for age, education, smoking, sex, and APOE genotype. Confidence intervals for weighted analyses were bootstrapped to account for error in estimating the weights.

Results

ACT participants were fairly similar to older adults in the region. The largest differences were more self-reported current cholesterol medication use in BRFSS and higher proportions with low education in ACT. Incorporating the weights had little impact on prevalence estimates for age-related macular degeneration or glaucoma. Weighted estimates were slightly higher for diabetic retinopathy (weighted 5.7% (95% Confidence Interval 4.3, 7.1); unweighted 4.1% (3.6, 4.6)) and cataract history (weighted 51.8% (49.6, 54.3); unweighted 48.6% (47.3, 49.9)). The weighted hazard ratio for recent diabetic retinopathy diagnosis and Alzheimer's disease was 1.84 (0.34, 4.29), versus 1.32 (0.87, 2.00) in unweighted ACT.

Conclusions

Most, but not all, associations were similar after participation weighting. Even in community-based cohorts, extending inferences to broader populations may benefit from evaluation with participation weights.

Morphological disruption and visual tuning alterations in the primary visual cortex in glaucoma (DBA/2J) mice

Glaucoma is a leading cause of irreversible blindness worldwide, and previous studies have shown that, in addition to affecting the eyes, it also causes abnormalities in the brain. However, it is not yet clear how the primary visual cortex (V1) is altered in glaucoma. This study used DBA/2J mice as a model for spontaneous secondary glaucoma. The aim of the study was to compare the electrophysiological and histomorphological characteristics of neurons in the V1 between 9-month-old DBA/2J mice and age-matched C57BL/6J mice. We conducted single-unit recordings in the V1 of light-anesthetized mice to measure the visually induced responses, including single-unit spiking and gamma band oscillations. The morphology of layer II/III neurons was determined by neuronal nuclear antigen staining and Nissl staining of brain tissue sections. Eighty-seven neurons from eight DBA/2J mice and eighty-one neurons from eight C57BL/6J mice were examined. Compared with the C57BL/6J group, V1 neurons in the DBA/2J group exhibited weaker visual tuning and impaired spatial summation. Moreover, fewer neurons were observed in the V1 of DBA/2J mice compared with C57BL/6J mice. These findings suggest that DBA/2J mice have fewer neurons in the V1 compared with C57BL/6J mice, and that these neurons have impaired visual tuning. Our findings provide a better understanding of the pathological changes that occur in V1 neuron function and morphology in the DBA/2J mouse model. This study might offer some innovative perspectives regarding the treatment of glaucoma.

Eye Adult Changes in Thought (Eye ACT) Study: Design and Report on the Inaugural Cohort

Background

Conflicting research on retinal biomarkers of Alzheimer's disease and related dementias (AD/ADRD) is likely related to limited sample sizes, study design, and protocol differences.

Objective

The prospective Eye Adult Changes in Thought (Eye ACT) seeks to address these gaps.

Methods

Eye ACT participants are recruited from ACT, an ongoing cohort of dementia-free, older adults followed biennially until AD/ADRD, and undergo visual function and retinal imaging assessment either in clinic or at home.

Results

330 participants were recruited as of 03/2023. Compared to ACT participants not in Eye ACT (N = 1868), Eye ACT participants (N = 330) are younger (mean age: 70.3 versus 71.2, p = 0.014), newer to ACT (median ACT visits since baseline: 3 versus 4, p < 0.001), have more years of education (17.7 versus 16.2, p < 0.001) and had lower rates of visual impairment (12% versus 22%, p < 0.001). Compared to those seen in clinic (N = 300), Eye ACT participants seen at home (N = 30) are older (77.2 versus 74.9, p = 0.015), more frequently female (60% versus 49%, p = 0.026), and have significantly worse visual acuity (71.1 versus 78.9 Early Treatment Diabetic Retinopathy Study letters, p < 0.001) and contrast sensitivity (-1.9 versus -2.1 mean log units at 3 cycles per degree, p = 0.002). Cognitive scores and retinal imaging measurements are similar between the two groups.

Conclusions

Participants assessed at home had significantly worse visual function than those seen in clinic. By including these participants, Eye ACT provides a unique longitudinal cohort for evaluating potential retinal biomarkers of dementia.

Relative Risks for Dementia among Individuals with Glaucoma: A Meta-Analysis of Observational Cohort Studies

PURPOSE

To investigate the relative risks (RRs) for dementia among individuals with glaucoma.

METHODS

We conducted a search of PubMed, Web of Science, Scopus, and Cochrane databases for observational cohort studies examining the association between glaucoma and dementia until March 2023. Two authors independently screened all titles and abstracts according to predefined inclusion and exclusion criteria. Pooled RR and 95% confidence intervals (CIs) were generated using random-effect models.

RESULTS

The meta-analysis included 18 cohort studies conducted in eight countries and involving 4,975,325 individuals. The pooled RR for the association between glaucoma and all-cause dementia was 1.314 (95% CI, 1.099-1.572; I2 = 95%). The pooled RRs for the associations of open-angle glaucoma with Alzheimer dementia and Parkinson disease were 1.287 (95% CI, 1.007-1.646; I2 = 96%) and 1.233 (95% CI, 0.677-2.243; I2 = 73%), respectively. The pooled RRs for the associations of angle-closure glaucoma with all-cause dementia and Alzheimer dementia were 0.978 (95% CI, 0.750-1.277; I2 = 17%) and 0.838 (95% CI, 0.421-1.669; I2 = 16%), respectively. No evidence of publication bias was detected in the Begg-Mazumdar adjusted rank correlation test (p = 0.47).

CONCLUSIONS

Based on current observational cohort studies, there is evidence supporting that glaucoma is a risk factor for dementia in the adult population.

Identification of Candidate Biomarkers of Alzheimer's Disease via Multiplex Cerebrospinal Fluid and Serum Proteomics

Alzheimer's disease (AD) is the most prevalent form of dementia among elderly people worldwide. Cerebrospinal fluid (CSF) is the optimal fluid source for AD biomarkers, while serum biomarkers are much more achievable. To search for novel diagnostic AD biomarkers, we performed a quantitative proteomic analysis of CSF and serum samples from AD and normal cognitive controls (NC). CSF and serum proteomes were analyzed via data-independent acquisition quantitative mass spectrometry. Our bioinformatic analysis was based on Gene Ontology (GO) functional annotation analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. In comparison to the controls, 8 proteins were more abundant in AD CSF, and 60 were less abundant in AD CSF, whereas 55 proteins were more and 10 were less abundant in the serum samples. ATPase-associated activity for CSF and mitochondrial functions for CSF and serum were the most enriched GO terms of the DEPs. KEGG enrichment analysis showed that the most significant pathways for the differentially expressed proteins were the N-glycan biosynthesis pathways. The area under the curve (AUC) values for CSF sodium-/potassium-transporting ATPase subunit beta-1 (AT1B1), serglycin (SRGN), and thioredoxin-dependent peroxide reductase, mitochondrial (PRDX3) were 0.867 (p = 0.004), 0.833 (p = 0.008), and 0.783 (p = 0.025), respectively. A panel of the above three CSF proteins accurately differentiated AD (AUC = 0.933, p = 0.001) from NC. The AUC values for serum probable phospholipid-transporting ATPase IM (AT8B4) and SRGN were moderate. The AUC of the CSF SRGN + serum SRGN was 0.842 (p = 0.007). These novel AD biomarker candidates are mainly associated with inflammation, ATPase activity, oxidative stress, and mitochondrial dysfunction. Further studies are needed to investigate the molecular mechanisms by which these potential biomarkers are involved in AD.

The Association Between Eye Disease and Incidence of Dementia: Systematic Review and Meta-Analysis

OBJECTIVES

To better demonstrate the relationship between common eye diseases and the risk of dementia, we conducted a systematic review and meta-analysis of cohort studies to investigate the relationship between common eye diseases and dementia.

DESIGN

Systematic review and meta-analysis.

SETTING AND PARTICIPANTS

Patients with common eye diseases.

METHODS

We conducted a systematic search of articles published up to August 25, 2022, of online databases including PubMed, EMBASE, and Web of Science. We included cohort studies that evaluated the association of glaucoma, age-related macular degeneration (AMD), diabetic retinopathy (DR), and cataracts with all-cause dementia, Alzheimer's disease (AD), and vascular dementia (VaD). Relative risks (RRs) and 95% CIs were pooled using random effects model, and heterogeneity was assessed by the I2 statistic. Subgroup analysis and sensitivity analysis were also performed.

RESULTS

In total, 25 studies were included in the meta-analysis, with a total of 11,410,709 participants. Pooled estimates suggested an increased risk of all-cause dementia associated with AMD (RR, 1.29; 95% CI, 1.13-1.48), glaucoma (RR, 1.16; 95% CI, 1.03-1.32), DR (RR, 1.40; 95% CI, 1.21-1.63), and cataract (RR,1.23; 95% CI, 1.09-1.40); an increased risk of AD associated with AMD (RR, 1.27; 95% CI, 1.06-1.52), glaucoma (RR, 1.18; 95% CI, 1.02-1.38), DR (RR, 1.21; 95% CI, 1.04-1.41), and cataracts (RR,1.22; 95% CI, 1.07-1.38). No association was observed between incident VaD and any eye diseases. The results of subgroup analyses were consistent with those in meta-analysis of DR and risk of all-cause dementia. Meta-regressions suggested geographic regions as potential sources of heterogeneity for the association between AMD and all-cause dementia, AMD and AD, glaucoma and dementia, glaucoma, and AD, respectively.

CONCLUSIONS AND IMPLICATIONS

AMD, glaucoma, DR, and cataract may be associated with an increased risk of all-cause dementia and AD, but not VaD. However, the results should be interpreted cautiously because of the high heterogeneity and unstable findings in some subgroup analyses.

Subjective vision assessment in companion dogs using dogVLQ demonstrates age-associated visual dysfunction

Introduction

Dim light vision as assessed by proxy and clinical tools is commonly impaired in older humans and impacts quality of life. Although proxy visual assessment tools have been developed for dogs, it is unclear if they are sensitive enough to detect subtle visual dysfunction in older dogs. We sought to determine if a newly designed proxy visual function questionnaire could detect age-associated differences in visual behaviors in varying lighting conditions in dogs.

Methods

A 27-item questionnaire (the dog variable lighting questionnaire, dogVLQ) was designed to assess visual behavior in dogs in different lighting settings. We conducted the dogVLQ, a previously validated visual function questionnaire the dog vision impairment score and performed light- and dark-adapted electroretinography (ERG) on a subset of dogs. Questionnaire scores were analyzed for dog age associations using correlation analysis.

Results

Questionnaire responses from 235 dog owners were obtained (122 female, 112 male dogs), 79 of which underwent ERG (43 female, 36 male dogs). Bright light visual behavior was significantly associated with light-adapted bright flash ERG amplitudes, visual behavior in near darkness was associated with dark-adapted ERG amplitudes. The dogVLQ identified worse vision in older dogs in bright light, dim light, and darkness; predicted onset was younger for vision in near darkness. Older dogs had more difficulty navigating transitions between lighting conditions.

Discussion

Subjective dog owner assessment of visual function associates with objective measurement of retinal function in dogs and supports reduced vision-mediated behaviors in older dogs.

Relationships between quantitative retinal microvascular characteristics and cognitive function based on automated artificial intelligence measurements

Introduction: The purpose of this study is to assess the relationship between retinal vascular characteristics and cognitive function using artificial intelligence techniques to obtain fully automated quantitative measurements of retinal vascular morphological parameters. Methods: A deep learning-based semantic segmentation network ResNet101-UNet was used to construct a vascular segmentation model for fully automated quantitative measurement of retinal vascular parameters on fundus photographs. Retinal photographs centered on the optic disc of 3107 participants (aged 50-93 years) from the Beijing Eye Study 2011, a population-based cross-sectional study, were analyzed. The main parameters included the retinal vascular branching angle, vascular fractal dimension, vascular diameter, vascular tortuosity, and vascular density. Cognitive function was assessed using the Mini-Mental State Examination (MMSE). Results: The results showed that the mean MMSE score was 26.34 ± 3.64 (median: 27; range: 2-30). Among the participants, 414 (13.3%) were classified as having cognitive impairment (MMSE score < 24), 296 (9.5%) were classified as mild cognitive impairment (MMSE: 19-23), 98 (3.2%) were classified as moderate cognitive impairment (MMSE: 10-18), and 20 (0.6%) were classified as severe cognitive impairment (MMSE < 10). Compared with the normal cognitive function group, the retinal venular average diameter was significantly larger (p = 0.013), and the retinal vascular fractal dimension and vascular density were significantly smaller (both p < 0.001) in the mild cognitive impairment group. The retinal arteriole-to-venular ratio (p = 0.003) and vascular fractal dimension (p = 0.033) were significantly decreased in the severe cognitive impairment group compared to the mild cognitive impairment group. In the multivariate analysis, better cognition (i.e., higher MMSE score) was significantly associated with higher retinal vascular fractal dimension (b = 0.134, p = 0.043) and higher retinal vascular density (b = 0.152, p = 0.023) after adjustment for age, best corrected visual acuity (BCVA) (logMAR) and education level. Discussion: In conclusion, our findings derived from an artificial intelligence-based fully automated retinal vascular parameter measurement method showed that several retinal vascular morphological parameters were correlated with cognitive impairment. The decrease in retinal vascular fractal dimension and decreased vascular density may serve as candidate biomarkers for early identification of cognitive impairment. The observed reduction in the retinal arteriole-to-venular ratio occurs in the late stages of cognitive impairment.

Age-associated changes in electroretinography measures in companion dogs

PURPOSE

To determine the association between age and retinal full-field electroretinographic (ERG) measures in companion (pet) dogs, an important translational model species for human neurologic aging.

METHODS

Healthy adult dogs with no significant ophthalmic abnormalities were included. Unilateral full-field light- and dark-adapted electroretinography was performed using a handheld device, with mydriasis and topical anaesthesia. Partial least squares effect screening analysis was performed to determine the effect of age, sex, body weight and use of anxiolytic medication on log-transformed ERG peak times and amplitudes; age and anxiolytic usage had significant effects on multiple ERG outcomes. Mixed model analysis was performed on data from dogs not receiving anxiolytic medications.

RESULTS

In dogs not receiving anxiolytics, median age was 118 months (interquartile range 72-140 months, n = 77, 44 purebred, 33 mixed breed dogs). Age was significantly associated with prolonged peak times of a-waves (dark-adapted 3 and 10 cds/m² flash p < 0.0001) and b-waves (cone flicker p = 0.03, dark-adapted 0.01 cds/m² flash p = 0.001). Age was also significantly associated with reduced amplitudes of a-waves (dark-adapted 3 cds/m² flash p < 0.0001, 10 cds/m² flash p = 0.005) and b-waves (light-adapted 3 cds/m² flash p < 0.0001, dark-adapted 0.01 cds/m² flash p = 0.0004, 3 cds/m² flash p < 0.0001, 10 cds/m² flash p = 0.007) and flicker (light-adapted 30 Hz 3 cds/m² p = 0.0004). Within the Golden Retriever breed, these trends were matched in a cross-sectional analysis of 6 individuals that received no anxiolytic medication.

CONCLUSIONS

Aged companion dogs have slower and reduced amplitude responses in both rod- and cone-mediated ERG. Consideration of anxiolytic medication use should be made when conducting ERG studies in dogs.

Hi-Fi fMRI: High-resolution, fast-sampled and sub-second whole-brain functional MRI at 3T in humans

Functional magnetic resonance imaging (fMRI) is a methodological cornerstone of neuroscience. Most studies measure blood-oxygen-level-dependent (BOLD) signal using echo-planar imaging (EPI), Cartesian sampling, and image reconstruction with a one-to-one correspondence between the number of acquired volumes and reconstructed images. However, EPI schemes are subject to trade-offs between spatial and temporal resolutions. We overcome these limitations by measuring BOLD with a gradient recalled echo (GRE) with 3D radial-spiral phyllotaxis trajectory at a high sampling rate (28.24ms) on standard 3T field-strength. The framework enables the reconstruction of 3D signal time courses with whole-brain coverage at simultaneously higher spatial (1mm ³ ) and temporal (up to 250ms) resolutions, as compared to optimized EPI schemes. Additionally, artifacts are corrected before image reconstruction; the desired temporal resolution is chosen after scanning and without assumptions on the shape of the hemodynamic response. By showing activation in the calcarine sulcus of 20 participants performing an ON-OFF visual paradigm, we demonstrate the reliability of our method for cognitive neuroscience research.

Vitreous Humor Biomarkers Reflect Pathological Changes in the Brain for Alzheimer's Disease and Chronic Traumatic Encephalopathy

BACKGROUND

Patients with eye disease have an increased risk for developing neurodegenerative disease. Neurodegenerative proteins can be measured in the eye; however, correlations between biomarker levels in eye fluid and neuropathological diagnoses have not been established.

OBJECTIVE

This exploratory, retrospective study examined vitreous humor from 41 postmortem eyes and brain tissue with neuropathological diagnoses of Alzheimer's disease (AD, n = 7), chronic traumatic encephalopathy (CTE, n = 15), both AD + CTE (n = 10), and without significant neuropathology (controls, n = 9).

METHODS

Protein biomarkers i.e., amyloid-β (Aβ 40,42), total tau (tTau), phosphorylated tau (pTau181,231), neurofilament light chain (NfL), and eotaxin-1 were quantitatively measured by immunoassay. Non-parametric tests were used to compare vitreous biomarker levels between groups. Spearman's rank correlation tests were used to correlate biomarker levels in vitreous and cortical tissue. The level of significance was set to α= 0.10.

RESULTS

In pairwise comparisons, tTau levels were significantly increased in AD and CTE groups versus controls (p = 0.08 for both) as well as AD versus AD+CTE group and CTE versus AD+CTE group (p = 0.049 for both). Vitreous NfL levels were significantly increased in low CTE (Stage I/II) versus no CTE (p = 0.096) and in low CTE versus high CTE stage (p = 0.03). Vitreous and cortical tissue levels of pTau 231 (p = 0.02, r = 0.38) and t-Tau (p = 0.04, r = -0.34) were significantly correlated.

CONCLUSION

The postmortem vitreous humor biomarker levels significantly correlate with AD and CTE pathology in corresponding brains, while vitreous NfL was correlated with the CTE staging. This exploratory study indicates that biomarkers in the vitreous humor may serve as a proxy for neuropathological disease.

The association between cataract and incidence of cognitive impairment in older adults: A systematic review and meta-analysis

BACKGROUND

Cataract has been shown to be associated with an increased risk of cognitive impairment. However, the results of previous studies have been inconsistent. This systematic review and meta-analysis aimed to investigate the association between cataract and the incidence of cognitive impairment in older adults.

METHODS

A comprehensive search of electronic databases from inception to January 2023 was performed to identify relevant studies. Data were extracted from eligible studies and a meta-analysis was performed to calculate the pooled hazard ratio (HR) and 95% confidence interval (CI).

RESULTS

We included 13 studies with 25 study arms involving a total of 798,694 participants. Compared with participants without cataract, those with cataract had a higher risk of developing all-cause dementia (pooled HR: 1.22; 95% CI: 1.08-1.38; I²=86%; 9 studies), Alzheimer's disease dementia (pooled HR: 1.18; 95% CI: 1.07-1.30; I²=0%; 9 studies), vascular dementia (pooled HR: 1.21; 95% CI: 1.02-1.43; I²=77%;3 studies) and mild cognitive impairment (pooled HR: 1.30; 95% CI: 1.13-1.50; I²=0%;2 studies). There was no significant association between cataract and mixed dementia (pooled HR: 1.03; 95% CI: 0.52-2.04; I²=78%;2 studies). We assessed the risk of bias of the included studies using the Newcastle-Ottawa Scale and found that most of them had a low or moderate risk of bias. The number of studies in each meta-analysis ranged from two to nine, with more studies available for all-cause dementia and Alzheimer's disease dementia than for vascular dementia and mixed dementia.

CONCLUSIONS

The findings suggest that cataract may be associated with cognitive impairment in older adults. However, the causal relationship between cataract and cognition remains unclear and requires further investigation.

Diabetic Retinopathy and Dementia Association, Beyond Diabetes Severity

PURPOSE

To investigate whether associations between diabetic retinopathy (DR) and dementia and Alzheimer's disease (AD) remain significant after controlling for several measures of diabetes severity.

DESIGN

Retrospective cohort study.

METHODS

Adult Changes in Thought (ACT) is a prospective cohort study of adults aged ≥65 years, randomly selected and recruited from the membership rolls of Kaiser Permanente Washington, who are dementia free at enrollment and followed biennially until incident dementia. The ACT participants were included in this study if they had type 2 diabetes mellitus at enrollment or developed it during follow-up, and data were collected through September, 2018 (3516 person-years of follow-up). Diabetes was defined by ≥ 2 diabetes medication fills in 1 year. Diagnosis of DR was based on International Classification of Diseases Ninth and Tenth Revision codes. Estimates of microalbuminuria, long-term glycemia, and renal function from longitudinal laboratory records were used as indicators of diabetes severity. Alzheimer's disease and dementia were diagnosed using research criteria at expert consensus meetings.

RESULTS

A total of 536 participants (median baseline age 75 [interquartile range 71-80], 54% women) met inclusion criteria. Significant associations between DR >5 years duration with dementia (hazard ratio 1.81 [95% CI 1.23, 2.65]) and AD (1.80 [1.15, 2.82]) were not altered by adjustment for estimates of microalbuminuria, long-term glycemia, and renal function (dementia: 1.69 [1.14, 2.50]; AD: 1.73 [1.10, 2.74]).

CONCLUSIONS

Among people with type 2 diabetes, DR itself appears to be an important biomarker of dementia risk in addition to glycemia and renal complications.

The Associations Between Cataracts and Alzheimer's Disease: A Bidirectional Two-Sample Mendelian Randomization Study

BACKGROUND

The relationship between cataracts and Alzheimer's disease (AD) has been reported in recent observational studies. However, it is still unclear whether a causal effect of cataracts on AD or reverse causation exists.

OBJECTIVE

To explore the association between cataracts and AD genetically, we performed a bidirectional two-sample Mendelian randomization study.

METHODS

We obtained genetic instrumental variables related to cataracts and AD from recently published genome-wide association studies (GWASs). SNP-outcome associations for AD were obtained from a GWAS with 111,326 cases and 677,663 controls. SNP-outcome associations for cataracts were drawn from two sources: a GWAS with 67,844 cases and 517,399 controls and the FinnGen consortium (42,843 cases and 262,698 controls). Inverse variance weighted (IVW) was used as the primary method for Mendelian randomization (MR) analyses.

RESULTS

No genetic evidence suggested that cataracts were associated with the risk of AD (IVW odds ratio =1.04, 95% confidence interval: 0.98-1.10, p=0.199). In contrast, an effect of genetically determined AD on a decreased risk of cataract was observed with suggestive evidence (IVW odds ratio =0.96, 95% confidence interval: 0.93-0.99, p=0.004). However, this result might be distorted by survival bias.

CONCLUSION

Genetically determined cataracts were not related to AD, as demonstrated by our study. In contrast, there was suggestive evidence that AD might prevent cataract development, but there might be potential survival bias. To define the exact association between the two diseases, more prospective research and studies on the pathogenesis are needed.

Risk of Subsequent Dementia or Alzheimer Disease Among Patients With Age-Related Macular Degeneration: A Systematic Review and Meta-analysis

PURPOSE

Alzheimer disease (AD), a common form of dementia, shares several clinical and pathologic features with age-related macular degeneration (AMD). Epidemiologic reports on the association of AMD with subsequent dementia or AD are inconsistent.

DESIGN

Systematic review and meta-analysis.

METHODS

The Meta-analysis of Observational Studies in Epidemiology reporting guidelines were applied. The Newcastle-Ottawa Scale was used to evaluate the risk of bias in the included cohort studies that examined the association of AMD with subsequent dementia or AD. We estimated the pooled hazard ratios (HRs) of dementia or AD using random effects model meta-analysis and subgroup analysis on different follow-up periods, AMD subtype, gender, age, study design, and methods to ascertain dementia or AD.

RESULTS

A total of 8 223 581 participants were included in 8 studies published during 2000-2021. The meta-analysis showed that AMD was significantly associated with subsequent dementia (pooled HR 1.22, 95% CI 1.01-1.47) or AD (pooled HR 1.21, 95% CI 1.03-1.43). Our secondary analysis revealed that the association was more noticeable in dry AMD than wet AMD.

CONCLUSIONS

Patients with AMD have higher risks of developing dementia or AD, and therefore identifying related comorbidities and retinal biomarkers is much warranted for older adults with AMD in ophthalmologic practice.

Risk of dementia in newly diagnosed glaucoma: a nationwide cohort study in Korea

PURPOSE

To investigate the risk of dementia in participants with newly diagnosed glaucoma.

DESIGN

A nationwide cohort study using authorized data provided by the Korean National Health Insurance Service (NHIS).

PARTICIPANTS

A total of 788,961 participants aged ≥ 45 years in 2006, who did not have dementia or glaucoma between 2002 and 2005, were included.

METHODS

Data were collected from a nationwide population-based retrospective cohort study using the Korean NHIS database. From January 2006 to December 2017, participants were tracked for the diagnosis of glaucoma or dementia using claims data. The prospective association between newly diagnosed glaucoma and the risk of dementia was investigated using a multivariable Cox proportional hazard model adjusted for age, sex, behavioral factors, and systemic and ocular comorbidities.

MAIN OUTCOME MEASURES

Hazard ratios and 95% confidence intervals for dementia development according to the parameters, including glaucoma diagnosis.

RESULTS

Overall, 7.0% of the participants developed dementia after an average of 7.4 years. A newly diagnosed glaucoma was associated with a higher risk of dementia (hazards ratio [HR] 1.89, 95% confidence interval [CI] 1.57 to 2.27) independent of age, sex, body mass index, income, smoking and drinking status, visual acuity, and other systemic comorbidities, such as diabetes, hypertension, stroke, and depression. An association between the risk of dementia and glaucoma was noted in participants with Alzheimer's disease (AD) but not in those with vascular dementia. The risk of dementia in relation to glaucoma was higher in older participants (HR = 3.15 (≥ 65 years) vs. 1.56 (< 65 years), P < 0.0001).

CONCLUSION

This nationwide cohort study found that individuals with newly diagnosed glaucoma were at a higher risk of developing dementia, particularly AD. This association was greater among older individuals in the studied population.

MicroRNAs as potential biomarkers and therapeutic targets in age-related macular degeneration

Age-related macular degeneration (AMD) involves degenerative and neovascular alteration in the macular region of the retina resulting in central vision loss. AMD can be classified into dry (dAMD) and wet AMD (wAMD). There is no established treatment for dAMD, and therapies available for wAMD have limited success. Diagnosis in early AMD stages is difficult due to the absence of clinical symptoms. Currently, imaging tests are used in the diagnosis of AMD, but cannot predict the clinical course. The clinical limitations to establishing a diagnosis of AMD have led to exploration for innovative and more sensitive tests to support the diagnosis and prognosis of the disease. MicroRNAs (miRNAs) are small single-stranded non-coding RNA molecules that negatively regulate genes by post-transcriptional gene silencing. Because these molecules are dysregulated in various processes implicated in the pathogenesis of AMD, they could contribute to the early detection of the disease and monitoring of its progression. Studies of miRNA profiling have indicated several miRNAs as potential diagnostic biomarkers of AMD, but no approved biomarker is available at present for early AMD detection. Thus, understanding the function of miRNAs in AMD and their use as potential biomarkers may lead to future advances in diagnosis and treatment. Here we present a brief review of some of the miRNAs involved in regulating pathological processes associated with AMD and discuss several candidate miRNAs proposed as biomarkers or therapeutic targets for AMD.

Associations of ophthalmic and systemic conditions with incident dementia in the UK Biobank

AIMS

To examine independent and interactive associations of ophthalmic and systemic conditions with incident dementia.

METHODS

Our analysis included 12 364 adults aged 55-73 years from the UK Biobank cohort. Participants were assessed between 2006 and 2010 at baseline and were followed up until the early of 2021. Incident dementia was ascertained using hospital inpatient, death records and self-reported data.

RESULTS

Over 1 263 513 person-years of follow-up, 2304 cases of incident dementia were documented. The multivariable-adjusted HRs (95% CI) for dementia associated with age-related macular degeneration (AMD), cataract, diabetes-related eye disease (DRED) and glaucoma at baseline were 1.26 (1.05 to 1.52), 1.11 (1.00 to 1.24), 1.61 (1.30 to 2.00) and (1.07 (0.92 to 1.25), respectively. Diabetes, heart disease, stroke and depression at baseline were all associated with an increased risk of dementia. Of the combination of AMD and a systemic condition, AMD-diabetes was associated with the highest risk for incident dementia (HR (95% CI): 2.73 (1.79 to 4.17)). Individuals with cataract and a systemic condition were 1.19-2.29 times more likely to develop dementia compared with those without cataract and systemic conditions. The corresponding number for DRED and a systemic condition was 1.50-3.24. Diabetes, hypertension, heart disease, depression and stroke newly identified during follow-up mediated the association between cataract and incident dementia as well as the association between DRED and incident dementia.

CONCLUSIONS

AMD, cataract and DRED but not glaucoma are associated with an increased risk of dementia. Individuals with both ophthalmic and systemic conditions are at higher risk of dementia compared with those with an ophthalmic or systemic condition only.

Cognitive Performance and Diabetic Retinopathy: What Your Eyes Can Reveal About Your Brain

BACKGROUND

Diabetic retinopathy (DR) is a chronic diabetes complication. People with Type 2 Diabetes Mellitus (T2DM) have two times the risk for dementia, suggesting it is a new chronic diabetes complication.

OBJECTIVE

Evaluate the association of DR with cognitive performance in a T2DM population.

METHODS

Cross-sectional study with 400 T2DM adults from whom socio-demographic, clinical, laboratory data were collected, and screening test for depression symptoms (Patient Health Questionaire- 9 (PHQ-9)), Mini-Mental State Examination (MMSE), Semantic Verbal Fluency Test, Trail Making Test A and B, Word Memory test were performed. All cognitive test scores were converted into Global Cognition z-Score (GCS(z)). The association between GCS(z) < 0 with DR was performed using a multivariate binary logistic regression model adjusted for age ≥ 65 years, school years ≤ 6 years, DM duration ≥ 10 years, depression symptoms score > 9 at PHQ-9, arterial hypertension, physical activity, diabetic retinopathy, macular edema, and cardiovascular disease.

RESULTS

After exclusions, the 251 eligible patients were 56.6% female, with a mean age of 61.1 (±9.8) years, DM duration of 12.6 (±8.9) years, and 7.6 (±4.2) years of school education. DR prevalence was 46.5%. Multivariate Logistic Regression Model showed an association between DR and GCS(z) < 0, with odds ratio (CI95%) of 2.50 (1.18-5.34), adjusted for age, low education level, arterial hypertension and depression symptoms (OD and CI95% respectively: 5.46(2.42-12.34); 12.19 (5.62-26.46); 2.55 (0.88-7.39); 3.53 (1.55-8.07)).

CONCLUSION

In this T2DM population, having DR increased the chance for worse cognitive performance even when adjusted for age, low education level, presence of arterial hypertension, and depression symptoms.

Lack of bidirectional association between age-related macular degeneration and Alzheimer's disease: A Mendelian randomization study

INTRODUCTION

Observational studies have reported inconsistent results on the relationship between age-related macular degeneration (AMD) and Alzheimer's disease (AD). Therefore, we aimed to determine whether there is a causal association between AMD and AD.

METHODS

This two-sample bidirectional Mendelian randomization (MR) study evaluated causal associations between advanced AMD and AD using summary data from large genome-wide association studies.

RESULTS

Genetic liability for advanced AMD showed no statistical causal association with AD risk (odds ratio [OR] = 0.999, 95% confidence interval [CI]: 0.955-1.044, P = .948). Reverse MR analysis provided little support for a causal effect of AD on advanced AMD (OR = 0.973, 95%CI: 0.938-1.008, P = .133).

DISCUSSION

This MR study found no evidence to support a bidirectional causality between advanced AMD and AD.

HIGHLIGHTS

We evaluated the bidirectional causal relationship between advanced AMD and AD. Advanced AMD showed no statistical causal association with risk of AD. We found no evidence to support a causal effect of AD on advanced AMD risk. The associations observed in epidemiological studies should not be considered causal.

Cognitive dysfunction and the 25-item National Eye Institute Visual Function Questionnaire

Introduction

Visual function and cognitive impairment are interrelated; however, little is known about the impact of modifying treatable vision impairment on the development of cognitive dysfunction. This study examines the relationship between cognition and self-reported visual function using the National Eye Institute's Visual Function Questionnaire (NEI VFQ).

Methods

Participants completed the NEI VFQ 25-Item questionnaire as well as the Mini-Mental State Examination (MMSE). Additionally, all participants were assigned a consensus clinical diagnosis based on established criteria. We used a general linear model and analysis of variance approach to compare means between multiple groups.

Results

A significant association between overall composite score on the NEI VFQ and total MMSE score was revealed (P = 0.04). On average, for every 1-point increase in MMSE score, the overall composite score increased by 0.40 units (95% confidence interval: 0.03-0.77).

Discussion

Reduced visual function should raise concerns about cognitive decline and prompt additional assessment.

Association of cognitive function with Neurofilament light chain in the aqueous humor of human eye

OBJECTIVES

To evaluate the predictive clinical role of neurofilament light chain (NfL), amyloid-β (Aβ), glial fibrillary acidic protein (GFAP), and phosphorylated tau at threonine 181 (p-tau181) proteins in human aqueous humor (AH) and quantify the retinal macular microvascular parameters by optical coherence tomography angiography (OCTA) as early diagnostic markers of Alzheimer's disease (AD).

METHODS

This prospective, single-site, cross-sectional, cohort study enrolled 55 participants, including 38 patients with neovascular age-related macular degeneration (nAMD) and 17 individuals with senile cataracts. The single-molecule array platform was used to quantitatively measure the levels of AH NfL, Aβ40, Aβ42, GFAP, and p-tau181 proteins in AH. The mini-mental state examination (MMSE) score was used to assess the global cognitive function. OCTA scan with 6 × 6 mm macular area was used to quantify the retinal thickness and microvascular densities of superficial retinal capillary plexuses and deep retinal capillary plexuses.

RESULTS

NfL, Aβ40, Aβ42, GFAP, and p-tau181 were detected in all AH samples by Simoa platform. Individuals with cataract had higher concentrations of NfL and p-tau181 but lower Aβ40 and Aβ42 and similar GFAP compared to those with nAMD. Lower MMSE scores showed a negative correlation with NfL concentration of AH not only in the nAMD group (p = 0.043), but also in the cataract group (p = 0.032). However, the MMSE scores were not associated with the levels of Aβ40, Aβ42, GFAP, or p-Tau181. Further analysis found that the Aβ40 and Aβ42 concentrations showed a strong positive correlation (p < 0.0001). In addition, the NfL concentration showed a mild positive correlation with that of GFAP in the cataract group (p = 0.021). Although it has not reached statistical significance, there was a correlation between the levels of NfL and Aβ42 in the nAMD group (p = 0.051). Moreover, the macular superficial vessel density values had a negative correlation with the concentration of NfL (p = 0.004) but a positive correlation with MMSE scores (p = 0.045). The macular deep vessel density values were negatively correlated with the concentration of p-tau181 (p = 0.031) and positively correlated with MMSE scores (p = 0.020).

CONCLUSION

The examination of AD-related biomarkers in human AH and OCTA may improve the ocular-based AD detection methods and contribute to forestalling the progression of preclinical AD.

A deep learning model for detection of Alzheimer's disease based on retinal photographs: a retrospective, multicentre case-control study

BACKGROUND

There is no simple model to screen for Alzheimer's disease, partly because the diagnosis of Alzheimer's disease itself is complex-typically involving expensive and sometimes invasive tests not commonly available outside highly specialised clinical settings. We aimed to develop a deep learning algorithm that could use retinal photographs alone, which is the most common method of non-invasive imaging the retina to detect Alzheimer's disease-dementia.

METHODS

In this retrospective, multicentre case-control study, we trained, validated, and tested a deep learning algorithm to detect Alzheimer's disease-dementia from retinal photographs using retrospectively collected data from 11 studies that recruited patients with Alzheimer's disease-dementia and people without disease from different countries. Our main aim was to develop a bilateral model to detect Alzheimer's disease-dementia from retinal photographs alone. We designed and internally validated the bilateral deep learning model using retinal photographs from six studies. We used the EfficientNet-b2 network as the backbone of the model to extract features from the images. Integrated features from four retinal photographs (optic nerve head-centred and macula-centred fields from both eyes) for each individual were used to develop supervised deep learning models and equip the network with unsupervised domain adaptation technique, to address dataset discrepancy between the different studies. We tested the trained model using five other studies, three of which used PET as a biomarker of significant amyloid β burden (testing the deep learning model between amyloid β positive vs amyloid β negative).

FINDINGS

12 949 retinal photographs from 648 patients with Alzheimer's disease and 3240 people without the disease were used to train, validate, and test the deep learning model. In the internal validation dataset, the deep learning model had 83·6% (SD 2·5) accuracy, 93·2% (SD 2·2) sensitivity, 82·0% (SD 3·1) specificity, and an area under the receiver operating characteristic curve (AUROC) of 0·93 (0·01) for detecting Alzheimer's disease-dementia. In the testing datasets, the bilateral deep learning model had accuracies ranging from 79·6% (SD 15·5) to 92·1% (11·4) and AUROCs ranging from 0·73 (SD 0·24) to 0·91 (0·10). In the datasets with data on PET, the model was able to differentiate between participants who were amyloid β positive and those who were amyloid β negative: accuracies ranged from 80·6 (SD 13·4%) to 89·3 (13·7%) and AUROC ranged from 0·68 (SD 0·24) to 0·86 (0·16). In subgroup analyses, the discriminative performance of the model was improved in patients with eye disease (accuracy 89·6% [SD 12·5%]) versus those without eye disease (71·7% [11·6%]) and patients with diabetes (81·9% [SD 20·3%]) versus those without the disease (72·4% [11·7%]).

INTERPRETATION

A retinal photograph-based deep learning algorithm can detect Alzheimer's disease with good accuracy, showing its potential for screening Alzheimer's disease in a community setting.

FUNDING

BrightFocus Foundation.

Glaucoma and cognitive function trajectories in a population-based study: Findings from the health and retirement study

INTRODUCTION

Prior studies on the association of glaucoma and cognitive function have reported mixed results.

METHODS

The Health and Retirement Study (HRS) is a nationally representative panel survey of Americans age ≥ 51 years. HRS-linked Medicare claims data were used to identify incident glaucoma cases (by glaucoma type). Cognitive function was measured using the Telephone Interview for Cognitive Status (TICS), administered in each wave (every 2 years). Separate linear mixed models were fitted with either prevalent or incident glaucoma as a predictor of TICS trajectories and adjusting for age, race/ethnicity, educational attainment, gender, and medical history. Negative model estimates indicate associations of glaucoma with worse cognitive function scores or steeper per-year declines in cognitive function scores.

RESULTS

Analyses of prevalent glaucoma cases included 1344 cases and 5729 controls. Analyses of incident glaucoma included 886 cases and 4385 controls. In fully-adjusted models, those with prevalent glaucoma had similar TICS scores to controls (β = 0.01; 95% Confidence Interval [CI]: -0.15, 0.18; p = 0.86). However, in those with incident glaucoma, we detected a statistically significant association between glaucoma and lower TICS scores (β = -0.29; 95% CI: -0.50, -0.08; p = 0.007). However, there was no statistically significant association between either prevalent or incident glaucoma and per-year rates of change in TICS scores. When categorizing glaucoma by type (primary open angle glaucoma, normal tension glaucoma, or other glaucoma), no significant associations were detected between either prevalent or incident glaucoma and levels of or rates of change in TICS scores in fully covariate adjusted models.

CONCLUSION

The observed associations between glaucoma and cognitive function were small and unlikely to be clinically meaningful. Compared to prior studies on this topic, this investigation provides robust evidence based on its larger sample size, longitudinal follow-up, and repeated measures of cognitive function in a population-based sample.

Increased probability of mood disorders after age-related macular degeneration: a population-based cohort study

We aim to investigate the association of mood disorders with age-related macular degeneration (AMD). This retrospective cohort study used data from 2000 and 2016 from National Health Insurance Research Database (NHIRD) in Taiwan. Patients with AMD diagnosis formed the exposed group, and an age- and sex-matched group without AMD served as the nonexposed group. Main outcomes were the incidence of mood disorders including psychological counseling, behavior therapy, sleep or anxiety-related disorders, and major depressive disorders (MDDs) in the exposed and non-exposed groups. The Cox proportional hazard regression analysis was used to evaluate the incidence and adjusted hazard ratio (aHR) of mood disorders. A total of 5916 and 11,832 individuals with and without AMD were enrolled into the exposed and nonexposed groups. There were 1017 (17.19%) and 1366 (11.54%) episodes of mood disorders occurred in the exposed and nonexposed groups, respectively. The aHRs of any psychological counseling, behavioral therapy, sleep or anxiety-related disorders, and MDD were significantly higher in patients with AMD than in those without AMD (all P < 0.05). Besides, patients with dry-AMD, participants aged 50-70 years, and women with AMD had a higher incidence of mood disorders (all P < 0.05) than did non-AMD individuals, patients > 70 years, and women without AMD. In conclusion, AMD occurrence leads to an increased rate of mood disorders, particularly among those with dry-AMD, middle aged participants (aged 50-70), and women.

Risk factors for cognitive decline in type 2 diabetes mellitus patients in Brazil: a prospective observational study

BACKGROUND

Type 2 Diabetes Mellitus (T2DM) patients are twice as likely to develop dementia. The study's goal was to evaluate cognitive performance and risk factors for cognitive decline in this population.

METHODS

Prospective observational study was conducted with 400 T2DM adults, of whom, during routine baseline and follow-up appointments, had socio-demographic, clinical, and laboratory data collected, and underwent physical examination, screening for depression symptoms (Patient Health Questionaire-9-PHQ-9), and cognitive tests: Mini-Mental State Examination (MMSE), Semantic Verbal Fluency Test, Trail Making Test A/B, and Word Memory Tests. Each cognitive test score was converted to a z-score and its average resulted in a new variable called Global Cognitive z-Score [GCS(z)]. Averages of the cognitive test scores and GCS(z) at both moments were compared by the Student's T-Test for paired samples. Multivariate binary logistic regression models were built to assess the association of GCS(z) < zero with risk factors for cognitive decline at the baseline and follow-up.

RESULTS

After exclusions, 251 patients were eligible, being 56.6% female, mean age of 61.1 (± 9.8) years, 12.6 (± 8.9) years of DM duration, and 7.6 (± 4.2) years of school education. Follow-up had 134 patients reevaluated and took place after a mean of 18.4(± 5.0) months. Eleven (14%) patients with a GCS(z) ≥ 0 at baseline turned into a GCS(z) < 0 at follow-up. There were no significant differences between the means of cognitive test scores and GCS(z) at the two evaluation moments. At the baseline, the multivariate logistic regression model identified five risk factors associated with GCS(z) < zero: age ≥ 65 years, schooling ≤ 6 years, arterial hypertension, depression symptoms, and diabetic retinopathy (DR), with odds ratio (OR) and 95% confidence interval (CI95%) respectively: 5.46 (2.42-12.34); 12.19 (5.62-26.46); 2.55 (0.88-7.39); 3.53 (1.55-8.07) e 2.50 (1.18-5.34). At follow-up, the risk factors for GCS(z) < zero were: schooling ≤ 6 years, DM duration ≥ 10 years, depression symptoms, arterial hypertension, and cardiovascular disease (CVD), OR and CI95% respectively: 10.15 (3.68-28.01); 2.68 (0.96-7.48); 4.92 (1.77-13.70); 7.21 (1.38-35.71) e 5.76 (1.93-17.18).

CONCLUSIONS

Based on our results, cognitive evaluation and follow-up should be incorporated on the routine of T2DM patients, especially for those with advanced age, low education level, prolonged DM duration, arterial hypertension, depression symptoms, CVD, and DR.

Age-Related Eye Diseases in Individuals With Mild Cognitive Impairment and Alzheimer's Disease

Introduction

Alzheimer's disease (AD) and age-related eye diseases pose an increasing burden as the world's population ages. However, there is limited understanding on the association of AD/cognitive impairment, no dementia (CIND) with age-related eye diseases.

Methods

In this cross-sectional, memory clinic-based study of multiethnic Asians aged 50 and above, participants were diagnosed as AD (n = 216), cognitive impairment, no dementia (CIND) (n = 252), and no cognitive impairment (NCI) (n = 124) according to internationally accepted criteria. Retinal photographs were graded for the presence of age-related macular degeneration (AMD) and diabetic retinopathy (DR) using standard grading systems. Multivariable-adjusted logistic regression models were used to determine the associations between neurological diagnosis and odds of having eye diseases.

Results

Over half of the adults had at least one eye disease, with AMD being the most common (60.1%; n = 356), followed by DR (8.4%; n = 50). After controlling for age, sex, race, educational level, and marital status, persons with AD were more likely to have moderate DR or worse (OR = 2.95, 95% CI = 1.15–7.60) compared with NCI. In the fully adjusted model, the neurological diagnosis was not associated with AMD (OR = 0.75, 95% CI = 0.45–1.24).

Conclusion

Patients with AD have an increased odds of having moderate DR or worse, which suggests that these vulnerable individuals may benefit from specific social support and screening for eye diseases.

Association Between Diabetic Retinopathy, Brain Structural Abnormalities, and Cognitive Impairment for Accumulated Evidence in Observational Studies

PURPOSE

To evaluate the association between diabetic retinopathy (DR) and cerebral disease or cognitive impairment.

DESIGN

Systematic review and meta-analysis.

METHOD

The hypothesis was formulated prior to data collection. Cross-sectional studies and cohort studies that assessed the association between any measure of DR and cerebral small vessel disease or any type of cognitive impairment in diabetic participants were included. The data were independently extracted by two investigators. This systematic review and meta-analysis adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analyses and Meta-analysis of Observational Studies in Epidemiology guidelines RESULTS: A total of 27 studies were included. The combined odds ratio of 5 cross-sectional/cohort studies that reported that the associations between DR and cerebral structural changes was 1.75 (95% confidence interval [CI]: 1.36-2.25). The combined hazard ratio of 4 cohort studies that examined the association between DR and cognitive impairment events was 1.47 (95% CI: 1.22-1.78). The combined odds ratio of 14 cross-sectional/cohort studies that examined the association between DR and different cognitive impairment events was 1.43 (95% CI: 1.06-1.93). The overall coefficient (β) of 4 studies that examined the relationship between DR and specific cognitive performance was 0.09 (95% CI: 0.00-0.18). Considering the quality of the data, we have performed subgroup analysis in studies scored >7 and studies scored ≤7, respectively, according to the Newcastle-Ottawa scale.

CONCLUSION

The present meta-analysis suggests that DR is associated with an increased risk of structural abnormalities in the brain and cognitive impairment. This association remained significant after adjusting for blood glucose, and the presence of hypertension, indicating that DR is an important danger signal for cerebral abnormalities.

The APOE E4 Allele Is Associated with Faster Rates of Neuroretinal Thinning in a Prospective Cohort Study of Suspect and Early Glaucoma

Purpose

Design

Participants

Methods

Main Outcome Measures

Results

Conclusions

Towards more efficient ophthalmic disease classification and lesion location via convolution transformer

OBJECTIVE

A retina optical coherence tomography (OCT) image differs from a traditional image due to its significant speckle noise, irregularity, and inconspicuous features. A conventional deep learning architecture cannot effectively improve the classification accuracy, sensitivity, and specificity of OCT images, and noisy images are not conducive to further diagnosis.  This paper proposes a novel lesion-localization convolution transformer (LLCT) method, which combines both convolution and self-attention to classify ophthalmic diseases more accurately and localize the lesions in retina OCT images.

METHODS

A novel architecture design is accomplished through applying customized feature maps generated by convolutional neutral network (CNN) as the input sequence of self-attention network. This design takes advantages of CNN's extracting image features and transformer's consideration of global context and dynamic attention. Part of the model is backward propagated to calculate the gradient as a weight parameter, which is multiplied and summed with the global features generated by the forward propagation process to locate the lesion.

RESULTS

Extensive experiments show that our proposed design achieves improvement of about 7.6% in overall accuracy, 10.9% in overall sensitivity, and 9.2% in overall specificity compared with previous methods. And the lesions can be localized without the labeling data of lesion location in OCT images.

CONCLUSION

The results prove that our method significantly improves the performance and reduces the computation complexity in artificial intelligence assisted analysis of ophthalmic disease through OCT images.

SIGNIFICANCE

Our method has a significance boost in ophthalmic disease classification and location via convolution transformer. This is applicable to assist ophthalmologists greatly.¹.

Alzheimer's Disease: A Silent Pandemic - A Systematic Review on the Situation and Patent Landscape of the Diagnosis

BACKGROUND

Alzheimer's disease (AD) is characterized by cognitive impairment, tau protein deposits, and amyloid beta plaques. AD impacted 44 million people in 2016, and it is estimated to affect 100 million people by 2050. AD is disregarded as a pandemic compared with other diseases. To date, there is no effective treatment or diagnosis.

OBJECTIVE

We aimed to discuss the current tools used to diagnose COVID-19, to point out their potential to be adapted for AD diagnosis, and to review the landscape of existing patents in the AD field and future perspectives for AD diagnosis.

METHOD

We carried out a scientific screening following a research strategy in PubMed; Web of Science; the Derwent Innovation Index; the KCI-Korean Journal Database; SciELO; the Russian Science Citation index; and the CDerwent, EDerwent, and MDerwent index databases.

RESULTS

A total of 326 from 6,446 articles about AD and 376 from 4,595 articles about COVID-19 were analyzed. Of these, AD patents were focused on biomarkers and neuroimaging with no accurate, validated diagnostic methods, and only 7% of kit development patents were found. In comparison, COVID-19 patents were 60% about kit development for diagnosis; they are highly accurate and are now commercialized.

CONCLUSION

AD is still neglected and not recognized as a pandemic that affects the people and economies of all nations. There is a gap in the development of AD diagnostic tools that could be filled if the interest and effort that has been invested to tackle the COVID-19 emergency could also be applied for innovation.

Diabetic retinopathy and cognitive dysfunction: a systematic review and meta-analysis

BACKGROUND

This study aims to determine the relationship between diabetic retinopathy (DR) and cognitive dysfunction as well as explores the effects of DR on different cognitive domains.

METHODS

A systematic search of PubMed, Embase, Web of Science, Wanfang data, CBM, CNKI, and VIP databases from their inception to October 2021. The pooled odds ratio (ORs), hazard ratio (HRs), and 95% confidence interval (CIs) were calculated.

RESULTS

Twenty-two studies met the inclusion criteria and meta-analysis included 15 studies. The presence of DR reflects a higher risk of cognitive dysfunction (OR = 2.45; 95% CI: 1.76-3.41; HR = 1.34 95% CI: 1.10-1.62). Cohort study combined risk was 2.62 (95% CI: 1.93-3.56), in cross-sectional study was 2.07 (95% CI: 1.11-3.88). The pooled OR was 2.38 (95% CI: 1.83-3.10) and 3.11 (95% CI: 1.15-8.40) in Asia and Oceania. No such association was found in North America (OR = 2.22; 95% CI: 0.77-6.38). The pooled risk was 2.47 (95% CI: 1.76-3.48) in patients with T2DM, while did not identify an association between these two conditions in T1DM. The combined unadjusted and adjusted ORs were 2.72 (95% CI: 1.99-3.73) and 2.06 (95% CI: 1.49-2.85). DR severity and the risk of cognitive impairment showed a positive correlation and mainly impaired the speeds of psychomotor and information processing.

CONCLUSIONS

DR can help to identify people at high risk of cognitive dysfunction. Further studies are indispensable for exploring the relationship between DR and cognitive impairment in the patients for different age, gender and race, as well as to assess the risk of cognitive impairment in different populations.

Exudative versus Nonexudative Age-Related Macular Degeneration: Physiopathology and Treatment Options

Age-related macular degeneration (AMD) is an eye disease typically associated with the aging and can be classified into two types—namely, the exudative and the nonexudative AMD. Currently available treatments for exudative AMD use intravitreal injections, which are associated with high risk of infection that can lead to endophthalmitis, while no successful treatments yet exist for the nonexudative form of AMD. In addition to the pharmacologic therapies administered by intravitreal injection already approved by the Food and Drug Administration (FDA) in exudative AMD, there are some laser treatments approved that can be used in combination with the pharmacological therapies. In this review, we discuss the latest developments of treatment options for AMD. Relevant literature available from 1993 was used, which included original articles and reviews available in PubMed database and also information collected from Clinical Trials Gov website using “age-related macular degeneration” and “antiangiogenic therapies” as keywords. The clinical trials search was limited to ongoing trials from 2015 to date.

Association Between Cataract Extraction and Development of Dementia

IMPORTANCE

Visual function is important for older adults. Interventions to preserve vision, such as cataract extraction, may modify dementia risk.

OBJECTIVE

To determine whether cataract extraction is associated with reduced risk of dementia among older adults.

DESIGN, SETTING, AND PARTICIPANTS

This prospective, longitudinal cohort study analyzed data from the Adult Changes in Thought study, an ongoing, population-based cohort of randomly selected, cognitively normal members of Kaiser Permanente Washington. Study participants were 65 years of age or older and dementia free at enrollment and were followed up biennially until incident dementia (all-cause, Alzheimer disease, or Alzheimer disease and related dementia). Only participants who had a diagnosis of cataract or glaucoma before enrollment or during follow-up were included in the analyses (ie, a total of 3038 participants). Data used in the analyses were collected from 1994 through September 30, 2018, and all data were analyzed from April 6, 2019, to September 15, 2021.

EXPOSURES

The primary exposure of interest was cataract extraction. Data on diagnosis of cataract or glaucoma and exposure to surgery were extracted from electronic medical records. Extensive lists of dementia-related risk factors and health-related variables were obtained from study visit data and electronic medical records.

MAIN OUTCOMES AND MEASURES

The primary outcome was dementia as defined by Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) criteria. Multivariate Cox proportional hazards regression analyses were conducted with the primary outcome. To address potential healthy patient bias, weighted marginal structural models incorporating the probability of surgery were used and the association of dementia with glaucoma surgery, which does not restore vision, was evaluated.

RESULTS

In total, 3038 participants were included (mean [SD] age at first cataract diagnosis, 74.4 (6.2) years; 1800 women (59%) and 1238 men (41%); and 2752 (91%) self-reported White race). Based on 23 554 person-years of follow-up, cataract extraction was associated with significantly reduced risk (hazard ratio, 0.71; 95% CI, 0.62-0.83; P < .001) of dementia compared with participants without surgery after controlling for years of education, self-reported White race, and smoking history and stratifying by apolipoprotein E genotype, sex, and age group at cataract diagnosis. Similar results were obtained in marginal structural models after adjusting for an extensive list of potential confounders. Glaucoma surgery did not have a significant association with dementia risk (hazard ratio, 1.08; 95% CI, 0.75-1.56; P = .68). Similar results were found with the development of Alzheimer disease dementia.

CONCLUSIONS AND RELEVANCE

This cohort study found that cataract extraction was significantly associated with lower risk of dementia development. If validated in future studies, cataract surgery may have clinical relevance in older adults at risk of developing dementia.

Novel Possible Protein Targets in Neovascular Age-Related Macular Degeneration: A Pilot Study Experiment

Age-related macular degeneration (AMD) is among the world's leading causes of blindness. In its neovascular form (nAMD), around 25% of patients present further anatomical and visual deterioration due to persistence of neovascular activity, despite gold-standard treatment protocols using intravitreal anti-VEGF medications. Thus, to comprehend, the molecular pathways that drive choroidal neoangiogenesis, associated with the vascular endothelial growth factor (VEGF), are important steps to elucidate the mechanistic events underneath the disease development. This is a pilot study, a prospective, translational experiment, in a real-life context aiming to evaluate the protein profiles of the aqueous humor of 15 patients divided into three groups: group 1, composed of patients with nAMD, who demonstrated a good response to anti-VEGF intravitreal injections during follow-up (good responsive); group 2, composed of patients with anti-VEGF-resistant nAMD, who demonstrated choroidal neovascularization activity during follow-up (poor/non-responsive); and group 3, composed of control patients without systemic diseases or signs of retinopathy. For proteomic characterization of the groups, mass spectrometry (label-free LC-MS/MS) was used. A total of 2,336 proteins were identified, of which 185 were distinctly regulated and allowed the differentiation of the clinical conditions analyzed. Among those, 39 proteins, including some novel ones, were analyzed as potential disease effectors through their pathophysiological implications in lipid metabolism, oxidative stress, complement system, inflammatory pathways, and angiogenesis. So, this study suggests the participation of other promising biomarkers in neovascular AMD, in addition to the known VEGF.

Diabetic Retinopathy Predicts Risk of Alzheimer’s Disease: A Danish Registry-Based Nationwide Cohort Study

Background:

Retinal neurodegeneration is evident in early diabetic retinopathy (DR) which may be associated with other neurodegenerative diseases like Alzheimer's disease (AD).

Objective:

To investigate diabetes and DR as a risk marker of present and incident AD.

Methods:

A register-based cohort study was performed. We included 134,327 persons with diabetes above 60 years of age, who had attended DR screening, and 651,936 age- and gender-matched persons without diabetes.

Results:

At baseline, the prevalence of AD was 0.7% and 1.3% among patients with and without diabetes, respectively. In a multivariable regression model, patients with diabetes were less likely to have AD at baseline (adjusted OR 0.63, 95% CI 0.59–0.68). During follow-up, incident AD was registered for 1473 (0.35%) and 6,899 (0.34%) persons with and without diabetes, respectively. Compared to persons without diabetes, persons with diabetes and no DR had a lower risk to develop AD (adjusted HR 0.87, 95% CI 0.81–0.93), while persons with diabetes and DR had higher risk of AD (adjusted HR 1.24, 95% CI 1.08–1.43). When persons with diabetes and no DR were used as references, a higher risk of incident AD was observed in persons with DR (adjusted HR 1.34, 95% CI 1.18–1.53).

Conclusion:

Individuals with diabetes without DR were less likely to develop AD compared to persons without diabetes. However, individuals with DR had a 34% higher risk of incident AD, which raise the question whether screening for cognitive impairment should be done among individuals with DR.

Vision impairment and cognitive decline among older adults: a systematic review

OBJECTIVES

There has been increasing epidemiological research examining the association between vision impairment (VI) and cognitive impairment and how poor vision may be a modifiable risk factor for cognitive decline. The objective of this systematic review is to synthesise the published literature on the association of VI with cognitive decline, cognitive impairment or dementia, to aid the development of interventions and guide public policies pertaining to the relationship between vision and cognition.

METHODS

A literature search was performed with Embase, Medline and Cochrane library databases from inception to March 2020, and included abstracts and articles published in peer-reviewed journals in English. Our inclusion criteria included publications that contained subjective/objective measures of vision and cognition, or a diagnosis of VI, cognitive impairment or dementia. Longitudinal or cross-sectional studies with ≥100 participants aged >50 years were included. The search identified 11 805 articles whose abstracts underwent screening by three teams of study authors. Data abstraction and quality assessment using the Effective Public Health Practice Project Quality Assessment Tool were performed by one author (NN). 10% of the articles underwent abstraction and appraisal by a second author (LA/VV), results were compared between both and were in agreement.

RESULTS

110 full-text articles were selected for data extraction, of which 53 were cross-sectional, 43 longitudinal and 14 were case-control studies. The mean age of participants was 73.0 years (range 50-93.1). Ninety-one (83%) of these studies reported that VI was associated with cognitive impairment.

CONCLUSION

Our systematic review indicates that a majority of studies examining the vision-cognition relationship report that VI is associated with more cognitive decline, cognitive impairment or dementia among older adults. This synthesis supports the need for additional research to understand the mechanisms underlying the association between VI and cognitive impairment and to test interventions that mitigate the cognitive consequences of VI.

Diabetic retinopathy as a potential marker of Parkinson's disease: a register-based cohort study

Neurodegeneration is an early event in the pathogenesis of diabetic retinopathy, and an association between diabetic retinopathy and Parkinson’s disease has been proposed. In this nationwide register-based cohort study, we investigated the prevalence and incidence of Parkinson’s disease among patients screened for diabetic retinopathy in a Danish population-based cohort. Cases (n = 173 568) above 50 years of age with diabetes included in the Danish Registry of Diabetic Retinopathy between 2013 and 2018 were matched 1:5 by gender and birth year with a control population without diabetes (n = 843 781). At index date, the prevalence of Parkinson’s disease was compared between cases and controls. To assess the longitudinal relationship between diabetic retinopathy and Parkinson’s disease, a multivariable Cox proportional hazard model was estimated. The prevalence of Parkinson’s disease was 0.28% and 0.44% among cases and controls, respectively. While diabetic retinopathy was not associated with present (adjusted odds ratio 0.93, 95% confidence interval 0.72–1.21) or incident Parkinson’s disease (adjusted hazard ratio 0.77, 95% confidence interval 0.56–1.05), cases with diabetes were in general less likely to have or to develop Parkinson’s disease compared to controls without diabetes (adjusted odds ratio 0.79, 95% confidence interval 0.71–0.87 and adjusted hazard ratio 0.88, 95% confidence interval 0.78–1.00). In a national cohort of more than 1 million persons, patients with diabetes were 21% and 12% were less likely to have prevalent and develop incident Parkinson’s disease, respectively, compared to an age- and gender-matched control population without diabetes. We found no indication for diabetic retinopathy as an independent risk factor for incident Parkinson’s disease.

Assessing bidirectional associations between cognitive impairment and late age-related macular degeneration in the Age-Related Eye Disease Study 2

INTRODUCTION

We aimed to investigate bidirectional associations between cognitive impairment and late age-related macular degeneration (AMD).

METHODS

Participants in the Age-Related Eye Disease Study 2 (AREDS2) received annual eye examinations and cognitive function testing (e.g., Modified Telephone Interview for Cognitive Status [TICS-M]). We examined bidirectional associations between cognitive impairment (e.g., a TICS-M score < 30) and late AMD at 5 and 10 years.

RESULTS

Five thousand one hundred eighty-nine eyes (3157 participants; mean age 72.7 years) were analyzed and followed for a median of 10.4 years. Eyes of participants with cognitive impairment at baseline were more likely to progress to late AMD at 5 years (hazard ratio [HR], 1.24; 95% confidence interval [CI], 1.08-1.43) and 10 years (HR, 1.20; 95% CI, 1.05-1.37) than eyes of participants without cognitive impairment. Worse baseline AMD severity was not associated with developing cognitive impairment.

DISCUSSION

Cognitive impairment is associated with late AMD progression in AREDS2. Our finding highlights the importance of eyecare for people with cognitive impairment.

Glaucoma Is Not Associated With Alzheimer's Disease or Dementia: A Meta-Analysis of Cohort Studies

Background: Previous studies evaluating the relationships of glaucoma with Alzheimer's disease (AD) and dementia showed inconsistent results. We performed a meta-analysis of cohort studies to evaluate the association between glaucoma with incidence of AD, all-cause dementia, and non-AD dementia. Methods: Cohort studies which evaluated the association between glaucoma with incidence of AD, all-cause dementia, and non-AD dementia in adult population with multivariate analyses were identified by systematic search of PubMed, Embase, and Cochrane's Library databases. A random-effects model incorporating the potential intra-study heterogeneity was used for the meta-analysis. Results: Eleven cohort studies including 4,645,925 participants were included. Results showed that compared to those without glaucoma at baseline, adult patients with glaucoma was not independently associated with increased incidence of AD [adjusted risk ratio (RR): 1.03, 95% confidence interval (CI): 0.93-1.05, P = 0.55; I ² = 83%], all-cause dementia (adjusted RR: 1.08, 95% CI: 0.97-1.19, P = 0.15; I ² = 79%), or non-AD dementia (adjusted RR: 1.05 95% CI: 0.91-1.21, P = 0.49; I ² = 82%). Sensitivity analyses by excluding one study at a time did not significantly affect the results of the meta-analyses. Moreover, subgroup analyses showed consistent results in meta-analysis of prospective or retrospective cohort studies, and in meta-analysis of patients with primary open-angle glaucoma or primary angle-closure glaucoma (P-values for subgroup difference all > 0.05). Conclusions: Current evidence from cohort studies did not support that glaucoma is an independent risk factor of AD, all-cause dementia, or non-AD dementia in adult population.

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 Dysfunction in Alzheimer's Disease and Implications for Biomarkers

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that manifests as cognitive deficits and memory decline, especially in old age. Several biomarkers have been developed to monitor AD progression. Given that the retina and brain share some similarities including features related to anatomical composition and neurological functions, the retina is closely associated with the progression of AD. Herein, we review the evidence of retinal dysfunction in AD, particularly at the early stage, together with the underlying molecular mechanisms. Furthermore, we compared the retinal pathologies of AD and other ophthalmological diseases and summarized potential retinal biomarkers measurable by existing technologies for detecting AD, providing insights for the future development of diagnostic tools.

Visual Impairment, Eye Diseases, and Dementia Risk: A Systematic Review and Meta-Analysis

BACKGROUND

Visual impairment and eye diseases have been associated with dementia, though with mixed findings and often in cross-sectional studies.

OBJECTIVE

To identify prospective studies investigating associations between visual impairment or common eye diseases and risk of all-cause dementia or key dementia subtypes.

METHODS

We searched Medline, PsycINFO, and Embase from inception to January 2020. We also conducted backward and forward citation searches of included studies and set up alerts to identify studies published after the search date. Random-effects meta-analysis was used to combine adjusted estimates across studies.

RESULTS

Thirty studies met our eligibility criteria. For visual impairment, pooled estimates indicated an increased risk of all-cause dementia (37,705 participants, 3,415 cases, risk ratio [RR] = 1.38, 95%confidence interval [CI]: 1.19-1.59, I2 = 28.6%). Pooled estimates also suggested an increased dementia risk associated with cataract (6,659 participants, 1,312 cases, hazard ratio [HR] = 1.17, 95%CI 1.00-1.38, I2 = 0.0%) and diabetic retinopathy (43,658 participants, 7,060 cases, HR = 1.34, 95%CI 1.11-1.61, I2 = 63.9%), respectively. There was no evidence of an association between glaucoma (175,357 participants, 44,144 cases, HR = 0.97, 95%CI 0.90-1.04, I2 = 51.5%) or age-related macular degeneration (7,800,692 participants, >  2,559 cases, HR = 1.15, 95%CI 0.88-1.50, I2 = 91.0%) and risk of dementia, respectively.

CONCLUSION

As visual impairment, cataract, and diabetic retinopathy are associated with an increased likelihood of developing dementia, early diagnosis may help identify those at risk of dementia. Given most causes of visual impairment are treatable or preventable, the potential for dementia prevention warrants further investigation.