Cognitive Function and Ophthalmological Diseases: The Beijing Eye Study

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.

Roles of Cognitive Function on Visual Field Reliability Indices among Glaucoma Patients

This study reports the prevalence of cognitive impairment (CI) in patients attending a glaucoma outpatient clinic at a tertiary hospital. It also comprehensively assesses possible associations between CI and visual field (VF) reliability indices among glaucoma patients. The retrospective analysis included 1464 eyes from 746 subjects (mean age, 70.6 ± 11.9; 401 males and 345 females). CI was evaluated using the Mini-Cog test, revealing a suspected prevalence of 8.0% (60 out of 746) among the patients. After adjusting for various background parameters using a mixed effects regression model, an abnormal Mini-Cog score was linked to higher false negative (FN) (p = 0.0034) and false positive (FP) (p = 0.0051) but not fixation loss (FL) (p = 0.82). Among the Mini-Cog components, a lower word recall test score was associated with higher FN (p < 0.0001), with a borderline difference in FP (p = 0.054) and no significant effect on FL (p = 0.09). Conversely, a lower clock drawing test score was associated with higher FP (p = 0.038), while FL (p = 0.49) and FN (p = 0.12) remained unaffected. These findings suggest that CI can impact the reliability of VF testing among glaucoma patients, highlighting the importance of assessing cognitive function in glaucoma care.

Visual impairment as a risk factor of cognitive function impairment A six-year cohort study

PURPOSE

To explore whether baseline visual impairment (VI) increases the risk of cognitive function impairment (CFI).

METHODS

We conducted a population-based cohort study, with a six-year follow-up period. The exposure factor of interest in this study was VI. The Mini-Mental State Examination (MMSE) was used to assess participants' cognitive function. The Logistic regression model was used to investigate whether baseline VI had an effect on CFI. Confounding factors were adjusted in the regression model. The odds ratio (OR) and 95% confidence interval (CI) were used to quantify the effect of VI on CFI.

RESULTS

A total of 3297 participants were included in the present study. The mean age of included participants was 58.5 ± 7.2 years. Male accounted for 1480 (44.9%) of all participants. At baseline, 127 (3.9%) of the participants had VI. The MMSE score of participants who had VI at baseline decreased by 1.7 ± 3.3 points on average during the six-year follow-up, and that of participants who had no VI at baseline decreased by 1.1 ± 3.3 points on average. The difference was significant (t = 2.03, p = 0.040). Results of the multivariable Logistic regression model showed that VI was a risk factor for CFI, with an OR of 1.052 (95%CI: 1.014 to 1.092, p = 0.017).

CONCLUSIONS

Averagely, participants with VI experienced a decline in cognitive function 0.1 points faster per year than participants without VI, as measured by MMSE score. VI is an independent risk factor for CFI.

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.

The association between vision impairment and cognitive outcomes in older adults: a systematic review and meta-analysis

OBJECTIVES

To provide a quantitative synthesis of studies on the relationship between vision impairment (VI) and cognitive outcomes in older adults.

METHOD

A systematic search was undertaken of relevant databases for original articles published before April 2020. Random effect models were used to obtain pooled estimates of the associations between VI and cognitive outcomes (cognitive impairment and dementia) with subgroup analyses of VI measures, cross-sectional associations of VI with cognitive impairment, and longitudinal associations of baseline VI with incident cognitive impairment and dementia. Potential sources of heterogeneity were explored by meta-regression. Publication bias was evaluated with Egger's test.

RESULTS

Sixteen studies including 76,373 participants were included in this meta-analysis, with five cross-sectional studies and eleven longitudinal studies. There was a significantly increased risk of cognitive outcomes with VI identified by subjective measures (odds ratio (OR)=1.63; 95% confidence interval (CI): 1.26-1.99) and objective measures (OR = 1.59; 95% CI: 1.40-1.78). The odds of baseline cognitive impairment were 137% higher in older adults with VI compared with those without VI (OR = 2.37, 95% CI: 1.84-3.03) at baseline. Compared with older adults without VI at baseline, those with baseline VI had a higher relative risk (RR) of incident cognitive impairment (RR = 1.41; 95% CI: 1.31-1.51) and dementia (RR = 1.44, 95% CI: 1.19-1.75).

CONCLUSIONS

VI was associated with increased risks of cognitive impairment and dementia across cross-sectional and longitudinal studies. Additional research and randomized clinical trials are warranted to examine the implications of treatment for VI, such as wearing glasses and cataract surgery, to avoid cognitive impairment and dementia.

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.

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.

Retinal Thickness Associates with Cognition Dysfunction in Young Adult with Type 1 Diabetes in Taiwan

BACKGROUND

Several factors could affect the cognitive dysfunction in patients with type 1 diabetes (T1D).

OBJECTIVES

To report the characteristic of cognitive dysfunction in T1D and find its association with the retinal thickness.

SUBJECTS

We recruited one hundred and seven patients with T1D in our study.

METHODS

Detailed clinical and demographic factors and Cambridge Automated Neuropsychological Test Battery (CANTAB) were performed in all participants. The age at onset>5 years old and ≤5 years old groups was defined as old- and young-onset groups. The levels of the average values of 5-year glycated hemoglobin (HbA1c_5) before study were collected. Ophthalmic study and central retinal thickness (CRT) were performed.

RESULTS

The median age of T1D was 24.9 years old and 57 participants were women. The median age at onset was 7.4 years old, and mean disease duration was 17.2 years. After adjusting off multiple covariates by the regression analyses, the young-onset group had significantly a longer latency in sustained attention than old-onset group (P = 0.02). The HbA1c_5 showed a significantly negative association with the sustained attention (P = 0.03). The average values of CRT showed significantly negative correlations with the reaction time in sustained attention and visual searching (P = 0.04 and P < 0.01, respectively).

CONCLUSIONS

Our results suggest that age at onset and glycemic control had significant impacts on different cognitive domains in T1D. The CRT had a significant correlation with sustained attention, which could be a surrogate markers of brain structural changes in T1D.

Association between visual impairment and cognitive disorders in low-and-middle income countries: a systematic review

OBJECTIVES

Visual impairment and cognitive disorders are common among older people in Low-and Middle-Income Countries (LMIC). Several recent studies performed in High-Income Countries suggested that visual impairment is associated with cognitive disorders. However, no synthesis of current knowledge exists for LMIC.

METHODS

We have conducted an extensive literature search combining six databases and two grey literature databases. We searched for studies assessing the link between visual and cognitive impairments carried out in LMIC. The systematic search was performed up to 14th February 2019.

RESULTS

Overall, eight studies were included in this review. Among them, five studies were performed in Asia and seven studies had a cross-sectional design. Mean age of the participants varied from 64.2 to 76.2 years. Participants were most often females. Only three studies were specifically focused on the association between visual impairment and cognitive disorders. Out of the eight studies included, four reported a significant association; two showed a possible association and two did not retrieve any statistically significant effect. Heterogeneity in assessments of visual and cognitive impairments was high.

CONCLUSION

In LMIC, very few studies explored the association between visual and cognitive impairments among older people. The current review seems to suggest that visual impairment is associated with cognitive disorders in LMIC. However, further studies are required to improve the knowledge on this relationship. Improving vision, in particular through optical correction and cataract surgery, could potentially be easy pathways to reduce cognitive disorders incidence and to improve quality of life of people affected by this disorder.

Lower Cognitive Function in Patients with Functionally and Structurally Severe Glaucoma: The LIGHT Study

PRECIS

This cross-sectional study of 172 patients with glaucoma showed that functional and structural glaucoma damage was significantly associated with cognitive impairment independent of age and visual acuity.

PURPOSE

The aim of this study was to determine whether functional and structural glaucoma damage is associated with cognitive function.

PATIENTS AND METHODS

This was a cross-sectional analysis comprising 172 patients with glaucoma with a mean age of 70.6 years. Functional glaucoma severity was evaluated according to the visual field mean deviation (severe, mean deviation ≤ -12▒dB; mild, mean deviation > -12▒dB), and structural glaucoma severity was determined based on circumpapillary retinal nerve fiber layer (RNFL) thickness. The main outcome measure was cognitive impairment defined by a mini-mental state examination (MMSE) score of ≤26 and MMSE-blind score of ≤16.

RESULTS

The prevalence of patients with cognitive impairment (MMSE score ≤26) was significantly higher in the severe glaucoma group than in the mild glaucoma group (33.3% vs. 15.7%; P=0.010, respectively). Similar results were obtained in the analyses with MMSE-blind score of ≤16 (14.7% vs. 1.4%; P=0.003, respectively). Multivariable logistic regression analysis adjusted for potential confounders, including age, body mass index, education, visual acuity, hypertension, diabetes, and depressive symptoms, indicated a higher odds ratio for cognitive impairment (MMSE score ≤26) in patients with severe glaucoma than in those with mild glaucoma (odds ratio, 2.62; 95% confidence interval, 1.006-6.84; P=0.049) and in relation to a 10-μm thinning of the RNFL (odds ratio, 1.42; 95% confidence interval, 1.05-1.93; P=0.025).

CONCLUSION

Functional and structural glaucoma damage was significantly associated with lower cognitive function independent of age and visual acuity in a glaucoma cohort.

Associations of Vision Impairment and Eye Diseases With Memory Decline Over 4 Years in China and the United States

PURPOSE

To examine whether vision impairment and eye diseases are independently associated with memory decline in older adults.

DESIGN

Cohort study.

METHODS

We included 8,315 participants aged 50-94 years in China Health and Retirement Longitudinal Study (CHARLS) from China and 8,939 participants aged 50-95 years in Health and Retirement Study (HRS) from the United States in our analysis.

RESULTS

During 4.0 years' follow-up, the composite memory decreased by 0.16 points in CHARLS. During 3.9 years' follow-up, the composite memory decreased by 0.51 in HRS. Distance vision impairment was inversely associated with an annual change in composite memory (β [95% CI]: -0.07 [-0.12, -0.01]) and immediate memory (-0.04 [-0.07, -0.02]) in CHARLS, and the corresponding values in HRS were -0.19 (-0.34, -0.05) and -0.07 (-0.13, -0.00), respectively. Near vision impairment was inversely associated with an annual change in delayed memory in CHARLS and composite memory, immediate memory, and delayed memory in HRS. In HRS, the association between distance vision impairment and memory decline was observed in individuals aged <65 years (β [95% CI]: -0.54 [-0.78, -0.30]) but not in those aged ≥65 years (-0.01 [-0.20, 0.18]). Cataract surgery or glaucoma was not significantly associated with memory decline in either CHARLS or HRS.

CONCLUSION

Distance vision impairment was independently associated with an accelerated rate of memory decline in both China and the United States. Near vision impairment was predictive of decline in delayed memory in China and of decline in composite, immediate, and delayed memory in the United States.

Relationship between Diabetic Retinopathy and Systemic Neurodegenerative Diseases: A Systematic Review and Meta-analysis

TOPIC

To examine the potential role of systemic neurodegeneration, this study aimed to provide an overview of the available evidence on the relationship between diabetic retinopathy (DR) and systemic neurodegeneration.

CLINICAL RELEVANCE

The association between DR and systemic neurodegeneration is inconsistent in the literature. A summary estimate on the measures of association is important to establish whether DR may be used as a risk marker of systemic neurodegeneration.

METHODS

We searched the literature databases PubMed/MEDLINE, EMBASE, and Cochrane Library on October 3, 2020, for all observational studies on humans evaluating the association between DR and systemic neurodegenerative diseases. Two authors conducted the literature search, study selection, and data extraction in an independent fashion. Studies were reviewed qualitatively in text and quantitatively in meta-analyses. Heterogeneity was evaluated with Cochran's Q and I², and Funnel plot was used to investigate for skewed results and possible publication bias.

RESULTS

We identified 27 eligible studies with a total of 1 398 041 patients with diabetes. Diagnosis of DR was made using fundus photography or examination (n = 20), health registries (n = 4), was self-reported (n = 1), or was not disclosed in the remaining studies. Neurodegenerative conditions studied were cognitive impairment (n = 23), Alzheimer's disease (n = 3), and Parkinson's disease (n = 1). In cross-sectional and longitudinal studies, respectively, presence of any DR was associated with present (odds ratio [OR], 1.57; 95% confidence interval [CI], 1.02-2.43, P = 0.043) and incident (OR, 2.36; 95% CI, 1.50-3.71, P = 0.00021) systemic neurodegeneration, but severity of DR was not associated with differences in systemic neurodegeneration (OR, 0.98; 95% CI, 0.45-2.15, P = 0.96).

CONCLUSIONS

In this systematic review, DR appears to be a marker of systemic neurodegeneration. Further studies are warranted to better elucidate the clinical practical implications of this relationship.

Diagnosis and Management of Cognitive Concerns in the Oldest-Old

Purpose of review

The fastest-growing group of elderly individuals is the "oldest-old," usually defined as those age 85 years and above. These individuals account for much of the rapid increase in cases of dementing illness throughout the world but remain underrepresented in the body of literature on this topic. The aim of this review is first to outline the unique contributing factors and complications that must be considered by clinicians in evaluating an oldest-old individual with cognitive complaints. Secondly, the evidence for management of these cognitive concerns is reviewed.

Recent findings

In addition to well-established associations between impaired cognition and physical disability, falls, and frailty, there is now evidence that exercise performed decades earlier confers a cognitive benefit in the oldest-old. Moreover, though aggressive blood pressure control is critical earlier in life for prevention of strokes, renal disease, and other comorbidities, hypertension started after age 80 is in fact associated with a decreased risk of clinical dementia, carrying significant implications for the medical management of oldest-old individuals. The oldest-old are more likely to reside in care facilities, where social isolation might be exacerbated by a consistently lower rate of internet-connected device use. The COVID-19 pandemic has not only highlighted the increased mortality rate among the oldest-old but has also brought the increased social isolation in this group to the forte.

Summary

Differing from the "younger-old" in a number of respects, the oldest-old is a unique population not just in their vulnerability to cognitive disorders but also in the diagnostic challenges they can pose. The oldest-old are more likely to be afflicted by sensory deficits, physical disability, poor nutrition, frailty, and depression, which must be accounted for in the assessment of cognitive complaints as they may confound or complicate the presentation. Social isolation and institutionalization are also associated with impaired cognition, perhaps as sequelae, precipitants, or both. Ante-mortem diagnostic tools remain particularly limited among the oldest-old, especially given the likelihood of these individuals to have multiple co-occurring types of neuropathology, and the presence of neuropathology in those who remain cognitively intact. In addition to the symptomatic treatments indicated for patients of all ages with dementia, management of cognitive impairment in the oldest-old may be further optimized by use of assistive devices, augmentation of dietary protein, and liberalization of medication regimens for risk factors such as hypertension.

Effect of Reading Rehabilitation for Age-Related Macular Degeneration on Cognitive Functioning: Protocol for a Nonrandomized Pre-Post Intervention Study

BACKGROUND

Age-related vision impairments and dementia both become more prevalent with increasing age. Research into the mechanisms of these conditions has proposed that some of their causes (eg, macular degeneration/glaucoma and Alzheimer's disease) could be symptoms of an underlying common cause. Research into sensory-cognitive aging has provided data that sensory decline may be linked to the progression of dementia through reduced sensory stimulation. While hearing loss rehabilitation may have a beneficial effect on cognitive functioning, there are no data available on whether low vision rehabilitation, specifically for reading, could have a beneficial effect on cognitive health.

OBJECTIVE

The research questions are: (1) Does low vision rehabilitation reduce reading effort? (2) If so, does reduced reading effort increase reading activity, and (3) If so, does increased reading activity improve cognitive functioning? The primary objective is to evaluate cognition before, as well as at 6 months and 12 months after, 3 weeks of low vision reading rehabilitation using magnification in individuals with age-related macular degeneration, with or without coexisting hearing impairments. We hypothesize that improvements postrehab will be observed at 6 months and maintained at 12 months for participants with vision loss and less so for those with dual sensory loss. The secondary objective is to correlate participant characteristics with all cognitive outcomes to identify which may play an important role in reading rehabilitation.

METHODS

We employ a quasiexperimental approach (nonrandomized, pre-post intervention study). A 3x3 design (3 groups x 3 time points) allows us to examine whether cognitive performance will change before and after 6 months and 12 months of a low vision reading intervention, when comparing 75 low vision and 75 dual sensory impaired (vision & hearing) participants to 75 age-matched healthy controls. The study includes outcome measures of vision (eg, reading acuity and speed), cognition (eg, short-term and long-term memory, processing speed), participant descriptors, demographics, and clinical data (eg, speech perception in noise, mental health).

RESULTS

The study has received approval, and recruitment began on April 24, 2019. As of March 4, 2021, 38 low vision and 7 control participants have been enrolled. Lockdown forced a pause in recruitment, which will recommence once the COVID-19 crisis has reached a point where face-to-face data collection with older adults becomes feasible again.

CONCLUSIONS

Evidence of protective effects caused by reading rehabilitation will have a considerable impact on the vision rehabilitation community and their clients as well as all professionals involved in the care of older adults with or without dementia. If we demonstrate that reading rehabilitation has a beneficial effect on cognition, the demand for rehabilitation services will increase, potentially preventing cognitive decline across groups of older adults at risk of developing macular degeneration.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04276610; Unique Protocol ID: CRIR-1284-1217; https://clinicaltrials.gov/ct2/show/NCT04276610.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/19931.

The Bidirectional Relationship between Vision and Cognition: A Systematic Review and Meta-analysis

TOPIC

Visual impairment (VI) and cognitive impairment (CIM) are prevalent age-related conditions that impose substantial burden on the society. Findings on the hypothesized bidirectional association of VI and CIM remains equivocal. Hence, we conducted a systematic review and meta-analysis to examine this bidirectional relationship.

CLINICAL RELEVANCE

Sixty percent risk of CIM has not been well elucidated in the literature. A bidirectional relationship between VI and CIM may support the development of strategies for early detection and management of risk factors for both conditions in older people.

METHODS

PubMed, Embase, and Cochrane Central registers were searched systematically for observational studies, published from inception until April 6, 2020, in adults 40 years of age or older reporting objectively measured VI and CIM assessment using clinically validated cognitive screening tests or diagnostic evaluation. Meta-analyses on cross-sectional and longitudinal associations between VI and CIM outcomes (any CIM assessed using screening tests and clinically diagnosed dementia) were examined. Random effect models were used to generate pooled odds ratios (ORs) and 95% confidence intervals (CIs). We also examined study quality, publication bias, and heterogeneity.

RESULTS

Forty studies were included (n = 47 913 570). Meta-analyses confirmed that persons with VI were more likely to have CIM, with significantly higher odds of: (1) any CIM (cross-sectional: OR, 2.38 [95% CI, 1.84-3.07]; longitudinal: OR, 1.66 [95% CI, 1.46-1.89]) and (2) clinically diagnosed dementia (cross-sectional: OR, 2.43 [95% CI, 1.48-4.01]; longitudinal: OR, 2.09 [95% CI, 1.37-3.21]) compared with persons without VI. Significant heterogeneity was explained partially by differences in age, sex, and follow-up duration. Also, some evidence suggested that individuals with CIM, relative to cognitively intact persons, were more likely to have VI, with most articles (8/9 [89%]) reporting significantly positive associations; however, meta-analyses on this association could not be conducted because of insufficient data.

DISCUSSION

Overall, our work suggests that VI is a risk factor of CIM, although further work is needed to confirm the association of CIM as a risk factor for VI. Strategies for early detection and management of both conditions in older people may minimize individual clinical and public health consequences.

Role of Retinal Amyloid-β in Neurodegenerative Diseases: Overlapping Mechanisms and Emerging Clinical Applications

Amyloid-β (Aβ) accumulations have been identified in the retina for neurodegeneration-associated disorders like Alzheimer's disease (AD), glaucoma, and age-related macular degeneration (AMD). Elevated retinal Aβ levels were associated with progressive retinal neurodegeneration, elevated cerebral Aβ accumulation, and increased disease severity with a decline in cognition and vision. Retinal Aβ accumulation and its pathological effects were demonstrated to occur prior to irreversible neurodegeneration, which highlights its potential in early disease detection and intervention. Using the retina as a model of the brain, recent studies have focused on characterizing retinal Aβ to determine its applicability for population-based screening of AD, which warrants a further understanding of how Aβ manifests between these disorders. While current treatments directly targeting Aβ accumulations have had limited results, continued exploration of Aβ-associated pathological pathways may yield new therapeutic targets for preserving cognition and vision. Here, we provide a review on the role of retinal Aβ manifestations in these distinct neurodegeneration-associated disorders. We also discuss the recent applications of retinal Aβ for AD screening and current clinical trial outcomes for Aβ-associated treatment approaches. Lastly, we explore potential future therapeutic targets based on overlapping mechanisms of pathophysiology in AD, glaucoma, and AMD.

The Association of Cognitive and Visual Function in a Nationally Representative Study of Older Adults in India

INTRODUCTION

Due to population aging, India is poised to experience a large increase in the burden of both dementia and vision impairment (VI). Prior studies from other settings suggest that VI may be a modifiable risk factor for cognitive decline and dementia. However, to date, no studies have examined the association of impaired visual acuity and cognition in India.

METHODS

A total of 3,784 participants in wave 1 of the population-based Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India underwent visual acuity testing and a cognitive test battery. Multivariable linear regression was used to model the cross-sectional associations of mild (<6/12-6/16), moderate (<6/18-6/60), and severe visual acuity impairment/blindness (<6/60) with cognitive performance scores corresponding to total cognition, orientation, memory, language/fluency, executive function, and informant-reported cognitive status. Models were adjusted for demographic, socioeconomic, and health characteristics.

RESULTS

The weighted percentage of participants with any VI was 52.6%. VI was independently associated with lower cognitive scores across all domains, even after adjustment for known dementia risk factors. In fully adjusted models of total cognition (mean score: 130.7), mild, moderate, and severe VI/blindness were associated with a significant change of -3.5 (95% CI: -6.3, -0.6), -8.2 (95% CI -10.5, -5.6), and -16.8 (95% CI -22.3, -11.3) units, respectively. A dose-response association between level of VI and cognitive function was observed for all cognitive outcomes except for language/fluency domain scores. Associations were robust when cognitive tests dependent on visual function were excluded. Across each fully adjusted model of total, domain-specific, and informant-reported cognitive performance, moderate VI was equivalent to 5-9 years of cognitive aging.

DISCUSSION/CONCLUSION

This study illustrates that VI is cross-sectionally associated with lower cognitive performance, largely in a dose-response pattern, across various cognitive domains in the Indian population. These findings are important for informing future longitudinal and interventional studies.

Glaucoma, but not cataracts, predicts lower verbal fluency performance: 3.8-year follow-up from the ELSA-Brasil study

Glaucoma, cataracts, and cognitive decline are most common in older ages. Although cross-sectional studies showed that these disorders are associated, follow-up studies are lacking. To investigate this issue, baseline and follow-up data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) were employed. We evaluated participants ≥ 55 years-old at follow-up without diagnosis of dementia, stroke, and other eye conditions except for glaucoma and cataracts. Cognition was evaluated using delayed word recall, verbal fluency, and trail making (version B) tests. Regression models were employed to investigate associations between glaucoma and cognition, adjusted by several confounders. Out of 3,867 participants, 379 and 118 presented cataracts and glaucoma, respectively. Only glaucoma was apredictor of lower verbal fluency (B = -0.23, 95% CI -035 to -012, p< 0.001). Other associations were not significant (ps>0.57). Our results suggest that glaucoma may be related to declining cognition.

Diffusional Kurtosis Imaging of White Matter Degeneration in Glaucoma

Glaucoma is an optic neuropathy characterized by death of retinal ganglion cells and loss of their axons, progressively leading to blindness. Recently, glaucoma has been conceptualized as a more diffuse neurodegenerative disorder involving the optic nerve and also the entire brain. Consistently, previous studies have used a variety of magnetic resonance imaging (MRI) techniques and described widespread changes in the grey and white matter of patients. Diffusion kurtosis imaging (DKI) provides additional information as compared with diffusion tensor imaging (DTI), and consistently provides higher sensitivity to early microstructural white matter modification. In this study, we employ DKI to evaluate differences among healthy controls and a mixed population of primary open angle glaucoma patients ranging from stage I to V according to Hodapp–Parrish–Anderson visual field impairment classification. To this end, a cohort of patients affected by primary open angle glaucoma (n = 23) and a group of healthy volunteers (n = 15) were prospectively enrolled and underwent an ophthalmological evaluation followed by magnetic resonance imaging (MRI) using a 3T MR scanner. After estimating both DTI indices, whole-brain, voxel-wise statistical comparisons were performed in white matter using Tract-Based Spatial Statistics (TBSS). We found widespread differences in several white matter tracts in patients with glaucoma relative to controls in several metrics (mean kurtosis, kurtosis anisotropy, radial kurtosis, and fractional anisotropy) which involved localization well beyond the visual pathways, and involved cognitive, motor, face recognition, and orientation functions amongst others. Our findings lend further support to a causal brain involvement in glaucoma and offer alternative explanations for a number of multidomain impairments often observed in glaucoma patients.

Spontaneous Feedforward Connectivity in Electrically Stimulated Retinal Degeneration Mice. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020;2020:3513-3516. [PMID: 33018761 DOI: 10.1109/embc44109.2020.9175231]

Retinal degeneration (Rd) is a neurodegenerative disorder primarily associated with the degeneration of the retina neurons and culminates in the eventual loss of visual perception or blindness. Decrease in fronto-, parietal and occipital brain connectivity have been reported in a number of neurodegeneration diseases involving cognitive decline. However, cortical communication in the brain of retinal degeneration patients remains largely unknown and strategies to remediate observed dysfunctional brain connectivity in such instance have not be thoroughly investigated. We used rd10 mice as a model to study brain connectivity in the human retinal degeneration disease, retinitis pigmentosa. Rd10 mice with sham matched controls were electrically stimulated at varying stimulation frequencies and the consequent perturbations in feedforward brain connectivity were studied in the visual cortex and pre-frontal cortex using electrocorticography (ECoG) and normalized symbolic transfer entropy (NSTE). Contra Vcx - contra PFx feed forward connectivity significantly (p<0.05) increased in theta, alpha and beta oscillatory bands of 2 Hz and 10 Hz stimulated rd10 respectively in comparison with sham group. Also, this increase was significantly maintained even after the end of the stimulation period.

Illustration of tessellation in Down syndrome

Background: Tessellated fundus refers to a specific change in the appearance of the internal layers of the eye in which the choroidal large vessels became visible through polygonal hypopigmented areas. Such hypopigmented areas alternate with hyperpigmented zones in a tigroid pattern. Fundus tessellation is often associated with myopia and choroidal thinning.Materials and Methods: We analyzed fundus images from 50 children with Down syndrome and 52 controls.Results: Tessellation was present in 64% of children with Down syndrome, compared with only 13.5% of controls (p < .0001). In most cases, tessellation was located peripapillary, and no difference was observed in tessellation localization between children with Down syndrome and controls (p = .60). Although more prevalent in myopic children with and without Down syndrome, tessellation was present in almost half (48%) of children with Down syndrome with hyperopia versus only 5% of controls with the same refractive status.Conclusions: Mechanical stretching of the choroid could explain the high rate of tessellation in myopes. Other factors must contribute to the higher prevalence of tessellated fundus in children with Down syndrome without myopia. We discuss potentially relevant factors and propose vascular involvement as a contributor to tessellation in our population with Down syndrome. Further studies assessing choroidal vasculature in individuals with Down syndrome are needed to confirm this theory.

Patterns and Risk Factor Profiles of Visual Loss in a Multiethnic Asian Population: The Singapore Epidemiology of Eye Diseases Study

PURPOSE

To describe the pattern and risk factor traits associated with visual loss (defined as either visual impairment [VI] or blindness) in a multiethnic Asian cohort of Malay, Indian, and Chinese individuals living in Singapore.

METHODS

A total of 10 020 participants from the Singapore Epidemiology of Eye Diseases Study were examined between 2004 and 2011. All underwent standardized examinations. VI (visual acuity <20/40 to ≥20/200) and blindness (visual acuity <20/200) were defined based on the US definition, better-seeing eye. Singapore Population Census 2010 was used to calculate age-standardized prevalence. Multiple logistic regression analysis was performed to determine the independent and joint risk factors associated with visual loss.

RESULTS

Malay individuals had higher age-standardized prevalence of best-corrected and presenting VI (5.4% and 19.9%, respectively) than Indian (3.6% and 18.0%) and Chinese individuals (3.3% and 17.2%). Cataract was the main cause for presenting and best-corrected blindness; cataract and diabetic retinopathy were the top causes for best-corrected VI, consistently observed across the 3 ethnic groups. Older age, female sex, lower socioeconomic status, diabetes, systemic comorbidities, and cognitive impairment were independently associated with increased risk of best-corrected visual loss (all P ≤ .027). Individuals aged ≥60 years with diabetes were 12.7 times (95% confidence interval, 8.39-19.23) likely to have best-corrected visual loss, compared with younger, nondiabetic individuals. Lower income and education explained 58.1% and 23.2% of best-corrected visual loss in this population, respectively.

CONCLUSION

In this urban multiethnic Asian population, we identified common traits associated with visual loss across Malay, Indian, and Chinese individuals. These results will be useful for the planning and designing of eye health services and strategies for Asia's rapidly developing populations living in urban communities. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.