Cognitive dysfunction and age-related macular degeneration

Primary Open-Angle Glaucoma Is Associated with Short-Term Memory Decline and Dementia in Individuals of African Ancestry

Background: Over the last decade, studies have suggested that primary open-angle glaucoma (POAG) may be associated with cognitive impairment and dementia, as both pathologies are age-related neurodegenerative processes. It remains unclear to what extent neurodegeneration in POAG extends to other neurological functions beyond vision, such as cognition. This follow-up study examined the potential association between POAG and cognitive decline in an African ancestry population. Methods: The Telephone-Montreal Cognitive Assessment (T-MoCA) was administered to POAG cases and controls previously enrolled in the Primary Open-Angle African American Glaucoma Genetics (POAAGG) study. Cases were assessed for retinal nerve fiber layer (RNFL) thickness and for the presence of dementia via chart review. Comparisons between POAG cases and controls were performed using two-sample t-tests for the T-MoCA total score and five subsection scores, and using chi-squared tests for incidence of dementia. Current scores were compared to scores from this same cohort from 7 years prior. Results: The T-MoCA was administered to 13 cases and 20 controls. The mean ± standard deviation (SD) T-MoCA total score was 15.5 ± 4.0 in cases and 16.7 ± 3.5 in controls (p = 0.36). However, there was a borderline significant difference in the delayed recall sub-score (2.3 ± 1.6 for cases vs. 3.4 ± 1.5 for controls, p = 0.052) and a significant difference in its sub-domain, the memory index score (MIS, 9.1 ± 4.3 for cases vs. 12.1 ± 3.0 for controls, p = 0.02). There were no significant differences between cases and controls for the remaining subsections. During 7 years of follow-up, a higher incidence of dementia was noted in POAG cases (7.1% for cases vs. 0% for controls, p = 0.058). Over 7 years, there was no significant deterioration in the cognitive performance of cases versus controls, and no association was seen between RNFL thinning and cognitive impairment. Conclusions: In this small-sample follow-up study of African ancestry individuals, POAG cases demonstrated worse short-term memory and higher incidence of dementia compared to controls. Future larger studies are needed to further investigate the presence and impact of neurodegeneration in POAG.

Abnormal functional connectivity strength in age-related macular degeneration patients: a fMRI study

OBJECTIVE

Age-related macular degeneration (AMD) is a serious blinding eye disease. Previous neuroimaging studies reported that AMD were accompanied by abnormalities of the brain. However, whether AMD patients were associated with functional connectivity strength (FCS) or not remains unknown. In our study, the purpose of the study was to assess FCS changes in AMD patients.

METHODS

In our study, 20 AMD patients and 20 healthy controls (HCs), matched closely by sex, age, and educational level were underwent MRI scanning. FCS method and seed-based functional connectivity (FC) method were applied to investigate the functional network changes between two groups. Moreover, support vector machine (SVM) method was applied to assess the FCS maps as a feature to classification of AMD diseases.

RESULTS

Our study reported that AMD patients showed decreased FCS values in the bilateral calcarine, left supplementary motor area, left superior parietal lobule and left paracentral lobule (ParaL) relative to the HC group. Meanwhile, our study found that the AMD patients showed abnormal FC within visual network, sensorimotor network and default mode network. Moreover, the SVM method showed that FCS maps as machine learning features shows good classification efficiency (area under curve = 0.82) in the study.

CONCLUSION

Our study demonstrated that AMD patients showed abnormal FCS with the visual network, sensorimotor network and default mode network, which might reflect the impaired vision, cognition and motor function in AMD patients. In addition, FCS indicator can be used as an effective biological marker to assist the clinical diagnosis of AMD.

Retinal inner nuclear layer thickness in the diagnosis of cognitive impairment explored using a C57BL/6J mouse model

Major neurocognitive disorder (NCD) affects over 55 million people worldwide and is characterized by cognitive impairment (CI). This study aimed to develop a non-invasive diagnostic test for CI based upon retinal thickness measurements explored in a mouse model. Discrimination indices and retinal layer thickness of healthy C57BL/6J mice were quantified through a novel object recognition test (NORT) and ocular coherence tomography (OCT), respectively. Based on criteria from the Diagnostic and statistical manual of mental disorders 5th ed. (DSM-V), a diagnostic test was generated by transforming data into rolling monthly averages and categorizing mice into those with and without CI and those with a high or low decline in retinal layer thickness. Only inner nuclear layer thickness had a statistically significant relationship with discrimination indices. Furthermore, our diagnostic test was 85.71% sensitive and 100% specific for diagnosing CI, with a positive predictive value of 100%. These findings have potential clinical implications for the early diagnosis of CI in NCD. However, further investigation in comorbid mice and humans is warranted.

Interplay between aging and other factors of the pathogenesis of age-related macular degeneration

Age-related macular degeneration (AMD) is a complex eye disease with the retina as the target tissue and aging as per definition the most serious risk factor. However, the retina contains over 60 kinds of cells that form different structures, including the neuroretina and retinal pigment epithelium (RPE) which can age at different rates. Other established or putative AMD risk factors can differentially affect the neuroretina and RPE and can differently interplay with aging of these structures. The occurrence of β-amyloid plaques and increased levels of cholesterol in AMD retinas suggest that AMD may be a syndrome of accelerated brain aging. Therefore, the question about the real meaning of age in AMD is justified. In this review we present and update information on how aging may interplay with some aspects of AMD pathogenesis, such as oxidative stress, amyloid beta formation, circadian rhythm, metabolic aging and cellular senescence. Also, we show how this interplay can be specific for photoreceptors, microglia cells and RPE cells as well as in Bruch's membrane and the choroid. Therefore, the process of aging may differentially affect different retinal structures. As an accurate quantification of biological aging is important for risk stratification and early intervention for age-related diseases, the determination how photoreceptors, microglial and RPE cells age in AMD may be helpful for a precise diagnosis and treatment of this largely untreatable disease.

Secretory autophagy: a turn key for understanding AMD pathology and developing new therapeutic targets?

INTRODUCTION

Age-related macular degeneration (AMD) is an eye disease leading to vision loss with poorly known pathogenesis and limited therapeutic options. Degradative autophagy (DA) is impaired in AMD, but emerging evidence points to secretary autophagy (SA) as a key element in AMD pathogenesis.

AREAS COVERED

SA may cause the release of proteins and protein aggregates, lipofuscin, beta amyloid, faulty mitochondria, pro-inflammatory and pro-angiogenic factors from the retinal pigment epithelium (RPE) that may contribute to drusen formation and choroidal neovascularization. SA may replace DA, when formation of autolysosome is impaired, and then a harmful cargo, instead of being degraded, is extruded from the RPE contributing to drusen and/or angiogenic environment. Therefore, the interplay between DA and SA may be critical for drusen formation and choroidal neovascularization, so it can be a turn key to understand AMD pathogenesis.

EXPERT OPINION

Although SA fulfills some beneficial functions, it is detrimental for the retina in many cases. Therefore, inhibiting SA may be a therapeutic strategy in AMD, but it is challenged by the development of selective SA inhibitors that would not affect DA. The TRIM16, SEC22B and RAB8A proteins, specific for secretory autophagosome, may be primary candidates as therapeutic targets, but their action is not limited to autophagy and therefore requires further studies.

Increased risk of Parkinson's disease among patients with age-related macular degeneration

BACKGROUND

This study aimed to investigate the risk of Parkinson's disease (PD) among patients with age-related macular degeneration (AMD) and its association with confounding comorbidities.

METHODS

A population-based retrospective cohort study was conducted using Longitudinal Health Insurance Database 2000 (LHID2000). We established AMD and non-AMD cohorts from January 1, 2000 to December 31, 2012 to determine the diagnosis of PD. A total of 20,848 patients were enrolled, with 10,424 AMD patients and 10,424 controls matched for age, sex, and index year at a 1:1 ratio. The follow-up period was from the index date of AMD diagnosis to the diagnosis of PD, death, withdrawal from the insurance program, or end of 2013. Multivariable Cox regression analysis was performed to examine the hazard ratio (HR) and 95% confidence interval (CI) for the risk of PD between the AMD and non-AMD cohorts.

RESULT

After adjusting for potential confounders, there was a higher risk of developing PD in the AMD cohort than in the non-AMD cohort (adjusted HR = 1.35, 95% CI = 1.16-1.58). A significant association could be observed in both female (aHR = 1.42, 95% CI = 1.13-1.80) and male (aHR = 1.28, 95% CI = 1.05-1.57) patients, aged more than 60 years (60-69: aHR = 1.51, 95% CI = 1.09-2.09, 70-79: aHR = 1.30, 95% CI = 1.05-1.60; 80-100: aHR = 1.40, 95% CI = 1.01-1.95), and with more than one comorbidity (aHR = 1.40, 95% CI = 1.20-1.64). A significant association between increased risk of PD and AMD was observed among patients with comorbidities of osteoporosis (aHR = 1.68, 95% CI = 1.22-2.33), diabetes (aHR = 1.41, 95% CI = 1.12-1.78) and hypertension (aHR = 1.36, 95% CI = 1.15-1.62) and medications of statin (aHR = 1.42, 95% CI = 1.19-1.69) and calcium channel blocker (CCB) (aHR = 1.32, 95% CI = 1.11-1.58). The cumulative incidence of PD was significantly higher over the 12-year follow-up period in AMD cohort (log-rank test, p < 0.001).

CONCLUSIONS

Patients with AMD may exhibit a higher risk of PD than those without AMD.

Cerebral white matter connectivity, cognition, and age-related macular degeneration

Age-related macular degeneration (AMD) is a common retina disease associated with cognitive impairment in older adults. The mechanism(s) that account for the link between AMD and cognitive decline remain unclear. Here we aim to shed light on this issue by investigating whether relationships between cognition and white matter in the brain differ by AMD status. In a direct group comparison of brain connectometry maps from diffusion weighted images, AMD patients showed significantly weaker quantitative anisotropy (QA) than healthy controls, predominantly in the splenium and left optic radiation. The QA of these tracts, however, did not correlate with the visual acuity measure, indicating that this group effect is not directly driven by visual loss. The AMD and control groups did not differ significantly in cognitive performance.Across all participants, better cognitive performance (e.g. verbal fluency) is associated with stronger connectivity strength in white matter tracts including the splenium and the left inferior fronto-occipital fasciculus/inferior longitudinal fasciculus. However, there were significant interactions between group and cognitive performance (verbal fluency, memory), suggesting that the relation between QA and cognitive performance was weaker in AMD patients than in controls.This may be explained by unmeasured determinants of performance that are more common or impactful in AMD or by a recruitment bias whereby the AMD group had higher cognitive reserve. In general, our findings suggest that neural degeneration in the brain might occur in parallel to AMD in the eyes, although the participants studied here do not (yet) exhibit overt cognitive declines per standard assessments.

The Relationship Between Cognitive Status and Known Single Nucleotide Polymorphisms in Age-Related Macular Degeneration

Recent literature has reported a higher occurrence of cognitive impairment among individuals with Age-related Macular Degeneration (AMD) compared to older adults with normal vision. This pilot study explored potential links between single nucleotide polymorphisms (SNPs) in AMD and cognitive status. Individuals with AMD (N = 21) and controls (N = 18) were genotyped for the SNPs CFHY402H, ARMS2A69S and FADS1 rs174547. Cognitive status was evaluated using the Montreal Cognitive Assessment. The two groups differed significantly on which subscales were most difficult. The control group had difficulty with delayed recall while those with AMD had difficulty on delayed recall in addition to abstraction and orientation. Homozygous carriers of the FADS1 rs174547 SNP had significantly lower scores than heterozygotes or non-carriers on the MoCA. The results suggest that the FADS1 SNP may play a role in visual impairment/cognitive impairment comorbidity as reflected in the poorer cognitive scores among homozygotes with AMD compared to those carrying only one, or no copies of the SNP.

Relationship between neural functional connectivity and memory performance in age-related macular degeneration

Age-related macular degeneration (AMD) has been linked to memory deficits, with no established neural mechanisms. We collected resting-state brain functional magnetic resonance imaging and standardized verbal recall tests from 42 older adults with AMD and 41 age-matched controls. We used seed-based whole brain analysis to quantify the strength of functional connectivity between hubs of the default mode network and a network of medial temporal regions relevant for memory. Our results indicated neither memory performance nor network connectivity differed by AMD status. However, the AMD participants exhibited stronger relationships than the controls between memory performance and connectivity from the memory network hub (left parahippocampal) to 2 other regions: the left temporal pole and the right superior/middle frontal gyri. Also, the connectivity between the medial prefrontal cortex and posterior cingulate cortex of default mode network correlated more strongly with memory performance in AMD compared to control. We concluded that stronger brain-behavior correlation in AMD may suggest a role for region-specific connectivity in supporting memory in the context of AMD.

Association of Age-Related Macular Degeneration on Alzheimer or Parkinson Disease: A Retrospective Cohort Study

PURPOSE

To determine the association of age-related macular degeneration (AMD) with Alzheimer disease (AD) and Parkinson disease (PD).

DESIGN

Retrospective cohort study.

METHODS

The study population consisted of 308,340 participants aged 50 years or older from the Korean National Health Insurance Service-Health Screening Cohort. After exclusion of participants with AMD during 2002, participants were detected for AMD during 2003-2005. Starting from January 1, 2006, all participants were followed up for AD and PD until December 31, 2013. Multivariate Cox proportional hazards regression was used to calculate the adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for AD and PD risk.

RESULTS

Compared to non-AMD participants, AMD patients had higher risk for AD (aHR 1.48, 95% CI 1.25-1.74) and PD (aHR 1.46, 95% CI 1.14-1.88). The risk-increasing association of AMD with AD (aHR 2.25, 95% CI 1.39-3.66) and PD (aHR 2.02, 95% CI 1.00-4.08) were preserved among participants who were never-smokers, did not consume alcohol, and exercised regularly. Finally, AMD was associated with higher risk of AD (aHR 1.96, 95% CI 1.46-2.65 for age <70 years and aHR 1.53, 95% CI 1.26-1.86 for age ≥70 years) and PD (aHR 1.90, 95% CI 1.29-2.80 for age <70 years and aHR 1.47, 95% CI 1.06-2.04 for age ≥70 years) according to subgroups divided by age.

CONCLUSIONS

Compared to non-AMD participants, AMD patients had higher risk for AD and PD even among those with healthy lifestyle behaviors. Patients with AMD must be closely monitored for possible subsequent development of AD or PD.

New therapeutic targets in the treatment of age-related macular degeneration

Age-related macular degeneration and especially neovascular age-related macular degeneration is the leading cause of low vision in developed countries. Even though the introduction of anti-VEGF drugs in recent years completely changed the management of this condition, its cost, the need for repeated intravitreal injections, and loss of efficacy in the long term are still issues to deal with. Currently, a new generation of novel therapies under development is attempting to address some of these limitations. Some of the most prominent among them are new anti-VEGFs such as brolucizumab or abicipar, drugs against angiopoietin-2 receptor such as faricimab, sustained-release systems, or tyrosine kinase inhibitors. As regards dry age-related macular degeneration, neuroprotection, the complement pathway, and stem cell therapy are the most promising targets currently under investigation.

Ocular amyloid imaging at the crossroad of Alzheimer's disease and age-related macular degeneration: implications for diagnosis and therapy

Alzheimer's disease (AD) and age-related macular degeneration (AMD) are important disorders of aging, but significant challenges remain in diagnosis and therapy. Amyloid-beta (Aβ), found in the brain and a defining feature of AD, has also been observed in the retina in both AD and AMD. While current diagnostic modalities for detecting Aβ in the brain are costly or invasive, Aβ in the retina can be noninvasively and conveniently imaged using modern photonic imaging systems such as optical coherence tomography (OCT). Moreover, since many of these retinal changes occur before degenerative changes can be detected in the brain, ocular amyloid biomarkers could be utilized to detect AD as well as AMD in their earliest stages when therapy may be most effective in halting disease progression. Novel technologies to quantify retinal biomarkers have the potential to facilitate early diagnosis and noninvasive monitoring of disease progression with important therapeutic implications.

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

INTRODUCTION

Identifying ophthalmic diseases associated with increased risk of Alzheimer's disease (AD) may enable better screening and understanding of those at risk of AD.

METHODS

Diagnoses of glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy (DR) were based on International Classification of Diseases, 9th revision, codes for 3877 participants from the Adult Changes in Thought study. The adjusted hazard ratio for developing probable or possible AD for recent (within 5 years) and established (>5 years) diagnoses were assessed.

RESULTS

Over 31,142 person-years of follow-up, 792 AD cases occurred. The recent and established hazard ratio were 1.46 (P = .01) and 0.87 (P = .19) for glaucoma, 1.20 (P = .12) and 1.50 (P < .001) for AMD, and 1.50 (P = .045) and 1.50 (P = .03) for DR.

DISCUSSION

Increased AD risk was found for recent glaucoma diagnoses, established AMD diagnoses, and both recent and established DR. People with certain ophthalmic conditions may have increased AD risk.

Dementia and Traffic Accidents: A Danish Register-Based Cohort Study

Background

As a consequence of a rapid growth of an ageing population, more people with dementia are expected on the roads. Little is known about whether these people are at increased risk of road traffic-related accidents.

Objective

Our study aims to investigate the risk of road traffic-related accidents for people aged 65 years or older with a diagnosis of dementia in Denmark.

Methods

We will conduct a nationwide population-based cohort study consisting of Danish people aged 65 or older living in Denmark as of January 1, 2008. The cohort is followed for 7 years (2008-2014). Individual’s personal data are available in Danish registers and can be linked using a unique personal identification number. A person is identified with dementia if the person meets at least one of the following criteria: (1) a diagnosis of the disease in the Danish National Patient Register or in the Danish Psychiatric Central Research Register, and/or (2) at least one dementia diagnosis-related drug prescription registration in the Danish National Prescription Registry. Police-, hospital-, and emergency room-reported road traffic-related accidents occurred within the study follow-up are defined as the study outcome. Cox proportional hazard regression models are used for the main analysis.

Results

Our study protocol has 3 phases including data collection, data analysis, and reporting. The first phase of register-based data collection of 853,228 individual’s personal information was completed in August, 2016. The next phase is data analysis, which is expected to be finished before December 2016, and thereafter writing publications based on the findings. The study started in January 2016 and will end in December 2018.

Discussion

This study covers the entire elderly population of Denmark, and thereby will avoid selection bias due to nonparticipation and loss to follow-up. Furthermore, this ensures that the study results are reliable and generalizable. However, underreporting of traffic-related accidents may occur, which will limit estimation of absolute risks.

Perspective: A Critical Look at the Ancillary Age-Related Eye Disease Study 2: Nutrition and Cognitive Function Results in Older Individuals with Age-Related Macular Degeneration

A large body of literature suggests that the dietary carotenoids lutein and zeaxanthin and long-chain polyunsaturated fatty acids such as docosahexaenoic acid are related to improved cognitive function across the life span. A recent report by the Age-Related Eye Disease Study (AREDS) group appears to contradict the general findings of others in the field. In this review, we look critically at the methods, study designs, and analysis techniques used in the larger body of literature and compare them with the recent AREDS reports.

Lower cognitive function in patients with age-related macular degeneration: a meta-analysis

Objective

To investigate the cognitive impairment in patients with age-related macular degeneration (AMD).

Methods

Relevant articles were identified through a search of the following electronic databases through October 2015, without language restriction: 1) PubMed; 2) the Cochrane Library; 3) EMBASE; 4) ScienceDirect. Meta-analysis was conducted using STATA 12.0 software. Standardized mean differences with corresponding 95% confidence intervals were calculated. All of the included studies met the following four criteria: 1) the study design was a case–control or randomized controlled trial (RCT) study; 2) the study investigated cognitive function in the patient with AMD; 3) the diagnoses of AMD must be provided; 4) there were sufficient scores data to extract for evaluating cognitive function between cases and controls. The Newcastle–Ottawa Scale criteria were used to assess the methodological quality of the studies.

Results

Of the initial 278 literatures, only six case–control and one RCT studies met all of the inclusion criteria. A total of 794 AMD patients and 1,227 controls were included in this study. Five studies were performed with mini-mental state examination (MMSE), two studies with animal fluency, two studies with trail making test (TMT)-A and -B, one study with Mini-Cog. Results of the meta-analysis revealed lower cognitive function test scores in patients with AMD, especially with MMSE and Mini-Cog test (P≤0.001 for all). The results also showed that differences in the TMT-A (except AMD [total] vs controls) and TMT-B test had no statistical significance (P>0.01). The Newcastle–Ottawa Scale score was ≥5 for all of the included studies. Based on the sensitivity analysis, no single study influenced the overall pooled estimates.

Conclusion

This meta-analysis suggests lower cognitive function test scores in patients with AMD, especially with MMSE and Mini-Cog test. The other cognitive impairment screening tests, such as animal fluency test and TMT, need more studies to assess.