Cognitive function, drusen, and age-related macular degeneration: a cross-sectional study

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.

Co-Prevalence of Alzheimer's Disease and Age-Related Macular Degeneration Established by Histopathologic Diagnosis

BACKGROUND

Previous epidemiologic studies have suggested an association between AMD and AD, and several therapeutic agents are being developed based on this principle. However, prior studies have provided conflicting results due in part to their reliance on clinical diagnoses that are not based on gold-standard histopathology.

OBJECTIVE

To use histopathologic standards for diagnosis in order to determine the co-prevalence of AD among patients with and without AMD.

METHODS

This is a cross-sectional study of 157 autopsy ocular specimens from patients with and without AMD that were greater than 75 years of age at death. Sarks staging was used to document the severity of AMD, and Braak and Braak staging was used to assess the severity of AD in corresponding brain specimens. The prevalence of AD within different severities of AMD was determined using univariable and multivariable logistic regression.

RESULTS

58% of autopsy eyes had AMD. The prevalence of AD was lower in AMD subjects (63%) compared to non-AMD subjects (73%), even when grouped by severity (all p > 0.15). The likelihood of AD was significantly less in AMD subjects, even after adjusting for age and sex in multivariable analysis (OR 0.47, p = 0.049).

CONCLUSION

Histopathologic diagnoses fail to support an increase in prevalence of AD among subjects with AMD, even when disease severity is considered.

Aging With Vision Loss: A Framework for Assessing the Impact of Visual Impairment on Older Adults

There is limited research examining the impact of visual impairment (VI) on older adults while considering the complexities of aging, leaving gaps in our understanding of how health consequences of VI might be averted. We created a framework integrating concepts from disability, geriatrics, and ophthalmology that conceptualizes how VI challenges successful aging. Here, VI influences multiple functional domains, and increases the risk of negative health outcomes. This model acknowledges that common causes, such as risk factors that affect eyes and other systems simultaneously, may also drive the relationship between VI and health outcomes. Finally, the model highlights how the impact of VI on aging outcomes can be addressed at multiple intervention points.

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.

Age-related macular degeneration and mortality: the Melbourne Collaborative Cohort Study

AimsTo assess associations between features of age-related macular degeneration (AMD) and mortality.MethodsA total of 21 129 participants from the Melbourne Collaborative Cohort Study aged 47-85 years (60% female) were assessed for AMD (2003-2007). Mortality data to December 31, 2012 were obtained through linkage with the National Death Index. Associations were assessed using Cox regression, adjusting for age, sex, smoking, region of birth, education, physical activity, diet and alcohol.ResultsLate AMD was identified in 122 (0.6%) participants, including those with choroidal neovascularisation (n=55, 0.3%), geographic atrophy (n=87, 0.4%) and reticular pseudodrusen (n=87, 0.4%). After a median follow-up period of 8.1 years, 1669 (8%) participants had died, including those from cardiovascular diseases (386), tobacco-related cancers (179), and neurodegenerative disease (157). There was evidence of an increased rate of all-cause mortality for those with choroidal neovascularisation (Hazard Ratio (HR) 1.71 95% CI 1.06-2.76) and geographic atrophy (HR 1.46 95% CI 0.99-2.16). Choroidal neovascularisation was also associated with an increased rate of cardiovascular mortality (HR 3.16 95% CI 1.62-6.15) and geographic atrophy was associated with an increased rate of death from tobacco-related cancer (HR 2.86 95% CI 1.15-7.09). Weak evidence was also present for an association between choroidal neovascularisation and death from neurodegenerative disease (HR 2.49 95% CI 0.79-7.85). Neither reticular pseudodrusen nor the earlier stages of AMD were associated with mortality.ConclusionsLate AMD is associated with an increased rate of all-cause mortality. Choroidal neovascularisation and geographic atrophy were associated with death from cardiovascular disease and tobacco-related cancer, respectively.

Screening for Cognitive Dysfunction Helped to Unmask Silent Cerebrovascular Disease in a Hypertensive Diabetic Patient — Case Report

The current guidelines for the diagnosis and treatment of hypertension recommend screening for cognitive impairment in all hypertensive patients as part of the clinical assessment. However, the implementation of this recommendation in clinical practice is still unsatisfactory. We present the case of an elderly hypertensive female patient in order to highlight the importance of screening for cognitive impairment. A patient with a history of poorly controlled hypertension for the last 12 years and recently diagnosed with type 2 diabetes mellitus is admitted complaining of asthenia, dizziness, visual acuity impairment, and difficulty to remember recent information. Cardiovascular imaging showed 70% internal carotid artery stenosis in a neurologically asymptomatic patient. Cognitive testing showed mild cognitive impairment. Retinal imaging identified stage III hypertensive retinopathy accompanied by irreversible end-organ damage due to microvascular changes. At this point brain MRI was performed, which identified both macro- and microvascular brain lesions in the periventricular white matter and sequelae of a former ischemic stroke in the territory of the left posterior cerebral artery. Cognitive testing helped to unmask silent cerebrovascular disease in an otherwise oligosymptomatic hypertensive diabetic patient. Cognitive function testing should be introduced in routine clinical practice in order to help unmask silent cerebrovascular disease.

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.

Association between neovascular age-related macular degeneration and dementia: a population-based case-control study in Taiwan

Background

Most available studies focusing on the association between neovascular age-related macular degeneration (AMD) and dementia have conflicting results. This study aimed to investigate the association between previously diagnosed AMD and dementia using a population-based dataset in Taiwan.

Methods

Data for this case-control study were retrospectively collected from the Taiwan National Health Insurance Research Database. We identified 13,402 subjects who had a diagnosis of dementia as cases, and 40,206 subjects without dementia as controls. A conditional logistic regression was used to examine the association of dementia with previously diagnosed neovascular AMD.

Results

We found that of the study sample of 53,608 subjects, 1.01% had previously diagnosed neovascular AMD, 1.35% and 0.90% for cases and the controls, respectively (p<0.001). The conditional logistic regression analysis suggested that the odds ratio of prior neovascular AMD for cases was 1.37 (95% confidence interval: 1.14~1.65) compared to the controls after adjusting for subjects’ age, monthly income, geographic location, urbanization level, and hyperlipidemia, diabetes, hypertension, stroke, ischemic heart disease, and whether or not a subjects underwent cataract surgery prior to index date than controls.

Conclusions

Dementia subjects were associated with a higher proportion of prior neovascular AMD than were the controls.