Frequency of coexistent eye diseases and cognitive impairment or dementia: a systematic review and meta-analysis

Hallmarks of aging in age-related macular degeneration and age-related neurological disorders: novel insights into common mechanisms and clinical relevance

Age-related macular degeneration (AMD) and age-related neurological diseases (ANDs), such as Alzheimer's and Parkinson's Diseases, are increasingly prevalent conditions that significantly contribute to global morbidity, disability, and mortality. The retina, as an accessible part of the central nervous system (CNS), provides a unique window to study brain aging and neurodegeneration. By examining the associations between AMD and ANDs, this review aims to highlight novel insights into fundamental mechanisms of aging and their role in neurodegenerative disease progression. This review integrates knowledge from the emerging field of aging research, which identifies common denominators of biological aging, specifically loss of proteostasis, impaired macroautophagy, mitochondrial dysfunction, and inflammation. Finally, we emphasize the clinical relevance of these pathways and the potential for cross-disease therapies that target common aging hallmarks. Identifying these shared pathways could open avenues to develop therapeutic strategies targeting mechanisms common to multiple degenerative diseases, potentially attenuating disease progression and promoting the healthspan.

Associations between vision impairment and eye diseases with dementia, dementia subtypes and cognitive impairment: An umbrella review

Vision impairment (VI) and eye diseases such as age-related macular degeneration (AMD), diabetic retinopathy (DR), glaucoma and cataract have been reported to be associated with cognitive impairment and dementia, however, to date, very little attempt has been made to collate and synthesizes such literature. Therefore, the aim of this umbrella review is to systematically assesses the credibility and certainty of evidence of associations between vision impairment (VI) and eye diseases with cognitive impairment, dementia and dementia subtypes. We conducted an umbrella review of meta-analyses by screening articles in any language in PubMed, MEDLINE (Ovid), EMBASE, Web of Science, Cochrane CENTRAL and CDSR published from database inception up to May 30, 2024. Quality appraisal of each included original meta-analysis was assessed using A Measurement Tool for Assessing Systematic Reviews 2 (AMSTAR2). The certainty of the evidence was based on statistical significance, study size, heterogeneity, small study effects, prediction intervals (PI), and bias. We followed an a-priori protocol registered with PROSPERO (CRD42024564249). We identified 13 meta-analyses (AMSTAR 2; high accuracy of the findings 1, moderate 10, and low 2) that included 232 original articles based on 99,337,354 participants. Overall, no evidence was highly suggestive or convincing. Suggestive evidence was found for associations between cataract and dementia (equivalent odds ratio [eOR] 1.20, 95 %CI, 1.16-1.25), cataract and Alzheimer's disease (eOR 1.21, 95 %CI, 1.15-1.28), and AMD and Alzheimer's disease (eOR 1.27, 95 %CI, 1.27-1.27). Weak evidence was found for associations between VI and dementia (eOR 1.50, 95 %CI, 1.23-1.84), DR and dementia (eOR 1.33, 95 %CI, 1.17-1.50), cataract and vascular dementia (eOR 1.26, 95 %CI, 1.09-1.45), VI identified by cross-sectional studies and cognitive impairment (eOR 2.37, 95 %CI, 2.31-2.44), and VI identified by objective measures and cognitive impairment (eOR 1.56, 95 %CI, 1.12-2.18). The observed suggestive level of evidence for the relationship between eye disease and dementia (as well as dementia subtypes) suggests that policy and interventions to aid in the prevention and management of eye disease may also aid in the prevention of dementia syndrome. Where the level of evidence is weak, further studies are needed with stronger methodological approaches.

Association Analysis between Cognitive Function Score and Inner Macular Thickness/Visual Field Sensitivity in Glaucoma Patients

(1) Background: Previous research has investigated the relationship between cognitive impairment, optical coherence tomography (OCT), visual fields (VF), and VF reliability in smaller patient samples using various cognitive assessment tools. This study analyzed the relationship between cognitive function scores using the Mini-Cog test and inner macular thickness (IMT) and VF sensitivity in glaucoma patients. (2) Methods: A retrospective analysis was conducted on 984 patients with 1897 eyes. Assessments included age, sex, intraocular pressure (IOP), and Mini-Cog test scores. Abnormal Mini-Cog scores were observed in 89 patients (9%). Using a mixed-effects model adjusted for background factors, the association between Mini-Cog scores and IMT, parafoveal (PF)-IMT, mean deviation (MD), pattern standard deviation, fixation losses (FL), false negatives (FN), and false positives (FP) was analyzed. (3) Results: Abnormal Mini-Cog scores (≤2) were associated with thinning of the IMT and PF-IMT, worse MDs, and higher FN and FP rates but not with PSD or FL. (4) Conclusions: Glaucoma patients with low cognitive function scores exhibited more advanced glaucoma-related changes in VF testing and morphological tests. Further longitudinal studies are needed to explore the relationship between glaucoma and cognitive impairment.

Rationale and design of the BeyeOMARKER study: prospective evaluation of blood- and eye-based biomarkers for early detection of Alzheimer's disease pathology in the eye clinic

BACKGROUND

Alzheimer's disease (AD) is a common, complex and multifactorial disease that may require screening across multiple routes of referral to enable early detection and subsequent future implementation of tailored interventions. Blood- and eye-based biomarkers show promise as low-cost, scalable and patient-friendly tools for early AD detection given their ability to provide information on AD pathophysiological changes and manifestations in the retina, respectively. Eye clinics provide an intriguing real-world proof-of-concept setting to evaluate the performance of these potential AD screening tools given the intricate connections between the eye and brain, presumed enrichment for AD pathology in the aging population with eye disorders, and the potential for an accelerated diagnostic pathway for under-recognized patient groups.

METHODS

The BeyeOMARKER study is a prospective, observational, longitudinal cohort study aiming to include individuals visiting an eye-clinic. Inclusion criteria entail being ≥ 50 years old and having no prior dementia diagnosis. Excluded eye-conditions include traumatic insults, superficial inflammation, and conditions in surrounding structures of the eye that are not engaged in vision. The BeyeOMARKER cohort (n = 700) will undergo blood collection to assess plasma p-tau217 levels and a brief cognitive screening at the eye clinic. All participants will subsequently be invited for annual longitudinal follow-up including remotely administered cognitive screening and questionnaires. The BeyeOMARKER + cohort (n = 150), consisting of 100 plasma p-tau217 positive participants and 50 matched negative controls selected from the BeyeOMARKER cohort, will additionally undergo Aβ-PET and tau-PET, MRI, retinal imaging including hyperspectral imaging (primary), widefield imaging, optical coherence tomography (OCT) and OCT-Angiography (secondary), and cognitive and cortical vision assessments.

RESULTS

We aim to implement the current protocol between April 2024 until March 2027. Primary outcomes include the performance of plasma p-tau217 and hyperspectral retinal imaging to detect AD pathology (using Aβ- and tau-PET visual read as reference standard) and to detect cognitive decline. Initial follow-up is ~ 2 years but may be extended with additional funding.

CONCLUSIONS

We envision that the BeyeOMARKER study will demonstrate the feasibility of early AD detection based on blood- and eye-based biomarkers in alternative screening settings, and will improve our understanding of the eye-brain connection.

TRIAL REGISTRATION

The BeyeOMARKER study (Eudamed CIV ID: CIV-NL-23-09-044086; registration date: 19th of March 2024) is approved by the ethical review board of the Amsterdam UMC.

Risk of glaucoma to subsequent dementia or cognitive impairment: a systematic review and meta-analysis

BACKGROUND

Substantial evidence supports that glaucoma and dementia share pathological mechanisms and pathogenic risk factors. However, the association between glaucoma, cognitive decline and dementia has yet to be elucidated.

OBJECTIVE

This study was aimed to assess whether glaucoma increase the risk of dementia or cognitive impairment.

METHODS

PubMed, Cochrane Library, Web of Science, and EMBASE databases for cohort or case-control studies were searched from inception to March 10, 2024. The Newcastle-Ottawa Quality Assessment Scale (NOS) was used to the risk of bias. Heterogeneity was rigorously evaluated using the I2 test, while publication bias was assessed by visual inspection of the funnel plot and by Egger' s regression asymmetry test. Subgroup analyses were applied to determine the sources of heterogeneity.

RESULTS

Twenty-seven studies covering 9,061,675 individuals were included. Pooled analyses indicated that glaucoma increased the risk of all-cause dementia, Alzheimer's disease, vascular dementia, and cognitive impairment. Subgroup analysis showed that the prevalence of dementia was 2.90 (95% CI: 1.45-5.77) in age ≥ 65 years and 2.07 (95% CI: 1.18-3.62) in age<65 years; the incidence rates in female glaucoma patients was 1.46 (95% CI: 1.06-2.00), respectively, which was no statistical significance in male patients. Among glaucoma types, POAG was more likely to develop dementia and cognitive impairment. There were also differences in regional distribution, with the highest prevalence in the Asia region, while glaucoma was not associated with dementia in Europe and North America regions.

CONCLUSION

Glaucoma increased the risk of subsequent cognitive impairment and dementia. The type of glaucoma, gender, age, and region composition of the study population may significantly affect the relationship between glaucoma and dementia.

Contrast Sensitivity, Visual Field, Color Vision, Motion Perception, and Cognitive Impairment: A Systematic Review

OBJECTIVES

To examine relationships between visual function (ie, contrast sensitivity, visual field, color vision, and motion perception) and cognitive impairment, including any definition of "cognitive impairment," mild cognitive impairment, or dementia.

DESIGN

Systematic review and meta-analyses.

SETTING AND PARTICIPANTS

Any settings; participants with (cases) or without (controls) cognitive impairment.

METHODS

We searched 4 databases (to January 2024) and included published studies that compared visual function between cases and controls. Standardized mean differences (SMD) with 95% CIs were calculated where data were available. Data were sufficient for meta-analyses when cases were people with dementia. The Joanna Briggs Institute checklists were used for quality assessment.

RESULTS

Fifty-one studies/69 reports were included. Cross-sectional evidence shows that people with dementia had worse contrast sensitivity function and color vision than controls: measured by contrast sensitivity (log units) on letter charts, SMD -1.22 (95% CI -1.98, -0.47), or at varied spatial frequencies, -0.92 (-1.28, -0.57); and by pseudoisochromatic plates, -1.04 (-1.59, -0.49); color arrangement, -1.30 (-2.31, -0.29); or matching tests, -0.51 (-0.78, -0.24). They also performed more poorly on tests of motion perception, -1.20 (-1.73, -0.67), and visual field: mean deviation, -0.87 (-1.29, -0.46), and pattern standard deviation, -0.69 (-1.24, -0.15). Results were similar when cases were limited to participants with clinically diagnosed Alzheimer disease. Sources of bias included lack of clarity on study populations or settings and definitions of cognitive impairment. The 2 included longitudinal studies with follow-ups of approximately 10 years were of good quality but reported inconsistent results.

CONCLUSIONS AND IMPLICATIONS

In the lack of longitudinal data, cross-sectional studies indicate that individuals with cognitive impairment have poorer visual function than those with normal cognition. Additional longitudinal data are needed to understand whether poor visual function precedes cognitive impairment and the most relevant aspects of visual function, dementia pathologies, and domains of cognition.

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.

Artificial intelligence in the diagnosis of glaucoma and neurodegenerative diseases

Artificial Intelligence is a rapidly expanding field within computer science that encompasses the emulation of human intelligence by machines. Machine learning and deep learning - two primary data-driven pattern analysis approaches under the umbrella of artificial intelligence - has created considerable interest in the last few decades. The evolution of technology has resulted in a substantial amount of artificial intelligence research on ophthalmic and neurodegenerative disease diagnosis using retinal images. Various artificial intelligence-based techniques have been used for diagnostic purposes, including traditional machine learning, deep learning, and their combinations. Presented here is a review of the literature covering the last 10 years on this topic, discussing the use of artificial intelligence in analysing data from different modalities and their combinations for the diagnosis of glaucoma and neurodegenerative diseases. The performance of published artificial intelligence methods varies due to several factors, yet the results suggest that such methods can potentially facilitate clinical diagnosis. Generally, the accuracy of artificial intelligence-assisted diagnosis ranges from 67-98%, and the area under the sensitivity-specificity curve (AUC) ranges from 0.71-0.98, which outperforms typical human performance of 71.5% accuracy and 0.86 area under the curve. This indicates that artificial intelligence-based tools can provide clinicians with useful information that would assist in providing improved diagnosis. The review suggests that there is room for improvement of existing artificial intelligence-based models using retinal imaging modalities before they are incorporated into clinical practice.

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.

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.