The risk of dementia in multiple sclerosis and neuromyelitis optica spectrum disorder

Dementia in People With Multiple Sclerosis: A Systematic Review and Meta-Analysis

INTRODUCTION

Multiple sclerosis (MS), as an autoimmune demyelinating disorder, is associated with cognitive dysfunction. Dementia can result from severe cognitive dysfunction or other pathways in MS, but the exact mechanisms and prevalence are unknown.

OBJECTIVE

This review aimed to determine the pooled prevalence and risk of dementia in people with MS (PwMS).

DESIGN

This meta-analysis was performed in accordance with the guidelines established by the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA).

METHODS

Embase, PubMed, Web of Science, and Scopus were comprehensively searched up to August 29, 2024, to identify observational studies that examined the prevalence or hazard ratio (HR) of dementia among PwMS. This meta-analysis used a random-effects model to calculate the pooled prevalence and risk of dementia among PwMS, where the prevalence rate and HR were the main metrics for effect size.

RESULTS

Ten studies, including a total of 37,831 PwMS, estimated the prevalence of dementia in PwMS to be 5.31% (I2 = 99.2%, 95% CI: 2.25%-11.98%). In addition, a meta-analysis of four studies assessed the HR of dementia among PwMS, revealing a pooled HR of 1.67 (p < 0.01, I2 = 73.5%, 95% CI: 1.31-2.13).

CONCLUSION

While dementia is not a common feature of MS, PwMS still have a significantly higher risk of developing it, compared to healthy indiviuals. However, the considerable variability across studies indicates that these estimates should be interpreted with caution, as inconsistencies in research approaches may have influenced the results. These findings warrant further validation.

Risk of Autoimmune Rheumatic Diseases in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder: A Nationwide Cohort Study in South Korea

OBJECTIVE

To investigate the risk of autoimmune rheumatic diseases (ARDs) in multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) compared with a control population using the Korean National Health Insurance Service database.

PATIENTS AND METHODS

The MS/NMOSD cohorts were collected from patients registered in the Korean National Health Insurance Service database between January 1, 2010, and December 31, 2017, using the International Classification of Diseases, Tenth Revision diagnosis codes and information in the Rare Intractable Disease management program. The incidence rate and risk of ARDs that occurred after a 1-year lag period was calculated and compared with that of control cohorts matched for age, sex, hypertension, diabetes mellitus, and dyslipidemia in a 1:10 ratio.

RESULTS

The incidence rates of ARDs in MS and NMOSD were 3.56 and 9.13 per 1000 person-years, respectively. The hazard ratios (HRs) of ARDs in MS and NMOSD were 5.35 (95% CI, 3.50 to 8.19) and 9.13 (95% CI, 5.83 to 14.28), respectively. The risk of Behçet disease (HR, 17.24; 95% CI, 4.12 to 72.14), systemic lupus erythematosus (HR, 12.25; 95% CI, 4.12 to 36.44), Sjögren syndrome (HR, 6.16; 95% CI, 1.80 to 21.04), and seropositive rheumatoid arthritis (HR, 3.32; 95% CI, 1.78 to 6.19) was increased in MS. In NMOSD, the risk of Sjögren syndrome (HR, 82.63; 95% CI, 19.00 to 359.38), systemic lupus erythematosus (HR, 30.85; 95% CI, 6.23 to 152.80), Behçet disease (HR, 15.36; 95% CI, 2.57 to 91.93), and seropositive rheumatoid arthritis (HR, 3.86; 95% CI, 1.80 to 8.31) was increased.

CONCLUSION

The risk of ARDs was increased in MS/NMOSD, and the risk of each ARD differed between MS and NMOSD.

Prevalence and Odds of Cognitive Impairment in Multiple Sclerosis Subtypes and Neuromyelitis Optica Spectrum Disorder: A Case-Control Study

Background

Autoimmune demyelinating disorders, such as multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD), are caused by persistent inflammation and damage to the central nervous system. Cognitive impairment (CI) is a growing challenge in these diseases, underscoring the need for a thorough exploration of its prevalence and risk across various subtypes. This study aimed to assess the prevalence and odds of CI using the Symbol Digit Modalities Test (SDMT) in various MS subtypes and NMOSD.

Materials and Methods

A case-control study involving 616 participants, including healthy controls (HC) and individuals with different MS subtypes (Relapsing Remitting MS (RRMS), Secondary Progressive MS (SPMS), Primary Progressive MS (PPMS)), clinically isolated syndrome (CIS), and NMOSD, was conducted. CI was defined as SDMT z-scores 1.5 standard deviations below the HC average. The chi-square test was used to assess the risk of CI.

Results

The prevalence of CI varied across different groups: HC (10.7%), RRMS (33.8%), SPMS (71.3%), PPMS (62.8%), CIS (19.2%), and NMOSD (32.8%). Odds ratios (OR) for CI were significantly increased in RRMS (OR: 4.23, confidence interval (CI): 2.18-8.22, P < 0.001), SPMS (OR: 20.58, CI: 10.36-40.88, P < 0.001), PPMS (OR: 14.02, CI: 5.80-33.86, P < 0.001), and NMOSD (OR: 4.04, CI: 2.07-7.87, P < 0.001) compared to HC.

Conclusion

This study emphasizes a significantly increased risk of CI in MS subtypes and NMOSD compared to HC. Although no significant difference in CI risk was found between individuals with RRMS and NMOSD, those with progressive forms of MS exhibited notably higher risks of CI.

Association between Age-Related Macular Degeneration with Visual Disability and Risk of Dementia: A Nationwide Cohort Study

OBJECTIVES

To investigate the prospective association between the risk of dementia and age-related macular degeneration (AMD) in patients with related visual disability (VD).

DESIGN

A nationwide population-based cohort study used authorized data provided by the Korean National Health Insurance Service.

SETTING AND PARTICIPANTS

A total of 1,788,457 individuals aged >50 years who participated in the Korean National Health Screening Program were enrolled.

METHODS

From January 2009 to December 2019, participants were tracked for a diagnosis of dementia using registered diagnostic codes from claims data. Participants with VD were defined as those registered in a national disability registration established by the Korean government. The prospective association of AMD and related VD with new-onset dementia was investigated using a multivariate-adjusted Cox proportional hazard model adjusted for age, sex, body mass index, income level, systemic comorbidities, psychiatric diseases, and behavioral factors.

RESULTS

During the average follow-up period of 9.7 ± 2.16 years, 4260 of 21,384 participants in the AMD cohort and 137,166 of 1,662,319 participants in the control cohort were newly diagnosed with dementia, respectively. Participants diagnosed with AMD showed a higher risk of new-onset dementia than those in the control group in the fully adjusted model [hazard ratio (HR) 1.11, 95% CI 1.07-1.14]. The risk of dementia was higher in participants diagnosed with AMD and associated VD (HR 1.28, 95% CI 1.15-1.43) compared to those without VD (HR 1.09, 95% CI 1.06-1.13).

CONCLUSIONS AND IMPLICATIONS

A diagnosis of AMD was associated with an increased risk of all-cause dementia and its major subtypes. Close monitoring of cognitive function in patients with AMD, especially those with VD, may help in early detection of all-cause dementia, which could reduce the socioeconomic burden and improve the quality of life of patients.

Alzheimer's disease (AD) in multiple sclerosis (MS): A systematic review of published cases, mechanistic links between AD and MS, and possible clinical evaluation of AD in MS

Background: Alzheimer's disease (AD) and multiple sclerosis (MS) are two neurological disorders that can pose enormous burden to a person's quality of life. Due to new therapeutic advancements that significantly extend the lifespan, there may be an increased prevalence of AD in elderly MS patients. Objective: Building on a previous review on MS-AD coexistence, this review not only aimed to broaden the pool of literature searched, but also investigated possible mechanistic links between clinical markers for MS and AD. Methods: We searched for newly reported cases of coexisting MS and AD in PubMed, Clinical Key, BioMed Central, and Europe PubMed Central databases; and identified 101 new cases in addition to the previously reported 24 cases by Luczynski et al. (2019). The resulting 125 comorbid cases necessitated an evaluation of literature on the pathogenesis of MS and AD. Results: This review highlights many overlaps between AD and MS (for instance, the immune cell dysfunction, glymphatic dysfunction, genetics, environmental factors, and others). We critically evaluated clinical and laboratory metrics used to identify AD in MS patients (e.g., MRI, amyloid-β and tau protein identification, miRNA biomarker evaluation, cerebrospinal fluid analysis, vitamin levels, gut microbiota etc.). Conclusions: Future research should refine these diagnostic criteria and focus on enhancing screening and detection methods for AD in MS patients. Furthermore, one should also investigate the primary causes of the increased comorbidity between AD and MS.

Neuropsychological Manifestations of Multiple Sclerosis

This review article summarizes the literature on the cognitive impairment seen amongst people with multiple sclerosis (MS) and how that impairment can impact not only their lives but also how their care needs to be managed. Recommendations regarding screening and monitoring of cognitive issues are reviewed, as well as how common comorbidities can further impact cognition. The current literature with respect to treatment options is also summarized. Finally, the article reviews the literature on some special populations living with MS.

Comparing Cognitive Profiles in Older Adults With Multiple Sclerosis and Alzheimer Disease: More Similarities Than Differences

Background and Objectives

Up to 65% of people with multiple sclerosis (MS) experience disease-related cognitive impairment, but even after decades of research, still very little is known about the cognitive issues among older adults with MS (EwMS; individuals aged 60+). To date, few studies have attempted to characterize cognitive impairment in this group or compare EwMS with those with other neurodegenerative diseases. Our goal was to address this knowledge gap by comparing EwMS with individuals experiencing cognitive impairment due to probable Alzheimer disease (AD) with biomarker confirmation.

Methods

We conducted an observational study of individuals seen for routine clinical care at the Cleveland Clinic. After excluding for potential confounding factors, 6 groups were assembled based on the results of their clinical workup and neuropsychological examination: cognitively normal, cognitively normal with MS, mild neurocognitive disorder (due to MS or AD), and major neurocognitive disorder (due to MS or AD). These groups were compared in terms of cognitive test performance, percentage of the group impaired on specific cognitive skills, and rates of cognitive impairment.

Results

The sample comprised 140 individuals (64 EwMS and 76 demographically matched individuals from a memory clinic). Among those with mild neurocognitive disorder, differences between MS and AD were marked. However, in those with major neurocognitive disorder, these differences largely disappeared, except persistent performance differences on a measure of rote verbal memory. EwMS outperformed those with AD on memory tests at each level of cognitive impairment. EwMS also exhibited both subcortical and cortical deficits, rather than solely subcortical deficits.

Discussion

The overall characterization of the cognitive profile of MS may be different than once described, involving both classically cortical and subcortical functions. Clinically, our results suggest that distinguishing between the cognitive effects of MS and AD at more severe levels of cognitive impairment may be less reliable than once thought. Future work to replicate these findings in other samples and deepen the understanding of cognition in older individuals with MS is needed.

The Inflammation-Induced Dysregulation of Reelin Homeostasis Hypothesis of Alzheimer's Disease

Alzheimer's disease (AD) accounts for most dementia cases, but we lack a complete understanding of the mechanisms responsible for the core pathology associated with the disease (e.g., amyloid plaque and neurofibrillary tangles). Inflammation has been identified as a key contributor of AD pathology, with recent evidence pointing towards Reelin dysregulation as being associated with inflammation. Here we describe Reelin signaling and outline existing research involving Reelin signaling in AD and inflammation. Research is described pertaining to the inflammatory and immunological functions of Reelin before we propose a mechanism through which inflammation renders Reelin susceptible to dysregulation resulting in the induction and exacerbation of AD pathology. Based on this hypothesis, it is predicted that disorders of both inflammation (including peripheral inflammation and neuroinflammation) and Reelin dysregulation (including disorders associated with upregulated Reelin expression and disorders of Reelin downregulation) have elevated risk of developing AD. We conclude with a description of AD risk in various disorders involving Reelin dysregulation and inflammation.