Age-dependent variation of female preponderance across different phenotypes of multiple sclerosis: A retrospective cross-sectional study

Laboratory Diagnosis of Intrathecal Synthesis of Immunoglobulins: A Review about the Contribution of OCBs and K-index

The diagnosis of MS relies on a combination of imaging, clinical examinations, and biological analyses, including blood and cerebrospinal fluid (CSF) assessments. G-Oligoclonal bands (OCBs) are considered a "gold standard" for MS diagnosis due to their high sensitivity and specificity. Recent advancements have involved the introduced of kappa free light chain (k-FLC) assay into cerebrospinal fluid (CSF) and serum (S), along with the albumin quotient, leading to the development of a novel biomarker known as the "K-index" or "k-FLC index". The use of the K-index has been recommended to decrease costs, increase laboratory efficiency, and to skip potential subjective operator-dependent risk that could happen during the identification of OCBs profiles. This review aims to provide a comprehensive overview and analysis of recent scientific articles, focusing on updated methods for MS diagnosis with an emphasis on the utility of the K-index. Numerous studies indicate that the K-index demonstrates high sensitivity and specificity, often comparable to or surpassing the diagnostic accuracy of OCBs evaluation. The integration of the measure of the K-index with OCBs assessment emerges as a more precise method for MS diagnosis. This combined approach not only enhances diagnostic accuracy, but also offers a more efficient and cost-effective alternative.

Prevalence and disease disability in immigrants with multiple sclerosis in Malmö, southern Sweden

BACKGROUND

Multiple sclerosis (MS) is the most common chronic demyelinating disease of the central nervous system and the major non-traumatic cause of permanent disability in young adults. Several migration studies have been performed over the years suggesting a pattern of higher disease disability in certain ethnic groups. To our knowledge, differences in disease progression in immigrants have not been studied in Sweden before. Thus, the aims of our study were to estimate the prevalence of multiple sclerosis among first-generation immigrants in the City of Malmö and to compare differences in disease severity with the native population.

METHODS

All persons with multiple sclerosis living in Malmö on prevalence day 31 Dec 2010 were included. Cases were classified according to the country of birth into Scandinavians, Western and non-Western.

RESULTS

The crude prevalence was 100/100,000 (95% CI, 80-124) among first-generation immigrants, 154/100,000 (95% CI, 137-173) among individuals with Scandinavian background, 123/100,000 (95% CI, 94-162) in the Western group and 76/100,000 (95% CI, 53-108) in the non-Western group. The mean Multiple Sclerosis Severity Score (MSSS) value among Scandinavians was 4.2 (SD 3.5), whereas the figures in the immigrant group were 4.6 (SD 3.3) and 5.2 (SD 3.7) among Westerns respectively non-Westerns, which differences were not statistically significant. When adjusting for gender, age at onset and initial disease course, the mean MSSS difference between the non-Western and the Scandinavian individuals was 1.7 (95% CI 0.18-3.3, p = 0.030). There were no differences on time to diagnosis or the time from diagnosis to treatment initiation between the three groups.

CONCLUSIONS

We found a lower prevalence among Western and non-Western first-generation immigrants compared to the Scandinavian population and a more severe disease in non-Western immigrants than in Scandinavians.

Data on Ocrelizumab Treatment Collected by MS Patients in Germany Using Brisa App

BACKGROUND

With a rising number of multiple sclerosis (MS) cases and increasing pressure on health systems, digital companion apps like Brisa, designed specifically for people with MS, can play an important role in the patient journey. These apps enable the collection of real-time longitudinal data that are critical to our understanding of the pathophysiology and progression of MS.

METHODS

This retrospective, descriptive analysis consists of data from Brisa users who registered between 6 August 2021 and 8 September 2022. Of the unique users, 37.7% (n = 1593) fulfilled the inclusion criteria including information about medication and demographics and tracked one or more symptoms and/or patient-reported outcomes. Users were classified as moderate-efficacy treatment users, high-efficacy treatment users and ocrelizumab users, and the reporting frequency and scores of symptoms and patient-reported outcomes were analyzed.

RESULTS

The largest cohort of Brisa users (405) reported treatment with ocrelizumab and were mostly diagnosed 2-5 years before the survey. The most reported MS symptoms were similar between OUs (ocrelizumab users), HETUs (high-efficacy treatment users) and METUs (moderate-efficacy treatment users). OUs on average reported symptoms and answered questionnaires more frequently. Baseline scores between HETUs and OUs were similar, whereas baseline scores of METUs were slightly lower in comparison. In a further analysis of OUs, disability scores increased with age; users aged 26-45 years had higher pain scores than 18-25-year-olds. No significant differences were found in quality of life, bowel control and vision between age groups.

CONCLUSION

These findings show that the characteristics of the Brisa cohort are similar to the results of other studies and registries and can provide a representative overview of everyday disease management. Thereby, these results can bridge the gap between clinical research and real patient experience, but they also raise new questions, such as how often the hard-and-early therapy approach is already used and whether baseline characteristics and reasons for choosing a particular treatment contribute to the different outcomes over time. Answering these questions requires further research and analysis.

Clinical and Treatment Considerations for the Pediatric and Aging Patients with Multiple Sclerosis

Chronologic aging is associated with multiple pathologic and immunologic changes that impact the clinical course of multiple sclerosis (MS). Clinical phenotypes evolve across the lifespan, from a highly inflammatory course in the very young to a predominantly neurodegenerative phenotype in older patients. Thus, unique clinical considerations arise for the diagnosis and management of the two age extremes of pediatric and geriatric MS populations. This review covers epidemiology, diagnosis, and treatment strategies for these populations with nuanced discussions on therapeutic approaches to effectively care for patients living with MS at critical transition points during their lifespan.

Sex, aging and immunity in multiple sclerosis and experimental autoimmune encephalomyelitis: An intriguing interaction

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) with a profound neurodegenerative component early in the disease pathogenesis. Age is a factor with a well-described effect on the primary disease phenotype, namely, the relapsing-remitting vs. the primary progressive disease. Moreover, aging is a prominent factor contributing to the transition from relapsing-remitting MS (RRMS) to secondary progressive disease. However, sex also seems to, at least in part, dictate disease phenotype and evolution, as evidenced in humans and in animal models of the disease. Sex-specific gene expression profiles have recently elucidated an association with differential immunological signatures in the context of experimental disease. This review aims to summarize current knowledge stemming from experimental autoimmune encephalomyelitis (EAE) models regarding the effects of sex, either independently or as a factor combined with aging, on disease phenotype, with relevance to the immune system and the CNS.

The borderland of multiple sclerosis and functional neurological disorder: A call for clinical research and vigilance

BACKGROUND AND PURPOSE

Functional neurological disorders (FNDs) have attracted much attention from the neurological medical community over the last decades as new developments in neurosciences have reduced stigma around these by showing brain network dysfunctions. An overlap with other neurological conditions such as multiple sclerosis (MS) is well known by clinicians but there is a lack of clinical and fundamental research in this field to better define diagnosis and therapeutic decisions, as well as a lack of deep understanding of the underlying pathophysiology.

AIM

We aimed to provide a critical commentary on the state of knowledge about the borderland between FNDs and MS.

METHODS

We based our commentary on a joint point of view between an FND specialist and an MS expert.

RESULTS

A brief review of the previous literature and relevant new studies covering the overlap between FNDs and MS is presented, along with suggestions for future research directions.

CONCLUSION

There are clear diagnostic criteria for both FNDs and MS and a strict application of these will help better diagnosis and prevent unnecessary treatment escalation in MS or absence of referral to multimodal therapy in FND. Better teaching of younger neurologists is needed as well as prospective research focusing on pathophysiology.

Sex bias in multiple sclerosis and neuromyelitis optica spectrum disorders: How it influences clinical course, MRI parameters and prognosis

This review is a condensed summary of representative articles addressing the sex/gender bias in multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD). The strong effects of sex on the incidence and possibly also the activity and progression of these disorders should be implemented in the evaluation of any phase of clinical research and also in treatment choice consideration in clinical practice and evaluation of MRI parameters. Some relationships between clinical variables and gender still remain elusive but with further understanding of sex/gender-related differences, we should be able to provide appropriate patient-centered care and research.

Sex and gender differences in autoimmune demyelinating CNS disorders: Multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD) and myelin-oligodendrocyte-glycoprotein antibody associated disorder (MOGAD)

Multiple sclerosis (MS), Neuromyelitis optica spectrum disorder (NMOSD) and Myelin-Oligodendrocyte-Glycoprotein antibody associated disorder (MOGAD) are demyelinating disorders of the central nervous system (CNS) of autoimmune origin. Here, we summarize general considerations on sex-specific differences in the immunopathogenesis and hormonal influences as well as key clinical and epidemiological elements. Gender-specific issues are widely neglected starting with the lacking separation of sex as a biological variable and gender comprising the sociocultural components. As for other autoimmune diseases, female preponderance is common in MS and NMOSD. However, sex distribution in MOGAD seems equal. As in MS, immunotherapy in NMOSD and MOGAD is crucial to prevent further disease activity. Therefore, we assessed data on sex differences of the currently licensed disease-modifying treatments for efficacy and safety. This topic seems widely neglected with only fragmented information resulting from post-hoc analyses of clinical trials or real-world post-marketing studies afflicted with lacking power and/or inherent sources of bias. In summary, biological hypotheses of sex differences including genetic factors, the constitution of the immune system and hormonal influences are based upon human and preclinical data, especially for the paradigmatic disease of MS whereas specific data for NMOSD and MOGAD are widely lacking. Epidemiological and clinical differences between men and women are well described for MS and to some extent for NMOSD, yet, with remaining contradictory findings. MOGAD needs further detailed investigation. Sex-specific analyses of safety and efficacy of long-term immunotherapies need to be addressed in future studies designed and powered to answer the pressing questions and to optimize and individualize treatment.

Demographic Patterns of MS Patients Using BRISA: An MS-Specific App in Germany

Background: Multiple sclerosis (MS) is a chronic, progressive neurological autoimmune disease impacting quality of life. BRISA is an app designed to help MS patients in Germany track their disease course by symptom-monitoring. This study aimed to understand demographic and health-related characteristics of BRISA users. Methods: Demographic data provided by 2095 users were analyzed to describe characteristics such as sex, age, type of MS, and medication. The distribution of tracked symptoms based on age and time since diagnosis were studied. Furthermore, the covariance of specific symptom pairs was analyzed. Results: BRISA users are predominantly female and between 26 and 55 years old. Relapsing–remitting MS was the most prevalent form of MS. First-line category 1 drugs were most frequently used, followed by high-efficacy category 3 drugs (e.g., monoclonal antibodies). The relative frequencies of use of category 1 and category 2 drugs (e.g., spingosine-1-phosphate-receptor modulators) significantly altered with time since diagnosis. Fatigue, concentration disorders, tingling, forgetfulness, and pain were the top five symptoms affecting users. Conclusion: The results highlight the diversity among MS patients and the need for extensive cohort characterization in the real-world scenario. In-depth analysis could help in identifying novel insights that could aid in disease management.

Immune Cell Contributors to the Female Sex Bias in Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is a chronic, autoimmune, demyelinating disease of the central nervous system (CNS) that leads to axonal damage and accumulation of disability. Relapsing-remitting MS (RR-MS) is the most frequent presentation of MS and this form of MS is three times more prevalent in females than in males. This female bias in MS is apparent only after puberty, suggesting a role for sex hormones in this regulation; however, very little is known of the biological mechanisms that underpin the sex difference in MS onset. Experimental autoimmune encephalomyelitis (EAE) is an animal model of RR-MS that presents more severely in females in certain mouse strains and thus has been useful to study sex differences in CNS autoimmunity. Here, we overview the immunopathogenesis of MS and EAE and how immune mechanisms in these diseases differ between a male and female. We further describe how females exhibit more robust myelin-specific T helper (Th) 1 immunity in MS and EAE and how this sex bias in Th cells is conveyed by sex hormone effects on the T cells, antigen presenting cells, regulatory T cells, and innate lymphoid cell populations.

The role of sex and pregnancy in multiple sclerosis: what do we know and what should we do?

INTRODUCTION

Multiple sclerosis (MS) is more prevalent in women than in men. The sex of the patient, and pregnancy, are reported to be associated with the clinical features of MS. The mechanism of this is unclear.

AREAS COVERED

This review summarizes data about sex differences in MS and the role of pregnancy. Possible mechanisms for the effects of sex and pregnancy are summarized, and practical suggestions for addressing these issues are provided.

EXPERT OPINION

There is considerable interdependence of the variables that are associated with MS. Men have a worse outcome of MS, and this could be due to the same factors that lead to greater incidence of neurodegenerative disease in men. The possible role of parity on the long-term outcome of MS is of interest. Future studies that look at the mechanisms of the effects of the sex of the patient on the outcome of MS are required. However, there are some actions that can be taken without further research. We can concentrate on public health measures that address the modifiable risk factors for MS and ensure that disease is controlled in women who intend to become pregnant and use appropriate disease modifying agents during pregnancy.

Endocannabinoid Modulation in Neurodegenerative Diseases: In Pursuit of Certainty

Simple Summary

Neurodegenerative diseases represent an important cause of morbidity and mortality worldwide. Existing therapeutic options are limited and focus mostly on improving symptoms and reducing exacerbations. The endocannabinoid system is involved in the pathophysiology of such disorders, an idea which has been highlighted by recent scientific work. The current work focusses its attention on the importance and implications of this system and its synthetic and natural ligands in disorders such as Alzheimer’s, Parkinson’s, Huntington’s and multiple sclerosis.

Abstract

Neurodegenerative diseases are an increasing cause of global morbidity and mortality. They occur in the central nervous system (CNS) and lead to functional and mental impairment due to loss of neurons. Recent evidence highlights the link between neurodegenerative and inflammatory diseases of the CNS. These are typically associated with several neurological disorders. These diseases have fundamental differences regarding their underlying physiology and clinical manifestations, although there are aspects that overlap. The endocannabinoid system (ECS) is comprised of receptors (type-1 (CB1R) and type-2 (CB2R) cannabinoid-receptors, as well as transient receptor potential vanilloid 1 (TRPV1)), endogenous ligands and enzymes that synthesize and degrade endocannabinoids (ECBs). Recent studies revealed the involvement of the ECS in different pathological aspects of these neurodegenerative disorders. The present review will explore the roles of cannabinoid receptors (CBRs) and pharmacological agents that modulate CBRs or ECS activity with reference to Alzheimer’s Disease (AD), Parkinson’s Disease (PD), Huntington’s Disease (HD) and multiple sclerosis (MS).

Development of an age-adjusted model for blood neurofilament light chain

OBJECTIVE

To develop an age-adjustment model for neurofilament light chain (NfL), an emerging injury marker in patients with a range of neurologic conditions including multiple sclerosis (MS).

METHODS

Serum and plasma samples were collected from a healthy donor (HD) cohort of 118 individuals aged 24 to 66 years, 90 patients with relapsing MS (RMS) and 22 patients with progressive MS (PMS). Serum and plasma samples were assessed for NfL using the SIMOA assay (Quanterix NfL Advantage Kit™). A log-linear model was used to evaluate the relationship between NfL and age and to calculate age-adjusted NfL levels.

RESULTS

Higher serum and plasma NfL levels were significantly associated with increasing HD age. Log-transformation of blood NfL levels reduced heteroscedasticity and skewness. A log-linear model enabled adjustment for age-related increase in serum and plasma NfL levels (2.3% [95% CI, 1.6-2.9] and 2.6% [95% CI, 1.3-3.3] per year, respectively). Following age adjustment, NfL did not show significant association with HD sex or ethnicity. While unadjusted serum NfL levels were elevated in patients with PMS (mean age 56 years) compared with those with RMS (mean age 37 years), age-adjusted NfL levels did not differ.

INTERPRETATION

A log-linear, age adjustment model was developed to enable comparison of NfL levels across populations with different ages. While additional data and evidence are needed for patient-level adoption, this could be a valuable tool for interpreting NfL levels across a range of patient groups with neurologic conditions.

Circulating miRNAs as Potential Biomarkers Distinguishing Relapsing-Remitting from Secondary Progressive Multiple Sclerosis. A Review

Multiple sclerosis (MS) is a debilitating neurodegenerative, highly heterogeneous disease with a variable course. The most common MS subtype is relapsing–remitting (RR), having interchanging periods of worsening and relative stabilization. After a decade, in most RR patients, it alters into the secondary progressive (SP) phase, the most debilitating one with no clear remissions, leading to progressive disability deterioration. Among the greatest challenges for clinicians is understanding disease progression molecular mechanisms, since RR is mainly characterized by inflammatory processes, while in SP, the neurodegeneration prevails. This is especially important because distinguishing RR from the SP subtype early will enable faster implementation of appropriate treatment. Currently, the MS course is not well-correlated with the biomarkers routinely used in clinical practice. Despite many studies, there are still no reliable indicators correlating with the disease stage and its activity degree. Circulating microRNAs (miRNAs) may be considered valuable molecules for the MS diagnosis and, presumably, helpful in predicting disease subtype. MiRNA expression dysregulation is commonly observed in the MS course. Moreover, knowledge of diverse miRNA panel expression between RRMS and SPMS may allow for deterring disability progression through successful treatment. Therefore, in this review, we address the current state of research on differences in miRNA panel expression between the phases.

Genetic, Environmental and Lifestyle Determinants of Accelerated Telomere Attrition as Contributors to Risk and Severity of Multiple Sclerosis

Telomeres are protective structures at the ends of linear chromosomes. Shortened telomere lengths (TL) are an indicator of premature biological aging and have been associated with a wide spectrum of disorders, including multiple sclerosis (MS). MS is a chronic inflammatory, demyelinating and neurodegenerative disease of the central nervous system. The exact cause of MS is still unclear. Here, we provide an overview of genetic, environmental and lifestyle factors that have been described to influence TL and to contribute to susceptibility to MS and possibly disease severity. We show that several early-life factors are linked to both reduced TL and higher risk of MS, e.g., adolescent obesity, lack of physical activity, smoking and vitamin D deficiency. This suggests that the mechanisms underlying the disease are connected to cellular aging and senescence promoted by increased inflammation and oxidative stress. Additional prospective research is needed to clearly define the extent to which lifestyle changes can slow down disease progression and prevent accelerated telomere loss in individual patients. It is also important to further elucidate the interactions between shared determinants of TL and MS. In future, cell type-specific studies and advanced TL measurement methods could help to better understand how telomeres may be causally involved in disease processes and to uncover novel opportunities for improved biomarkers and therapeutic interventions in MS.

Th17-Related Cytokines as Potential Discriminatory Markers between Neuromyelitis Optica (Devic's Disease) and Multiple Sclerosis-A Review

Multiple sclerosis (MS) and Devic’s disease (NMO; neuromyelitis optica) are autoimmune, inflammatory diseases of the central nervous system (CNS), the etiology of which remains unclear. It is a serious limitation in the treatment of these diseases. The resemblance of the clinical pictures of these two conditions generates a partial possibility of introducing similar treatment, but on the other hand, a high risk of misdiagnosis. Therefore, a better understanding and comparative characterization of the immunopathogenic mechanisms of each of these diseases are essential to improve their discriminatory diagnosis and more effective treatment. In this review, special attention is given to Th17 cells and Th17-related cytokines in the context of their potential usefulness as discriminatory markers for MS and NMO. The discussed results emphasize the role of Th17 immune response in both MS and NMO pathogenesis, which, however, cannot be considered without taking into account the broader perspective of immune response mechanisms.

A comprehensive assessment of patient experience and disease-related awareness in multiple sclerosis: A questionnaire-based nation-wide survey in Turkey

BACKGROUND

Comprehensive assessment of multiple sclerosis (MS) patients in terms of patient profile, clinical and disease-related factors has great epidemiological value. This study aimed to evaluate patient experience and disease-related awareness in MS patients through a nation-wide survey in Turkey Methods: A total of 1379 MS patients participated in this cross-sectional questionnaire survey conducted between November 2018 and December 2018. The online questionnaire form included items on sociodemographic, disease-related, first-admission, treatment and follow up characteristics as well as the disability status.

RESULTS

Patients were diagnosed at median 28.0 years of age, while the average time from admission to diagnosis and time from diagnosis to treatment were 1.2 years and 2.5 months, respectively. Neurology (45.4%) and ophthalmology (23.3%) were the most common clinics for the first admission, while numbness-weakness in lower and upper extremities (37.6%) and double vision-visual problems (30.6%) were the most common symptoms on initial admission. Treatment was initiated after the diagnosis in 1213(88.0%) patients, while 166 (12.0%) patients were treatment-naïve. Treatment discontinuation, treatment switch and use of alternative treatment methods were reported by 31.3%, 49.3% and 22.8% of patients, respectively. The ophthalmology admissions (with double vision or visual problems) were associated with the shortest time from presentation to diagnosis as compared with neurosurgery and internal medicine admissions (median 1.0 vs. 3.0 and 4.0 months, p<0.001). The neurology admissions (with numbness-weakness in extremities) were associated with more prompt (median 0.3 vs. 0.5 months, p=0.032) and more frequent onset of treatment after diagnosis (64.5% vs. 2.2% to 15.2%, p<0.001). Time from presentation to diagnosis was longer in patients aged >50 years (median 6.0 months vs. 2.0 months, p<0.001), in patients using alternative medicine (median 3.0 months vs. 1 month, p=0.001) and in patients admitted to a non-MS-center (median 3.0 months vs. 2.0 months, p=0.002). Median (min-max) age at diagnosis was significantly lower in patients with vs. without treatment discontinuation for any reason (26.0(10-56) vs. 29.0(3-60) years, p<0.001) and treatment switching (27.0(5-93) vs. 30.0(3-60) years, p<0.001).

CONCLUSIONS

In conclusion, our findings revealed higher likelihood of earlier diagnosis and earlier treatment in patients admitted to an MS-center and in those presenting with ocular problems and sensory-motor deficits, respectively. Our findings also emphasize the association of older patient age with higher likelihood of diagnostic delay, and increased likelihood of treatment discontinuation for any reason and/or treatment switching in case of older patient age, younger age at diagnosis and diagnostic delay. In this regard, our findings highlight the need for improved awareness among patients as well as clinicians on initial manifestations of MS to enable admission or referral to an MS-center and to prevent delay in diagnosis, particularly for onset symptoms other than ocular or sensory-motor characteristics.

The effect of yoga practice on muscular strength improvement in patients with multiple sclerosis

Background/Aims

Multiple sclerosis is a common condition in the central nervous system where patients experience many issues, including muscle weakness. This study offers an investigation of continuous hatha yoga exercises on patients with multiple sclerosis.

Methods

A total of 22 participants with multiple sclerosis were selected, 11 were allocated to the intervention group, and 11 to the control group. In both groups, surface electromyography and dynamometer were performed at the beginning and the end of the study. The intervention group undertook 90-minute sessions of hatha yoga training three times a week for 6 months and the control group did not do any particular exercise during this period.

Results

Dynamometer results indicated that yoga significantly improved the muscle strength of the participants with multiple sclerosis (before the intervention: 40.00 Nm ± 14.66 Nm vs 56.82 Nm ± 20.28 Nm after the intervention, P=0.037). However, there was no significant difference in muscle strength changes between the intervention and control groups (16.82 Nm ± 23.26 Nm vs -2.86 Nm ± 23.36 Nm, P=0.171). Yoga significantly increased participants muscle strength according to the surface electromyography signals (before the intervention: 39.91 V ± 8.86 V vs 54.09 v ± 8.95 V after the intervention, P=0.007). The muscle strength of the control group participants with multiple sclerosis decreased after 6 months, however it was not statistically significant (41.55 Nm ± 9.3 Nm vs 34.55 Nm ± 8.36 Nm, P=0.073). The comparison of changes showed that the surface electromyography signals in the intervention group were significantly higher than those of the control group (P=0.001).

Conclusions:

Yoga exercises, in addition to common multiple sclerosis treatment methods, can be considered as a complementary therapy to improve the physical aspects of multiple sclerosis symptoms.

SeXX Matters in Multiple Sclerosis

Multiple sclerosis (MS) is the most common chronic inflammatory and neurodegenerative disease of the central nervous system (CNS). An interesting feature that this debilitating disease shares with many other inflammatory disorders is that susceptibility is higher in females than in males, with the risk of MS being three times higher in women compared to men. Nonetheless, while men have a decreased risk of developing MS, many studies suggest that males have a worse clinical outcome. MS exhibits an apparent sexual dimorphism in both the immune response and the pathophysiology of the CNS damage, ultimately affecting disease susceptibility and progression differently. Overall, women are predisposed to higher rates of inflammatory relapses than men, but men are more likely to manifest signs of disease progression and worse CNS damage. The observed sexual dimorphism in MS may be due to sex hormones and sex chromosomes, acting in parallel or combination. In this review, we outline current knowledge on the sexual dimorphism in MS and discuss the interplay of sex chromosomes, sex hormones, and the immune system in driving MS disease susceptibility and progression.

Age-dependent variation of female preponderance across different phenotypes of multiple sclerosis: A retrospective cross-sectional study

Introduction

Multiple sclerosis (MS) is an autoimmune disease of the CNS, which predominantly affects women. Studies investigating the sex distribution in MS are sparse. We aim to analyze the female‐to‐male ratio (F/M ratio) in different MS phenotypes in association with age at diagnosis and year of birth.

Methods

We performed a retrospective cross‐sectional analysis by cumulating data (sex, year of birth, age at diagnosis, and MS phenotypes) from unpublished and published studies of the participating centers.

Results

Datasets of 945 patients were collected. The overall F/M ratio was 1.9:1.0 and female preponderance was present in all phenotypes except for primary progressive MS (PPMS), in which men were predominantly affected (F/M ratio: 0.5:1.0). Female preponderance declined with increasing age at diagnosis and was no longer present in relapsing‐remitting MS (RRMS) patients > 58 years of age.

Conclusion

Our data demonstrate an age dependency of female preponderance in MS except for PPMS. This could be influenced by the lifecycle of sex hormone secretion in women. In PPMS, a male preponderance was observed in all age‐groups, which might point to pathophysiological mechanisms being less influenced by sex hormones.