How long is the presymptomatic phase of multiple sclerosis?

Myopia in late adolescence and subsequent multiple sclerosis among men

BACKGROUND

Risk factors such as low vitamin D level has been implicated in the etiology of multiple sclerosis (MS) and may be relevant to myopia, such that there may be an association between myopia and MS.

METHODS

Using linked Swedish national register data, we conducted a cohort study of men who were born in Sweden between 1950 and 1992, lived in Sweden between 1990 and 2018, and enrolled in military conscription assessment (n = 1,847,754). Myopia was defined based on the spherical equivalent refraction measured at conscription assessment, around age 18 years. Multiple sclerosis was identified using the Patient Register. Cox regression produced hazard ratios (HR) with 95% confidence intervals (95% CI), with adjustment for demographic and childhood socioeconomic characteristics and residential region. Due to changes in the assessment of refractive error, the analysis was stratified into two groups by the year of conscription assessment: 1969-1997 and 1997-2010.

RESULTS

Among 1,559,859 individuals during a maximum of 48 years of follow-up from age 20 to 68 years (44,715,603 person-years), there were 3,134 MS events, and the incidence rate 7.0 (95% CI [6.8, 7.3] per 100,000 person-years). Among individuals with conscription assessments during 1997-2010, there were 380 MS events. There was no evidence of an association between myopia and MS, with HR 1.09 (95% CI 0.83, 1.43). Among individuals who underwent conscription assessment in 1969-1997, there were 2754 MS events. After adjusting for all covariates, there was no evidence of an association between myopia and MS (HR 0.99 [95% CI 0.91, 1.09]).

CONCLUSION

Myopia in late adolescence is not associated with a subsequent raised risk of MS and thus there does not appear to be important shared risk factors.

Secondary Prevention in Radiologically Isolated Syndromes and Prodromal Stages of Multiple Sclerosis

Following the extraordinary progress in the treatment of multiple sclerosis (MS), two major unmet needs remain: understanding the etiology of the disease and, hence, designing definitive cures (this perspective is neither at hand, nor it can be taken for granted that the etiologic targets will be readily treatable); the prevention of an overt and disabling disease, which seems to be a more realistic and pragmatic perspective, as the integration of genetic data with endophenotypes, MRI, and other biomarkers ameliorates our ability to identify early neuroinflammation. Radiologically isolated syndrome (RIS; diagnosed when the unanticipated MRI finding of brain spatial dissemination of focal white matter lesions highly suggestive of MS occurs in subjects without symptoms of MS, and with normal neurological examinations) and the recently focused “prodromal MS” are conditions at risk of conversion toward overt disease. Here, we explore the possibility of secondary prevention approaches in these early stages of neuroinflammation. RIS and prodromal MS are rare conditions, which suggest the importance of Study Groups and Disease Registry to implement informative clinical trials. We summarize ongoing preventive approaches in the early stages of the demyelinating process, especially in RIS conditions. Moreover, we highlight the importance of the biomarkers and the predictors of evolution to overt disease, which may be useful to select the individuals at risk of conversion to clinically isolated syndrome (CIS) and/or clinically definite MS. Finally, we illustrate the importance of the endophenotypes to test the frontline immunomodulatory approach for preventive strategies. Future investigations, especially in relatives of patients, based on MRI techniques and biological studies (better with integrated approaches) may provide opportunities to understand the MS early causal cascade and may help to identify a “therapeutic window” to potentially reverse early disease processes.

Immune signatures of prodromal multiple sclerosis in monozygotic twins

Multiple sclerosis is an autoimmune disease shaped by genetic and environmental factors. Because of the heterogeneity of the human population, it has been difficult to identify “immune signatures” of the disease. Here we investigated a cohort of identical twin pairs who are discordant for multiple sclerosis. In each twin pair, the immune signatures were remarkably similar, pointing to a strong influence of shared genetic and environmental factors. However, when we focused on a subgroup of seemingly healthy cotwins who showed subtle signs of “subclinical neuro-inflammation,” we identified a distinct signature of memory T cells. Insight into the immunological mechanisms associated with the initiation of the disease is relevant not only to the therapy but also for prevention of the disease.

The tremendous heterogeneity of the human population presents a major obstacle in understanding how autoimmune diseases like multiple sclerosis (MS) contribute to variations in human peripheral immune signatures. To minimize heterogeneity, we made use of a unique cohort of 43 monozygotic twin pairs clinically discordant for MS and searched for disease-related peripheral immune signatures in a systems biology approach covering a broad range of adaptive and innate immune populations on the protein level. Despite disease discordance, the immune signatures of MS-affected and unaffected cotwins were remarkably similar. Twinship alone contributed 56% of the immune variation, whereas MS explained 1 to 2% of the immune variance. Notably, distinct traits in CD4⁺ effector T cell subsets emerged when we focused on a subgroup of twins with signs of subclinical, prodromal MS in the clinically healthy cotwin. Some of these early-disease immune traits were confirmed in a second independent cohort of untreated early relapsing-remitting MS patients. Early involvement of effector T cell subsets thus points to a key role of T cells in MS disease initiation.

Non-infectious comorbidity in patients with multiple sclerosis: A national cohort study in Sweden

Background

Comorbidity is of significant concern in multiple sclerosis (MS). Few population-based studies have reported conditions occurring in MS after diagnosis, especially in contemporary cohorts.

Objective

To explore incident comorbidity, mortality and hospitalizations in MS, stratified by age and sex.

Methods

In a Swedish population-based cohort study 6602 incident MS patients (aged ≥18 years) and 61,828 matched MS-free individuals were identified between 1 January 2008 and 31 December 2016, using national registers. Incidence rates (IRs) and incidence rate ratios (IRRs) with 95% CI were calculated for each outcome.

Results

IRs of cardiovascular disease (CVD) were higher among MS patients than MS-free individuals, (major adverse CVD: IRR 1.42; 95% CI 1.12–1.82; hemorrhagic/ischemic stroke: 1.46; 1.05–2.02; transient ischemic attack: 1.65; 1.09–2.50; heart failure: 1.55; 1.15–2.10); venous thromboembolism: 1.42; 1.14–1.77). MS patients also had higher risks of several non-CVDs such as autoimmune conditions (IRR 3.83; 3.01–4.87), bowel dysfunction (2.16; 1.86–2.50), depression (2.38; 2.11–2.68), and fractures (1.32; 1.19–1.47), as well as being hospitalized and to suffer from CVD-related deaths ((1.91; 1.00–3.65), particularly in females (3.57; 1.58–8.06)).

Conclusion

MS-patients experience a notable comorbidity burden which emphasizes the need for integrated disease management in order to improve patient care and long-term outcomes of MS.

Infections in patients with multiple sclerosis: A national cohort study in Sweden

BACKGROUND

Multiple sclerosis (MS) patients have an increased risk of infections, but few population-based studies have reported infections occurring in MS in the years immediately after diagnosis.

OBJECTIVE

To explore incident infections in MS, stratified by age and sex.

METHODS

In a Swedish population-based cohort study 6602 incident MS patients (aged ≥18 years), matched at diagnosis with 61,828 matched MS-free individuals were identified between 1st January 2008 and 31st December 2016, using national registers. Incidence rates (IR) and incidence rate ratios (IRR) with 95% CI were calculated for each outcome.

RESULTS

The IRRs were 2.54 (95% CI 2.28-2.83) for first serious infection and 1.61 (1.52-1.71) for first non-serious infection. Compared with MS-free individuals, MS patients had higher IRs for skin, respiratory/throat infections, pneumonia/influenza, bacterial, viral, and fungal infections, with the highest IRR observed for urinary tract/kidney infections (2.44; 2.24-2.66). The cumulative incidence for most of these infections was higher among MS patients than MS-free individuals, both 0 to <5 and 5 to <9 years after index date.

CONCLUSION

The burden of infections around the time of MS diagnosis and subsequent infection risk, underscore the need for careful considerations regarding the risk-benefit across different disease-modifying therapies.

Hospital diagnosed pneumonia before age 20 years and multiple sclerosis risk

Introduction

Respiratory inflammation has been proposed as a risk factor for MS. This study aims to determine if hospital-diagnosed pneumonia in adolescence (before age 20 years) is associated with subsequent multiple sclerosis (MS).

Methods

This case-control study included incident MS cases after age 20 years identified using the Swedish national registers. Cases were matched with 10 general population controls by age, sex and region. Pneumonia diagnoses were identified between 0–5, 6–10, 11–15 and 16–20 years of age. Conditional logistic regression models adjusted for infectious mononucleosis (IM) and education calculated ORs with 95% CIs. Urinary tract infections (UTIs), a common complication of MS, before age 20 years were included as a control diagnosis for reverse causation.

Results

There were 6109 cases and 49 479 controls included. Pneumonia diagnosed between age 11–15 years was associated with subsequent MS (adj OR 2.00, 95% CI 1.22 to 3.27). Although not statistically significant, sensitivity analyses showed similar magnitude associations of pneumonia between age 11–15 years and MS. No statistically significant associations with MS for pneumonia at other age groups were observed. Adjustment for IM had no notable effect on associations, but was statistically significantly associated with MS. UTIs were not associated with MS.

Conclusion

Pneumonia at 11–15 years of age was associated with MS, suggesting a possible role for inflammation of the respiratory system in the aetiology of MS during a period of susceptibility in adolescence. Further research on respiratory infections prior to MS onset should be conducted to replicate this finding and determine explanatory causal mechanisms.

Higher body mass index at ages 16 to 20 years is associated with increased risk of a multiple sclerosis diagnosis in subsequent adulthood among men

Background:

Evidence for the association between body mass index (BMI) and multiple sclerosis (MS) among men remains mixed.

Objective and methods:

Swedish military conscription and other registers identified MS after age of 20 years and BMI at ages 16–20 years ( N = 744,548).

Results:

Each unit (kg/m2) BMI increase was associated with greater MS risk (hazard ratio and 95% confidence interval = 1.034, 1.016–1.053), independent of physical fitness (1.021, 1.001–1.042). Categorised, overweight and obesity were associated with statistically significant raised MS risk compared to normal weight, but not after adjustment for physical fitness.

Conclusion:

MS risk rises with increasing BMI, across the entire BMI range.