Characteristics in childhood and adolescence associated with future multiple sclerosis risk in men: cohort study

Stress and Multiple Sclerosis - Systematic review and meta-analysis of the association with disease onset, relapse risk and disability progression

OBJECTIVE

This systematic review and meta-analysis address the evidence on the association of psychological stressors with onset of multiple sclerosis, inflammatory disease activity (relapses or new disease activity on magnetic resonance imaging, MRI) and disability progression.

METHODS

PubMed was searched from 1946 to 15 July 2022. Studies and certain stressors were selected when they assessed stressors independent from stress elicited by the disease process itself. Risk of bias was assessed by the CASP Case Control Study Checklist and the CASP Cohort Study Checklist. Normal-Normal Hierarchical Model (NNHM) for random-effects meta-analysis was used in the Bayesian framework.

RESULTS

30 studies reporting data from 26 cohorts reporting on 24.781 cases could be identified. Ten studies addressed stressors and MS disease onset showing a weak to modest effect of psychological stressors. A meta-analysis of three studies investigating diagnosed stress disorders and MS risk showed a 1.87-fold (CI 1.061 to 3.429) increased MS risk. Stress and MS relapse risk were addressed in 19 heterogeneous studies. Meta-analyses from two independent cohorts investigating the same military threat of a population showed a threefold increased risk for relapses in association with war (relapse rate: 3.0, CI 1.56 to 5.81). In addition, two studies confirmed an association of stressful life events and MRI activity. Three studies of stressors and disease progression were included indicating some effect on disease progression.

CONCLUSIONS

Taken together studies indicate a minor to modest impact of psychological stressors on disease onset, inflammatory activity and progression of MS. Possible case-selection bias and lack of confounder analysis were present in many studies.

Shifting our attention earlier in the multiple sclerosis disease course

PURPOSE OF REVIEW

Revisions of multiple sclerosis (MS) diagnostic criteria enable clinicians to diagnose patients earlier in the biologic disease course. Prompt initiation of therapy correlates with improved clinical outcomes. This has led to increased attention on the earliest stages of MS, including the MS prodrome and radiologically isolated syndrome (RIS). Here, we review current understanding and approach to patients with preclinical MS.

RECENT FINDINGS

MS disease biology often begins well before the onset of typical MS symptoms, and we are increasingly able to recognize preclinical and prodromal stages of MS. RIS represents the best characterized aspect of preclinical MS, and its diagnostic criteria were recently revised to better capture patients at highest risk of conversion to clinical MS. The first two randomized control trials evaluating disease modifying therapy use in RIS also found that treatment could delay or prevent onset of clinical disease.

SUMMARY

Despite progress in our understanding of the earliest stages of the MS disease course, additional research is needed to systematically identify patients with preclinical MS as well as capture those at risk for developing clinical disease. Recent data suggests that preventive immunomodulatory therapies may be beneficial for high-risk patients with RIS; though management remains controversial.

The association between weight during early life and multiple sclerosis onset in a nationwide Dutch birth year cohort

BACKGROUND

The relationship between being overweight during early life and disease course in multiple sclerosis (MS) is unresolved. We investigated the association between being overweight or obese during early life (childhood and adolescence) and MS case status, age of first symptom onset and onset type in people with MS (pwMS) of the same birth year.

METHODS

We enrolled 363 PwMS and 125 healthy controls (HC) from Project Y, a Dutch population-based cross-sectional cohort study including all PwMS born in 1966 and age and sex-matched HC. The associations between weight during childhood and adolescence (non-overweight vs. overweight or obese) and MS, age at symptom onset and onset type (relapsing vs. progressive) were assessed using logistic and linear regressions. In addition, sex-separated associations were explored.

RESULTS

Being overweight or obese during childhood (OR = 2.82, 95% CI 1.17-6.80) and adolescence (OR = 2.45, 95% CI 1.13-5.34) was associated with developing MS. Furthermore, being overweight or obese during adolescence was associated with a younger age of onset (β = -0.11, p = 0.041). Of all 47 patients with a primary progressive (PP) onset type, only one patient (2.1%) was overweight or obese during childhood, whereas 45 patients with a relapsing remitting (RR) onset (14.3%) were overweight or obese during childhood (PP vs. RR p = 0.017; PP vs. HC p = 0.676; RR vs. HC, p = 0.015). However, using logistic regression analysis we did not find evidence of a significant association.

CONCLUSION

In a nationwide population-based birth year cohort, being overweight or obese during childhood or adolescence is associated with MS prevalence and an earlier age of onset, but does not seem to associate with the type of onset.

Association of adverse childhood experiences with adulthood multiple sclerosis: A systematic review of observational studies

INTRODUCTION

Adverse childhood experiences (ACEs) are proposed to increase the risk of developing multiple sclerosis (MS) later in life. This systematic review aimed to explore the correlation between ACEs and MS development, age of onset, quality of life in MS patients and MS relapse rates.

METHODS

We searched a total of six databases in June 2022 and retrieved the relevant studies. The population included adult (18+) individuals who either had been diagnosed or were at risk for developing MS and also had exposure to ACEs. Our primary outcomes include the risks of MS development, age of MS onset, and MS relapse rate in patients who were exposed to different types of ACEs.

RESULTS

A total of 11 studies were included in our review. A study reported that among 300 women diagnosed with MS, 71 (24%) reported a history of childhood abuse; moreover, with further research, it was concluded that ACEs were associated with the development of MS. Abuse that occurred 2-3 times per week was associated with an 18.81-fold increased risk of having MS when compared to the unexposed sample. The relapse rate of MS was found to be substantially greater in severe cases of ACEs compared to individuals who did not report any ACEs.

CONCLUSIONS

Results support a significant association between ACEs and the development of MS; individuals with a positive history of ACEs develop MS symptoms earlier. Moreover, the severity of ACEs is also linked with increased relapse rates of MS.

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.

Association between Adverse Childhood Experiences and Multiple Sclerosis in Icelandic Women-A Population-Based Cohort Study

BACKGROUND

A growing literature, mostly based on selected populations, indicates that traumas may be associated with autoimmune diseases, yet few studies exist on adverse childhood experiences (ACEs) and multiple sclerosis (MS) in the general population.

OBJECTIVE

We assessed cross-sectional associations between self-reported ACEs and MS among Icelandic women in the population-based Stress-And-Gene-Analysis (SAGA) cohort.

METHODS

Participants (n = 27,870; mean age 44.9 years) answered a web-based survey that included the ACE-International Questionnaire and a question about MS diagnosis. Log-linear Poisson regression models estimated MS prevalence ratios and 95% confidence intervals for ACEs adjusted for covariates.

RESULTS

214 women reported having been diagnosed with MS (crude prevalence = 7.7 per 1000). Compared to women without MS, women with MS reported more fatigue, body pain and bladder problems. The average cumulative number of ACEs was 2.1. After adjustment for age, education, childhood deprivation, smoking and depressive symptoms, MS prevalence did not increase with increasing ACEs exposure (PR = 1.00, 95% CI = 0.92, 1.09). Thirteen ACE categories, including abuse, neglect, household dysfunction and violence were not individually or independently associated with MS.

CONCLUSION

Limited by self-reported data and cross-sectional design, results do not consistently support associations between ACEs in the development of MS among adult Icelandic women.

Physical activity and risk of multiple sclerosis: A Mendelian randomization study

Multiple evidence from epidemiological studies has suggested association between physical activity and risk of multiple sclerosis (MS). However, the conclusion was still controversial between studies, and whether the association was causal or confounded is elusive. To evaluate the role of physical activity with different intensities in the risk of MS, we first estimated their genetic correlation, and then conducted two-sample and multivariable Mendelian randomization analyses based on summary statistics from previous large genome-wide association studies. A significant genetic correlation was identified between moderate physical activity and the risk of MS (genetic correlation: -0.15, SE=0.05, P=2.9E-03). Meanwhile, higher moderate physical activity was significantly associated with a reduced risk of MS (OR:0.87, 95% CI:0.80-0.96, P=3.45E-03). Such association was further verified using summary statistics from another study on overall physical activity (OR:0.36, 95% CI:0.17-0.76, P=6.82E-03). The results were robust under all sensitivity analyses. Current results suggested moderate physical activity could reduce the risk of MS. These findings help better understand the role of physical activity in MS, and provide some lifestyle recommendations for individuals susceptible to MS.

Preventive exercise attenuates IL-2-driven mood disorders in multiple sclerosis

BACKGROUND

Elevated levels of specific proinflammatory molecules in the cerebrospinal fluid (CSF) have been associated with disability progression, enhanced neurodegeneration and higher incidence of mood disorders in people with multiple sclerosis (MS). Studies in animal models of MS suggest that preventive exercise may play an immunomodulatory activity, with beneficial effects on both motor deficits and behavioral alterations. Here we explored the impact of lifestyle physical activity on clinical presentation and associated central inflammation in a large group of newly diagnosed patients with MS. Furthermore, we addressed the causal link between exercise-mediated immunomodulation and mood symptoms in the animal setting.

METHODS

A cross-sectional study was conducted on 235 relapsing-remitting MS patients at the time of the diagnosis. Patients were divided into 3 groups ("sedentary", "lifestyle physical activity" and "exercise") according to the level of physical activity in the six months preceding the evaluation. Patients underwent clinical, neuropsychological and psychiatric evaluation, magnetic resonance imaging and lumbar puncture for diagnostic purposes. The CSF levels of proinflammatory and anti-inflammatory cytokines were analyzed and compared with a group of 80 individuals with non-inflammatory and non-degenerative diseases. Behavioral and electrophysiological studies were carried out in control mice receiving intracerebral injection of IL-2 or vehicle. Behavior was also assessed in mice with experimental autoimmune encephalomyelitis (EAE), animal model of MS, reared in standard (sedentary group) or running wheel-equipped (exercise group) cages.

RESULTS

In exercising MS patients, depression and anxiety were reduced compared to sedentary patients. The CSF levels of the interleukin-2 and 6 (IL-2, IL-6) were increased in MS patients compared with control individuals. In MS subjects exercise was associated with normalized CSF levels of IL-2. In EAE mice exercise started before disease onset reduced both behavioral alterations and striatal IL-2 expression. Notably, a causal role of IL-2 in mood disorders was shown. IL-2 administration in control healthy mice induced anxious- and depressive-like behaviors and impaired type-1 cannabinoid (CB1) receptor-mediated neurotransmission at GABAergic synapses, mimicking EAE-induced synaptic dysfunction.

CONCLUSIONS

Our results indicate an immunomodulatory effect of exercise in MS patients, associated with reduced CSF expression of IL-2, which might result in reduced mood disorders. These data suggest that exercise in the early stages may act as a disease-modifying therapy in MS although further longitudinal studies are needed to clarify this issue.

Sex-Specific Environmental Impacts on Initiation and Progression of Multiple Sclerosis

The immunological mechanisms that contribute to multiple sclerosis (MS) differ between males and females. Females are 2–3 times more likely to develop MS compared to males, however the reason for this discrepancy is unknown. Once MS is established, there is a more inflammatory yet milder form of disease in females whereas males generally suffer from more severe disease and faster progression, neural degradation, and disability. Some of these differences relate to genetics, including genetic control of immune regulatory genes on the X-chromosome, as well as immune modulatory properties of sex hormones. Differences in MS development may also relate to how sex interacts with environmental risk factors. There are several environmental risk factors for MS including late-onset Epstein Barr virus infection, low serum vitamin D levels, low UV radiation exposure, smoking, obesity, and lack of physical activity. Most of these risk factors impact males and females differently, either due to biological or immunological processes or through behavioral differences. In this review, we explore these differences further and focus on how the interaction of environmental risk factors with sex hormones may contribute to significantly different prevalence and pathology of MS in males and females.

Relationships between accelerometer-measured and multiple sclerosis: a 2-sample Mendelian randomization study

BACKGROUND

Observational studies suggest that physical activity (PA) can independently modify the risk of developing multiple sclerosis (MS).

OBJECTIVE

To investigate the causal effect of PA on MS by Mendelian randomization (MR) approaches.

METHODS

Through a genome-wide association study including 91,105 participants from UK Biobank, we obtained 5 single-nucleotide polymorphisms (SNPs) associated with accelerometer-measured PA (P < 5 × 10^-8). Summary-level data for MS were obtained from a meta-analysis, incorporating 14,802 subjects with MS and 26,703 healthy controls of European ancestry. MR analyses were performed using the inverse-variance-weighted method, weighted median estimator, and MR-PRESSO method. Additional analyses were further performed using MR-Egger intercept and Cochran's Q statistic to verify the robustness of our findings.

RESULTS

We failed to detect a causal effect of PA on MS (OR, 0.60; 95% confidence interval [CI], 0.30-1.20; P = 0.15) per in the random-effects IVW analysis. Additional MR methods yielded consistent results. MR-Egger regression suggested no evidence of horizontal pleiotropy (Intercept = 0.14, P = 0.21) and there seemed no substantial heterogeneity (I² = 29.8%, P = 0.22) among individual SNPs.

CONCLUSION

Our findings suggest that enhancing PA might not modify the risk of developing MS independent of established risk factors.

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.

A systematic review of morbidities suggestive of the multiple sclerosis prodrome

INTRODUCTION

The identification of a prodromal phase in multiple sclerosis (MS) could have major implications for earlier recognition and management of MS. The authors conducted a systematic review assessing studies of morbidities before, or at, MS onset or diagnosis.Areas covered: Two independent reviewers searched Medline, Embase, Psycinfo and CINAHL from inception to February 8^th, 2019. To be eligible, studies had to be published in English and report the relative occurrence of at least one morbidity or symptom before, or at, MS onset or diagnosis among MS cases in comparison to a control group not known to have MS. Findings were narratively synthesized. Study quality was assessed using the Newcastle-Ottawa scale (NOS, maximum score 9).Expert opinion: Twenty-nine studies were included, which comprised 83,590 MS cases and 396,343 controls. Most were case-control studies (25/29), 8/29 were of high quality (NOS≥8) and 19/29 examined the period before MS symptom onset. Most studies assessing anxiety, depression, migraine and lower cognitive performance found these conditions to be more prevalent before MS onset or diagnosis relative to controls. There was limited evidence to implicate other conditions. Thus, there is evidence that anxiety, depression, migraine and lower cognitive performance form part of the MS prodrome.

Association of Obesity With Multiple Sclerosis Risk and Response to First-line Disease Modifying Drugs in Children

Importance

Obesity reportedly increases the risk of pediatric multiple sclerosis (MS), but little is known about its association with disease course.

Objective

To investigate the association of obesity with pediatric MS risk and with first-line therapy response among children with MS.

Design, Setting, and Participants

This single-center retrospective study used the medical records and database at the Center for MS in Childhood and Adolescence, Göttingen, Germany. The study included 453 patients with relapsing-remitting pediatric MS and body mass index (BMI) measurement taken within 6 months of diagnosis. Onset of the disease occurred between April 28, 1990, and June 26, 2016, and the mean disease duration was 38.4 months. Data were collected from July 14, 2016, to December 18, 2017.

Main Outcomes and Measures

Data on BMIs were stratified by sex and age using German BMI references and compared with the BMI data of 14 747 controls from a nationwide child health survey for odds ratio (OR) estimates. Baseline magnetic resonance imaging findings, intervals between first and second MS attacks, annualized relapse rates before and during treatment with interferon beta-1a or -1b and glatiramer acetate, frequency of second-line treatment, and Expanded Disability Status Scale (EDSS) scores were compared between nonoverweight (BMI≤90th percentile), overweight (BMI>90th-97th percentile), and obese (BMI>97th percentile) patients.

Results

In total, 453 patients with pediatric MS were included, of whom 306 (67.5%) were female, and the mean (SD) age at diagnosis was 13.7 (2.7) years. At diagnosis, 126 patients (27.8%) were overweight or obese, with obesity associated with statistically significant twofold odds of MS in both sexes (girls OR, 2.19; 95% CI, 1.5-3.1; P < .001 vs boys OR, 2.14; 95% CI, 1.3-3.5; P = .003). Obese patients, compared with nonoverweight patients, had statistically significantly more relapses on first-line treatment with interferon beta and glatiramer acetate (ARR, 1.29 vs 0.72; P < .001) and a higher rate of second-line treatment (21 [56.8%] of 37 vs 48 [38.7%] of 124; P = .06). Baseline neuroimaging, interval between first and second MS attacks, pretreatment relapses, and EDSS progression scores were not correlated with BMI.

Conclusions and Relevance

In this study, increased pediatric MS risk appeared to be associated with obesity, and obese patients did not respond well to first-line medications; altered pharmacokinetics appeared to be most likely factors in treatment response, suggesting that achieving healthy weight or adjusting the dose according to BMI could improve therapy response.

Preclinical disease activity in multiple sclerosis: A prospective study of cognitive performance prior to first symptom

OBJECTIVE

To prospectively investigate potential signs of preclinical multiple sclerosis (MS) activity and when they are present prior to first symptom using data from a historical cohort.

METHODS

We linked the cognitive performance of all Norwegian men born 1950-1995 who underwent conscription examination at age 18 to 19 years to the Norwegian MS registry to identify those later developing MS, and randomly selected controls frequency-matched on year of birth from the Norwegian Conscript Service database. In this nested case-control study, cognitive test scores were available for 924 male cases and 19,530 male controls. We estimated mean score differences among cases and controls (Student t test) and the risk of developing MS comparing lower to higher scores (Cox regression) in strata of years to clinical onset.

RESULTS

Men developing first clinical MS symptoms up to 2 years after the examination scored significantly lower than controls (Δ = 0.80, p = 0.0095), corresponding to a 6 intelligence quotient (IQ)-point difference. Those scoring lowest, that is, >1 standard deviation below the controls' mean, had an increased MS risk during the 2 following years (relative risk = 2.81, 95% confidence interval = 1.52-5.20). Whereas results were similar for relapsing-remitting MS cases (RRMS), those developing primary-progressive MS (PPMS) scored a significant 4.6 to 6.9 IQ points lower than controls up to 20 years prior to first progressive symptoms.

INTERPRETATION

RRMS may start years prior to clinical presentation, and disease processes in PPMS could start decades prior to first apparent progressive symptoms. Cognitive problems could be present in both MS forms before apparent symptoms. Apart from potential implications for clinical practice and research, these findings challenge our thinking about the disease. Ann Neurol 2016;80:616-624.

Body size and physical exercise, and the risk of multiple sclerosis

BACKGROUND

Whether large body size increases multiple sclerosis (MS) risk in men is not well understood. Concurrently, physical exercise could be an independent protective factor.

OBJECTIVE

To prospectively investigate the association between body mass index (BMI) and aerobic fitness, indicators of body size and exercise, and MS risk in men.

METHODS

We performed a population-based nested case-control study within the historical cohort of all Norwegian men, born in 1950-1975, undergoing mandatory conscription at the age of 19 years. 1016 cases were identified through linkage to the Norwegian MS registry, while 19,230 controls were randomly selected from the cohort. We estimated the effect of BMI and fitness at conscription on MS risk using Cox regression.

RESULTS

Higher BMI (≥25 vs 18.5-<25 kg/m²) was significantly associated with increased MS risk (adjusted relative risk (RR_adj) = 1.36, 95% confidence interval (CI): 1.05-1.76). We also found a significant inverse association between aerobic fitness (high vs low) and MS risk independent of BMI (RR_adj = 0.69, 95% CI: 0.55-0.88, p-trend = 0.003), remaining similar when men with MS onset within 10 years from conscription were excluded ( p-trend = 0.03).

CONCLUSION

These findings add weight to evidence linking being overweight to an increased MS risk in men. Furthermore, they suggest that exercise may be an additional modifiable protective factor for MS.

Physical activity is associated with a decreased multiple sclerosis risk: The EnvIMS study

Background:

The lifestyle factors smoking and obesity have been associated with the risk of multiple sclerosis (MS). Physical activity (PA) may also be of importance.

Objective:

To examine the association between PA and MS risk in Italy, Norway, and Sweden and to evaluate the possible influence by established risk factors.

Methods:

In this case–control study, 1904 cases and 3694 controls were asked to report their average weekly amounts of light and vigorous PA during adolescence on a scale ranging from none to more than 3 hours activity. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) and adjusted for potential confounders.

Results:

Vigorous PA was inversely associated with MS risk in the pooled analysis ( p-trend < 0.001) with an age- and sex-adjusted OR of 0.74 (95% CI: 0.63–0.87) when comparing the highest and lowest levels. Adjusting for outdoor activity, infectious mononucleosis, body size, and smoking yielded similar results. The association was present in all countries and was not affected by exclusion of patients with early disease onset. Light PA was not associated with the risk of MS.

Conclusion:

Our findings suggest that vigorous PA can modify the risk of developing MS independent of established risk factors.

Stress resilience and the risk of inflammatory bowel disease: a cohort study of men living in Sweden

OBJECTIVE

To determine if low psychosocial stress resilience in adolescence (increasing chronic stress arousal throughout life) is associated with an increased inflammatory bowel disease (IBD) risk in adulthood. Subclinical Crohn's disease (CD) and ulcerative colitis (UC) can exist over many years and we hypothesise that psychosocial stress may result in conversion to symptomatic disease through its proinflammatory or barrier function effects.

DESIGN

National register-based cohort study of men followed from late adolescence to middle age.

SETTING

A general population cohort of men in Sweden.

PARTICIPANTS

Swedish population-based registers provided information on all men born between 1952 and 1956 who underwent mandatory Swedish military conscription assessment (n=239 591). Men with any gastrointestinal diagnoses (except appendicitis) prior to follow-up were excluded.

PRIMARY OUTCOME MEASURES

An inpatient or outpatient diagnosis of CD or UC recorded in the Swedish Patient Register (1970-2009).

RESULTS

A total of 938 men received a diagnosis of CD and 1799 UC. Lower stress resilience in adolescence was associated with increased IBD risk, with unadjusted HRs (95% CIs) of 1.54 (1.26 to 1.88) and 1.24 (1.08 to 1.42), for CD and UC, respectively. After adjustment for potential confounding factors, including markers of subclinical disease activity in adolescence, they are 1.39 (1.13 to 1.71) and 1.19 (1.03 to 1.37).

CONCLUSIONS

Lower stress resilience may increase the risk of diagnosis of IBD in adulthood, possibly through an influence on inflammation or barrier function.

Multiple sclerosis and risk of young-adult-onset Hodgkin lymphoma

Objective:

To determine whether there is an association between multiple sclerosis (MS) and young-adult-onset Hodgkin lymphoma (YAHL) as this will signal etiologic similarities relevant both to inherited characteristics and environmental exposures in childhood.

Methods:

Swedish general population registers identified a cohort of 29,617 with an MS diagnosis between 1968 and 2012, matched with a cohort of 296,164 without MS. Cox regression was used to assess the association of MS with subsequent YAHL (defined as onset between ages 15 and 39 years; n = 20), with adjustment, for age/period, sex, county of residence, and level of education.

Results:

The adjusted hazard ratio (and 95% confidence interval) for the association of MS with YAHL is 3.30 (1.01–10.73), resulting from 4 and 16 events in the MS and non-MS cohorts, respectively. All 4 of the YAHL diagnoses in MS occurred in women, and the association of MS with YAHL has a hazard ratio of 4.04 (1.17–13.94) among women. There was no notable association of MS with older-onset Hodgkin lymphoma.

Conclusion:

There may be common risks for YAHL and MS, consistent with an etiologic role in MS for early-life exposures, such as to infectious agents.