Health phenome of Parkinson's patients reveals prominent mood-sleep cluster

Background

Associations between phenotypic traits, environmental exposures, and Parkinson's disease have largely been evaluated one-by-one, piecemeal, and pre-selections. A comprehensive picture of comorbidities, phenotypes, exposures, and polypharmacy characterizing the complexity and heterogeneity of real-world patients presenting to academic movement disorders clinics in the US is missing.

Objectives

To portrait the complexity of features associated with patients with Parkinson's disease in a study of 933 cases and 291 controls enrolled in the Harvard Biomarkers Study.

Methods

The primary analysis evaluated 64 health features for associations with Parkinson's using logistic regression adjusting for age and sex. We adjusted for multiple testing using the false discovery rate (FDR) with £ 0.05 indicating statistical significance. Exploratory analyses examined feature correlation clusters and feature combinations.

Results

Depression (OR = 3.11, 95% CI 2.1 to 4.71), anxiety (OR = 3.31, 95% CI 2.01-5.75), sleep apnea (OR 2.58, 95% CI 1.47-4.92), and restless leg syndrome (RLS; OR 4.12, 95% CI 1.81-12.1) were significantly more common in patients with Parkinson's than in controls adjusting for age and sex with FDR £ 0.05. The prevalence of depression, anxiety, sleep apnea, and RLS were correlated, and these diseases formed part of a larger cluster of mood traits and sleep traits linked to PD. Exposures to pesticides (OR 1.87, 95% CI 1.37-2.6), head trauma (OR 2.33, 95% CI 1.51-3.73), and smoking (OR 0.57, 95% CI 0.43-0.75) were significantly associated with the disease consistent with previous studies. Vitamin supplementation with cholecalciferol (OR 2.18, 95% CI 1.4-3.45) and coenzyme Q10 (OR 2.98, 95% CI 1.89-4.92) was more commonly used by patients than controls. Cumulatively, 43% (398 of 933) of Parkinson's patients had at least one psychiatric or sleep disorder, compared to 21% (60 of 291) of healthy controls.

Conclusions

43% of Parkinson's patients seen at Harvard-affiliated teaching hospitals have depression, anxiety, and disordered sleep. This syndromic cluster of mood and sleep traits may be pathophysiologically linked and clinically important.

Childbirth delivery mode and the risk of multiple sclerosis: a prospective population-based study

BACKGROUND

Caesarean section (CS) may affect the risk of developing multiple sclerosis (MS) in the offspring, possibly through changes in gut microbiota composition, but findings from previous studies are inconsistent. We investigated whether birth by CS was associated with the risk of adult-onset MS.

METHODS

We conducted a prospective population-based cohort study, including all individuals born in Norway between 1967 and 2003, using the Medical Birth Registry of Norway linked with the Norwegian Multiple Sclerosis Registry and Biobank. The follow-up was until 2021. We used multivariable Cox models to estimate HRs for MS risk with 95% CIs.

RESULTS

Among 2 046 637 individuals in the cohort, 4954 MS cases were identified. Being born by CS was associated with a modest increase in MS risk (HR=1.18, 95% CI 1.05 to 1.32). In the sibling-matched analysis, we found no association between CS and MS risk. We found an interaction between CS and gestational age (p=0.03): CS was associated with an increased risk of MS in individuals born preterm (HR=1.62, 95% CI 1.18 to 2.24), whereas there was no association in individuals born at term (HR=1.13, 95% CI 0.99 to 1.27). In a subgroup analysis of individuals born in 1988 and onwards, emergency CS was related to an elevated MS risk (HR=1.40, 95% CI 1.07 to 1.83), whereas planned CS was not (HR: 1.10, 95% CI 0.77 to 1.58).

CONCLUSIONS

CS was associated with a modestly higher risk of developing MS. However, the stronger associations seen in subgroups who likely experienced a more complicated pregnancy/delivery may point to confounding underlying these associations.

Association Between Use of Any of the Drugs Prescribed in Norway and the Subsequent Risk of Parkinson Disease: A Drug-wide Association Study

BACKGROUND AND OBJECTIVES

The incidence rate of Parkinson disease (PD) has been increasing rapidly during the past years. Yet, no treatments exist to prevent or slow the progression of the disease. Moreover, we are unable to detect early disease stages during which intervention with disease-modifying therapies is most likely to succeed. The objective of this study was to perform an agnostic drug-wide association study estimating the association between the use of any of the drugs prescribed in Norway and the subsequent risk of PD.

METHODS

This registry-based cohort study use data from the entire Norwegian population between 2004 and 2019 linked to the Norwegian Prescription Registry, with more than 600 million individual prescriptions. Drug classes were screened according to Anatomical Therapeutic Chemical codes at level 2, corresponding to therapeutic subgroups. We used Cox regression models to estimate hazard ratios (HRs) and 95% CIs for the associations between drug classes and PD risk. All p values were corrected for multiple testing using the false discovery rate. In addition, we conducted sensitivity analyses of exposure definition as well as time-lag and dose-response analyses.

RESULTS

The study population comprised 3,223,672 individuals, 15,849 of whom developed PD during the follow-up. We identified 31 drug classes that were statistically significantly associated with PD risk in Norway during the follow-up. Drugs acting on the renin-angiotensin system (HR 0.92, 95% CI 0.89-0.95), corticosteroids for systemic use (0.88, 95% CI 0.84-0.93), and vaccines (0.89, 95% CI 0.82-0.96) were associated with a decreased risk of PD even up to 10 years before PD onset. Drug classes used to treat symptoms related to prodromal signs of PD, such as constipation, urological issues, and depression, were associated with an increased risk of subsequent diagnosis of PD with HRs of 1.6 (95% CI 1.49-1.73), 1.48 (1.42-1.53), and 1.94 (1.87-2.01), respectively.

DISCUSSION

This drug-wide study identified 31 drug classes that were associated with the PD risk change. It reveals the links of renin-angiotensin system medications, vaccines, and corticosteroids with PD risk and suggests that monitoring drug usage using pharmacoepidemiology may allow identifying individuals with prodromal PD.

Beta2-adrenoreceptor agonists and long-term risk of Parkinson's disease

INTRODUCTION

There is limited information on how the association between Parkinson's disease and the use of beta2-adrenoreceptor (β2AR) agonists varies among groups of short-, long-, and ultra-long-acting β2AR agonists (SABA, LABA and ultraLABA).

METHODS

In this prospective study of the Norwegian population, we estimated the incidence of Parkinson's disease according to exposure to β2AR agonists as a time-dependent variable by means of Cox regression. We adjusted for educational level, comorbidity and performed a sensitivity analysis excluding individuals with chronic obstructive pulmonary disease (COPD), all factors associated with smoking. Anticholinergics and corticosteroids as drugs with the same indication were analyzed for comparison.

RESULTS

In the follow-up period from 2005 to 2019, 15,807 incident Parkinson's cases were identified. After adjustments for sex, education and age as the timescale, SABA (Hazard ratio (HR) = 0.84; 95%CI: 0.79, 0.89; p < 0.001), LABA (HR = 0.85; 95%CI: 0.81, 0.90; p < 0.001) and ultraLABA (HR = 0.6; 95%CI: 0.49, 0.73; p < 0.001) were all associated with a lower risk of Parkinson's disease. After exclusion of COPD patients, corticosteroids and anticholinergics were no longer inversely associated, whereas β2AR agonists remained associated.

CONCLUSION

Of drugs with the same indication of use, only β2AR agonists remained inversely associated with PD risk after all adjustments, with ultraLABA displaying the overall strongest association. Although the precision of the estimate is limited by the modest number of exposed PD cases without COPD, the association is intriguing and suggest that longer-acting, more lipophilic, and thus likely more brain-penetrant β2AR agonists could be prioritized for further studies.

Association of adverse childhood experiences with the development of multiple sclerosis

OBJECTIVE

To study whether exposure to childhood emotional, sexual or physical abuse is associated with subsequent multiple sclerosis (MS) development.

METHODS

A nationwide, prospective cohort study based on participants in the Norwegian Mother, Father and Child cohort study. Enrolment took place 1999-2008, with follow-up until 31 December 2018. Childhood abuse before age 18 years was obtained from self-completed questionnaires. We identified MS diagnoses through data-linkage with national health registries and hospital records. The Cox model was used to estimate HRs for MS with 95% CIs, adjusting for confounders and mediators.

RESULTS

In this prospective cohort study, 14 477 women were exposed to childhood abuse and 63 520 were unexposed. 300 women developed MS during the follow-up period. 71 of these (24%) reported a history of childhood abuse, compared with 14 406 of 77 697 (19%) women that did not develop MS. Sexual abuse (HR 1.65, 95% CI 1.13 to 2.39) and emotional abuse (HR 1.40, 95% CI 1.03 to 1.90) in childhood were both associated with an increased risk of developing MS. The HR of MS after exposure to physical abuse was 1.31 (95% CI 0.83 to 2.06). The risk of MS was further increased if exposed to two (HR 1.66, 95% CI 1.04 to 2.67) or all three abuse categories (HR 1.93, 95% CI 1.02 to 3.67).

INTERPRETATION

Childhood sexual and emotional abuse were associated with an increased risk of developing MS. The risk was higher when exposed to several abuse categories, indicating a dose-response relationship. Further studies are needed to identify underlying mechanisms.

Incidence of cancer in multiple sclerosis before and after the treatment era- a registry- based cohort study

BACKGROUND

Whether disease-modifying therapies (DMTs) influence cancer in multiple sclerosis (MS) is uncertain.

OBJECTIVES

Assess incidence of cancer diagnosis among Norwegian MS patients compared to the general population in 1953 to 1995 and 1996 to 2017-reflecting era before and after introduction of DMTs.

METHODS

We performed a nationwide cohort study comprising 6949 MS patients and 37,922 controls, matched on age, sex and county. The cohort was linked to Norwegian Cancer Registry, Cause of Death Registry and National Educational database. We used Poisson regression to calculate incidence rate ratio (IRR) of cancer.

RESULTS

During 1953-1995 MS patients had similar cancer frequency compared to controls (IRR: 1.11 (95% Confidence Intervals (CI): 0.90-1.37)), although MS patients had increased frequency of cancer in endocrine glands (IRR: 2.51 (1.27-4.93). During 1996-2017 we identified significant increased frequency of cancer among MS patients compared to controls (IRR: 1.38 (95% CI: 1.28-1.52): in brain (IRR: 1.97 (1.41-2.78)), meninges (IRR: 2.44 (1.54-3.77)), respiratory organs (IRR: 1.96 (1.49-2.63)). The excess cancer diagnosis was most frequent among MS patients ≥ 60 years of age (HR 1.30 (1.15-1.47)).

CONCLUSION

Incidence of cancer among MS patients compared to controls was higher in 1996 to 2017, corresponding in time to the introduction of DMT for MS. This was observed more frequently among MS patients older than 60 years of age.

Exposure to breastfeeding and risk of developing multiple sclerosis

BACKGROUND

Early-life factors are reported to modulate the risk of developing multiple sclerosis (MS) among adults. The association between exposure to breastfeeding and the risk of MS is debated. We aimed to disclose whether past exposure to breastfeeding and its duration are associated with the risk of developing MS.

METHODS

We used a cohort design linking prospectively collected information on breastfeeding from the Cohort of Norway community-based surveys on health status (CONOR) with the Norwegian MS Registry and the population-based Medical Birth Registry of Norway that includes information on all births in Norway since 1967. MS clinical onset was collected throughout 2016. A total of 95 891 offspring born between 1922 and 1986 to mothers participating in CONOR were included. We identified 215 offspring within this cohort who developed adult-onset MS. Associations between breastfeeding and MS risk were estimated as hazard ratios using Cox proportional hazard models adjusting for maternal factors including education.

RESULTS

We found no association between having been breastfed for ≥4 months and MS risk, also after adjusting for various maternal factors (hazard ratio = 0.90; 95% confidence interval 0.68-1.19). The estimates did not change for different durations of breastfeeding. The results were similar when adjusting for other perinatal factors.

CONCLUSION

Our study could not confirm previous findings of an association between breastfeeding and risk of MS. Breastfeeding information was less likely to be biased by knowledge of disease compared with case-control studies.

Antibiotic Use and Risk of Multiple Sclerosis: A Nested Case-Control Study in Emilia-Romagna Region, Italy

INTRODUCTION

Known risk factors for multiple sclerosis (MS) include smoking, a low vitamin D status, obesity, and EBV, while the inflammatory feature of the disease strongly suggests the presence of additional infectious agents. The association between use of antibiotics and MS risk that could shed light on these factors is still undetermined. We aimed to evaluate the association between antibiotics and MS risk, in the Emilia-Romagna region (RER), Italy.

METHODS

All adult patients with MS seen at any RER MS center (2015-2017) were eligible. For each of the 877 patients included, clinical information was collected and matched to 5 controls (RER residents) (n = 4,205) based on age, sex, place of residence, and index year. Information on antibiotic prescription was obtained through the linkage with the RER drug prescription database.

RESULTS

Exposure to any antibiotic 3 years prior to the index year was associated with an increased MS risk (OR = 1.52; 95% CI = 1.29-1.79). Similar results were found for different classes. No dose-response effect was found.

DISCUSSION/CONCLUSIONS

Our results suggest an association between the use of antibiotics and MS risk in RER population. However, further epidemiological studies should be done with information on early life and lifestyle factors.

Perinatal Depression and Anxiety in Women With Multiple Sclerosis: A Population-Based Cohort Study

Objective

To assess the occurrence of perinatal depression and anxiety in women before and after diagnosis of multiple sclerosis (MS).

Methods

A total of 114,629 pregnant women were included in the Norwegian Mother, Father and Child Cohort study (1999–2008). We assessed depression and anxiety by questionnaires during and after pregnancy. Women with MS were identified from national health registries and hospital records and grouped into (1) MS diagnosed before pregnancy (n = 140) or MS diagnosed after pregnancy with (2) symptom onset before pregnancy (n = 98) or (3) symptom onset after pregnancy (n = 308). Thirty-five women were diagnosed with MS in the postpartum period. The reference group (n = 111,627) consisted of women without MS.

Results

Women with MS diagnosed before pregnancy had an adjusted odds ratio of 2.0 (95% confidence interval, 1.2–3.1) for depression in the third trimester. Risk factors were adverse socioeconomic factors and history of psychiatric disease and physical/sexual abuse. The risk of anxiety was not increased. Women diagnosed with MS in the postpartum period had especially high risk of postpartum depression. Women with MS symptom onset within 5 years after pregnancy had increased risk of both depression and anxiety during pregnancy, whereas women with more than 5 years until symptom onset did not.

Conclusion

Women diagnosed with MS have increased risk of perinatal depression. Women with MS symptom onset within 5 years after pregnancy have increased risk of both depression and anxiety during pregnancy.

Low vitamin D, but not tobacco use or high BMI, is associated with long-term disability progression in multiple sclerosis

BACKGROUND

Low vitamin D levels, tobacco use and high body mass index (BMI) have been linked to adverse disease outcomes in multiple sclerosis (MS), but their influence on long-term disability progression remains unclear. Therefore, we explored whether these modifiable lifestyle factors were associated with 10-year clinical disability progression in patients with MS.

METHODS

In this prospective study, a cohort of 88 patients with relapsing-remitting MS completed a randomized controlled study on ω-3 fatty acids between 2004 and 2008. During 24 months, serum 25-hydroxyvitamin D (25(OH)D), serum cotinine (nicotine metabolite), and BMI were repeatedly measured. In 2017, a follow-up study was conducted among 80 of the participants, including disability assessment by the Expanded Disability Status Scale (EDSS). Linear regression was used to explore associations between the lifestyle factors and the EDSS change over 10 years.

RESULTS

Higher seasonally adjusted 25(OH)D levels were associated with lower 10-year EDSS progression (change in EDSS per 1 SD increase in 25(OH)D in a model adjusted for sex, age and baseline EDSS: -0.45 point, 95% CI: -0.75 to -0.16, p=0.003). Further adjustments for potential confounders related to lifestyle and disease status gave similar results. The association was mainly driven by low 25(OH)D levels during spring, as well as seasonally adjusted levels below 80 nmol/L. No clear association was found for BMI and cotinine.

CONCLUSION

Lower 25(OH)D levels, but apparently not tobacco use or higher BMI, were significantly associated with worse long-term disability progression in MS.

Shedding light on the link between early life sun exposure and risk of multiple sclerosis: results from the EnvIMS Study

BACKGROUND

Lower levels of sun exposure in childhood have been suggested to be associated with increased risk of multiple sclerosis (MS). In this paper we extend previous work, using two novel analytical strategies.

METHODS

Data collected in the Environmental risk factors In MS (EnvIMS) study, a case-control study with MS cases and population-based controls from Canada, Italy and Norway, were used. Participants reported on sun exposure behaviours for 5-year age intervals from birth; we focused on the first three age intervals (≤15 years). We compared two life course epidemiology conceptual models, the critical period and the accumulation model. We also used latent class analysis to estimate MS risk for different latent sun exposure behaviour groups.

RESULTS

The analyses included 2251 cases and 4028 controls. The accumulation model was found to be the best model, which demonstrated a nearly 50% increased risk of MS comparing lowest reported summer sun exposure with highest [risk ratio (RR) = 1.47 (1.24, 1.74)]. The latent sun exposure behaviour group, characterized by low sun exposure during summer and winter and high sun protection use, had the highest risk of MS; a 76% increased risk as compared with the group with high sun exposure and low sun protection use [RR = 1.76 (1.27, 2.46)].

CONCLUSIONS

Our analyses provide novel insights into the link between sun exposure and MS. We demonstrate that more time indoors during childhood and early adolescence is linked with MS risk, and that sun protection behaviours in those who spend most time indoors may play a key role in increasing risk.

Risk of cancer among multiple sclerosis patients, siblings, and population controls: A prospective cohort study

Background:

Risk of cancer in multiple sclerosis (MS) patients compared to their siblings is unknown.

Objective:

The objective was to prospectively investigate the risk of cancer among MS patients compared to siblings without MS and to population controls.

Methods:

We retrieved data on MS patients born between 1930 and 1979 from the Norwegian Multiple Sclerosis Registry and population studies and on cancer diagnosis from the Cancer Registry of Norway. We used adjusted Cox proportional hazard regression to estimate cancer risk among 6883 MS patients, 8918 siblings without MS, and 37,919 population controls.

Results:

During 65 years of follow-up, cancer risk among MS patients was higher than that among population controls (hazard ratio (HR) = 1.14, 95% confidence interval (CI): 1.05–1.23) in respiratory organs (HR = 1.66, 95% CI: 1.26–2.19), urinary organs (HR = 1.51, 95% CI: 1.12–2.04), and the central nervous system (HR = 1.52, 95% CI: 1.11–2. 09). Siblings had higher risk of hematological cancers compared with MS patients (HR = 1.82, 95% CI: 1.21–2.73) and population controls (HR = 1.72, 95% CI: 1.36–2.18).

Conclusion:

MS patients were associated with increased risk of cancer compared to population controls. Siblings had increased risk of hematological cancer. This indicates that MS and hematological cancer could share a common etiology.

Liver injury with drugs used for multiple sclerosis: A contemporary analysis of the FDA Adverse Event Reporting System

Background:

Drug-induced liver injury (DILI) has been observed in patients with multiple sclerosis (MS), raising concerns on the liver safety of MS drugs.

Objective:

To describe DILI events with MS drugs by analyzing the FDA Adverse Event Reporting System.

Methods:

DILI reports were extracted and classified in overall liver injury (OLI), including asymptomatic elevation of liver enzymes, and severe liver injury (SLI). We performed disproportionality analysis by calculating adjusted reporting odds ratios (RORs) with 95% confidence interval (CI) and case-by-case evaluation for concomitant drugs with hepatotoxic potential.

Results:

Fampridine showed statistically significant ROR for both OLI and SLI, whereas teriflunomide and fingolimod generated solid disproportionality (ROR > 2) only for OLI (ROR, 2.31; 95% CI, 2.12–2.52; and 2.53; 2.40–2.66, respectively). Among monoclonal antibodies, only alemtuzumab generated higher-than-expected ROR for OLI (1.34; 1.09–1.65). We also detected the expected hepatotoxic potential of beta interferon and mitoxantrone. Concomitant reporting of hepatotoxic drugs ranged from 26% (dimethyl fumarate) to 90% (mitoxantrone).

Conclusion:

These real-world pharmacovigilance findings suggest that DILI might be a common feature of MS drugs and call for (1) formal population-based study to verify the risk of fampridine and (2) awareness by clinicians, who should assess the possible responsibility of MS drugs when they diagnose DILI.

Evidence-based practice profiles among bachelor students in four health disciplines: a cross-sectional study

BACKGROUND

Despite the recognition of integrating evidence-based practice (EBP) in educational programs, there is limited research about bachelor students' EBP profiles (EBP knowledge, attitudes and behaviour) in the health disciplines nursing, occupational therapy, physiotherapy and radiography. The aim of this study was to assess EBP profiles among bachelor students in health disciplines, and explore differences between health disciplines, educational institutions, students' assessment of EBP teaching and expectations of EBP performance.

METHODS

A survey using the 'Evidence-Based Practice Profile - Norwegian version' (EBP²-N) was conducted among final year bachelor students in health disciplines from four educational institutions. The questionnaire consisted of five domains (Relevance, Terminology, Confidence, Practice and Sympathy) and assessed the five steps of EBP. We performed regression analyses to analyse mean differences in domain scores between health disciplines, Cohen's d to illustrate the magnitude of the largest difference in each domain, Omega squared to describe portion of variance in domain scores, and Spearman's rho (r_s) to assess the monotonic relationship between EBP²-N domains and assessment of EBP teaching and expectations of EBP performance, respectively.

RESULTS

Students reported highest overall mean score for Relevance, with an estimated standardized mean of 81.2 (CI 95% = 80.4-82.0). The other EBP²-N domains had estimated standardized means of 54 and less. Statistically significant differences (p < 0.03) between health disciplines were observed for all domains. The largest mean difference was found for Relevance with highest score for occupational therapy and lowest for radiography, with an estimated Cohen's d of 1.11. Moderate positive associations were observed between Relevance scores and students' assessment of EBP teaching (r_s = 0.31), and expectations of EBP performance from teachers (r_s = 0.36). We also observed a moderate positive correlation between Confidence and students' assessment of EBP teaching (r_s = 0.46).

CONCLUSION

Bachelor students in health disciplines found EBP relevant, but revealed low understanding of EBP terminology, low confidence with EBP skills, and low use of EBP in clinical situations. We observed differences in EBP profiles between health disciplines and between educational institutions. The differences in scores raise questions about the understanding of EBP within disciplines, and the complexity of EBP in educational settings.

Self-reported and objectively assessed knowledge of evidence-based practice terminology among healthcare students: A cross-sectional study

Background

Self-reported scales and objective measurement tools are used to evaluate self-perceived and objective knowledge of evidence-based practice (EBP). Agreement between self-perceived and objective knowledge of EBP terminology has not been widely investigated among healthcare students.

Aim

The aim of this study was to examine agreement between self-reported and objectively assessed knowledge of EBP terminology among healthcare students. A secondary objective was to explore this agreement between students with different levels of EBP exposure.

Methods

Students in various healthcare disciplines and at different academic levels from Norway (n = 336) and Canada (n = 154) were invited to answer the Terminology domain items of the Evidence-Based Practice Profile (EBP²) questionnaire (self-reported), an additional item of ‘evidence based practice’ and six random open-ended questions (objective). The open-ended questions were scored on a five-level scoring rubric. Interrater agreement between self-reported and objective items was investigated with weighted kappa (K_w). Intraclass correlation coefficient (ICC) was used to estimate overall agreement.

Results

Mean self-reported scores varied across items from 1.99 (‘forest plot’) to 4.33 (‘evidence-based practice’). Mean assessed open-ended answers varied from 1.23 (‘publication bias’) to 2.74 (‘evidence-based practice’). For all items, mean self-reported knowledge was higher than that assessed from open-ended answers (p<0.001). Interrater agreement between self-reported and assessed open-ended items varied (K_w = 0.04–0.69). The overall agreement for the EBP² Terminology domain was poor (ICC = 0.29). The self-reported EBP² Terminology domain discriminated between levels of EBP exposure.

Conclusion

An overall low agreement was found between healthcare students’ self-reported and objectively assessed knowledge of EBP terminology. As a measurement tool, the EBP² Terminology scale may be useful to differentiate between levels of EBP exposure. When using the scale as a discriminatory tool, for the purpose of academic promotion or clinical certification, users should be aware that self-ratings would be higher than objectively assessed knowledge.

α-Linolenic acid is associated with MRI activity in a prospective cohort of multiple sclerosis patients

BACKGROUND

The plant-based ω-3 fatty acid α-linolenic acid (ALA) has been associated with lower MS risk. It is currently unknown whether ALA affects disease activity.

OBJECTIVE

To investigate the association between ALA levels and disease activity.

METHODS

We conducted a cohort study including 87 multiple sclerosis (MS)-patients who originally participated in a randomized trial of ω-3 fatty acids (the OFAMS study). We measured serum levels of ALA during follow-up and used random intercept logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CIs) for the association between ALA levels, new magnetic resonance imaging (MRI) lesions, Expanded Disability Status Scale (EDSS) progression and new relapses adjusting for age at inclusion, sex, and use of interferon beta-1a.

RESULTS

In continuous (per 1-SD increase) multivariable-adjusted analyses, higher ALA levels were significantly associated with lower odds of new T2-lesions (OR: 0.59, 95% CI: 0.37-0.95) during follow-up. The effect estimates were similar for new T1Gd + lesions (OR: 0.73, 95% CI: 0.48-1.11), EDSS-progression (OR: 0.62, 95% CI: 0.34-1.16) and new relapses (OR: 0.49, 95% CI: 0.22-1.10), but these estimates did not reach statistical significance. Further adjustment for vitamin D and tobacco use did not materially change the results.

CONCLUSION

We found that higher levels of ALA were associated with lower disease activity in MS-patients.

β2-Adrenoreceptor is a regulator of the α-synuclein gene driving risk of Parkinson's disease

Copy number mutations implicate excess production of α-synuclein as a possibly causative factor in Parkinson's disease (PD). Using an unbiased screen targeting endogenous gene expression, we discovered that the β2-adrenoreceptor (β2AR) is a regulator of the α-synuclein gene (SNCA). β2AR ligands modulate SNCA transcription through histone 3 lysine 27 acetylation of its promoter and enhancers. Over 11 years of follow-up in 4 million Norwegians, the β2AR agonist salbutamol, a brain-penetrant asthma medication, was associated with reduced risk of developing PD (rate ratio, 0.66; 95% confidence interval, 0.58 to 0.76). Conversely, a β2AR antagonist correlated with increased risk. β2AR activation protected model mice and patient-derived cells. Thus, β2AR is linked to transcription of α-synuclein and risk of PD in a ligand-specific fashion and constitutes a potential target for therapies.

Diabetes is associated with decreased migraine risk: A nationwide cohort study

Background Results from studies on diabetes and migraine risk are conflicting, which may be due to methodological limitations. Prospective studies with long follow-up could increase our understanding of the relationship between the two diseases. Method We performed a cohort study including the whole Norwegian population alive on 01.01.2004, using prescriptions registered in the Norwegian prescription database to identify individuals developing type 1 diabetes, type 2 diabetes and migraine during follow-up (10 years). We used Cox proportional hazards regression to estimate rate ratios with corresponding 95% confidence intervals for the effect of diabetes on migraine risk, adjusting for age, sex, and educational level. Result We identified 7,883 type 1 diabetes patients and 93,600 type 2 patients during the study period. Type 1 diabetes was significantly associated with a subsequent decreased migraine risk during follow-up in the age- and sex-adjusted analyses (0.74; 0.61-0.89). Type 2 diabetes was also associated with a significantly lower migraine risk (0.89; 0.83-0.95). Further adjustment for educational level yielded similar results for both diabetes. Conclusion Both type 1 and type 2 diabetes were significantly associated with a decreased risk of migraine. This suggests that diabetes or diabetes treatment may have a protective effect on the development of migraine.

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.

Bakers' exposure to flour dust

We aimed to characterize bakers' personal exposure to airborne flour dust with respect to the health-related aerosol fractions inhalable, extrathoracic, and thoracic dust, and to examine possible production-related determinants of dust exposure. Sixty-eight bakers from 7 bakeries in Bergen, Norway (2009-2012) participated in the exposure assessment, comprising full-shift personal samples of inhalable dust (n = 107) and thoracic dust (n = 61). The relation between possible determinants and exposure was estimated using mixed effects models, while associations between the various aerosol fractions across task groups and type of bakeries were described by Pearson's correlation coefficients. Bakers' overall geometric mean personal exposure to inhalable, extrathoracic, and thoracic dust were 2.6 mg/m³ (95% CI: 2.0, 3.2), 2.2 mg/m³ (95% CI: 1.9, 2.7), and 0.33 mg/m³ (95% CI 0.3, 0.4), respectively. A total of 29% of the measurements of inhalable dust were above the Norwegian Occupational Exposure Limit of 3 mg/m³. The exposure variability of inhalable dust could not be explained by any of the examined production-related determinants, while the daily production volume explained 18% of the variance in thoracic dust exposure. Overall, the thoracic dust represented 15% of the inhalable dust, being rather stable across the production-related determinants. The overall correlation between inhalable and thoracic dust was nevertheless moderate (r = 0.52, p < 0.001), with the highest correlation for craft bakers (r = 0.62) and no correlation during dough forming (r = 0.01). Bakers are exposed to flour dust at a level that most likely represents an excess risk of developing chronic diseases of the respiratory system, and a decrease of present exposure level is imperative. Extrathoracic dust-likely the most relevant sub-fraction in respect to flour-induced sensitization and occupational rhinitis-represented the main proportion of the measured inhalable dust. The variation in correlation coefficients between the dust fractions across bakery types and task groups underlines the need of more knowledge about how these aerosol fractions are distributed across the production process and bakery types.

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.

Level of education and multiple sclerosis risk over a 50-year period: Registry-based sibling study

BACKGROUND

The conflicting results from studies on socioeconomic status (SES) and multiple sclerosis (MS) risk might be due to a change in the distribution of environmental exposures over time or to methodological limitations in previous research.

OBJECTIVE

To examine the association between SES and MS risk during 50 years.

METHODS

We included patients registered in Norwegian MS registries and prevalence studies born between 1930 and 1979, and identified their siblings and parents using the Norwegian Population Registry. Information on education was retrieved from the National Education Registry, categorized into four levels (primary, secondary, undergraduate and graduate) and compared in patients and siblings using conditional logistic regression.

RESULTS

A total of 4494 MS patients and 9193 of their siblings were included in the analyses. Level of education was inversely associated with MS risk ( p trend < 0.001) with an odds ratio (OR) of 0.73 (95% confidence interval (CI): 0.59-0.90) when comparing the highest and lowest levels. The effect estimates did not vary markedly between participants born before or after the median year of birth (1958), but we observed a significant effect modification by parental education ( p = 0.047).

CONCLUSION

Level of education was inversely associated with MS risk, and the estimates were similar in the earliest and latest birth cohorts.

Environmental modifiable risk factors for multiple sclerosis: Report from the 2016 ECTRIMS focused workshop

Multiple sclerosis (MS) is an inflammatory and neurodegenerative demyelinating disease of the central nervous system (CNS), most likely autoimmune in origin, usually beginning in early adulthood. The aetiology of the disease is not well understood; it is viewed currently as a multifactorial disease which results from complex interactions between genetic predisposition and environmental factors, of which a few are potentially modifiable. Improving our understanding of these factors can lead to new and more effective approaches to patient counselling and, possibly, prevention and management of the disease. The 2016 focused workshop of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) addressed the topic of environmental, modifiable risk factors for MS, gathering experts from around the world, to collate experimental and clinical research into environmental factors that have been associated with the disease onset and, in a few cases, disease activity and progression. A number of factors, including infections, vitamin D deficiency, diet and lifestyle factors, stress and comorbidities, were discussed. The meeting provided a forum to analyse available evidence, to identify inconsistencies and gaps in current knowledge and to suggest avenues for future research.

Negative interaction between smoking and EBV in the risk of multiple sclerosis: The EnvIMS study

Background:

Results from previous studies on a possible interaction between smoking and Epstein–Barr virus (EBV) in the risk of multiple sclerosis (MS) are conflicting.

Objectives:

To examine the interaction between smoking and infectious mononucleosis (IM) in the risk of MS.

Methods:

Within the case–control study on Environmental Factors In Multiple Sclerosis (EnvIMS), 1904 MS patients and 3694 population-based frequency-matched healthy controls from Norway, Italy, and Sweden reported on prior exposure to smoking and history of IM. We examined the interaction between the two exposures on the additive and multiplicative scale.

Results:

Smoking and IM were each found to be associated with an increased MS risk in all three countries, and there was a negative multiplicative interaction between the two exposures in each country separately as well as in the pooled analysis ( p = 0.001). Among those who reported IM, there was no increased risk associated with smoking (odds ratio (OR): 0.95, 95% confidence interval (CI): 0.66–1.37). The direction of the estimated interactions on the additive scale was consistent with a negative interaction in all three countries (relative excess risk due to interaction (RERI): −0.98, 95% CI: −2.05–0.15, p = 0.09).

Conclusion:

Our findings indicate competing antagonism, where the two exposures compete to affect the outcome.

Prevalence of bladder, bowel and sexual problems among multiple sclerosis patients two to five years after diagnosis

Most multiple sclerosis (MS) patients experience some sexual, bladder and/or bowel dysfunction during the course of the disease - one of MS most disabling features. This study estimated the frequency of these problems among patients, two to five years after diagnosis, and investigated how these problems are associated with health-related quality of life (using the Multiple Sclerosis Quality of Life-54 questionnaire). The study population comprised a cohort of patients (n=56), diagnosed in a three-year period, in Hordaland County, Norway. The patients were examined clinically, including scoring of the Expanded Disability Status Scale (EDSS), and completed questionnaires related to bowel and bladder dysfunction, sexual problems and health-related quality of life. More than half the patients had bladder and sexual problems. The frequency of self-reported bladder problems corresponded to the relatively high levels of residual urine found. The presence of these problems was associated with lower scores on the quality of life scales. Further, the bowel problems reported were markedly associated with the quality of life scores. Since treatments and preventive strategies can manage many of these problems, we suggest increasing the focus on these aspects of the disease when consulting patients, including at early stages.

Vitamin D, HLA-DRB1 and Epstein-Barr virus antibody levels in a prospective cohort of multiple sclerosis patients

BACKGROUND AND PURPOSE

Our objective was to study the association between serum levels of anti Epstein-Barr virus nuclear antigen 1 (EBNA-1) antibody and 25-hydroxyvitamin D (25(OH)D) in a prospective cohort of patients with relapsing-remitting multiple sclerosis.

METHOD

The study comprised 90 patients with relapsing-remitting multiple sclerosis, all participants in a randomized clinical trial of ω-3 fatty acids (the OFAMS study). Repeated, paired measurements of serum 25(OH)D and serum EBNA-1 immunoglobulin G (IgG) levels were obtained at baseline and every 6 months for 24 months. The association between serum EBNA-1 IgG and serum 25(OH)D levels was analysed using generalized linear models for hierarchical data.

RESULTS

There was a significant variation in EBNA-1 IgG antibody level between sampling months (Fdf 11 = 1.8, P = 0.043, one-way anova). There was a negative association between EBNA-1 IgG and 25(OH)D [B = -0.230, 95% confidence interval (CI) (-0.440, -0.023), P = 0.030] and a positive association between EBNA-1 IgG and HLA-DRB1*15 positive status [B = 94.7, 95% CI (2.423, 186.9), P = 0.044]. The association between 25(OH)D and EBNA-1 IgG remained significant after adjusting for the patient's age, gender, HLA-DRB1*15, retinol levels and interferon β-1a treatment.

CONCLUSION

Our study demonstrates monthly differences in EBNA-1 IgG levels and an association between EBNA-1 IgG, 25(OH)D levels and HLA-DRB1*15. These results indicate that EBNA-1 IgG serum levels are affected by genetic and environmental factors that also modulate multiple sclerosis risk.

Level of education and multiple sclerosis risk after adjustment for known risk factors: The EnvIMS study

BACKGROUND

Several recent studies have found a higher risk of multiple sclerosis (MS) among people with a low level of education. This has been suggested to reflect an effect of smoking and lower vitamin D status in the social class associated with lower levels of education.

OBJECTIVE

The objective of this paper is to investigate the association between level of education and MS risk adjusting for the known risk factors smoking, infectious mononucleosis, indicators of vitamin D levels and body size.

METHODS

Within the case-control study on Environmental Factors In MS (EnvIMS), 953 MS patients and 1717 healthy controls from Norway reported educational level and history of exposure to putative environmental risk factors.

RESULTS

Higher level of education were associated with decreased MS risk (p trend = 0.001) with an OR of 0.53 (95% CI 0.41-0.68) when comparing those with the highest and lowest level of education. This association was only moderately reduced after adjusting for known risk factors (OR 0.61, 95% CI 0.44-0.83). The estimates remained similar when cases with disease onset before age 28 were excluded.

CONCLUSION

These findings suggest that factors related to lower socioeconomic status other than established risk factors are associated with MS risk.

The EnvIMS Study: Design and Methodology of an International Case-Control Study of Environmental Risk Factors in Multiple Sclerosis

Background: Multiple sclerosis (MS) is a chronic disease of the central nervous system, often resulting in significant neurological disability. The causes of MS are not known; however, the incidence of MS is increasing, thereby suggesting that changes in lifestyle and/or environmental factors may be responsible. On this background, the Environmental Risk Factors in MS Study or EnvIMS study was designed to further explore the etiology of MS. The design and methodology are described, providing details to enable investigators to (i) use our experiences to design their own studies; (ii) take advantage of, and build on the methodological work completed for, the EnvIMS study; (iii) become aware of this data source that is available for use by the research community. Methods: EnvIMS is a multinational case-control study, enrolling 2,800 cases with MS and 5,012 population-based controls in Canada, Italy, Norway, Serbia and Sweden. The study was designed to investigate the most commonly implicated risk factors for MS etiology using a self-report questionnaire. Results/Conclusions: The use of a common methodology to study MS etiology across several countries enhances the comparability of results in different geographic regions and research settings, reduces the resources required for study design and enhances the opportunity for data harmonization.

Timing of use of cod liver oil, a vitamin D source, and multiple sclerosis risk: The EnvIMS study

Background:

Low vitamin D levels have been associated with an increased risk of multiple sclerosis (MS), although it remains unknown whether this relationship varies by age.

Objective:

The objective of this paper is to investigate the association between vitamin D₃ supplementation through cod liver oil at different postnatal ages and MS risk.

Methods:

In the Norwegian component of the multinational case-control study Environmental Factors In Multiple Sclerosis (EnvIMS), a total of 953 MS patients with maximum disease duration of 10 years and 1717 controls reported their cod liver oil use from childhood to adulthood.

Results:

Self-reported supplement use at ages 13–18 was associated with a reduced risk of MS (OR 0.67, 95% CI 0.52–0.86), whereas supplementation during childhood was not found to alter MS risk (OR 1.01, 95% CI 0.81–1.26), each compared to non-use during the respective period. An inverse association was found between MS risk and the dose of cod liver oil during adolescence, suggesting a dose-response relationship (p trend = 0.001) with the strongest effect for an estimated vitamin D₃ intake of 600–800 IU/d (OR 0.46, 95% CI 0.31–0.70).

Conclusions:

These findings not only support the hypothesis relating to low vitamin D as a risk factor for MS, but further point to adolescence as an important susceptibility period for adult-onset MS.

Assessing subjective quality of life domains after multiple sclerosis diagnosis disclosure

BACKGROUND AND OBJECTIVE

An investigation of the domains Italian patients with multiple sclerosis (MS) named as constituting their quality of life over time.

DESIGN

We assessed, in 68 patients, QoL domains using the Schedule for the Evaluation of Individual QoL: (a) before MS diagnosis disclosure, (b) thirty days after disclosure, and (c) after one and (d) four years' follow-up.

RESULTS

The life domains most frequently named by patients were as follows: Family, Work and Finance, Hobbies, Health, Relationship with Friends and Job Effectiveness. Only Health and Job Effectiveness domains varied with time. The Health domain became a critical dimension when MS diagnosis was revealed. In addition, patients tended to be more satisfied with their health after disclosure compared to pre-diagnosis. Job Effectiveness seemed to be an important aspect until 1 year after diagnosis disclosure, but it tended to become less crucial over time. Family seems to be the most important domain over time, and psychological adaptation to MS seems to be characterized by a reconceptualization of aspects that revolve around oneself, such as professional success, rather than relational or affective factors.

CONCLUSIONS

Evaluating the most relevant life domains for patients and their alteration over time may provide practitioners with an important tool in making health-related decisions, thus improving health outcomes and QoL.

Comorbidity between Type 2 Diabetes and Depression in the Adult Population: Directions of the Association and Its Possible Pathophysiological Mechanisms

Type 2 diabetes and depression are regarded as comorbid conditions, and three possible directions of the association between the diseases can underlie this observation of comorbidity. First, common etiology can increase a person's risk of both diseases; second, persons with type 2 diabetes have increased prevalence or risk of future development of depression; or third, persons with depression have increased prevalence or risk of development of type 2 diabetes. This review gives an overview over possible pathophysiological mechanisms for each of the directions of the association between type 2 diabetes and depression and further discusses epigenetics as an additional, direction independent approach. We argue that unspecific pathophysiological mechanisms involved in the stress response might, at least to some extent, explain each of the directions of the association between type 2 diabetes and depression, while changes in brain structure and function among persons with diabetes and possible increased risk of development of type 2 diabetes after use of antidepressant agents could represent more disease specific mechanisms underlying the comorbidity.

Body size and the risk of multiple sclerosis in Norway and Italy: The EnvIMS study

Background:

Obesity may be a risk factor for developing multiple sclerosis (MS).

Objective:

We examined if body size influences the risk of MS in a population-based, case control study.

Methods:

A total of 953 cases and 1717 controls from Norway and 707 cases and 1333 controls from Italy reported their body size by choosing a silhouette 1 to 9 (largest) every fifth year from age 5 to 30 and at time of study. The body size-related MS risk was defined by odds ratios (ORs) in logistic regression analyses adjusting for age, smoking and outdoor activity.

Results:

In Norway a large body size (silhouettes 6–9) compared to silhouette 3 increased the risk of MS, especially at age 25 (OR 2.21; 95% CI 1.09–4.46 for men and OR 1.43; 95% CI 0.90–2.27 for women). When comparing silhouette 9 to 1, we found a significant dose-response from age 10 until age 30 peaking at age 25 (sex-adjusted OR 2.83; 95% CI 1.68–4.78). The association was present for at least 15 years prior to disease onset. No significant associations were found in Italy.

Conclusions:

Obesity from childhood until young adulthood is a likely risk factor for MS with a seemingly stronger effect in Norway than in Italy.

Physical health-related quality of life predicts disability pension due to musculoskeletal disorders: seven years follow-up of the Hordaland Health Study Cohort

BACKGROUND

Musculoskeletal diseases are characterized by a high degree of comorbidity with common mental disorders and are a major cause of health-related exclusion from working life. Using a prospective design we aimed to examine the relative importance of physical and mental health-related quality of life as predictors of disability pension due to musculoskeletal diseases.

METHODS

A subsample (N = 18,581) born 1953-1957, participated in the The Hordaland Health Study (HUSK) during 1997-1999, and was followed through December 31st 2004. Baseline measures of health-related quality of life were estimated using the Physical (PCS) and Mental Component Summary (MCS) of the Short Form-12 (SF-12). Further information on education, occupation, smoking, physical activity, number of musculoskeletal pain sites and BMI were provided by questionnaires and health examination. The association between self-perceived physical and mental health and subsequent disability pension, obtained from the national database of health and social benefits was estimated using Cox regression analyses.

RESULTS

Participants reporting poor physical health (quartile 1) had a marked increased risk for disability pension due to musculoskeletal diseases (age and gender-adjusted hazard ratio = 22.1, 95% CI = 12.5-39.0) compared with those reporting good/somewhat good physical health (quartiles 4 and 3 combined). Adjustment for socioeconomic status and lifestyle factors slightly attenuated the association (hazard ratio = 16.7), and adding number of reported pain sites weakened the association even more (hazard ratio = 7.1, 95% CI = 3.8-12.8). Also, participants reporting poor mental health had a higher risk for disability pension due to musculoskeletal diseases (age and gender adjusted hazard ratio = 1.8, 95% CI = 1.3-2.6); however, in the final model the risk was not statistically significant.

CONCLUSIONS

The physical component in health-related quality of life (SF-12) was a strong predictor of disability pension due to musculoskeletal diseases, whereas the mental component played a less prominent role.

Month of birth and risk of multiple sclerosis: confounding and adjustments

A month of birth effect on multiple sclerosis (MS) risk has been reported from different countries. Recent critics have suggested that this finding is caused by confounding and that adequately adjusting for year and place of birth would markedly reduce this effect. All inhabitants in Norway are registered in the Norwegian Population Registry (Statistics Norway), making this an ideal area for performing adjusted analyses. Using the entire Norwegian population born between 1930 and 1979 (n = 2,899,260), we calculated the excess between observed and expected number of births for each month for 6649 Norwegian MS patients, 5711 mothers, 5247 fathers, and 8956 unaffected siblings. The analyses were adjusted for year of birth and place of birth according to the 19 counties in Norway. An unadjusted analysis revealed 13% fewer MS births than expected in February (P = 0.0015; Bonferroni corrected P = 0.018), 10% more in April (P = 0.0083; Bonferroni corrected P = 0.0996) and 15% more in December (P = 0.00058; Bonferroni corrected P = 0.007). Adjustments for both year and place of birth significantly altered our results for February and December, but even after these adjustments there were still 10% more MS births than expected in April (P = 0.00796; Bonferroni corrected P = 0.096). MS patients had a higher incidence of April births than their siblings (Fisher-exact test; P = 0.011), mothers (Fisher-exact test; P = 0.004), and fathers (Fisher-exact test; P = 0.011) without MS. Adjustments for confounding significantly affected our results. However, even after adjustments, there appears to be a persistent higher than expected frequency of April births in the MS population.

Sun exposure and multiple sclerosis risk in Norway and Italy: The EnvIMS study

Objectives:

The objective of this paper is to estimate the association between multiple sclerosis (MS) and measures of sun exposure in specific age periods in Norway and Italy.

Methods:

A total of 1660 MS patients and 3050 controls from Italy and Norway who participated in a multinational case-control study (EnvIMS) reported sun habits during childhood and adolescence.

Results:

A significant association between infrequent summer outdoor activity and increased MS risk was found in Norway and in Italy. The association was strongest between the ages of 16 and 18 years in Norway (odds ratio (OR) 1.83, 95% confidence interval (CI) 1.30–2.59), and between birth and age 5 years in Italy (OR 1.56, 95% CI 1.16–2.10). In Italy a significant association was also found during winter (OR 1.42, 95% CI 1.03–1.97). Frequent sunscreen use between birth and the age of 6 years was associated with MS in Norway (OR 1.44, 95% CI 1.08–1.93) after adjusting for outdoor activity during the same period. Red hair (OR 1.67, 95% CI 1.06–2.63) and blonde hair (OR 1.36, 95% CI 1.09–1.70) were associated with MS after adjusting for outdoor activity and sunscreen use.

Conclusion:

Converging evidence from different measures underlines the beneficial effect of sun exposure on MS risk.

Prevalence and characteristics of depressive disorders in type 1 diabetes

BACKGROUND

Persons with diabetes and depression have increased risk of complications and increased mortality. We aimed to investigate the prevalence, clinical characteristics and impact with regard to glycosylated haemoglobin (HbA1c) of depressive disorders in persons with type 1 diabetes at an outpatient specialist diabetes clinic.

FINDINGS

A total of 51 persons with type 1 diabetes were diagnosed according to Mini International Neuropsychiatric Interview (M.I.N.I) with regard to dysthymia and previous or ongoing depressive episodes during spring 2005. HbA1c was measured at the day of the interview, and self-reported information on family history of depressive disorders was obtained. Eight persons (16%; 95% CI: 7%, 29%) were in the midst of a major depressive episode, 4 of these also reported a previous episode of depression. Seven of the 8 persons with an ongoing major depressive episode met the criteria for melancholia. Three persons (6%) met the criteria for dysthymia, and 6 persons (12%) had previous episode(s) of depression, without being currently depressed. The 17 (33%; 95% CI: 21%, 48%) persons with ongoing and/or previous depressive disorder had increased HbA1c (8.5%; 95% CI: 7.6%, 9.4%) compared to those without depressive disorders (7.9%; 95% CI: 7.5%, 8.3%), although the difference did not reach statistical significance.

CONCLUSIONS

Persons with type 1 diabetes had a high prevalence of depressive disorders, mainly depressive episodes that also met the criteria for melancholia, a subtype often considered a more serious and "biologic" form of depression. We were not able to demonstrate that persons with depressive disorders had poorer regulated diabetes compared to those without depressive disorders.

Season of infectious mononucleosis and risk of multiple sclerosis at different latitudes; the EnvIMS Study

BACKGROUND

Seasonal fluctuations in solar radiation and vitamin D levels could modulate the immune response against Epstein-Barr virus (EBV) infection and influence the subsequent risk of multiple sclerosis (MS).

METHODS

Altogether 1660 MS patients and 3050 controls from Norway and Italy participating in the multinational case-control study of Environmental Factors In Multiple Sclerosis (EnvIMS) reported season of past infectious mononucleosis (IM).

RESULTS

IM was generally reported more frequently in Norway (p=0.002), but was associated with MS to a similar degree in Norway (odds ratio (OR) 2.12, 95% confidence interval (CI) 1.64-2.73) and Italy (OR 1.72, 95% CI 1.17-2.52). For all participants, there was a higher reported frequency of IM during spring compared to fall (p<0.0005). Stratified by season of IM, the ORs for MS were 1.58 in spring (95% CI 1.08-2.31), 2.26 in summer (95% CI 1.46-3.51), 2.86 in fall (95% CI 1.69-4.85) and 2.30 in winter (95% CI 1.45-3.66).

CONCLUSIONS

IM is associated with MS independently of season, and the association is not stronger for IM during spring, when vitamin D levels reach nadir. The distribution of IM may point towards a correlation with solar radiation or other factors with a similar latitudinal and seasonal variation.

Poor self-rated health associated with an increased risk of subsequent development of lung cancer

PURPOSE

Self-rated health has shown to be a strong predictor of mortality and some major chronic diseases. The purpose of this study was to investigate whether poor self-rated health also was related to an increased risk of subsequent development of cancer.

METHODS

Information on self-rated health, life-style factors, and other health-related risk factors was ascertained in a cohort of 25,532 persons participating in the Hordaland Health Study in 1997-1999. Information on development of cancer during 10 years of follow-up was obtained from the Norwegian Cancer Registry. The relationship between self-rated health and development of cancer was examined using Cox regression analysis adjusting for smoking and other life-style factors.

RESULTS

Respondents reporting a poor health showed a non-significant increased risk of overall cancer. Sub-analysis of the four most common types of cancer showed a statistically significant association between self-rated health and lung cancer. The adjusted hazard ratio was 3.88 (95% CI; 0.99, 15.8) for those rating their health as poor compared to very good (p for trend = 0.038). For the other types of cancer, we found a non-significant elevated risk associated with poor self-rated health.

CONCLUSION

Respondents who perceive their health as poor had an increased risk of developing lung cancer also after adjusting for smoking. This suggests that self-rated health reflects a broad range of factors important for development of this cancer type. Nevertheless, due to the explorative analysis of the specific cancer types, these findings need to be repeated before elaborate interpretations can be made.

Co-morbidity between diabetes, migraine and depression

Background: Young persons using oral antidiabetic agents have increased prevalence of medically treated migraine and depression. In the general population there is a well-known association between migraine and depression. Using medication as a proxy for disease, we investigated to which extent the previously reported increased prevalence of migraine in young persons using oral antidiabetic agents could be explained by co-morbid depression. Methods: Data on all individuals in Norway aged 20-39 years being prescribed anti-diabetic (n=5 055), migraine (n=26 058) and/or antidepressant agents (n=57 424) in 2006 was obtained from the Norwegian Prescription Database and analysed in a cross-sectional design using logistic regression. Results: Persons using oral antidiabetic agents but no antidepressant agents had an overall increased sex and age adjusted OR of using migraine agents compared to persons not using oral anti-diabetic agents (OR= 1.48; 95% CI: 1.26, 1.74). Persons using antidiabetic and antidepressant agents also had an increased OR of receiving migraine agents (OR=1.37; 1.03, 1.82). Estimating these risks for men and women separately, no major differences were found. Conclusion: The findings in the present study give no support for the hypothesis that the increased prevalence of migraine in young persons treated with oral antidiabetic agents partly could be explained by co-morbid depression.

The healthy worker effect in cancer incidence studies

Use of the general population as a reference might cause serious underestimation of the risk of cancer in working populations because of the healthy worker effect. Using incidence rates, we studied how this underestimation varied according to subtypes of cancer by comparing a large cohort of randomly selected Norwegian workers hired between 1981 and 2003 (n = 366,114) with the general Norwegian population. The cohort was linked to the Cancer Registry of Norway, including all new cancer cases (n = 11,271) reported up to 2003. We found marked potential for the healthy worker effect for overall cancer incidence in male workers (standardized incidence ratio (SIR) = 0.91, 95% confidence interval: 0.89, 0.93) but not in female workers (SIR = 0.99, 95% confidence interval: 0.95, 1.03). A statistically significantly lower incidence was found among men for cancers of the head and neck (SIR = 0.78), lung (SIR = 0.81), prostate (SIR = 0.93), kidney (SIR = 0.83), and bladder (SIR = 0.77) and for leukemia (SIR = 0.80), whereas an increased incidence was found for malignant melanoma among both men (SIR = 1.09) and women (SIR = 1.29) and for ovarian cancer in women (SIR = 1.32). Depending on the type of cancer being studied, marked potential exists for both underestimation and overestimation of cancer risk when the general population is used as the reference for studies of worker populations.