High consumption of coffee is associated with decreased multiple sclerosis risk; results from two independent studies

Current therapeutic targets and multifaceted physiological impacts of caffeine

Caffeine, which shares consubstantial structural similarity with purine adenosine, has been demonstrated as a nonselective adenosine receptor antagonist for eliciting most of the biological functions at physiologically relevant dosages. Accumulating evidence supports caffeine's beneficial effects against different disorders, such as total cardiovascular diseases and type 2 diabetes. Conversely, paradoxical effects are also linked to caffeine ingestion in humans including hypertension-hypotension and tachycardia-bradycardia. These observations suggest the association of caffeine action with its ingested concentration and/or concurrent interaction with preferential molecular targets to direct explicit events in the human body. Thus, a coherent analysis of the functional targets of caffeine, relevant to normal physiology, and disease pathophysiology, is required to understand the pharmacology of caffeine. This review provides a broad overview of the experimentally validated targets of caffeine, particularly those of therapeutic interest, and the impacts of caffeine on organ-specific physiology and pathophysiology. Overall, the available empirical and epidemiological evidence supports the dose-dependent functional activities of caffeine and advocates for further studies to get insights into the caffeine-induced changes under specific conditions, such as asthma, DNA repair, and cancer, in view of its therapeutic applications.

A case-control study of drinking beverages and the risk of multiple sclerosis in Iran

BACKGROUND

There is no study in the world on the relationship between consuming black and green tea as beverages containing polyphenols and the risk of MS. This study aimed to determine the association between the consumption of green and black tea, coffee, non-alcoholic beer, milk, fruit juices and carbonated beverages with the risk of MS.

METHODS AND MATERIALS

This case-control study was performed on 150 patients with MS and 300 healthy individuals as a control group among patients who were referred to the ophthalmology ward of a referral hospital in Ahvaz with the groups matching for age. The data collection tool was a researcher-made questionnaire including demographic information and beverage consumption. Analysis was performed using univariate and multiple logistic regression models.

RESULTS

The mean age of patients at the time of diagnosis was 38.55 ± 8.88 years. The results showed that drinking milk (OR = 5.46), natural juice (OR = 2.49), and carbonated beverages (OR = 16.17) were associated with an increased chance of developing MS. However, drinking non-alcoholic beer (OR = 0.48), black tea (OR = 0.20), green tea (OR = 0.29) and coffee (OR = 0.07) were associated with a reduced chance of developing MS.

CONCLUSION

The results show that drinking black and green tea, non-alcoholic beer, and coffee are associated with a decrease in the chance of developing MS. The results of this study can be used to design interventional research and to change people's lifestyles to prevent MS.

A coffee enriched with guarana, selenium, and l-carnitine (GSC) has nutrigenomic effects on oxi-inflammatory markers of relapsing-remitting multiple sclerosis patients: A pilot study

Relapsing-remitting multiple sclerosis (RRMS) is the most common clinical course of multiple sclerosis (MS), characterized by a chronic inflammatory state and elevated levels of oxidative markers. Food supplements with potential anti-inflammatory, antioxidant and neuroprotective effects have been tested as possible adjuvants in the treatment of MS. In this sense, this pilot study was carried out with the aim of verifying whether a minimum daily dose of a guarana, selenium and l-carnitine (GSC) based multi supplement, mixed in cappuccino-type coffee, administered for 12 weeks to 28 patients with RRMS could differentially modulate oxidative blood markers (lipoperoxidation, protein carbonylation and DNA oxidation) and inflammatory blood markers (protein levels of cytokines IL-1β, IL-6, TNF-α, IFN-γ, IL-10, gene expression of these cytokines, and NLRP3 and CASP-1 molecules, and C-reactive protein levels). The results indicate that a low concentration of GSC is capable of decreasing the plasma levels of oxidized DNA and pro-inflammatory cytokines of RRMS patients. The results support further research into the action of GSC on clinical symptoms, not only in patients with MS, but also with other neurological conditions.

Trends in the environmental risks associated with earlier onset in multiple sclerosis

BACKGROUND

Several environmental and lifestyle factors relating to sunlight/vitamin D, body mass index (BMI), and smoking are associated with the risk of developing multiple sclerosis (MS). However, their relation to disease progression, particularly age at symptomatic onset, remains inconsistent, which may be the result of significant changes in human-environment interactions over the last century. This study investigates historical trends in the association between common MS environmental risk factors and age at disease onset.

METHODS

Using a narrative approach, we evaluated the current literature for published studies assessing the association between vitamin-D, BMI, and tobacco smoking exposures with the risk of early/pediatric-onset MS and direct correlations with age at MS onset using MEDLINE, EMBASE, and Web of Science. Measures were plotted by the average calendar year of disease onset for each cohort to examine trends over time. In total, 25, 9, and 11 articles were identified for vitamin D, BMI, and smoking-related exposures, respectively.

RESULTS

Higher sun exposure habits and residential solar radiation were associated with older age at onset. On the contrary, two studies observed a negative correlation between age at onset and serum 25-hydroxyvitamin D (25(OH)D) levels. Higher adolescent BMI was generally associated with younger age at onset, although genetic susceptibility for childhood obesity was not significantly associated. Tobacco smoking was associated with later disease onset, despite being a risk factor for MS. Association with age at onset was inflated for more recent studies relating to smoking, while often weaker for serum vitamin D and BMI.

CONCLUSION

Current findings indicate a likely association between age at onset and environmental risk factors, such as sun exposure, adolescent BMI, and tobacco smoking, in certain populations. However, findings are often inconsistent and assessment of the relationships and potential changes over time require further investigation.

Mendelian randomization as a tool to gain insights into the mosaic causes of autoimmune diseases

Autoimmune diseases (ADs) are a broad range of disorders which are characterized by long-term inflammation and tissue damage arising from an immune response against one's own tissues. It is now widely accepted that the causes of ADs include environmental factors, genetic susceptibility and immune dysregulation. However, the exact etiology of ADs has not been fully elucidated to date. Because observational studies are plagued by confounding factors and reverse causality, no firm conclusions can be drawn about the etiology of ADs. Over the years, Mendelian randomization (MR) analysis has come into focus, offering unique perspectives and insights into the etiology of ADs and promising the discovery of potential therapeutic interventions. In MR analysis, genetic variation (alleles are randomly dispensed during meiosis, usually irrespective of environmental or lifestyle factors) is used instead of modifiable exposure to explore the link between exposure factors and disease or other outcomes. Therefore, MR analysis can provide a valuable method for exploring the causal relationship between different risk factors and ADs when its inherent assumptions and limitations are fully considered. This review summarized the recent findings of MR in major ADs, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS), and type 1 diabetes mellitus (T1DM), focused on the effects of different risk factors on ADs risks. In addition, we also discussed the opportunities and challenges of MR methods in ADs research.

Neurodegenerative Diseases: Can Caffeine Be a Powerful Ally to Weaken Neuroinflammation?

In recent years, there has been considerable research showing that coffee consumption seems to be beneficial to human health, as it contains a mixture of different bioactive compounds such as chlorogenic acids, caffeic acid, alkaloids, diterpenes and polyphenols. Neurodegenerative diseases (NDs) are debilitating, and non-curable diseases associated with impaired central, peripheral and muscle nervous systems. Several studies demonstrate that neuroinflammation mediated by glial cells—such as microglia and astrocytes—is a critical factor contributing to neurodegeneration that causes the dysfunction of brain homeostasis, resulting in a progressive loss of structure, function, and number of neuronal cells. This happens over time and leads to brain damage and physical impairment. The most known chronic NDs are represented by Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and Huntington’s disease (HD). According to epidemiological studies, regular coffee consumption is associated with a lower risk of neurodegenerative diseases. In this review, we summarize the latest research about the potential effects of caffeine in neurodegenerative disorders prevention and discuss the role of controlled caffeine delivery systems in maintaining high plasma caffeine concentrations for an extended time.

The adenosinergic signaling in the pathogenesis and treatment of multiple sclerosis

Multiple sclerosis (MS) is a highly disabling, progressive neurodegenerative disease with no curative treatment available. Although significant progress has been made in understanding how MS develops, there remain aspects of disease pathogenesis that are yet to be fully elucidated. In this regard, studies have shown that dysfunctional adenosinergic signaling plays a pivotal role, as patients with MS have altered levels adenosine (ADO), adenosine receptors and proteins involved in the generation and termination of ADO signaling, such as CD39 and adenosine deaminase (ADA). We have therefore performed a literature review regarding the involvement of the adenosinergic system in the development of MS and propose mechanisms by which the modulation of this system can support drug development and repurposing.

Caffeine and rheumatoid arthritis: A complicated relationship

The current ideal goal of rheumatoid arthritis (RA) management is to resolve joint and systemic inflammation by using pharmacological interventions, assuming this will correspondingly lead to overall well-being. Nonetheless, it has emerged that a substantial number of RA patients do not reach optimal disease control. Thus suggesting the holistic management of subjective symptoms might be overlooked. This poses significant medical challenges; hence the proposal of incorporating lifestyle interventions as part of a multidimensional approach. Among these aspects, both patients and physicians perceive the important role of nutrition. This review shall examine how caffeine, one of the most studied bioactive components of the most widely consumed beverages, may potentially interfere with RA management. In particular, the mechanism by which caffeine affects RA pathogenesis, as a trigger for RA onset or flare, including its influence on rheumatic drug metabolism and the most common RA comorbidities and constitutional symptoms are outlined, highlighting important knowledge gaps and unmet research needs.

Impact of Caffeine on Alzheimer’s Disease Pathogenesis—Protective or Risk Factor?

Alzheimer’s disease (AD), the most common dementia worldwide, remains without an effective treatment to this day despite intensive research conducted during the last decades. In this context, researchers have turned their attention towards the prevention of this pathology, focusing on early detection and better control of the most important risk factors, concomitantly with trying to find potentially protective factors that may delay the onset of AD. From the multitude of factors studied, coffee (especially its main component, caffeine) is a current interesting research topic, taking into consideration the contradictory results of recent years’ studies. On the one hand, much of the evidence from fundamental research suggests the potentially protective trait of caffeine in AD, while other data mainly from human studies lean toward no correlation or even suggesting that caffeine is a veritable risk factor for dementia. Given the methodological heterogeneity of the studies, this review aims to bring new evidence regarding this topic and to try to clearly establish a correlation between the two entities. Thus, in the first part, the authors make a clear distinction between the effects of coffee and the effects of caffeine in AD, presenting a rich basis of clinical trials on both animal models and the human subject. Subsequently, the main pathophysiological mechanisms that would explain the action of caffeine in the etiopathogenesis of AD are reviewed. Finally, the role of computational models is presented, having beneficial impact on both better understanding of the disease mechanism and the development of new therapeutic approaches for AD prevention.

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

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

Caffeine Inhibits Activation of the NLRP3 Inflammasome via Autophagy to Attenuate Microglia-Mediated Neuroinflammation in Experimental Autoimmune Encephalomyelitis

The activation of microglia is an important cause of central nervous system (CNS) inflammatory cell infiltration and inflammatory demyelination in experimental autoimmune encephalomyelitis (EAE). Furthermore, the proinflammatory response induced by the NLR family pyrin domain containing 3 (NLRP3) inflammasome can be amplified in microglia after NLRP3 inflammasome activation. Autophagy is closely related to the inflammatory response. Caffeine exerts anti-inflammatory and autophagy-stimulating effects, but the specific mechanism remains unclear. This study examined the mechanism underlying the anti-inflammatory effect of caffeine on EAE. In this study, C57BL/6 mice were immunized to induce EAE and treated with caffeine to observe its effect on prognosis. The effects of caffeine on autophagy and inflammation were also analysed in mouse primary microglia (PM) and the BV2 cell line. The data demonstrated that caffeine reduced the clinical score, the infiltration of inflammatory cells, the demyelination level, and the activation of microglia in EAE mice. Furthermore, caffeine increased the LC3-II/LC3-I levels and decreased the NLRP3 and P62 levels in EAE mice, whereas the autophagy inhibitor 3-methylamine (3-MA) blocked these effects. In vitro, caffeine promoted autophagy by suppressing the mechanistic target of rapamycin (mTOR) pathway and inhibited activation of the NLRP3 inflammasome. However, autophagy-related gene 5 (ATG5)-specific siRNA abolished the anti-inflammatory effect of caffeine treatment in PM and BV2 cells. Taken together, these data suggest that caffeine exerts a newly discovered effect on EAE by reducing NLRP3 inflammasome activation via the induction of autophagy in microglia.

Caffeine as a Factor Influencing the Functioning of the Human Body-Friend or Foe?

Nowadays, caffeine is one of the most commonly consumed substances, which presents in many plants and products. It has both positive and negative effects on the human body, and its activity concerns a variety of systems including the central nervous system, immune system, digestive system, respiratory system, urinary tract, etc. These effects are dependent on quantity, the type of product in which caffeine is contained, and also on the individual differences among people (sex, age, diet etc.). The main aim of this review was to collect, present, and analyze the available information including the latest discoveries on the impact of caffeine on human health and the functioning of human body systems, taking into account the role of caffeine in individual disease entities. We present both the positive and negative sides of caffeine consumption and the healing properties of this purine alkaloid in diseases such as asthma, Parkinson's disease, and others, not forgetting about the negative effects of excess caffeine (e.g., in people with hypertension, children, adolescents, and the elderly). In summary, we can conclude, however, that caffeine has a multi-directional influence on various organs of the human body, and because of its anti-oxidative properties, it was, and still is, an interesting topic for research studies including those aimed at developing new therapeutic strategies.

Targeting Adenosine Receptors in Neurological Diseases

Adenosine plays a significant role in neurotransmission process by controlling the blood pressure, while adenosine triphosphate (ATP) acts as a neuromodulator and neurotransmitter and by activation of P2 receptors, regulates the contractility of the heart. Adenosine signaling is essential in the process of regeneration by regulating proliferation, differentiation, and apoptosis of stem cells. In this review, we have selected neurological disorders (Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, and epilepsy) with clinical trials using antagonists and epigenetic tools targeting adenosine receptor as a therapeutic approach in the treatment of these disorders. Promising results have been reported from many clinical trials. It has been found that higher expression levels of A2A and P2X7 receptors in neurological disorders further complicate the disease condition. Therefore, modulations of these receptors by using antagonists of these receptors or SAM (S-adenosylmethionine) therapy as an epigenetic tool could be useful in reversing the complications of these disorders. Finally, we suggest that modulation of adenosine receptors in neurological disorders can increase the regenerative phase by increasing the rate of proliferation and differentiation in the damaged tissues.

Correlation of Dietary Intake and Helicobacter pylori Infection with Multiple Sclerosis, a Case-Control Study in Rafsanjan, Iran, 2017-18

Background: Multiple sclerosis (MS) is an autoimmune disease affecting the central nervous system. Some environmental factors, such as Helicobacter pylori infection (HPI), are likely to be considered a protective factor in MS. Dietary intake may provide exposure to or have protective effects for MS. The present study aimed to determine the relationship between serum anti-H. pylori IgG antibody (HPIA) level and dietary intake in patients with MS referred to the MS Clinic in Rafsanjan city, Iran.

Methods: The present case-control study was conducted on 97 patients with MS and 95 controls. The two groups had no significant difference in age and gender (p > 0.05). HPIA was checked, and the food frequency questionnaire was completed in both groups to measure nutritional intake. All data were analyzed by the SPSS 20 software using independent t-test, Chi-Square, Mann–Whitney U test, and correlation.

Results: The median serum HPIA level was significantly lower in MS cases than in controls. Furthermore, the median consumption of glutamic acid, arginine, serine, aspartic acid, alanine, proline, and caffeine was significantly lower in MS cases than in controls. A significant positive correlation was found between the levels of linoleic acid, lactose, Ca, molybdenum, galactose, leucine, and valine, and the level of HPIA in controls.

Conclusion: Our study results demonstrated that some dietary nutrients had correlations with MS and HPI. Therefore, professionals from multiple disciplines must find which foods contain these dietary nutrients in future studies.

Effect of Caffeine Consumption on the Risk for Neurological and Psychiatric Disorders: Sex Differences in Human

Caffeine occurs naturally in various foods, such as coffee, tea, and cocoa, and it has been used safely as a mild stimulant for a long time. However, excessive caffeine consumption (1~1.5 g/day) can cause caffeine poisoning (caffeinism), which includes symptoms such as anxiety, agitation, insomnia, and gastrointestinal disorders. Recently, there has been increasing interest in the effect of caffeine consumption as a protective factor or risk factor for neurological and psychiatric disorders. Currently, the importance of personalized medicine is being emphasized, and research on sex/gender differences needs to be conducted. Our review focuses on the effect of caffeine consumption on several neurological and psychiatric disorders with respect to sex differences to provide a better understanding of caffeine use as a risk or protective factor for those disorders. The findings may help establish new strategies for developing sex-specific caffeine therapies.

An atlas on risk factors for multiple sclerosis: a Mendelian randomization study

Objectives

We conducted a systematic review and wide-angled Mendelian randomization (MR) study to examine the association between possible risk factors and multiple sclerosis (MS).

Methods

We used MR analysis to assess the associations between 65 possible risk factors and MS using data from a genome-wide association study including 14 498 cases and 24 091 controls of European ancestry. For 18 exposures not suitable for MR analysis, we conducted a systematic review to obtain the latest meta-analyses evidence on their associations with MS.

Results

Childhood and adulthood body mass index were positively associated with MS, whereas physical activity and serum 25-hydroxyvitamin D were inversely associated with MS. There was evidence of possible associations of type 2 diabetes, waist circumference, body fat percentage, age of puberty and high-density lipoprotein cholesterol. Data of systematic review showed that exposure to organic solvents, Epstein Barr virus and cytomegalovirus virus infection, and diphtheria and tetanus vaccination were associated with MS risk.

Conclusions

This study identified several modifiable risk factors for primary prevention of MS that should inform public health policy.

Electronic supplementary material

The online version of this article (10.1007/s00415-020-10119-8) contains supplementary material, which is available to authorized users.

Coffee consumption is not associated with risk of multiple sclerosis: A Mendelian randomization study

OBJECTIVE

. Coffee consumption has been suggested to decrease the risk of multiple sclerosis (MS). In this study, we aim to investigate the causal effect of coffee consumption on risk of MS by Mendelian randomization (MR) approaches.

METHODS

. Through a genome-wide association study including 375,833 participants from UK Biobank, we obtained single-nucleotide polymorphisms (SNPs) associated with habitual coffee consumption (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, which was conducted by the International Multiple Sclerosis Genetics Consortium. MR analyses were performed using inverse-variance-weighted method, weighted median estimator, and MR-Egger regression. Additional analyses were further performed using MR-Egger intercept and Cochran's Q statistic to verify the robustness of our findings.

RESULTS

. Nine coffee-associated SNPs were selected as instrumental variables. We failed to detect a causal effect of coffee consumption on MS risk (odds ratio, 1,00; 95% confidence interval, 0.98-1.01; P = 0.48). In the main MR analysis. Consistent results were yielded in sensitivity analyses using the weighted median and MR-Egger methods, and no horizontal pleiotropy (P = 0.49) was identified.

CONCLUSION

. Our MR results indicated that coffee consumption might not be causally associated with risk of MS occurrence. Further well-designed genetic-epidemiological studies investigating the effect of coffee intake on the disease course, such as relapse and progression, are warranted.

Targeting Purinergic Signaling and Cell Therapy in Cardiovascular and Neurodegenerative Diseases

Extracellular purines exert several functions in physiological and pathophysiological mechanisms. ATP acts through P2 receptors as a neurotransmitter and neuromodulator and modulates heart contractility, while adenosine participates in neurotransmission, blood pressure, and many other mechanisms. Because of their capability to differentiate into mature cell types, they provide a unique therapeutic strategy for regenerating damaged tissue, such as in cardiovascular and neurodegenerative diseases. Purinergic signaling is pivotal for controlling stem cell differentiation and phenotype determination. Proliferation, differentiation, and apoptosis of stem cells of various origins are regulated by purinergic receptors. In this chapter, we selected neurodegenerative and cardiovascular diseases with clinical trials using cell therapy and purinergic receptor targeting. We discuss these approaches as therapeutic alternatives to neurodegenerative and cardiovascular diseases. For instance, promising results were demonstrated in the utilization of mesenchymal stem cells and bone marrow mononuclear cells in vascular regeneration. Regarding neurodegenerative diseases, in general, P2X7 and A_2A receptors mostly worsen the degenerative state. Stem cell-based therapy, mainly through mesenchymal and hematopoietic stem cells, showed promising results in improving symptoms caused by neurodegeneration. We propose that purinergic receptor activity regulation combined with stem cells could enhance proliferative and differentiation rates as well as cell engraftment.

Multiple Sclerosis Risk Factors and Pathogenesis

PURPOSE OF REVIEW

This article summarizes recent advances in the identification of genetic and environmental factors that affect the risk of developing multiple sclerosis (MS) and the pathogenic processes involved in acute relapses and relapse-independent disability progression.

RECENT FINDINGS

The number of single-nucleotide polymorphisms associated with increased risk of MS has increased to more than 200 variants. The evidence for the association of Epstein-Barr virus infection, vitamin D deficiency, obesity, and smoking with increased risk of MS has further accumulated, and, in cases of obesity and vitamin D deficiency, the evidence for causal association has strengthened. Interactions between genetic and environmental factors have been studied more extensively. Dietary factors and changes in the gut microbiota are emerging as possible modulators of the disease risk. Several processes important to MS pathogenesis have been newly investigated or investigated more comprehensively, including the role of B cells, innate immune cells, meningeal inflammation, cortical and gray matter demyelination, and early axonal and neuronal loss.

SUMMARY

MS is a complex disease in which the interaction between genetic and environmental factors causes a cascade of events, including activation of the adaptive and innate immune system, blood-brain barrier breakdown, central nervous system demyelination, and axonal and neuronal damage with variable degrees of repair. These events manifest as potentially reversible focal neurologic symptoms or progressive nonremitting physical and cognitive disability, or both. Advances in the understanding of the risk factors and pathogenic mechanisms of MS have resulted in improved therapeutic strategies. The results of ongoing or future studies are needed to successfully and fully translate these advances into clinical practice.

Environmental risk factors for multiple sclerosis in Japanese people

BACKGROUND

The prevalence of multiple sclerosis (MS) has been increasing worldwide in recent years, especially among females. The same increasing trends are even observed in East Asian countries, where the prevalence of MS is relatively low compared with Northern European ancestries. Whether the environmental risk factors for MS are shared between Asian and North European ancestries, and the types of environmental factors that contribute to the low and recent increase in MS prevalence in Asian countries remain unknown. This study provides the first comprehensive survey of environmental risks for MS in East Asia.

METHODS

Patients with MS were recruited from the Department of Neurology at Kyushu University Hospital, Japan between 01 April 2017 and 31 March 2018. Healthy controls (HCs) were recruited by public notification. All participants were residents of Kyushu Island and were required to complete medical history and lifestyle questionnaires. Dietary data were collected using a Food Frequency Questionnaire comprising intake of approximately 140 food and beverage items in the past 1 year. One hundred and three patients with MS and 124 healthy controls (HCs) completed the questionnaires. Age at onset and disability score measured by the Kurtzke Expanded Disability Status Scale (EDSS) were obtained from medical records.

RESULTS

Frequency of obesity (body mass index ≥25 kg/m²) at present time was higher in MS patients than in HCs (19.4% vs. 7.4%, p = 0.009), while body mass index at age 18-20 years did not differ between the two groups. Frequency of current or ex-smokers was higher in MS patients than in HCs (50.5% vs. 22.8%, p < 0.0001) and disability measured by the EDSS was more severe in MS patients with active smoking history than in patients without such history (p = 0.006 after adjusting for sex). Passive smoking after age 16 years was also a risk factor for MS (odds ratio: 1.31, 95% confidence interval: 1.05-1.63, p = 0.015). Longer sunlight exposure in early childhood was a protective factor for MS (odds ratio: 0.65 during summer and 0.71 during winter at age 6-10 years; 0.71 during summer and 0.72 during winter at age 11-15 years). MS patients had earlier age of menarche than HCs (mean: 12.4 years vs. 12.9 years, p = 0.031). Intake of grains was lower in MS patients than in HCs, with intake of rice in particular being significantly lower in MS patients than in HCs (mean: 235.2 g/day vs. 280.6 g/day, p = 0.006). Previously reported foods associated with MS in Northern European ancestries were not replicated in Japanese people.

CONCLUSION

Smoking and earlier age of menarche are positively associated and sunlight exposure in early childhood is negatively associated with MS in Japanese people as shown in Caucasians. Intake of steamed short-grain white rice, a staple food in Japan, is newly found to be negatively associated with MS in Japanese people. Although the causality is unclear because the participants were prevalent cases, these environmental factors may be involved in the rising prevalence of MS in Japanese females.

Protective Effects of the Caffeine Against Neurodegenerative Diseases

Background:

Recent studies and increased interest of the scientific community helped to clarify the neurological health property of caffeine, one of the pharmacologically active substances most consumed in the world.

Methods:

This article is a review search to provide an overview on the current state of understanding neurobiochemical impact of caffeine, focusing on the ability of the drug to effectively counteract several neurodegenerative disorders such as Alzheimer’s, Parkinson’s, Huntington’s diseases, Multiple sclerosis and Amyotrophic lateral sclerosis.

Results:

Data collection shown in this review provide a significant therapeutic and prophylactic potentiality of caffeine which acts on human brain through several pathways because of its antioxidant activity combined with multiple molecular targets. However, the need to adjust the CF dosage to individuals, because some people are more sensitive to drugs than others, may constituted a limit to the CF effectiveness.

Conclusion:

What emerges from the complex of clinical and epidemiological studies is a significant CF potential impact against all neurological disorders. Although, further studies are needed to fully elucidate the several mechanisms of drug action which in part are still elusive.

Use of Vitamins and Dietary Supplements by Patients With Multiple Sclerosis: A Review

Importance

Surveys of patients with multiple sclerosis report that most are interested in modifying their diet and using supplements to potentially reduce the severity and symptoms of the disease. This review provides an updated overview of the current state of evidence for the role that vitamins and dietary supplements play in multiple sclerosis and its animal models, with an emphasis on recent studies, and addresses biological plausibility and safety issues.

Observations

Several vitamins and dietary supplements have been recently explored both in animal models and by patients with multiple sclerosis. Most human trials have been small or nonblinded, limiting their generalizability. Biotin and vitamin D are currently being tested in large randomized clinical trials. Smaller trials are ongoing or planned for other supplements such as lipoic acid and probiotics. The results of these studies may help guide clinical recommendations.

Conclusions and Relevance

At the present time, the only vitamin with sufficient evidence to support routine supplementation for patients with multiple sclerosis is vitamin D. Vitamin deficiencies should be avoided. It is important for clinicians to know which supplements their patients are taking and to educate patients on any known efficacy data, along with any potential medication interactions and adverse effects of individual supplements. Given that dietary supplements and vitamins are not subject to the same regulatory oversight as prescription pharmaceuticals in the United States, it is recommended that vitamins and supplements be purchased from reputable manufacturers with the United States Pharmacopeia designation.

Bifidobacteria: A probable missing puzzle piece in the pathogenesis of multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disorder in which the immunopathogenesis is not fully understood. In the recent years, the role of gut microbiome in the pathogenesis of this disorder has been highlighted. Bifidobacteria as a component of gut microbiome might also be involved in MS pathogenesis. Being emerged in early days after birth, bifidobacteria have a prominent role in immune system maturation and function. Some factors like mode of delivery, breast feeding, mother's blood group and her secretory state and also environmental factors could influence its level in the early infancy, which may remain throughout lifetime. In this review, we discussed possible immunopathogenic link between the bifidobacteria and MS.

[Aspects of nutrition for prevention and treatment of chronic neurological diseases]

Chronic neurodegenerative and neuroinflammatory diseases, such as idiopathic Parkinson's syndrome, amyotrophic lateral sclerosis and multiple sclerosis, represent a therapeutic challenge. Their pathophysiology is not well understood and a cure for any of these diseases is not possible. Over the past decades lifestyle and nutritional habits in modern industrial nations have changed and evidence is increasing that the prevalence of chronic diseases as well their clinical presentation are also changing. Epidemiological investigations indicate that nutritional components might have an impact on the pathogenesis of chronic neurological diseases. A profound understanding of these correlations could foster a better prevention as well as treatment of such chronic disabling diseases. This continuing medical education article summarizes the current understanding of selected nutritional components and their effect on the development and clinical course of chronic neurological disorders.

Lifestyle-based modifiable risk factors in multiple sclerosis: review of experimental and clinical findings

Multiple sclerosis (MS) is a lifelong inflammatory and neurodegenerative disease influenced by multiple lifestyle-based factors. We provide a narrative review of the effects of modifiable risk factors that are identified as being associated with risk to develop MS and/or influencing the future clinical disease outcomes. The emerging data regarding the beneficial effects of diet modifications and exercise are further reviewed. In contrast, obesity and comorbid cardiovascular diseases are associated with increased MS susceptibility and worse disease progression. In addition, the potential influence of smoking, coffee and alcohol consumption on MS onset and disability development are discussed. Successful management of the modifiable risk factors may lead to better long-term outcomes and improve patients' quality of life. MS specialists should participate in educating and facilitating lifestyle-based modifications as part of their neurological consults.

A randomised double-blind placebo-controlled feasibility trial of flavonoid-rich cocoa for fatigue in people with relapsing and remitting multiple sclerosis

The impact of flavonoids on fatigue has not been investigated in relapsing and remitting multiple sclerosis (RRMS).

OBJECTIVE

To determine the feasibility and estimate the potential effect of flavonoid-rich cocoa on fatigue and fatigability in RRMS.

METHODS

A randomised double-blind placebo-controlled feasibility study in people recently diagnosed with RRMS and fatigue, throughout the Thames Valley, UK (ISRCTN69897291). During a 6-week intervention participants consumed a high or low flavonoid cocoa beverage daily. Fatigue and fatigability were measured at three visits (weeks 0, 3 and 6). Feasibility and fidelity were assessed through recruitment and retention, adherence and a process evaluation.

RESULTS

40 people with multiple sclerosis (10 men, 30 women, age 44±10 years) were randomised and allocated to high (n=19) or low (n=21) flavonoid groups and included in analysis. Missing data were <20% and adherence to intervention of allocated individuals was >75%. There was a small effect on fatigue (Neuro-QoL: effect size (ES) 0.04, 95% CI -0.40 to 0.48) and a moderate effect on fatigability (6 min walk test: ES 0.45, 95% CI -0.18 to 1.07). There were seven adverse events (four control, three intervention), only one of which was possibly related and it was resolved.

CONCLUSION

A flavonoid beverage demonstrates the potential to improve fatigue and fatigability in RRMS.

Lifestyle and Environmental Factors in Multiple Sclerosis

Lifestyle and environmental factors potently influence the risk of multiple sclerosis (MS), because genetic predisposition only explains a fraction of the risk increase. There is strong evidence for associations of Epstein-Barr virus (EBV) infection, smoking, sun exposure/vitamin D, and adolescent obesity to risk of MS. There is also circumstantial evidence on organic solvents and shift work, all associate with greater risk, although certain factors like nicotine, alcohol, and a high coffee consumption associate with a reduced risk. Certain factors, smoking, EBV infection, and obesity interact with human leukocyte antigen (HLA) risk genes, arguing for a pathogenic pathway involving adaptive immunity. There is a potential for prevention, in particular for people at greater risk such as relatives of individuals with MS. All of the described factors for MS may influence adaptive and/or innate immunity, as has been argued for MS risk gene variants.

The Beneficial and Debilitating Effects of Environmental and Microbial Toxins, Drugs, Organic Solvents and Heavy Metals on the Onset and Progression of Multiple Sclerosis

Multiple sclerosis (MS), a chronic inflammatory disease of the central nervous system is common amongst young adults, leading to major personal and socioeconomic burdens. However, it is still considered complex and challenging to understand and treat, in spite of the efforts made to explain its etiopathology. Despite the discovery of many genetic and environmental factors that might be related to its etiology, no clear answer was found about the causes of the illness and neither about the detailed mechanism of these environmental triggers that make individuals susceptible to MS. In this review, we will attempt to explore the major contributors to MS autoimmunity including genetic, epigenetic and ecological factors with a particular focus on toxins, chemicals or drugs that may trigger, modify or prevent MS disease.

Review of Two Popular Eating Plans within the Multiple Sclerosis Community: Low Saturated Fat and Modified Paleolithic

The precise etiology of multiple sclerosis (MS) is unknown but epidemiologic evidence suggests this immune-mediated, neurodegenerative condition is the result of a complex interaction between genes and lifetime environmental exposures. Diet choices are modifiable environmental factors that may influence MS disease activity. Two diets promoted for MS, low saturated fat Swank and modified Paleolithic Wahls Elimination (WahlsElim), are currently being investigated for their effect on MS-related fatigue and quality of life (NCT02914964). Dr. Swank theorized restriction of saturated fat would reduce vascular dysfunction in the central nervous system (CNS). Dr. Wahls initially theorized that detailed guidance to increase intake of specific foodstuffs would facilitate increased intake of nutrients key to neuronal health (Wahls™ diet). Dr. Wahls further theorized restriction of lectins would reduce intestinal permeability and CNS inflammation (WahlsElim version). The purpose of this paper is to review the published research of the low saturated fat (Swank) and the modified Paleolithic (Wahls™) diets and the rationale for the structure of the Swank diet and low lectin version of the Wahls™ diet (WahlsElim) being investigated in the clinical trial.

The Impact of Coffee and Caffeine on Multiple Sclerosis Compared to Other Neurodegenerative Diseases

Background: The literature concerning the effect of coffee and caffeine on Multiple Sclerosis (MS) with focus on fatigue is investigated in this review. Potentially clinically relevant effects were also assessed in studies concerning comparable neurodegenerative diseases, such as Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS). Since the existing studies obtained very inconclusive results, we systematically reviewed these studies to summarize the evidence on the possible effects of coffee and caffeine on those disease entities. Previous studies suggested that coffee and caffeine intake is associated with a reduced risk of developing MS and other neurological diseases.

Methods: The PubMed database was searched using the keywords “coffee” OR “caffeine” in combination with keywords for each of the different diseases. Besides the keyword search, we included studies by reference list search. Studies on the effects of coffee and caffeine on the single neurological diseases were included for this review. A total of 51 articles met our inclusion criteria. The reviewed articles assessed the impact of coffee and caffeine on the susceptibility for neurological diseases, as well as the effect of coffee and caffeine on disease progression and possible symptomatic effects like on performance enhancement.

Results: Higher intake of coffee and caffeine was associated with a lower risk of developing PD. In some of the MS studies there, is evidence for a similar effect and experimental studies confirmed the positive impact. Interestingly in MS coffee and caffeine may have a stronger impact on disease course compared to effects on disease susceptibility. In ALS no such beneficial effect could be observed in the clinical and experimental studies.

Conclusion: This literature assessment revealed that coffee and especially caffeine could have a preventative role in the development of several neurodegenerative diseases if provided in comparatively high doses. The systematic assessment indicates that coffee and caffeine intake must not be considered as a health risk. Additional clinical studies are needed to fully understand how far coffee and caffeine intake should be considered as a potential therapeutic approach for certain disease entities and conditions.

Environmental exposures and the risk of multiple sclerosis in Saudi Arabia

Background

Multiple sclerosis (MS) is the most common non-traumatic condition that leads to disability among young individuals. It is associated with demyelination, inflammation, and neurodegeneration within the central nervous system. Information on risk factors of multiple sclerosis is crucial for the prevention and control of the disease. The aim of this study was to determine risk factors of MS among adults in Saudi Arabia.

Methods

A matched multicenter case-control study, including 307 MS patients and 307 healthy controls, was conducted in MS clinics and wards in 3 main cities of Saudi Arabia. Age, gender, and hospital were matched. Information on demographics, family history of MS, past medical and family history, sun exposure at different age periods, tobacco use, diet, consanguinity, and coffee consumption was obtained from self-administered questionnaires. ORs and 95% confidence intervals (CIs) were calculated. A conditional logistic regression model was used to control for potential confounding factors.

Results

The conditional logistic regression adjusted for age and gender showed that being the first child in the family (Adjusted Odds Ratio (AOR) 1.68, 95% CI: 1.03–2.74), having a family history of MS (AOR 5.83, 95% CI: 2.83–12), eating fast food ≥5 times weekly (AOR 2.05, 95% CI: 1.03–4.08), and having had measles (AOR 3.77, 95% CI: 2.05–6.96), were independently associated with an increased risk of MS.

In contrast, eating ≥5 servings of fruit per week (AOR 0.25, 95% CI: 0.16–0.38), drinking coffee daily (AOR 0.46, 95% CI: 0.31–0.68), and having a high level of sun exposure at the primary school level and university level (AOR 0.57, 95% CI: 0.38–0.85 and AOR 0.48, 95% CI: 0.30–0.76, respectively) were independently associated with a decreased risk of MS.

Conclusions

Our study suggested that high levels of sun exposure during primary school and university, consumption of fruits and drinking coffee protect against MS. In contrast, eating fast food was associated with an increased risk of the disease. Encouraging outdoor activity and healthy diets in school, especially for females, is highly recommended.

Electronic supplementary material

The online version of this article (10.1186/s12883-018-1090-8) contains supplementary material, which is available to authorized users.

Purinergic Receptors in Neurological Diseases With Motor Symptoms: Targets for Therapy

Since proving adenosine triphosphate (ATP) functions as a neurotransmitter in neuron/glia interactions, the purinergic system has been more intensely studied within the scope of the central nervous system. In neurological disorders with associated motor symptoms, including Parkinson's disease (PD), motor neuron diseases (MND), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Huntington's Disease (HD), restless leg syndrome (RLS), and ataxias, alterations in purinergic receptor expression and activity have been noted, indicating a potential role for this system in disease etiology and progression. In neurodegenerative conditions, neural cell death provokes extensive ATP release and alters calcium signaling through purinergic receptor modulation. Consequently, neuroinflammatory responses, excitotoxicity and apoptosis are directly or indirectly induced. This review analyzes currently available data, which suggests involvement of the purinergic system in neuro-associated motor dysfunctions and underlying mechanisms. Possible targets for pharmacological interventions are also discussed.

Molecular and Metabolic Imaging in Multiple Sclerosis

Multiple sclerosis is a multifactorial disease with heterogeneous pathogenetic mechanisms, which deserve to be studied to evaluate new possible targets for treatments and improve patient management. MR spectroscopy and PET allow assessing in vivo the molecular and metabolic mechanisms underlying the pathogenesis of multiple sclerosis. This article focuses on the relationship between these imaging techniques and the biologic and chemical pathways leading to multiple sclerosis pathology and its clinical features. Future directions of research are also presented.

The Evidence for Dietary Interventions and Nutritional Supplements as Treatment Options in Multiple Sclerosis: a Review

PURPOSE OF REVIEW

This review aims to critically evaluate published studies examining diets and nutritional supplements (excepting vitamin D) for the impact on prevention and prognosis of multiple sclerosis (MS).

RECENT FINDINGS

There is a negative relationship between the Mediterranean diet and vascular disease, and vascular co-morbidities are associated with a worse MS prognosis. Low-fat, fish-based diets, sodium-restricted diets, calorie restriction, the paleo diet, and gluten-free diets have been examined, mostly in observational studies; results are inconclusive. With regard to nutritional supplements, pilot data show a possible benefit of biotin with respect to disability worsening in people with progressive MS (PMS). The best designed randomized controlled trials (RCTs) for PUFA supplementation have not shown significant impact, but several weaker RCTs have. Many other nutritional supplements have been tested, including several anti-oxidants. While some early studies show positive results, no result has been definitive. Unfortunately, there is no strong evidence for a direct benefit of any given dietary intervention on MS risk or prognosis. However, due to its relationship with vascular co-morbidities, the Mediterranean diet has the strongest rationale for employment in PwMS. Higher-quality clinical trials are needed to ascertain the possible benefits of nutritional supplements.

Adenosine A2A Receptor Signaling in the Immunopathogenesis of Experimental Autoimmune Encephalomyelitis

Our increasing appreciation of adenosine as an endogenous signaling molecule that terminates inflammation has generated excitement regarding the potential to target adenosine receptors (ARs) in the treatment of multiple sclerosis (MS), a disease of chronic neuroinflammation. Of the four G protein-coupled ARs, A2ARs are the principal mediator of adenosine’s anti-inflammatory effects and accordingly, there is a growing body of evidence surrounding the role of A2ARs in experimental autoimmune encephalomyelitis (EAE), the dominant animal model of MS. Such evidence points to a complex, often paradoxical role for A2ARs in the immunopathogenesis of EAE, where they have the ability to both exacerbate and alleviate disease severity. This review seeks to interpret these paradoxical findings and evaluate the therapeutic promise of A2ARs. In essence, the complexities of A2AR signaling arise from two properties. Firstly, A2AR signaling downregulates the inflammatory potential of TH lymphocytes whilst simultaneously facilitating the recruitment of these cells into the CNS. Secondly, A2AR expression by myeloid cells – infiltrating macrophages and CNS-resident microglia – has the capacity to promote both tissue injury and repair in chronic neuroinflammation. Consequently, the therapeutic potential of targeting A2ARs is greatly undermined by the risk of collateral tissue damage in the periphery and/or CNS.

In Vivo PET Imaging of Adenosine 2A Receptors in Neuroinflammatory and Neurodegenerative Disease

Adenosine receptors are G-protein coupled P1 purinergic receptors that are broadly expressed in the peripheral immune system, vasculature, and the central nervous system (CNS). Within the immune system, adenosine 2A (A_2A) receptor-mediated signaling exerts a suppressive effect on ongoing inflammation. In healthy CNS, A_2A receptors are expressed mainly within the neurons of the basal ganglia. Alterations in A_2A receptor function and expression have been noted in movement disorders, and in Parkinson's disease pharmacological A_2A receptor antagonism leads to diminished motor symptoms. Although A_2A receptors are expressed only at a low level in the healthy CNS outside striatum, pathological challenge or inflammation has been shown to lead to upregulation of A_2A receptors in extrastriatal CNS tissue, and this has been successfully quantitated using in vivo positron emission tomography (PET) imaging and A_2A receptor-binding radioligands. Several radioligands for PET imaging of A_2A receptors have been developed in recent years, and A_2A receptor-targeting PET imaging may thus provide a potential additional tool to evaluate various aspects of neuroinflammation in vivo. This review article provides a brief overview of A_2A receptors in healthy brain and in a selection of most important neurological diseases and describes the recent advances in A_2A receptor-targeting PET imaging studies.

Coffee and autoimmunity: More than a mere hot beverage!

Coffee is one of the world's most consumed beverage. In the last decades, coffee consumption has attracted a huge body of research due to its impact on health. Recent scientific evidences showed that coffee intake could be associated with decreased mortality from cardiovascular and neurological diseases, diabetes type II, as well as from endometrial and liver cancer, among others. In this review, on the basis of available data in the literature, we aimed to investigate the association between coffee intake and its influence on the immune system and the insurgence of the most relevant autoimmune diseases. While some studies reported conflicting results, general trends have been identified. Coffee consumption seems to increase the risk of developing rheumatoid arthritis (RA) and type 1 diabetes mellitus (T1DM). By contrast, coffee consumption may exert a protective role against multiple sclerosis, primary sclerosing cholangitis, and ulcerative colitis. Concerning other autoimmune diseases such as systemic lupus erythematosus, psoriasis, primary biliary cholangitis and Crohn's disease, no significant association was found. In other studies, coffee consumption was shown to influence disease course and management options. Coffee intake led to a decrease in insulin sensitivity in T1DM, in methotrexate efficacy in RA, and in levothyroxine absorption in Hashimoto's disease. Further, coffee consumption was associated with cross reactivity with gliadin antibodies in celiac patients. Data on certain autoimmune diseases like systemic sclerosis, Sjögren's syndrome, and Behçet's disease, among others, are lacking in the existent literature. As such, further research is warranted.

Dietary factors in rheumatic autoimmune diseases: a recipe for therapy?

Today, we are facing a new era of digitization in the health care system, and with increased access to health care information has come a growing demand for safe, cost-effective and easy to administer therapies. Dietary habits have a crucial influence on human health, affecting an individual's risk for hypertension, heart disease and stroke, as well as influencing the risk of developing of cancer. Moreover, an individual's lifestyle choices can greatly influence the progression and manifestation of chronic autoimmune rheumatic diseases. In light of these effects, it makes sense that the search for additional therapies to attenuate such diseases would include investigations into lifestyle modifications. When considering the complex web of factors that influence autoimmunity, it is not surprising to find that several dietary elements are involved in disease progression or prevention. In this Review, several common nutritional components of the human diet are presented, and the evidence for their effects on rheumatic diseases is discussed.

Health benefits of methylxanthines in neurodegenerative diseases

Methylxanthines (MTXs) are consumed by almost everybody in almost every area of the world. Caffeine, theophylline and theobromine are the most well-known members of this family of compounds; they are present, inter alia, in coffee, tea, cacao, yerba mate and cola drinks. MTXs are readily absorbed in the gastrointestinal tract and are able to penetrate into the central nervous system, where they exert significant psychostimulant actions, which are more evident in acute intake. Coffee has been paradigmatic, as its use was forbidden in many diseases, however, this negative view has radically changed; evidence shows that MTXs display health benefits in diseases involving cell death in the nervous system. This paper reviews data that appraise the preventive and even therapeutic potential of MTXs in a variety of neurodegenerative diseases. Future perspectives include the use of MTXs to advance the understanding the pathophysiology of, inter alia, Alzheimer's disease (AD) and Parkinson's disease (PD), and the use of the methylxanthine chemical moiety as a basis for the development of new and more efficacious drugs.

Having a Coffee Break: The Impact of Caffeine Consumption on Microglia-Mediated Inflammation in Neurodegenerative Diseases

Caffeine is the major component of coffee and the most consumed psychostimulant in the world and at nontoxic doses acts as a nonselective adenosine receptor antagonist. Epidemiological evidence suggests that caffeine consumption reduces the risk of several neurological and neurodegenerative diseases. However, despite the beneficial effects of caffeine consumption in human health and behaviour, the mechanisms by which it impacts the pathophysiology of neurodegenerative diseases still remain to be clarified. A promising hypothesis is that caffeine controls microglia-mediated neuroinflammatory response associated with the majority of neurodegenerative conditions. Accordingly, it has been already described that the modulation of adenosine receptors, namely, the A2A receptor, affords neuroprotection through the control of microglia reactivity and neuroinflammation. In this review, we will summarize the main effects of caffeine in the modulation of neuroinflammation in neurodegenerative diseases.

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.

Interactions between genetic, lifestyle and environmental risk factors for multiple sclerosis

Genetic predisposition to multiple sclerosis (MS) only explains a fraction of the disease risk; lifestyle and environmental factors are key contributors to the risk of MS. Importantly, these nongenetic factors can influence pathogenetic pathways, and some of them can be modified. Besides established MS-associated risk factors - high latitude, female sex, smoking, low vitamin D levels caused by insufficient sun exposure and/or dietary intake, and Epstein-Barr virus (EBV) infection - strong evidence now supports obesity during adolescence as a factor increasing MS risk. Organic solvents and shift work have also been reported to confer increased risk of the disease, whereas factors such as use of nicotine or alcohol, cytomegalovirus infection and a high coffee consumption are associated with a reduced risk. Certain factors - smoking, EBV infection and obesity - interact with HLA risk genes, pointing at a pathogenetic pathway involving adaptive immunity. All of the described risk factors for MS can influence adaptive and/or innate immunity, which is thought to be the main pathway modulated by MS risk alleles. Unlike genetic risk factors, many environmental and lifestyle factors can be modified, with potential for prevention, particularly for people at the greatest risk, such as relatives of individuals with MS. Here, we review recent data on environmental and lifestyle factors, with a focus on gene-environment interactions.