Public Health Considerations in Multiple Sclerosis

Nida Naushad

Catherine Stratton

Yetsa A. Tuakli-Wosornu

Introduction

The fundamental goal of public health is to prevent disease; promote physical, mental, and social health; and prolong life at the population level (World Health Organization [WHO]). Chronic diseases such as multiple sclerosis (MS) have wide-reaching population-level impacts, so an understanding of these conditions is a central component of public health science. Today, MS affects approximately 2.5 million people worldwide, and the prevalence of this condition is growing. Given the morbidity and long-term disability associated with MS, which may include weakness, chronic pain, gait disturbance, and bladder dysfunction, it is important to understand the disease from a public health perspective. In this chapter, we discuss:

Screening and prevention strategies
Health disparities related to MS
The socioeconomic impact of MS
Population-level awareness about MS

Better understanding of these aspects of MS can lead to the creation of programs and policies that promote prevention and early diagnosis,
increase access to care and support, and improve overall quality of life for the millions of people living with MS.

Risk Factors

MS is a multifactorial disease, which likely arises as a result of a combination of genetics plus environmental exposures that lead to disease phenotype. Researchers have identified a number of genetic and environmental risk factors, which we also reviewed in our discussion of the epidemiology of MS in Chapter 1 (Table 14.1).

Risk Factors and Interventions

Genetics

In the 1890s, scientists noted a familial aggregation of MS, which led to the question of the role genetic factors played in disease development.¹ It has been concluded that first-degree relatives are at a 15- to 25-fold greater risk of developing MS compared with the general population.² A study of half-siblings in Canada found that there was an increased risk of MS among maternal half-siblings versus among paternal half-siblings, which informed how important maternal susceptibility to MS is for inheritance risk.³ Furthermore, another study investigated a group of
interracial marriages in Canada between Caucasians and North American Aboriginals; the study found that index cases with a Caucasian mother and North American Aboriginal father had a higher rate of sibling recurrence versus patients with an Aboriginal mother and a Caucasian father, supporting the role of maternal genetics in MS development.⁴

TABLE 14.1 FACTORS THAT MAY INFLUENCE MS DEVELOPMENT

Genetics (e.g., HLA type)

Gender

Latitude

Month and place of birth

High-salt diet

Gut microbiome

Vitamin D

Psychological or emotional stress

Cigarette smoking

Organic solvents

Obesity

Sex hormones

EBV

Early life infections

EBV, Epstein-Barr virus; HLA, human leukocyte antigen; MS, multiple sclerosis.

Sex

Similar to many other autoimmune diseases, MS is more common among women than among men.⁵ Incidence rates are rising more quickly among women as well, so recent statistics estimate that the ratio of women to men with MS is 2.3 to 3.5:1.⁶ Of note, pregnancy appears to be a protective factor that is associated with lower risk of onset and better prognosis in MS.⁷ Despite the greater incidence of disease among women, research suggests that men have an increased likelihood of developing a more severe presentation of disease,⁸ follow a more malignant course,⁹ and have worse recovery after an initial flare-up in their symptoms.¹⁰

Epstein-Barr Virus

The Epstein-Barr virus (EBV) is a double-stranded DNA γ-herpesvirus causing lifelong infection in over 90% of the world’s adult population.¹¹ Delayed primary infection with EBV, evidenced by infectious mononucleosis, seems to be an important factor in developing MS.¹² MS is less common among those with early childhood infection, which is often asymptomatic or mild.¹³ There is also a low risk of developing MS among those who were never infected.¹³ This understanding of EBV has numerous implications for treatment strategies. Studies show that antiviral therapy may reduce relapses or reduce the number of new active brain lesions in some of those affected. One study found that therapy with acyclovir decreased the relapse rate by 34% in patients with relapsing-remitting MS.¹¹ The apparent relationship between EBV and MS has broader public health implications; researchers have posited the utility of a vaccine against MS or early exposure to EBV as a means of prevention.¹³

Vitamin D Hypothesis

With some exceptions, there is an increased incidence of MS among those living further from the equator. This distribution exists even after accounting for HLA-DRB1 allele frequencies, suggesting that there is an environmental factor associated with latitude, such as ultraviolet (UV) radiation exposure/vitamin D.¹⁴ UV radiation exposure has been associated with reduced MS risk, 20-fold stronger than other environmental factors.¹⁵ However, an unusual relationship is found in northern Scandinavia, where there is a lower MS prevalence in spite of the weak sunlight.¹⁴ Of
note, this population has a much higher dietary vitamin D intake than that found in the rest of Europe.¹⁴ A move to encourage increased vitamin D intake (e.g., via supplementation) could be a public health initiative in at-risk populations.

Smoking

Smoking cigarettes and exposure to secondhand smoke have been associated with an increased risk of MS.¹⁶ Duration of exposure to passive smoking was associated with MS risk in a dose-dependent manner among never smokers. Those who reported smoking more than 10 pack-years and exposure to passive smoking for more than 20 years had nearly three times higher risk of developing MS compared with those who reported no exposure to tobacco smoke. Furthermore, smoking is associated with worse MS prognosis, with those who started smoking at a younger age being the most likely to develop progressive disease at an earlier onset.¹⁷ Thus, public health initiatives to decrease rates of smoking may also help improve MS outcomes. The following are examples of programs that promote smoking cessation:

A multipronged approach, which combines both pharmacotherapy and behavioral support, increases rates of smoking cessation compared with usual care or minimal intervention. A combination intervention seems to increase an individual’s chance of quitting by about 10% to 25%.¹⁸
Mobile phone-based text message interventions have been shown to reduce smoking rates at 6 months. It should be noted that most of these studies were conducted in high-income countries, and so their generalizability to low-income countries is unclear.¹⁹
Programs that utilize incentives appear to increase rates of smoking cessation, while the incentives are in place. Programs that require participants to make a deposit have higher rates of smoking cessation, although they also have lower rates of enrollment.²⁰
Mass media campaigns can be an effective way to promote smoking cessation among the general public. Campaigns that contain information about the negative health effects of smoking seem to be most effective at increasing knowledge, have higher perceived effectiveness ratings, and are most likely to result in quitting behavior.²¹

Obesity

Obesity is associated with an increased MS risk, and that risk is modulated by the level of obesity. There is an increased odds of MS with increasing levels of obesity.²²,²³,²⁴ It is believed that the association between obesity and MS may be stronger among females, as obesity is associated with a
significantly increased risk of MS or clinically isolated syndrome in girls but not in boys.²³ The relationship between obesity and MS is particularly important given the childhood obesity epidemic. Thus, initiatives to decrease obesity, such as the following, may also have a positive impact on MS outcomes:

Behavioral weight management programs that combine both diet and physical activity seem to be more effective in the long term than programs focusing on diet or physical activity alone.²⁵
Programs that aim to prevent childhood obesity are particularly effective if targeting children ages 6 to 12 years.²⁶ There is moderately strong evidence that school-based interventions are effective for preventing childhood obesity.²⁷ Programs and policies that may be helpful to reduce childhood obesity include a school curriculum that provides education about healthy eating, physical activity, and body image; increased opportunities for physical activity throughout the school week; more nutrition food in schools; support for teachers and staff to implement health promotion activities; and a home environment that encourages increased activity, more nutritious meals, and less screen time.²⁶ Community health workers in the home, clinic, school, or community setting may also help improve body mass index among children.²⁸
Modifying the built environment may also positively influence health. Environmental factors that had a greater effect include bans or restriction on unhealthy foods, mandates offering healthier foods, altering rules for food purchased using low-income food vouchers, and improvements to active transportation infrastructure.²⁹

Diet

Diet has a significant impact on body weight, cholesterol levels, and other vascular risk factors that affect MS risk and disease course. These include effects mediated by dietary metabolites derived directly from food, dietary induction of metabolite production by gut microbiota, and diet-mediated changes in gut microbial composition. To summarize, some proinflammatory dietary factors that people with MS may want to avoid include saturated fatty acids of animal origin, trans fats, red meat, sweetened drinks, increased dietary salt, cow milk proteins of the milk fat globule membrane (MGFM proteins), and salt.³⁰ A low-calorie diet rich in vegetables, fruit, legumes, fish, prebiotics, and probiotics is beneficial because it helps upregulate oxidative metabolism, downregulate the synthesis of proinflammatory molecules, and restore or maintain a healthy symbiotic gut microbiota.³⁰ The Mediterranean diet, which is a diet rich in vegetables, legumes, and fruits; moderate in fish; and low in meat, has been positively correlated with a reduced risk of acquiring MS.³¹

Given this baseline understanding, we have detailed some of the dietary factors that affect MS:

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