A web of hidden dangers in modern life could be fueling a sharp rise in late-onset MS across America – with seemingly healthy adults in midlife being diagnosed in alarming numbers.
Multiple sclerosis (MS) is a devastating disease that causes the immune system to attack the brain and spinal cord, stripping the insulated coating from nerves and scrambling communication between the brain and body.
For decades, it was seen as a disease of young adulthood, striking most between 20 and 40. But new evidence shows that picture is changing.
In one study looking at Norwegian adults, while MS diagnoses in younger adults have leveled out, the proportion of cases beginning after age 50 jumped from 2.6 percent before 1970 to nearly 12 percent after 2010.
And in Italy, incidence among adults in their 60s more than tripled between 2005 and 2020. The researchers said this could reflect an ever-aging population, better diagnostics or, crucially, ‘changing environmental risk factors.’
‘Improved diagnosis is probably not the whole explanation,’ UK-based Neurologist Dr Rab Nawaz Khan, who has seen first-hand the same phenomenon in his own clinics, told the Daily Mail. ‘The trend is real – but we cannot point to one proven reason. It’s likely that a combination of factors are at play.’
Studies suggest that environmental factors – from years of smoking to low levels of vitamin D – may influence when MS strikes, he said. Lifestyle choices made decades earlier could influence whether someone develops MS in their 50s or 60s.
So what’s really driving a rise in older people getting MS, and what can you do to minimize your risk?
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Is a lack of sunlight driving the rise?
One of the most intriguing theories behind the rise in MS among older adults focuses on vitamin D. Best known for keeping bones healthy, vitamin D also plays a vital role in regulating the immune system.
Despite its name, vitamin D acts more like a hormone than a vitamin. We get relatively little from our diets; instead, the body produces it when ultraviolet (UV) rays from sunlight strike the skin.
Low vitamin D is common in the United States, affecting roughly 40 percent of the population, with some studies noting that up to nearly two-thirds of adults have insufficient levels.
Modern lifestyles mean many people simply don’t make enough. Spending more time indoors, regular sunscreen use, darker skin, obesity and living in northern regions with limited winter sunlight can all increase the risk of deficiency.
Scientists believe vitamin D helps keep the immune system from turning on the body itself.
When vitamin D levels fall too low, this delicate balance may be lost, allowing the immune system to mistakenly attack myelin, the protective coating around nerve fibers in the brain and spinal cord.
As myelin is damaged, nerve signals slow or become disrupted, causing symptoms such as numbness, muscle weakness, vision problems and difficulties with balance.
Low vitamin D levels may also weaken the blood-brain barrier, making it easier for rogue immune cells to enter the central nervous system and trigger this attack.
‘MS patients are usually deficient in vitamin D, and that may have to do with their sun exposure,’ Dr Erin Longbrake, a neurologist who specializes in MS at Yale Medicine, told the Daily Mail.
The theory is supported by a large meta-analysis of 14 studies, which found that people with vitamin D deficiency had a 54 percent higher risk of developing MS than those with sufficient levels.
Vitamin D deficiency is increasingly linked to MS, making sun exposure and supplementation key considerations
In studies that excluded participants taking vitamin D supplements, the risk was even higher – more than double.
Whether increasing vitamin D levels can actually prevent MS is less clear.
A long-term study of more than 180,000 women found that those with the highest vitamin D intake had a 33 percent lower risk of developing MS. Women who took at least 400 IU of vitamin D supplements daily had a 41 percent lower risk.
However, many clinical trials of vitamin D supplementation have been small, short and poorly designed, making it difficult to draw firm conclusions. There may be a benefit, but it is unlikely to be as large or as consistent as early studies suggested.
Even so, experts say maintaining healthy vitamin D levels is a sensible precaution, particularly for people at higher risk of developing MS.
Dr Michael Kornberg, a neurologist at Johns Hopkins, told the Daily Mail that vitamin D plays a crucial role in overall health, and for those with a family history of MS, maintaining normal levels through supplementation is strongly advised.
How America’s obesity crisis could be to blame
Obesity, but particularly during childhood and adolescence, is one of the strongest known risk factors for developing multiple sclerosis later in life.
Studies suggest obesity roughly doubles the risk of MS, particularly in women. Women with a body mass index (BMI) of 30 or above at age 18 have more than twice the risk of developing the disease compared with those of a healthy weight, research suggests.
The age at which MS strikes has shifted over time. In the 1970s, most cases peaked around age 30. By 2010-2022, a second peak emerged around age 45, reflecting the growing number of late-onset cases
The danger appears even greater when obesity is combined with other risk factors, such as carrying an MS-related gene.
‘Developing MS is not a one-hit type of thing. It’s all of the little pebbles being added onto the scale, and it finally tips over into disease,’ Longbrake said.
Fat tissue is far more than an energy store – it is an active organ that continually releases hormones and chemical messengers that influence the immune system.
In people with obesity, fat cells produce large amounts of inflammatory proteins called cytokines, creating a state of chronic, low-grade inflammation throughout the body.
In addition, obesity increases leptin production, a hormone involved in regulating hunger and satiety that also promotes inflammation and has been found to be elevated in people with active MS.
Together, these changes may prime the immune system to attack the myelin.
Obesity is also associated with a more aggressive course of disease once MS develops.
A Swedish study of nearly 3,000 people with relapsing-onset MS found that being overweight at diagnosis accelerated disability progression, particularly among those who had been overweight since early adulthood.
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People with a BMI above 28 reached disability milestones significantly sooner.
Those who were overweight at both age 20 and diagnosis were 64 percent more likely to reach a disability score of three out of six, typically by around age 55, and 51 percent more likely to reach a score of four in their early 60s.
Encouragingly, participants who had been overweight at 20 but lost weight before developing MS did not face the same increased risk, suggesting early weight loss may slow disability progression.
For people diagnosed later in life, this is particularly important. An Italian study of patients diagnosed with MS after age 60 found disability accumulated rapidly, with most requiring a walking aid within about six years of diagnosis.
How smoking is the biggest driver of MS
Smoking is one of the strongest and most well-studied risk factors for multiple sclerosis. Research shows that smokers are about 50 percent more likely to develop MS than non-smokers. Some studies put the risk even higher – up to nearly double.
The more a person smokes, the greater their risk appears to be. And those who start smoking before age 15 may be especially vulnerable.
‘Avoiding tobacco cigarettes is probably the best lifestyle factor and the most important one for lowering your risk of developing MS,’ Kornberg said.
In a 2022 study published in Frontiers in Immunology, researchers looked at more than 9,400 people with MS and compared them to the same number of healthy people without the disease.
Compared to 1970-1979, the 2010-2022 curve shows a clear second peak around age 45-driven largely by a rise in late-onset MS among women
The numbers were striking. Among those with MS, 44 percent had been regular smokers at some point compared to 36 percent of healthy people. And 38 percent of MS patients were still smoking at the time of their diagnosis, versus 29 percent of controls.
After crunching the numbers, the researchers concluded that at least 13 percent of MS cases could be prevented if people avoided smoking entirely.
When you consider that nearly 1 million Americans live with MS, that’s tens of thousands of cases that could potentially be avoided.
The danger doesn’t stop with active smoking. Even exposure to secondhand smoke has been linked to a higher risk of MS. A Swedish study found that never-smokers who were regularly exposed to passive smoke had a 30 percent greater chance of developing the disease compared to those with no exposure.
And studies have found that using Swedish snus, a form of smokeless tobacco, does not appear to increase the risk of MS, pointing to inhaled chemicals in cigarette smoke as the more likely culprit.
Smokers are also more likely to develop progressive forms of MS where symptoms steadily worsen over time. Brain scans show that smokers lose brain tissue more quickly and develop more damage than non-smokers.
Smoking also has anti-estrogen effects, which may matter because hormones appear to play a role in MS risk, particularly in women.
And the toxins in cigarette smoke, including compounds that damage nerves directly, may accelerate the aging-related processes that make the brain more vulnerable to MS as people get older.
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Timing may also matter. While some MS risk factors seem to have their biggest impact during childhood and adolescence, smoking is different.
People who start smoking in their teens and continue for decades are exposing their bodies to harmful chemicals over a much longer period.
That long-term exposure could be setting the stage for a disease that doesn’t become obvious until their 50s or 60s.
Common viral infection that triggers the illness
Epstein-Barr virus (EBV), the virus that causes infectious mononucleosis, is perhaps the strongest known environmental risk factor for multiple sclerosis. About 95 percent of Americans are infected by the age of 40.
A landmark study found that people infected with EBV were 32 times more likely to develop MS than those who remained uninfected.
In most cases, evidence of infection appeared in the blood about five years before the disease was diagnosed. More than 99 percent of people with MS carry antibodies showing they have previously been infected with the virus.
How does a common virus end up triggering an autoimmune disease of the brain and spinal cord?
Scientists are still piecing together the answer, but they know EBV infects immune cells known as B cells and remains in the body for life. Those same B cells are thought to play a central role in MS.
Late-onset MS is on the rise. Among adults aged 60 to 69 in Catania, Italy, incidence rates more than tripled over a 16-year period — from 1.12 to 3.12 per 100,000 person-years — with the sharpest increase occurring in men
One theory is that EBV periodically reactivates, repeatedly stimulating the immune system until it eventually turns against the body’s own nervous tissue. Another suggests the initial infection permanently alters the immune system, leaving it more prone to autoimmune disease even after the virus becomes dormant.
Researchers have also uncovered evidence of a phenomenon known as molecular mimicry.
Some EBV proteins closely resemble proteins found in myelin, the protective coating around nerve fibers. The immune system may therefore mistake myelin for the virus and attack it, thereby damaging nerve cells.
While several vaccines against EBV are now in development, scientists are still studying whether preventing infection could reduce the risk of MS.
‘Humans have co-evolved with EBV for a long time, so there are still unknowns as far as what happens if you vaccinate against it,’ Longbrake said. ‘We don’t know if there might be unintended consequences, but vaccines are being developed.’