The way the disease manifests in late-onset MS can be different from what normally happens in adult-onset MS, which most commonly affects people in their mid-20s and 30s.
Causes
MS is a chronic disease of the central nervous system (CNS), which includes your brain, spinal cord, and optic nerves, located in your eyes. In MS, your immune system attacks your nerve cells and the fatty myelin sheath surrounding them, causing scarring.
The myelin scar tissue essentially jams communication between your brain and your body. The resulting distortion and blocking of messages between the brain and spinal cord lead to the symptoms and disability that are recognized as MS.
It’s not yet known what turns on the immune system response when you have MS. However, this appears to occur in people with a genetic susceptibility to the disease who are exposed to one or more environmental triggers, including smoking, stress, and vitamin D deficiency.
It’s also unknown why some people develop MS later than others. Further research needs to be done to understand the causes and onset of MS more clearly.
Types
There are three kinds of MS.
Relapsing-Remitting MS (RRMS)
With relapsing-remitting MS, people have relapses or flares—bouts of disability alternating with periods of normal function. Once the attack is over, MS symptoms may disappear. RRMS is by far the most common type of MS, affecting 85—90% of MS patients, most of whom are younger adults.
Secondary Progressive MS (SPMS)
Secondary progressive MS occurs when RRMS takes on a progressive form. Within 25 years of having RRMS, an estimated 90% of untreated patients gradually transitioned to SPMS.
Primary Progressive MS (PPMS)
With primary progessive MS, there’s a slow and steady decline in function due to permanent damage to nerves. Relapses and plateaus may occur in some people. PPMS usually starts with problems walking, such as foot-dragging or stiffness in one or both legs. Over the course of months and years, the degree of disability increases.
This type affects around 15% of people with MS. Older adults are more likely to be diagnosed with PPMS than younger adults.
Diagnostic Challenges
It’s fairly rare for people over the age of 50 to be diagnosed with MS, but it’s unclear exactly how many people are affected by late-onset MS. Many studies estimate that around 4% of MS patients start having MS symptoms after the age of 50.
Unfortunately, MS may be harder to diagnose in this population for a variety of reasons. One of the main barriers is that MS has not been studied in the older adult population as much as in younger adults.
This is important because the disease may vary between younger and older people, including the range of symptoms experienced. Because of this, late-onset MS is often missed by healthcare providers who are more familiar with the disease in younger adults.
Even some diagnostic tests may be incorrectly interpreted if steps are not taken to explore immune-mediated diseases.
For example, magnetic resonance imaging (MRI) scans commonly used to diagnose MS may show the white-matter brain damage consistent with MS but be interpreted as damage caused by any one of several vascular diseases common in older people.
In late-onset MS, symptoms can easily mimic those of other disorders including:
Stroke Parkinson’s disease Dementia Lou Gehrig’s disease (amyotrophic lateral sclerosis, or ALS) Major depressive disorder
Disease Progression
While the initial symptoms of late-onset MS develop later in life, research suggests that physical disability and loss of motor function occur faster and more frequently when MS develops later.
Studies differ on which type of MS is diagnosed more often in late-onset MS; some say PPMS, while others say RRMS. PPMS does tend to be diagnosed when people are in their 40s and 50s though, around the same time that the majority of people with RRMS transition into secondary progressive MS (SPMS).
A 2016 study published in the journal PLoS One concluded that people with late-onset MS reached a higher disability level faster—a median time of 6.5 years—compared to a median of 12.8 years for people with adult-onset MS. Males were also found to progress significantly faster to disability than females.
Treatment
Your treatment plan will depend on the type of MS you’ve been diagnosed with, other medical conditions you may have, and how severe your disease is. Your neurologist will go over the strategies for managing MS that will be most effective for you and your individual situation.
Medications
If you’ve recently found out you have MS and you’re over 50, your medication options may be more limited than they are for a younger adult.
This is partly because many past clinical trials on medications for MS purposely excluded people over 50, so it’s not always clear what’s most effective or safe for those in this age group. Thankfully, many newer studies have expanded the age of participants to 60 or 65.
The drugs used to treat MS are called disease-modifying therapies (DMTs) and they work by targeting the immune system and slowing down disease progression. There are some potential limitations to DMTs for people over 50.
Ocrevus (ocrelizumab), the only DMT approved by the Food and Drug Administration (FDA) for treating PPMS, has been shown to significantly decrease disability. However, the 2017 study that found this used patients with an average age of 45 years, which may not accurately reflect the drug’s effectiveness in older people.
And as with any powerful medication, Ocrevus has side effects, including some that could be especially problematic for older people, such as increasing the risk of respiratory infections and causing abnormal tissue growth.
For RRMS, patients who are over the age of 50 may not respond as well as younger patients to Novantrone (mitoxantrone), one of the DMTs that’s FDA-approved to treat both RRMS and secondary progressive MS.
Rehabilitation Therapies
Even though medications for PPMS are limited, there are many rehabilitation treatments available to help with MS symptoms. Your healthcare provider may recommend one or more of the following:
Physical therapy (PT): A physical therapist can help you build muscle strength and teach you techniques to compensate for loss of function. Occupational therapy (OT): OT can help you modify your home so you’re better able to work around your limitations when taking care of yourself. This could include a bath transfer bench and rearranging cabinets so the items are easy to reach. You also can learn ways to move your body to reduce fatigue. Speech-language therapy: A speech-language therapist can help you improve your breathing, teach you strategies that minimize swallowing problems and aspiration, and reduce your speech difficulties. Cognitive rehabilitation: This therapy helps with cognitive abilities like memory, attention, organization, and language. Vocational rehabilitation: Specialists can help you make your job more accommodating to your needs or find one is a better fit.
A Word From Verywell
In the end, the course of late-onset MS and how different it is from regular adult-onset MS is still not entirely clear, but a prompt and accurate diagnosis is as critically important in late-onset MS as it is at any age.
This is because starting treatment with disease-modifying medications as soon as possible can reduce MS attacks and new lesions, as well as slow the progression of the disease. If you think you might have symptoms of MS, be sure to see your healthcare provider.
