How Late-Onset MS Differs From Young-Onset MS

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Do you or someone you care about have multiple sclerosis (MS)? If so, at what age was it diagnosed? Late-onset MS is commonly defined as the occurrence of the first symptoms after age 50. (Adult-onset MS is most often diagnosed in people who are in their mid-20s to 30s.)

Overview of MS

MS is a chronic disease of the central nervous system (CNS), which includes your brain, spinal cord, and optic (eye) nerves. In MS, your immune system attacks nerve cells and the fatty myelin sheath surrounding them, causing scarring.

The myelin scar tissue “jams” communication between your brain and your body. The resulting distortion and blocking of messages between the brain and spinal cord leads to the symptoms and disability that occur in MS.

It’s not yet known what “turns on” the immune system response in a person who gets MS. However, this appears to occur in people with an inherited (genetic) susceptibility to the disease who are exposed to one or more environmental “triggers.”

Challenges With Diagnosing Late-Onset MS

People over the age of 50 are diagnosed with MS in about 3 to 4 percent of cases, according to a study in Multiple Sclerosis and Related Disorders. Unfortunately, MS may be harder to diagnose in people over 50, for a variety of reasons.

MS has not been studied in the older adult population as much as in younger adults. This is important because the disease may vary in a number of ways between younger and older people, including different symptoms. So symptoms of late-onset MS may not suggest the diagnosis to doctors who are more familiar with MS symptoms in younger adults.

In late-onset MS, the person’s symptoms can easily mimic those of other disorders. Some of these disorders include:

Symptoms of late-onset MS can be mistaken for signs of normal aging. For example, on a magnetic resonance imaging (MRI) scan of the brain (an important diagnostic test for MS), a doctor may mistake the white-matter brain damage caused by MS for brain changes due to blood vessel (vascular) disease.

Some symptoms of late-onset MS that can overlap with conditions of normal aging include:

How Late-Onset MS Differs From Young-Onset MS

You may be interested to learn that a person’s age, when diagnosed with MS, also affects the course of the disease.

Although CNS damage in late-onset MS is similar to that seen in young adults, some research suggests that older people start showing signs of disability sooner.

According to a study in the Journal of Neurology, which compared 52 people who developed MS after the age of 50 to people who developed MS at a younger age (less than 40 years old), motor symptoms were more common in the late-onset MS group.

On the other hand, visual symptoms, signs of optic neuritis, and dysarthria were less common in late-onset MS. Sensory symptoms (for example, numbness and tingling), ataxia, cognitive function, and fatigue did not differ between the two groups. 

In addition, according to this same study, spinal cord lesions, as seen on MRIs, were more common in people with late-onset MS, and lesions in the cerebellum were more common in people with younger-onset MS. 

To further support these findings, another study found that motor symptoms caused by transverse myelitis were more common in people with late-onset multiple sclerosis. 

Besides the difference in symptoms between late-onset MS and adult-onset MS, those with late-onset MS are more likely to be diagnosed with primary progressive MS (a type of MS) whereas those with adult-onset MS are more likely to have relapsing-remitting MS. Late-onset MS also portends an overall poorer prognosis (disease outcome) than adult-onset MS.

Lastly, while there tends to be a delay in time when women with adult-onset MS require a cane or crutch to walk, as compared to men with adult-onset MS, there is no gender difference in disability progression with patients with late-onset MS—and it is unclear why, but the authors cleverly propose that menopause (a time when a woman's ovaries stop producing estrogen) may be involved.

A Word From Verywell

In the end, the course of late-onset MS and how different it is from young-onset MS is still not entirely clear. That being said, a prompt and accurate diagnosis is as critically important in late-onset MS as it is at any age. This is because promptly starting treatment with disease-modifying medications can reduce MS attacks and new lesions, as well as slow the progression of the disease. 

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