The two conditions share a surprising number of risk factors, but could one disease actually cause the other?

At first glance, multiple sclerosis (MS) and osteoporosis appear to be two very different diseases. One attacks the nerves and the other the bones. But dig a little deeper and it’s clear they have a lot in common.

“I think there are a number of correlations,” Kathleen Costello, associate vice president of clinical care for the National MS Society, told Healthline. “In fact, if you look at the risk factors for osteoporosis and you look at MS, you can see an obvious connection between the two.”

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Osteoporosis is a disease that causes bones to become fragile and more likely to break. If left untreated, it can progress until fractures occur, usually in the hip, spine, or wrist.

According to Costello, when comparing MS and osteoporosis, you have to consider both their modifiable risk factors (determined by our choices), and their non-modifiable ones, such as which genes we inherit from our parents.

“Looking at the non-modifiable — age, history, family history, Caucasian, female — without my saying ‘MS’ or ‘osteoporosis’ you wouldn’t know [which I was talking about] because actually those are risk factors for both,” Costello said.

But the modifiable risks, she said, are “probably where the real correlation occurs.”

Two major risk factors for MS are low vitamin D levels and smoking. “And the same is true for osteoporosis,” Costello said. People living with MS are also often less active due to their condition and that’s “a huge contributor for developing osteoporosis,” she added.

Corticosteroids, often used to treat MS patients having relapses, are notorious for wreaking havoc on bones. They interfere with bone-making cells, while increasing the number of cells that deplete bone. They also make it harder to absorb calcium and they inhibit hormones such as estrogen, which are important for our bones.

“People with MS have a huge amount of risk for the development of osteoporosis,” Costello said.

The evidence is proving Costello right. In a study published earlier this year in CNS Drugs, researchers from the State University of New York at Buffalo concluded that MS patients have a greater risk of osteoporosis and fractures because of the combined effect of many factors: inactivity, low vitamin D levels, and the use of glucocorticoids and anticonvulsant drugs.

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“Osteoporosis used to be considered an endocrine disease,” Costello explained. “As women aged they lost estrogen and were more likely to develop osteoporosis. While that is true, it is now also considered to be an inflammatory disease because there are inflammatory cytokines, [found in cells of the immune system] that have been identified as being contributors to bone loss.”

Costello added: “There are also cytokines that have been identified as bone building, so it’s not the fact they are there, but it’s the balance they happen to be in that drives whether you lose bone or you don’t.”

MS is an inflammatory disease, and some of the same cytokines that cause inflammation in MS have also been seen in osteoporosis patients.

“People with MS have a huge amount of risk for the development of osteoporosis.” — Kathleen Costello

While it appears that the two conditions often go hand in hand, that doesn’t mean they alway occur together. “Not everyone with MS is going to develop osteoporosis,” said Costello. Doctors can’t say for sure whether one condition causes the other.

In a 2011 study published in Acta Neurologica Scandinavica, researchers from Norway argued that multiple sclerosis is a cause of secondary osteoporosis because data have shown that bone mineral density decreases as a patient’s MS disability increases. But the connection has not been proven.

“I think it deserves more study to see how much of this inflammation in MS contributes … to the development of osteoporosis,” Costello said.

If you have MS, speak to your primary care doctor or neurologist about bone health. The doctor can begin by checking your vitamin D levels and measuring your bone density.

The doctor may start you on vitamin D supplements, since Costello says the best source of vitamin D, sunshine, is “like kryptonite to people with MS.”

You can’t control your age, gender, or race, but there are other changes you can make to decrease your odds of developing osteoporosis.

According to researchers at the University of Mississippi Medical Center, in a study published in theInternational Journal of MS Care, “Measures to reduce or prevent osteoporosis in those with MS include education regarding adequate calcium and vitamin D intake, avoidance of smoking and excessive alcohol intake, and regular exercise, particularly weight-bearing exercise.”

“Make sure you tell your doctor if you’ve fallen,” urged Costello. It happens so often to those with MS that it’s a running joke for some patients. But bone fractures are no laughing matter.

Remove throw rugs, clutter, and extension cords that cross your path. You should also remember that canes and walkers are tools and you shouldn’t be afraid to use them if necessary.

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