Multiple Sclerosis (MS) is an autoimmune disorder that primarily targets the central nervous system, causing inflammation and demyelination of nerve fibers in the brain and spinal cord. While the focus of MS management is often on neurological symptoms, research highlights a significant connection between this chronic condition and skeletal health. The disease process and its associated factors can profoundly disrupt the body’s bone maintenance cycle. Recognizing this relationship is an important part of comprehensive care, as it helps mitigate complications that affect a person’s quality of life and mobility.
The Link to Reduced Bone Density
The primary consequence of MS on the skeletal system is a significant loss of Bone Mineral Density (BMD). Studies consistently show that individuals with MS have a substantially higher prevalence of low BMD compared to the general population. This reduced density manifests as two conditions: osteopenia, a moderate decrease in bone density, and osteoporosis, the more severe form where bones become porous and fragile.
The pooled prevalence of osteopenia in people with MS is estimated to be around 41 to 43%, while osteoporosis affects approximately 14 to 17% of this population. This elevated risk occurs at an earlier age in MS patients than in the general public. The fragile nature of osteoporotic bone significantly increases the likelihood of fractures, often from minimal trauma.
The risk of experiencing a fracture is almost twice as high for individuals with MS. Specifically, the risk of a hip fracture is nearly three times greater compared to healthy controls. These fractures, particularly in the hip and spine, can lead to severe pain, long-term disability, and a reduction in independence. Addressing the underlying bone loss is a preventive measure against these skeletal events.
Underlying Causes of Bone Loss
The deterioration of bone health in MS is driven by a complex interplay of factors related to the disease, its treatments, and secondary lifestyle changes. The autoimmune nature of MS itself contributes to bone loss through systemic inflammation. Pro-inflammatory cytokines are released during chronic inflammation and disrupt the balance between bone-forming cells (osteoblasts) and bone-resorbing cells (osteoclasts).
These inflammatory chemicals shift the balance toward excessive bone resorption, causing bone destruction to outpace new bone formation. The direct neurological impact of MS may also interfere with bone homeostasis, as the autonomic nervous system helps regulate bone metabolism. This means the disease process can impair bone density even in highly mobile individuals.
A major contributor is the use of corticosteroids, often prescribed in high doses to manage acute MS relapses. These glucocorticoids interfere with the body’s ability to absorb calcium and suppress the activity of osteoblasts, inhibiting new bone formation. While necessary for managing relapses, prolonged exposure to these medications accelerates bone density loss over time.
Secondary lifestyle factors also strongly impact the skeletal system. Reduced mobility, often due to fatigue, weakness, or spasticity, leads to a decrease in weight-bearing activity. Bone tissue requires mechanical stress, or “loading,” to maintain its density and strength. Without this stimulation, the bone weakens. This lack of activity is a major determinant of bone loss.
Another prevalent issue is Vitamin D insufficiency, which is found in a high percentage of MS patients. Because MS symptoms can be worsened by heat, many individuals intentionally limit sun exposure, which is the body’s primary source for synthesizing Vitamin D. Low Vitamin D levels impair calcium absorption and can lead to secondary hyperparathyroidism, a condition where the body draws calcium out of the bones to maintain blood calcium levels, further accelerating bone loss.
Screening, Prevention, and Management Strategies
Given the multiple factors contributing to bone loss, a proactive approach to screening and management is highly recommended for all individuals with MS. The primary diagnostic tool is the Dual-Energy X-ray Absorptiometry (DEXA) scan, which measures Bone Mineral Density, typically at the hip and spine. It is often recommended that MS patients undergo their first DEXA scan within a couple of years of diagnosis to establish a baseline.
For patients with normal bone density, follow-up DEXA scans are typically advised every three to five years to monitor for any progression of bone loss. Early detection through this method allows for the timely implementation of preventative or therapeutic interventions. Fall prevention strategies are also an integral part of management, as the risk of fracture is a combination of fragile bones and increased fall frequency.
Optimizing nutritional intake is a fundamental preventative step, focusing on adequate daily intake of Calcium and Vitamin D. Experts recommend that adults aim for 1,000 to 1,500 milligrams of elemental calcium per day, through diet and supplementation if necessary. Correcting Vitamin D insufficiency is also a priority, often requiring supplements to achieve sufficient serum levels, especially since sun exposure may be limited.
The importance of physical activity cannot be overstated, even for those with limited mobility. Weight-bearing exercises, which involve working against gravity, provide the necessary mechanical load to stimulate bone strength. This can include walking, if possible, or adapted resistance training and moderate-intensity exercises tailored to the individual’s level of disability. Physical therapy is often employed to devise safe, customized routines that also focus on balance to lower the risk of falls.
For individuals diagnosed with osteoporosis, medical management is often necessary to halt bone loss and promote new bone growth. The most common pharmacological treatment includes bisphosphonates, which work by slowing down the activity of the bone-resorbing osteoclasts. These medications can help increase bone density and significantly reduce the risk of future fractures.