MS vs NMOSD: Understanding the Differences and the Impact on Diverse Communities

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are both chronic, autoimmune diseases and can appear similar at first glance. Both share overlapping symptoms, but they are not the same, and understanding their differences is crucial for correct diagnosis and effective long-term management.

Key Differences Between MS and NMOSD

Though some symptoms of MS and NMOSD are shared, such as weakness, numbness, pain, vision changes, and fatigue, others are more specific for NMOSD, such as blindness, persistent hiccups and nausea, and uncontrollable vomiting. Other key differences include the underlying cause of damage, nature of relapse, and diagnosis.

MS typically involves the immune system attacking the protective covering (myelin) of nerve fibers in the brain and spinal cord, causing communication problems between the brain and the rest of the body, while NMOSD most often targets the optic nerves (which control vision), the spinal cord, and the brain.

MS tends to have a more gradual onset, and its relapses may cause less permanent disability. NMOSD relapses, by contrast, can be very severe and may result in irreversible damage with every attack. Even a single relapse can cause blindness or paralysis, and disability tends to accumulate over time if attacks continue.

Another key distinguishing factor between NMOSD and MS is the presence of anti-aquaporin-4 antibodies (anti-AQP4), which are found in most people living with NMOSD.

NMOSD and the Role of Ancestry

NMOSD can cause unpredictable relapses, also called attacks, which may lead to serious and sometimes permanent disability—such as vision loss, paralysis, or severe pain. Unlike more common autoimmune diseases, NMOSD is considered rare and needs a different approach to treatment. 

Though anyone can develop NMOSD, research shows it does not affect all populations equally. Around 7,000 people in the United States are estimated to be living with NMOSD, with women being about five times more likely to be affected than men. 

Ancestry plays a significant role as well. Data suggest those of African or Asian descent are at much higher risk of developing NMOSD than those of Caucasian ancestry.

Additionally, the impact of the disease can be more severe among certain groups. 

People of African or Asian ancestries not only experience NMOSD at higher rates, but they also tend to develop symptoms at an earlier age compared to those of Caucasian ancestry. Studies also show that people of African ancestry may face a higher risk of more severe attacks and may be at an increased risk for disease worsening from these attacks. 

These disparities suggest that a combination of genetic and environmental factors may be involved in who develops NMOSD and how the disease progresses. That’s why it’s so important for individuals—especially those in higher-risk populations—to be educated about NMOSD and to communicate any symptoms they are experiencing to their doctor.

Getting the Right Diagnosis and Care

Because NMOSD can mimic MS, but requires different treatment, having access to the right diagnostic tests is critical. A cell-based assay blood test can confirm the presence of anti-AQP4 antibodies and help distinguish NMOSD from MS. If you or a loved one has new or worsening symptoms—even if you have already been diagnosed with MS—consider asking your doctor whether additional testing for NMOSD may be appropriate, especially if you are of African or Asian ancestry.

Connect with your local Patient Education Manager to learn more about NMOSD, how it may impact certain racial and ethnic groups differently, and the importance of getting an accurate diagnosis.

Alexion, AstraZeneca Rare Disease is focused on serving patients and families affected by rare diseases and devastating conditions through the discovery, development and delivery of life-changing medicines. Through their ProjectREDTM (Racial and Ethnic Disparities) initiative, they aim to address diagnostic and care disparities faced by NMOSD patients of African and Asian ancestries. 

© 2025, Alexion Pharmaceuticals, Inc. All rights reserved. US/UNB-N/0632 V1 08/2025