Q. Why do some people with MS progress faster than others?
A. People with multiple sclerosis (MS) may share a diagnosis, but they can have very different experiences with the disease.“When we say ‘MS,’ there’s a gamut of severity,” says Daniel Ontaneda, a neurologist at the Cleveland Clinic. Symptoms can range from mild to debilitating and include visual problems, muscle weakness, numbness or tingling, and difficulties with coordination, thinking, or memory.
MS is an autoimmune disease in which the protective coating of nerve cells, called myelin, breaks down over time. Ontaneda says the disease usually has two stages. First there are episodic attacks of symptoms followed by periods of recovery. Later in the course of the disease, “patients tend to worsen day by day,” he says. But why some patients enter this “progressive” phase sooner than others is unclear.
Several factors tend to correlate with a quicker onset of the progressive stage. These include a shorter interval between symptom relapses early on in the disease, early motor symptoms such as muscle weakness or movement difficulties, and a later age of onset of the disease. Physicians can also track progression using MRI imaging of the brain and spinal cord, which shows areas of myelin destruction. Both the number and severity of lesions seen on an MRI usually correspond to how quickly the disease is progressing.
Even among these measures, “when we look at individual patients, there’s a lot of variability,” Ontaneda says. Ongoing research is working to measure factors that make some fare better than others.