At the same time multiple sclerosis patients are seeing an overall drop in their bodies' nerve signals, it looks like certain nerve cells are becoming hyperactive.

It sounds counterintuitive, but that’s the idea a study in Neuroscience puts forth to explain why the people with this autoimmune disease are so prone to seizures. According to the research, neurons in the brain called parvalbumin interneurons are supposed to prevent the hyperactivity but the disease has reduced their numbers.

“This causes the inhibition to be removed and induce seizures,” the University of California, Riverside, said in a statement.

Read: How Fast Will Multiple Sclerosis Develop?

As multiple sclerosis develops, the protective layer around a person’s nerve fibers is destroyed, preventing signals from getting transmitted between the brain and the rest of the body. That lack of communication leads to a loss of function, such as motor issues and muscle weakness.

The researchers used mice to study how that breakdown of the protective layer, known as the myelin sheath, contributes to seizures. They found that when the body’s immune system damages the protection around its own nerve fibers in the brain, the parvalbumin interneurons that are “important for keeping hyperactivity down, are modified and lost,” UC Riverside said about its scientists’ work. The university added that the researchers are now looking to see whether the seizures continue when the mice’s myelin sheaths are repaired.

The seizures are more than just an unpleasant side effect of multiple sclerosis. According to the study in Neuroscience, “seizures are more common in patients with early onset or progressive forms of the disease and prognosticate rapid progression to disability and death.”

If the researchers can develop a drug to stop the seizures by reducing nerve hyperactivity, that treatment may also help epilepsy patients, UC Riverside researcher and biomedical science professor Seema Tiwari-Woodruff said in the statement.

Source: Tiwari-Woodruff SK, Lapato AS, Szu JI, Hasselmann JP, Khalaj AJ and Binder DK. Chronic demyelination-induced seizures. Neuroscience. 2017.

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