MS and the Connected Disconnect

Brain activity connected to cognitive decline in MS patients

(RxWiki News) Multiple sclerosis is notorious for doing damage to the brain's ability to communicate with the rest of the body. But what creates the decline in mental clarity that some patients experience?

It turns out that the brain's communication system and a patient's cognitive abilities are closely connected – but maybe not in the way that you would think.

Researchers have found that people with MS who have an enhanced brain “default mode” experience greater difficulty with decision-making, planning, memory, and other cognitive tasks.

"If you're experiencing cognitive decline with MS, talk to your doctor."

The study was conducted by a team of scientists working at Washington University, the University Medical Center at Hamburg-Eppendorf and the University of Tübingen. They wanted to learn about how structural damage to the brain is connected to cognitive problems caused by MS, and if it's related to how different regions of the brain communicate, or “network.”

MS attacks brain cell branches, hampering their ability to communicate. The brain tries to overcome the damage by redirecting energy to allow signals to go through damaged branches.

But that in itself may create a problem, researchers speculate. With the energy brought in to push signals through broken pathways, the brain might have a harder time reconfiguring itself for cognitive tasks like speaking, movement, and recalling memory.

They looked at 16 patients with early-stage MS, who had been diagnosed within the past four years. The patients were put through behavioral and cognitive tests, brain scans to identify damage, and researchers also evaluated the connectedness of different brain regions.

The MS patients were then compared to a group of 16 healthy people.

In the brain scans of the patients with MS, the scientists could see the visible damage to brain cell branches. The more damage they had, the higher the likelihood that the patient experienced problems with brain function.

The emphasis of the study was on something the researchers called “cognitive efficiency” or how efficiently the brain works.

Patients with lower cognitive efficiency, surprisingly, had better connections in the brain's default mode network. That network is the brain regions that are active when the rest of the brain is at wakeful rest – not doing anything in particular. It's like the programs that are running on your computer when you're not using it.

In MS patients, as connectedness in default mode went up, cognitive abilities went down.

Scientists don't yet know why this correlation exists as it does, but they believe that understanding how it works could improve diagnosis and treatment.

The study was published in the Proceedings of the National Academy of Sciences, in January 2012.

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Review Date: 
January 12, 2012