The findings come from studies of computer-assisted brain scans using a specialized magnetic resonance imaging (MRI) device. University at Buffalo, N.Y., researchers Rohit Bakshi, MD, and colleagues are the first to use this technique to study multiple sclerosis. Bakshi reported the findings at this week's annual meeting of the American Neurological Association in San Francisco.
Multiple sclerosis has been considered a disease of the white matter in the brain and spinal cord -- the neural pathways that allow areas of gray matter to communicate with one another. But the new findings link iron deposits in the gray matter to movement and thinking impairments in multiple sclerosis.
"If we're going to treat this disease, we have to know where the damage is," Bakshi says in a news release. "Traditionally, we thought MS was strictly a white-matter disease. ... We were able to visualize gray matter structures deep in the brain of MS patients and found some to be atrophied."
These areas of brain damage contained abnormally high levels of iron. It's not yet clear that the iron is the cause of the brain damage. It could be that dying brain cells leave a trail of iron behind.
Walking, Thinking, and Gray Matter
Bakshi's team put 41 multiple sclerosis patients through a walking test. They also gave tests of learning, speed of information processing, and memory to 28 MS patients.
The more unnatural darkness the brain scans saw in a patient's gray matter, the worse the patient's MS symptoms. It was the only factor studied that independently predicted impaired walking and thinking.
"We suspect that MS patients have defective blood-brain barriers, the cell layer that prevents potentially toxic substances from entering the brain," Bakshi says. "Excessive iron entering the brain may damage the deep gray matter structures."
If iron is indeed the culprit, it seems possible to do something about it. Bakshi's team is exploring two ideas. The first is simply to remove excess iron from patients' bodies, and then to devise a way to prevent future iron build-up.
If that is impractical, it may be possible to prevent iron from killing brain cells. The excess iron may be causing free radicals -- extremely reactive molecules that damage brain cells. Antioxidants -- such as vitamins C and E, or even more powerful agents -- might mop up free radicals before they do their dirty work.
Even if the iron deposits are the effect, rather than the cause, of brain cell death, the study still offers a way to measure the severity of MS and the efficacy of new treatments.