CHICAGO, Aug. 30 (Xinhua) -- A phase two clinical trial of the investigational drug ibudilast shows that the drug slows brain shrinkage.

The study involves 28 clinical sites including Washington University School of Medicine, where 255 patients were randomly assigned to take up to 10 capsules of ibudilast or a placebo daily for nearly two years. Every six months, the participants underwent MRI brain scans. The researchers applied a variety of analysis techniques to the MRI images to assess differences in brain changes between the two groups.

The researchers found the brains of patients in both groups continued to atrophy over the course of the study, but the decline was slower in the ibudilast group. Reducing the rate of atrophy may delay the worsening of symptoms.

"The study was not large enough to prove a clinical effect, but the data suggest that people's disabilities may not have worsened as rapidly in the treatment group," said co-author Robert T. Naismith, an associate professor of neurology at Washington University School of Medicine.

The most common side effects reported by participants included nausea and diarrhea, as well as headaches and depression. There was no significant difference between the groups in the number of patients who reported adverse effects.

People with a progressive form of multiple sclerosis (MS) face a gradual decline of brain function that slowly strips away the ability to walk and may cause problems with speech and vision. The finding provides a glimmer of hope for people with a form of MS.

Future research will test whether reducing brain shrinkage affects thinking, walking and other problems in people with MS, and will examine whether ibudilast slows the progression of disability in MS patients.

The study was published on August 29 in the New England Journal of Medicine.