MS is a chronic, progressive neurodegenerative disorder that results from the attack on the central nervous system (brain, spinal cord and optical nerves) by the body’s own immune system, causing inflammation and damage to the myelin layer that covers and protects neurons. Myelin loss leads to impairment in signal transmission along the nerve fibers, affecting motor function (coordination, balance, speech and vision), causing irreversible neurological disability and paralysis. Most MS patients experience their first symptom between 20 and 40 years of age and it is estimated that more than 2.3 million people in the world suffer from the disease. There is currently no cure for MS.
RRMS is the most frequent form of the disease, which is clinically characterized by recurring episodes of neurological symptoms. Natalizumab (Tysabri, Biogen) is a humanized monoclonal antibody used in the treatment of RRMS patients and it has been shown to reduce disease activity. Patients under natalizumab treatment for 6 months to 2 years have been found to have a significant reduction in the decline of their cognitive functions; some patients even experience an improvement in cognitive abilities. A reduction in relapse rate has also been reported. However, the long-term effects of natalizumab therapy on cognitive performance beyond the second year of treatment are unknown.
In the study, researchers investigated the impact of natalizumab treatment on cognitive impairment in a cohort of 24 patients with RRMS who were treated for 3 years. Patients were assessed through neuropsychological tests and in terms of relapse rate and expanded disability status scale (EDSS) score.
Researchers found that after three years of natalizumab treatment, a significant reduction in the number of impaired neuropsychological tests was achieved, along with a considerable decrease in annualized relapse rate and a stable EDSS in comparison to baseline. A particular significant improvement was found in memory, attention and executive function test scores.
The team also analyzed brain cortical atrophy in a patient subgroup through magnetic resonance imaging (MRI). Preliminary results showed that after 3 years of natalizumab treatment there were no alterations in gray matter volume but a significantly greater parahippocampal and prefrontal gray matter density, which correlated with the neuropsychological improvement observed.
The research team concluded that natalizumab therapy can reduce cognitive impairment in RRMS patients in a long-term period of three years. The team suggests that natalizumab most likely has a neuroprotective role concerning cortical gray matter in the brain.
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