Cognitive dysfunction in patients with multiple sclerosis treated with different types of interferon beta: a randomized clinical trial.

BACKGROUND: Multiple sclerosis (MS) is a chronic autoimmune disease that can deteriorate cognitive function in at least 50% of patients even in the early stages.

OBJECTIVE: We conducted a three-arm parallel study with balanced randomization to evaluate the effect of various disease-modifying therapies (DMTs) on cognitive function in MS.

METHODS: Ninety newly diagnosed, definite MS subjects referred to Ghaem Medical Center, Mashhad, Iran, were enrolled into this study between 2006 and 2009. They were randomly categorized into three DMT groups; Avonex, Rebif and Betaferon. Cognition status was assessed in MS patients at baseline and 12 months after treatment with DMTs using the 5 tests of the Brief Repeatable Battery of Neuropsychological Tests (BRB-N).

RESULTS: The Symbol Digit Modalities Test scores improved in all groups at 12 month vs. baseline (Avonex: 34.50 vs. 38.95, p=0.011; Rebif: 35.30 vs. 40.13, p=0.001; Betaferon: 26.18 vs. 29.32, p=0.029). The Selective Reminding Test (SRT)-Total, the 10/36-Delay, and the Paced Auditory Serial Addition Test-Easy were improved in Avonex and Rebif but not in Betaferon group. The SRT-Delay and Word List Generation were improved only in the Avonex group. There was no significant difference in other components of the BRB-N among these three treatment groups.

CONCLUSIONS: Different types of DMTs may improve some aspects of cognitive function in patients with MS. Treatment with Avonex and Rebif (Interferon beta-1a preparations) were more helpful in resolving the cognitive impairments in MS patients compared to Betaferon (Interferon beta-1b) as investigated in this study.