Neuropsychological effects of interferons

Fischer JS, Priore RL, Jacobs LD et al.  Neuropsychological effects of interferon B-1a in relapsing multiple sclerosis.  Neurology 2000; 48: 885- 892.

Study looked specifically at Avonex to 166 patients 104 weeks apart.  The neuropsych battery was divided into Set A (information processing and learning/memory) ,  Set B ( visuospatial and problem solving), and Set C (verbal abilities and attention span).  Avonex benefitted A set, with a trend in B set and no effect on C.  Secondary analysis showed a treatment effect on time to worsening with PASAT. 

Subject selection-- disease duration at least one year, at least 2 relapsed in 3 years, and EDSS 1-3.5 inclusive.  age 18-55. Study was placebo controlled.  Actual tests used were , for Set A, signnificant group, CalCap Sequential reaction time (information processing), Ruff Figural Fluency Test error ratio, and CVLT Trials 1-5 (total).

Set B tests were WMS-R Visual Memory Span (forward), WCST perseverative responses, visual search number of trials, TOL % planning time. 

Set C tests were WAIS-R information, and digit span forward.

Secondary outcomes were RFFT error ratios, RFFT unique designs, CVLT trials 1-5 (total), PASAT processing . 

Results-- on set A, the CVLT test was most important.  On Set B, Tower of London was most important.  Set C was negative tests.  In secondary outcomes, slopes were correct direction in all variables, RFFT appeared significant, and  practice effects were noted in all groups. 

Authors contrast to 2 other studies of cognition with treatment for MS.  One was a copaxone study (Weinstein et al, Arch Neurol, 1999) which was negative, and one was for Betaseron, that showed an effect for visual memory  (Pliskin et al, Neurology, 1996).  However, neither of those was as good of a study.