Effects of using same- versus alternate-form memory tests during short-interval repeated assessments in multiple sclerosis

Repeated neuropsychological testing gives rise to practice effects in that patients become familiar with test material as well as test-taking procedures. Using alternate forms prevents the learning of specific test stimuli, potentially mitigating practice effects. However, changing forms could diminish test-retest reliability coefficients. Our objective was to examine test-retest effects in multiple sclerosis (MS) patients randomly assigned to same- (SF) or alternate-form (AF) conditions. Thirty-four MS patients underwent neuropsychological evaluation. The battery included the California Verbal Learning Test II (CVLT-II) and the Brief Visuospatial Memory Test-Revised (BVMT-R), memory tests recommended by a recently convened consensus panel. Patients were randomly assigned to SF or AF groups and then tested at baseline and follow-up examination 1 week later. Analysis of variance tests (ANOVAs) revealed significant group × time interactions, with SF patients showing greater gain than AF patients. SF practice effects were often large, compromising test validity. Reliability coefficients were either equivalent or higher in the AF group, a finding attributed to ceiling effects and reduced variance in the SF group at retest. The generalizability of the findings may be limited to short test-retest intervals and the MS population. Nevertheless, I conclude that the use of CVLT-II and BVMT-R alternate forms likely helps preserve test validity without compromising test-retest reliability.