LS mean change from baseline at Week 26 on the newly defined SIB subscales. LS, least-squares; Stderr, standard error of the LS mean; SIB, Severe Impairment Battery. Analysis based on the Intent-To-Treat Last Observation Carried Forward (ITT-LOCF) population. P-values (derived from LS mean) calculated using an analysis of covariance (ANCOVA) model with treatment and center as factors, and baseline as a covariate. Negative change scores indicate deterioration. Newly defined SIB subscales named Factor 1 = visual, Factor 2 = language, Factor 3 = working memory/memory, Factor 4 = praxis and social skills, Factor 5 = naming. *P < 0.05 versus placebo.