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We conducted an exploratory analysis of the influence of baseline neuropsychological (NP) profiles on the effect of EGb 761 (definition see editorial) in Alzheimer's disease (AD). Using this perspective, we stratified the intent-to-treat data set collected during a 52-week, randomized, double-blind, placebo-controlled study with 120 mg EGb 761 based on cut-off points applied to naming and constructional praxis items of the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog). Mean changes over baseline and percentage of responders in each NP group and overall efficacy were analyzed, using the ADAS-Cog subscale as outcome measurements for assessing cognitive performance and the Geriatric Evaluation using the Relative's Rating Instrument (GERRI) to measure social functioning. Three subgroups were identified: (1) right AD (RAD) subgroup, including 83 patients with primarily visual-constructional impairment; (2) left AD (LAD) with 25 patients showing predominant verbal deficits; (3) general AD (GAD) including 60 patients impaired in both cognitive domains. At the endpoint, the EGb 761 group of RAD showed an improvement of 1.7 points according to ADAS-Cog and 0.15 points according to GERRI, while the placebo group worsened by 1.3 and 0.02 points, respectively. The LAD patients worsened regardless of treatment; however, to a lesser degree in those receiving EGb 761 as assessed by the increase of 4.7 ADAS-Cog points and 0.13 GERRI points compared to 6.8 points and 0.20 points, respectively, for placebo. In GAD, the EGb 761 group showed minimal changes, whereas the placebo group slightly worsened on both assessments, resulting in favorable treatment differences of 1.6 ADAS-Cog points and 0.23 GERRI points. Retrospective analysis of overall efficacy indicated that a quantitative treatment effect favorable to EGb 761 could be observed in cognitive performance (p = 0.04) and social functioning (p = 0.02), even taking NP differences and baseline severity into account. However, qualitative EGb 761 effects could greatly depend on NP profiles--improvement could be expected with RAD patients, while EGb 761 effect should be considered more in terms of stabilization for GAD and delayed worsening for LAD population.
P L Le Bars (Sun,) studied this question.