Recently attention has focused on the need to specify and validate cognitive measures for use in studies of prodromal Alzheimer's disease (AD), MCI and mild AD. Expert guidance has suggested focusing on cognitive domains compromised early in AD, specifically episodic memory (EM), working memory (WM) and executive function (EF). The ADAS-cog includes tests of EM that have been shown to dissociate the performance of healthy controls from MCI and mild AD. However, the ADAS-cog is deficient with respect to tests of WM and EF, areas that are indexed by elements of the NTB. Data from the recently reported phase 2b clinical trial of EVP-6124 in AD patients were used to validate a 'Cognitive Composite' (CC) composed of ADAS-cog Word Recall, Word Recognition and Orientation, combined with the COWAT and CFT from the NTB. Z-s cores were calculated for each of the components using the baseline mean and standard deviation for all study participants and were then averaged to obtain the CC score. Using placebo group data only, test-retest reliability was calculated by correlating the baseline z- score with those obtained at week 4. Internal consistency was calculated using all baseline scores. Concurrent validity was established by correlating the baseline CC composite with baseline ADAS cog, MMSE and CDR-SB scores. The analyses described above demonstrated: i) Test-retest reliability, r =0.89. ii) Internal consistency: A high degree of internal consistency, Cronbach's alpha = 0.80. iii) Concurrent validity: CC baseline correlation of r =-0.89 for ADAS-Cog 13, 0.69 for MMSE, and r = -0.51 for the CDR-SB. The results of this analysis suggest that the CC is a reliable and stable measure of cognition in patients with mild-to-moderate AD. The combination of five, brief and validated measures yields a measure likely to be of use in assessing patients in the mild and prodromal stages of AD.