For varenicline versus placebo ( n = 66 randomized ) , there was no significant difference in the week 6 least square ( LS ) mean ADAS-Cog 75 total score ( primary endpoint ; 18.07 vs. 18.49 ; p = 0.3873 ) and a slight worsening in the week 6 LS mean NPI ( 3.82 vs. 2.55 ; p = 0.0468 ) , primarily driven by decreased appetite/eating .