 The primary objective of the original study was to assess the safety of semagacestat in Alzheimers disease AD patients during 24 months of open-label treatment. Baseline for the efficacy measures is defined as the baseline for feeder studies LFAN NCT00594568 and LFBC NCT00762411. For all safety analyses adverse events, baseline for patients will be week 0 of this study LFBF. 