The purpose of this study is to determine T-cell mediated inflammatory immune response in some participants previously exposed to atabecestat.

This is an exploratory Phase 0 study in participants who previously participated in studies (54861911ALZ2002 [NCT02260674], 54861911ALZ2003 [NCT02569398], or 54861911ALZ2004 [NCT02406027]) with atabecestat. In this study, participants will only have blood drawn. The primary hypotheses for this study is that adverse event of elevated liver enzymes observed in some participants is caused by a T-cell dependent inflammatory response. Participants will be monitored for adverse events and will be called 1 day after the blood draw to assess for any adverse events.

Inclusion Criteria:

• Participant who received and discontinued atabecestat in one of the following prior trials (54861911ALZ2002, 54861911ALZ2003, or 54861911ALZ2004)
• Must sign an informed consent form (ICF) indicating that he or she understands the purpose of, and procedures required for, the study and is willing to participate in the study
• Willing and able to adhere to the prohibitions and restrictions specified for this study

Exclusion Criteria:

• Anemic based on the last blood draw in the prior atabecestat trial
• Donated more than (>) 450 milliliter (mL) of blood in the past 3 months
• Currently participating in an atabecestat study (54861911ALZ2002, 54861911ALZ2003, or 54861911ALZ2004)