Efficacy and Safety of MK-7622 as Adjunct Therapy in Participants With Alzheimer's Disease (MK-7622-012)

If double-blind treatment dose is not tolerated during first 2 weeks, participant will be
discontinued. After first 2 weeks, if dose is not tolerated regimen may be modified
according to defined algorithm, beginning with administration of reduced dose for up to 2
weeks, then rechallenge at original dose, if tolerability issues diminish or resolve at
reduced dose.

Inclusion Criteria:

- Diagnosis of probable AD based on both a) the National Institute of Neurological and
Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders
Association (NINCDS-ADRDA) criteria and b) the Diagnostic and Statistical Manual of
Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR) criteria for AD

- AD is of mild to moderate severity

- Clear history of cognitive and functional decline over at least one year that is
either a) documented in medical records or b) documented by history from an informant
who knows the participant well

- On a stable and effective daily dose of AChEI (either donepezil, rivastigmine, or
galantamine), for at least two months before Screening, and willing to remain on the
same dose for the duration of the trial. Effective doses are considered to be:
donepezil, 10 mg total daily dose administered orally; rivastigmine, 9.5 or 13.3
mg/24 hours administered by transdermal patch or 6-12 mg total daily dose
administered orally; galantamine, 16-24 mg total daily dose administered orally

- Able to read at a 6th grade level or equivalent, and must have a history of academic
achievement and/or employment sufficient to exclude mental retardation

- Participant must have a reliable and competent trial partner who must have a close
relationship with the subject

Exclusion Criteria:

- History of clinically significant stroke

- Evidence of a neurological disorder other than the disease being studied (ie,
probable AD)

- History of seizures or epilepsy within the last 5 years before Screening

- Evidence of a clinically relevant or unstable psychiatric disorder, excluding major
depression in remission

- Participant is at imminent risk of self-harm or of harm to others

- History of alcoholism or drug dependency/abuse within the last 5 years before
Screening

- Participant does not have a magnetic resonance imaging (MRI) scan obtained within 12
months of Screening and is unwilling or not eligible to undergo an MRI scan at
Screening

- History of hepatitis or liver disease that has been active within the six months
prior to Screening Visit

- Recent or ongoing, uncontrolled, clinically significant medical condition within 3
months of the Screening Visit (e.g., diabetes, hypertension, thyroid or endocrine
disease, congestive heart failure, angina, cardiac or gastrointestinal disease,
dialysis, or abnormal renal function) other than the condition being studied such
that participation in the trial would pose a significant medical risk to the
participant. Controlled co-morbid conditions are not exclusionary if stable within
three months of the Screening Visit

- History or current evidence of long QT syndrome, corrected QT (QTc) interval ≥470
milliseconds (for male subjects) or ≥480 milliseconds (for female subjects), or
torsades de pointes

- History of malignancy occurring within the five years before Screening, except for
adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer,
or localized prostate carcinoma which has been treated with potentially curative
therapy with no evidence of recurrence for ≥3 year posttherapy

- Clinically significant vitamin B12 deficiency, or increased thyroid stimulating
hormone (TSH) in the six months before Screening

- Major surgery within 3 months of Screening