A Clinical Study of MK-2214 in People With Early Alzheimer's Disease (MK-2214-004)

Base Period: Change from Baseline in Tau PET Standardized Uptake Value Ratio (SUVr)

Participants will have tau PET imaging to assess tau pathology. Tau is a protein that accumulates in AD \& damages brain cells. SUVr is SUV in the region of interest divided by SUV in a reference region (cerebellum). The change from baseline in tau PET SUVr will be reported.

Base Period: Number of Participants Who Experience One or More Adverse Events (AEs)

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The number of participants who experience one or more AEs will be reported.

Base Period: Number of Participants Who Discontinue Study Intervention Due to an AE

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The number of participants who discontinue study intervention due to an AE will be reported.

Base Period: Change from Baseline in the Clinical Dementia Rating-Sum of Boxes (CDR-SB) Total Score

The CDR-SB is used for cognitive assessment in people with AD. The CDR is a clinical scale that describes 5 degrees of impairment in performance on each of 6 categories of function including memory, orientation, judgment and problem solving, community affairs, home and hobbies, and personal care. The ratings of degree of impairment obtained on each of the 6 categories of function are synthesized into 1 global rating of dementia CDR score ranging from 0 (normal) to 3 (severe). A total score is calculated as the sum of the category scores, with a range of 0 (normal) to 18 (severe). Higher scores indicate more impairment. The change from baseline in CDR-SB total score will be reported.

Base Period: Change from Baseline in the Composite Tau PET SUVr in Braak Region III and IV

Participants will have tau PET imaging to assess tau pathology. Tau is a protein that accumulates in AD \& damages brain cells. SUVr is SUV in the region of interest, divided by SUV in a reference region (cerebellum). Braak staging ranges from Braak I to VI. Description for Braak III includes amygdala, parahippocampal gyrus, fusiform gyrus, \& lingual gyrus, and Braak IV includes insula, inferior temporal, lateral temporal, posterior cingulate, \& inferior parietal. The composite tau PET SUVr is a weighted average of tau PET SUVr values obtained from multiple brain regions, with weights being the percentage volume of each region within the composite. The change from baseline in composite tau PET SUVr in Braak regions III and IV will be reported.

Base Period: Change from Baseline in the Composite Tau PET SUVr

Participants will have tau PET imaging to assess tau pathology. Tau is a protein that accumulates in AD \& damages brain cells. SUVr is SUV in the region of interest, divided by SUV in a reference region (cerebellum). The composite tau PET SUVr is a weighted average of tau PET SUVr values obtained from multiple brain regions, with weights being the percentage volume of each region within the composite. The change from baseline in composite tau PET SUVr will be reported.

Base Period: Change from Baseline in the Composite Tau PET SUVr in Braak Region I to VI

Participants will have tau PET imaging to assess tau (protein that accumulates in AD \& damages brain cells) pathology. SUVr is SUV in the region of interest, divided by SUV in a reference region (cerebellum). Braak staging ranges from I-VI (Braak I (transentorhinal); II (entorhinal \& hippocampus); III (amygdala, parahippocampal gyrus, fusiform gyrus, \& lingual gyrus); IV (insula, inferior temporal, lateral temporal, posterior cingulate, \& inferior parietal); V (orbitofrontal, superior temporal, inferior frontal, cuneus, anterior cingulate, supramarginal gyrus, lateral occipital, precuneus, superior parietal, superior frontal, \& rostro medial frontal); VI (paracentral, postcentral, precentral, \& pericalcarine)). Composite tau PET SUVr is weighted average of tau PET SUVr values from multiple brain regions, with weights being percentage volume of each region. The change from baseline in composite tau PET SUVr in Braak region I to IV will be reported.