CDR-SB integrates assessments from 3 domains of cognition (memory, orientation, judgment/problem-solving) and 3 domains of function (community affairs, home/hobbies, personal care). Following caregiver interview and systematic patient examination, the rater assigns a score describing the participant's current performance level in each of these domains of life functioning. Prespecified severity anchors range from none = 0, questionable = 0.5, mild = 1, moderate = 2 to severe = 3 (the personal care domain omits the 0.5 score). "Sum of boxes" scoring methodology sums the score for each of the 6 domains and provides a value ranging from 0 to 18 that can change in increments of 0.5 or greater. Higher scores indicate greater disease severity. Mixed model for repeated measures (MMRM) analysis was used to analyze change from baseline in CDR-SB. A positive change from baseline indicates clinical decline.

ITT was defined as all randomized participants who had received at least one dose of study treatment (Aducanumab or Placebo). 'Number of Participants Analyzed' signifies number of participants analyzed in this outcome measure.

The MMSE is a widely used performance-based test of global cognitive status. It consists of 11 tasks that assess orientation, word recall, attention and calculation, language abilities, and visuospatial functions. The scores from the 11 tests are combined to obtain the total score, which ranges from 0 to 30, with lower scores over time indicating increasing cognitive impairment. MMRM analysis was used to analyze change from baseline in MMSE. A negative change from baseline indicates clinical decline.

ITT was defined as all randomized participants who had received at least one dose of study treatment (Aducanumab or Placebo). 'Number of Participants Analyzed' signifies number of participants analyzed in this outcome measure.

ADAS-Cog13 comprises both cognitive tasks and clinical ratings of cognitive performance. The scale items capture word recall, ability to follow commands, the ability to correctly copy or draw an image, naming, the ability to interact with everyday objects, orientation, word recognition, memory, comprehension of spoken language, word-finding, and language ability, with a measure for delayed word recall and concentration/distractibility. The total score ranges from 0 to 85. An increase in score over time indicates increasing cognitive impairment. MMRM analysis was used to analyze change from baseline in ADAS-Cog 13. A positive change from baseline indicates clinical decline.

ITT was defined as all randomized participants who had received at least one dose of study treatment (Aducanumab or Placebo). 'Number of Participants Analyzed' signifies number of participants analyzed in this outcome measure.

The ADCS-ADL-MCI consists of 17 instrumental items (e.g., shopping, preparing meals, using household appliances) and 1 basic item (getting dressed). Ratings reflect caregiver observations about the patient's actual functioning over the previous month and provide an assessment of change in the functional state of the participant over time. The total score ranges from 0 to 53, with lower values over time reflecting functional deterioration. MMRM analysis was used to analyze change from baseline in ADAS-ADL-MCI. A negative change from baseline indicates clinical decline.

ITT was defined as all randomized participants who had received at least one dose of study treatment (Aducanumab or Placebo). 'Number of Participants Analyzed' signifies number of participants analyzed in this outcome measure.