221AD301 Phase 3 Study of Aducanumab (BIIB037) in Early Alzheimer's Disease

Key Inclusion Criteria:

- Must meet all of the following clinical criteria for MCI due to AD or mild AD and must
have:

- A Clinical Dementia Rating (CDR)-Global Score of 0.5.

- Objective evidence of cognitive impairment at screening

- An MMSE score between 24 and 30 (inclusive)

- Must have a positive amyloid Positron Emission Tomography (PET) scan

- Must consent to apolipoprotein E (ApoE) genotyping

- If using drugs to treat symptoms related to AD, doses must be stable for at least 8
weeks prior to screening visit 1

- Must have a reliable informant or caregiver

Key Exclusion Criteria:

- Any medical or neurological condition (other than Alzheimer's Disease) that might be a
contributing cause of the subject's cognitive impairment

- Have had a stroke or Transient Ischemic Attack (TIA) or unexplained loss of
consciousness in the past 1 year

- Clinically significant unstable psychiatric illness in past 6 months

- History of unstable angina, myocardial infarction, advanced chronic heart failure, or
clinically significant conduction abnormalities within 1 year prior to Screening

- Indication of impaired renal or liver function

- Have human immunodeficiency virus (HIV) infection

- Have a significant systematic illness or infection in past 30 days

- Relevant brain hemorrhage, bleeding disorder and cerebrovascular abnormalities

- Any contraindications to brain magnetic resonance imaging (MRI) or PET scans

- Alcohol or substance abuse in past 1 year

- Taking blood thinners (except for aspirin at a prophylactic dose or less)

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply