
    study was discontinued based on futility analysis done and not based on safety concerns.
    follow-up visits and closing out study activities are completed
  
["alzheimer's disease"]
['aducanumab (biib037)', 'aducanumab (biib037)', 'placebo']

        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
      