
    this study was prematurely discontinued because the program for progressive supranuclear palsy
    was discontinued due to lack of efficacy of study drug.
  
['progressive supranuclear palsy']
['placebo', 'abbv-8e12']

        Key Inclusion Criteria:

          -  Male or female participant with age 40 years or greater at the time of signed consent

          -  Meets the criteria for possible or probable progressive supranuclear palsy (PSP;
             Steele-Richardson-Olszewski Syndrome)

          -  Presence of PSP symptoms for less than 5 years

          -  Participant is able to walk 5 steps with minimal assistance (stabilization of one arm
             or use of cane/walker)

          -  Participant has an identified, reliable, study partner (e.g., caregiver, family
             member, social worker, or friend)

        Key Exclusion Criteria:

          -  Participants who weigh less than 44 kg (97 lbs) at screening

          -  Mini-Mental State Examination (MMSE) score less than 15 at screening

          -  Any contraindication or inability to tolerate brain magnetic resonance imaging (MRI)

          -  Participant resides at a skilled nursing or dementia care facility, or admission to
             such a facility is planned during the study period

          -  Evidence of any clinically significant neurological disorder other than PSP

          -  The participant has a history of or currently has schizophrenia, schizoaffective
             disorder or bipolar disorder according to Diagnostic and Statistical Manual of Mental
             Disorders, 5th Edition (DSM-V) or International Classification of Diseases (ICD-10)
             criteria

          -  Participant has had a significant illness or infection requiring medical intervention
             in the past 30 days
      