['alzheimer disease']
['placebo', 'placebo', 'bi 409306', 'donepezil']

        Inclusion criteria:

          -  Patients with early signs of dementia of Alzheimer Type

          -  Male and female patients with an age of at least 55 years

          -  Previous use of Alzheimer's Disease (AD) medications (AChEIs, memantine) is allowed up
             3 month prior to screening. Patients who are currently taking AChEIs are eligible as
             long as they have been using a stable dose for at least 3 months prior to screening
             and no change is foreseen for the duration of the study. This dose must be consistent
             with the product label in the concerned country. Patients currently taking memantine
             are excluded.

          -  Patients must have at least 6 years of formal education and fluency in the test
             language as verbally confirmed by the patient and documented by the study
             investigator.

          -  Patients must have a reliable study partner (per investigator judgement, for instance
             a family member, partner etc., guardian or, if applicable, a legal representative)

        Exclusion criteria:

          -  Cognitive impairment or dementia with any etiology other than Alzheimer's Disease (AD)

          -  Substantial concomitant cerebrovascular disease (defined by a history of a stroke /
             intracranial haemorrhagia) temporally related to the onset of worsening of cognitive
             impairment per investigator judgement

          -  Medical history or diagnosis of any of symptomatic and unstable/uncontrolled
             conditions per investigator judgement

          -  Any other psychiatric disorders such as schizophrenia, or mental retardation

          -  Previous participation in investigational drug studies of mild cognitive
             impairment/Dementia of Alzheimer Type (DAT) within three months prior to screening.
             Having received active treatment in any other study targeting disease modification of
             AD like Aß immunization and tau therapies. Previous participation in studies with
             non-prescription medications, vitamins or other nutritional formulations is allowed.

          -  Clinically significant uncompensated hearing loss in the judgment of the investigator.
             Use of hearing aids is allowed.
      