Here is the design of a clinical trial:

Official Title: Exercise Augmenting Cognition tDCS (EXACT): A Pilot Study of a Combined Exercise and Transcranial Direct Current Stimulation Intervention for Cognition

Included conditions:
- Mild Cognitive Impairment
- Alzheimer Disease

Study Armgroups:
- {'label': 'Exercise and tDCS', 'type': 'EXPERIMENTAL', 'description': 'Patients randomized to this group will attend Toronto Rehabilitation Institute - University Health Network (TRI-UHN) for an individualized exercise program and active tDCS intervention.', 'interventionNames': ['Other: tDCS', 'Other: Exercise']}
- {'label': 'Exercise Education and tDCS', 'type': 'OTHER', 'description': 'Patients randomized to this group will undergo treatment as usual, receiving routine advice about physical activity and active tDCS intervention.', 'interventionNames': ['Other: tDCS', 'Other: Exercise Education']}
- {'label': 'Exercise and Sham tDCS', 'type': 'OTHER', 'description': 'Patients randomized to this group will attend TRI-UHN for an individualized exercise program and sham tDCS intervention.', 'interventionNames': ['Other: Exercise', 'Other: Sham tDCS']}

Interventions:
- {'type': 'OTHER', 'name': 'tDCS', 'description': 'All study participants randomized to tDCS will receive active tDCS.', 'armGroupLabels': ['Exercise Education and tDCS', 'Exercise and tDCS']}
- {'type': 'OTHER', 'name': 'Exercise', 'description': 'Participants will exercise at TRI according to an individualized exercise prescription.', 'armGroupLabels': ['Exercise and Sham tDCS', 'Exercise and tDCS']}
- {'type': 'OTHER', 'name': 'Exercise Education', 'description': 'Exercise education/ treatment as usual will include routine advice about physical activity for older adults.', 'armGroupLabels': ['Exercise Education and tDCS'], 'otherNames': ['Treatment as usual']}
- {'type': 'OTHER', 'name': 'Sham tDCS', 'description': 'The same procedure for tDCS will be used for the sham condition, except without active current.', 'armGroupLabels': ['Exercise and Sham tDCS']}

Primary Outcomes:
- {'measure': "Change in cognition: The Word Recognition Task from the Alzheimer's Disease Assessment Scale Cog (ADAS-Cog)", 'description': 'Assess recognition memory. Words incorrectly recognized will be tallied. Word Recognition scores range from 0 to 12. Higher scores represent a worse outcome.', 'timeFrame': 'Change over 2 weeks (Baseline to Endpoint)'}

Please estimate the sample size based on the assumption: 
83% power, alpha of 0.05, adjusting for 4 covariates, medium effect size
Sample size calculation
          The sample size calculation was performed using G*Power version 3.1.9.2 (Kiel, Germany). The sample size was based on findings from a study reporting a 2-point change in MMSE score following anodal tDCS in mild to moderate AD [33]. No studies to date have assessed changes in the MoCA following anodal tDCS. However, a strong correlation between the MMSE and MoCA (râ=â0.86) in mild AD [89] implies that a similar change in the MoCA could be found in this population. Based on that assumption, a sample size of 60 completers (20 per treatment group) achieves 83% power for a repeated measures analysis of covariance (ANCOVA), adjusting for 4 covariates with an alpha of 0.05 to detect a medium effect size.