Who will take informed consent? {26a}
All prospective participants will complete informed consent electronically to participate in the primary P3 cohort, which will include optional consent to be contacted and screened for inclusion in sub-studies, including this nested trial. Those meeting the AD definition (above) will be invited to complete a brief screening questionnaire for the current trial. Once it is determined that a prospective participant is eligible to participate, they will be contacted by trained research assistants, who will explain the study procedures in full detail, provide the participant with written copies of the consent form, and obtain written informed consent for participation in the nested trial.