Cohort name Country Reference Follow‐up Funding	Original Cohort (N total) Exclusion criteria Study population (n, sex and age at baseline(a))	Ascertainment of outcome	Exposure groups(a) n	Incident cases	Model covariates	Results
PREADVISE USA, Canada and Puerto Rico Kryscio et al. (2017) Approx. 5 yr RCT + 7 yr observational follow‐up Public	N = 7,540 Population sampled: Subsample of participants from SELECT Exclusion: dementia, active neurologic and/or neuropsychiatric conditions affecting cognition; history of serious head injury and substance abuse; no follow‐up visit n = 3,786 Sex: Males Ethnicity: 8.4% Black, 2.5% Hispanic, 89.1% White Age: > 60 yr	Incidence of dementia; Memory Impairment Screening (MIS) test at follow‐up visit; cases identified based on MIS test and i) followed by diagnostic by local clinician, or ii) AD8 Dementia Screening Interview ≥ 1 plus a self‐reported dementia diagnosis, use of a memory enhancing prescription drug, or cognitive score ≥ 1.5 SDs below expected performance	n, per group G1, placebo*: 1,830 G2, 200 μg Se/d*: 1,881 *5.4 ± 1.2 yr of intervention	Incident cases of dementia, n G1: 85 G2: 78	Baseline age, black race, APOE ε4 carrier status (present or absent), college education, baseline MIS score, and the presence/absence of the following self‐reported co‐morbidities at PREADVISE baseline: coronary artery bypass graft (CABG), congestive heart failure (CHF), diabetes, hypertension, stroke, sleep apnoea, and memory change or problem	HR (95% CI) for incidence of dementia G1: ref. G2: 0.92 (0.63, 1.34) Modified intent‐to‐treat analysis G1: ref. G2: 0.83 (0.61, 1.13) Weighted for treatment compliance G1: ref. G2: 0.80 (0.59, 1.09)

PREADVISE: Prevention of Alzheimer's Disease with Vitamin E and Selenium; RCT: randomised controlled trial; SELECT: Selenium and Vitamin E Cancer Prevention Trial; yr: year.

(a) Mean ± SD (range), unless specified otherwise.