Table 2Inclusion and exclusion criteria

CategoryCriteria
Study populationHumans, all races, ethnicities, and cultural groups
KQ 1–6: Adults age ≥ 50 years old; drawn from a general population or general medical setting, with normal cognition or mild cognitive impairment
Study geographyDeveloped countries: United States, Canada, United Kingdom, Western Europe, Australia, New Zealand, Hong Kong, Japan, Republic of China (Taiwan), Singapore, South Korea, Israel
Factors/interventionsSee Table 1, above
Study outcomesKQ1 & 3: Diagnosis of Alzheimer’s disease using an acceptable standard (e.g., National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s Disease and Related Disorders Criteria)
KQ2 & 4: Diagnosis of mild cognitive impairment using an acceptable standard (e.g., Petersen’s criteria) or change in cognition using at least two measurements on an acceptable measure
Outcome timingKQ1 & 3: At least 1 year after the exposure or intervention
KQ2 & 4: At least 2 years after the exposure or intervention
Time period1984 to October 27, 2009
Publication languagesEnglish only
Admissible evidence (study design and other criteria)Good quality systematic reviews that addressed a question of interest and used eligibility criteria consistent with our inclusion/exclusion criteria
Original research studies that provide sufficient detail regarding methods and results to enable use of the data and results; relevant outcomes must be able to be abstracted from data presented in the papers. If risk for non-specific dementia only were reported, we required ≥ 60% of the outcomes to be AD.
Eligible original research designs include:
KQ 3 & 4: Randomized controlled trials (RCTs);
KQ 1–4: Observational studies: longitudinal designs comparing exposed to unexposed. For TBI, sleep apnea, and toxic environmental, case-control studies were also eligible.
Sample sizes must be appropriate for the study question: RCTs ≥ 50; longitudinal observational ≥ 300

Abbreviations: AD = Alzheimer’s disease; KQ = key question; RCT = randomized controlled trial; TBI = traumatic brain injury

From: 2, Methods

Cover of Preventing Alzheimer's Disease and Cognitive Decline
Preventing Alzheimer's Disease and Cognitive Decline.
Evidence Reports/Technology Assessments, No. 193.
Williams JW, Plassman BL, Burke J, et al.

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