ED-based diagnostic research for dementia screening is limited to a few studies using an inadequate criterion standard with variable masking of interpreter's access to the index test and the criterion standard. Standardizing the geriatric ED cognitive assessment methods, measures, and nomenclature is necessary to reduce uncertainties about diagnostic accuracy, reliability, and relevance in this acute care setting. The AMT-4 is currently the most accurate ED screening instrument to increase the probability of dementia and the Brief Alzheimer's Screen is the most accurate to decrease the probability of dementia. Dementia screening as one marker of vulnerability to initiate comprehensive geriatric assessment is warranted based on test-treatment threshold calculations.