In any clinical trial or observational study, a certain level of cognitive function is required in order to ensure participant safety and ability to comply with the study protocol. Participants should adequately understand what is involved in their participation, as well as any potential risks or benefits of participation. The costs of using a specific screening method, however, need to be weighed against the information obtained. This prevents the inefficient use of available resources, such as avoiding assessments that require an extremely long administration time and unnecessarily increase participant burden. Due to the inherent challenges in obtaining a valid assessment of cognitive function in a time efficient manner, all potential assessment measures should be evaluated with a "best fit" approach. Keeping this "best fit" approach in mind, we reviewed and evaluated a number of screening tests for assessing cognitive impairment based on recommendations provided by experts in the field. Based on our review, we provide recommendations about existing methods for screening cognitive function in older research participants. Using the "best fit" approach, we would recommend the Mini-Mental State Examination (MMSE) to screen for cognitive impairment in older research participants. Other measures, such as the Cognitive Abilities Screening Instrument (CASI) and Modified Mini-Mental State (3MS), are indeed promising, but the MMSE can be administered in a time efficient manner and has the highest amount of supporting literature.