Table 1.

How to overcome barriers to achieving population representation in brain aging research

Participant and study challenges	Solutions and accommodations
Time constraints due to work obligations or limited social/financial support (e.g., childcare assistance)	• Offer research testing appointments during evenings or weekends. • Divide lengthy appointments into multiple shorter sessions, distributed across days if possible. • Provide childcare options at or near the research facility.
Physical distance from research center/lack of transportation	• Provide transportation reimbursement (e.g., mileage allowance) or offer transportation using ride-hailing services in areas where public transportation is limited. • Use satellite research campuses. • Offer testing virtually, via web or smartphones, or in-person at participant’s home (e.g., mobile testing services). The incorporation of alternate testing mediums requires researchers to ensure that the tests are valid and comparable to other forms of testing, to avoid introduction of confounding factors.
Lack of awareness of opportunities to participate	• Advertise study in diverse geographical locations to recruit individuals from a broader range of communities (e.g., spanning income levels, rural and urban neighborhoods, etc.). • Use a variety of advertising mediums to increase reach of recruitment [e.g., social media, radio, print (physical and digital), signage in public locations]. • Form relationships with community leaders and organizations who can help raise awareness about research opportunities. • Continuously monitor recruitment progress to gain insights on what methods are working best and adapt recruitment methods accordingly.
Lack of reliable communication channels to schedule, confirm appointment reminders, etc.	• Obtain and utilize multiple communication mediums (e.g., phone, email, text, messaging); expand beyond phone or email by including social-media-based calling and messaging. • Request participant to provide alternate points of contact (e.g., co-workers, friends, family members).
Mistrust in research and/or medical and scientific organizations	• Validate, address, and empathize with the participant’s feelings of mistrust/concerns throughout both the recruitment process but also during study procedures. Minimize use of jargon throughout recruitment and study procedures. • Employ and train research staff and scientists who are socioeconomically, racially, ethnically, and culturally representative of the participant population. • Employ bilingual research assistants to help communicate study goals, procedures, and methods to non-English speaking participants. • Minimize power dynamics (e.g., remind participants that research testing is optional, and that their comfort and safety takes precedence over research testing requirements). • Express cultural sensitivity. • Provide opportunities for community members to learn more about the research they are contributing to (e.g., public lectures at community events). • Disseminate study updates and findings in a platform accessible and comprehensible to the general public and community organizations. • Align community interests in research by collaborating with community members in the development of study methods and goals.
Physical and health-related impediments that result in direct or indirect participant exclusion	• Conduct comprehensive health screening to assess device compatibility (e.g., BMI, MRI compatibility, claustrophobia) before scheduling participants so that physical barriers to participating can be anticipated and potentially accommodated in advance of testing session. • Relax exclusion criteria during health screening to allow individuals with poorer health status/history to participate. • Adopt procedures or use devices (e.g., mock-MRI scanners, larger bore MRI scanners) that acclimate participants to study environment and/or accommodate physical limitations. • Communicate with participant’s primary care physician to assess and confirm suitability (e.g., to evaluate whether implanted devices are MRI compatible). If a participant does not have a primary care physician, take time to carefully review the participant’s medical history with a doctor or MRI technicians on your team to evaluate eligibility. Alternately or in addition, establish a network of healthcare resources for participants by forming collaborations with local clinics and community health centers that could provide participants with access to medical consultations.
Prone to being unfairly disadvantaged on cognitive screening tests	• Adopt cognitive screeners that are not biased towards higher educational attainment or require specific language fluency. • Adjust cognitive screening criteria to account for racial/ethnic minority group differences or educational differences.
Minimizing data loss and impacts of last-minute cancellations	• Adapt procedures to accommodate phenotypic differences that might impede or affect data collection (e.g., using electroencephalogram electrodes designed for coarse hair, training researchers to work with and measure a range of hair types, accounting for the effect of melanin when using functional near-IR spectroscopy). • Utilize specialized hardware and software to minimize data loss that may be higher in certain cohorts due to greater physical discomfort during data collection (e.g., real-time motion monitoring, customized head molds, real-time prospective motion correction). • Allow for more data collection time during testing sessions. • Send frequent appointment reminders using multiple communication channels. • Identify backup participants in case of last-minute cancellations.
Lower likelihood of retention in interventional and longitudinal studies (nonrandom attrition)	• Obtain and utilize multiple communication channels and obtain alternate points of contact (see above), to increase likelihood of successful follow-up communication. • Allocate greater funds to transportation costs for cases where participant relocates to distant locations outside of original recruitment region. • Relax exclusion criteria, to the extent that is possible and safe, for follow-up testing sessions to allow for study completion. • Consider protocol modifications that are more flexible, and allow returning participants to engage in specific study segments based on changes in their health and cognitive status. • Establish feedback sessions aimed at assessing participants’ experiences during testing, addressing any concerns they may have, and providing a process for gaining insights that can improve study procedures during follow-up visits. • Share personalized data summaries, progress charts, or visual representations of the data collected during interim periods of the study.