Table 1.

Survey questions in order with response options and response formats

Question	Response options	Response format
Which of these answer(s) best describe reasons that make participation difficult for you? (Please select all that apply.)	I am no longer interested I do not have enough time The tasks take too much time I do not understand the tasks/the tasks are too difficult I do not want to answer some questions in the task I do not like it I forgot I had technical difficulties I do not see a benefit for me I had a difficult incident/experience with the tasks. Explain*^ I do not have any difficulties with participation I had a difficult incident/experience with the tasks. Explain:* Other:*^	Check if applicable *Includes free text reply option
What (if anything) can help you overcome these difficulties?	N/A	Free text reply^
On a scale from 1–5, rate how important each reason was to you for joining the Brain Health Registry.	I want to learn about Brain diseases such as Alzheimer’s I want to learn about my own brain health I want to help with current research/treatments for brain health I want to help research to benefit the brain health of future generations Someone I know has/had a brain disease such as Alzheimer’s I was referred by someone I know Other*#
On a scale from 1–5, rate how important this reason is to you for continuing participation in the Brain Health Registry	I want to learn about Brain diseases such as Alzheimer’s I want to learn about my own brain health I want to help with current research/treatments for brain health I want to help research to benefit the brain health of future generations Someone I know has/had a brain disease such as Alzheimer’s I was referred by someone I know I enjoy completing the study tasks Other*#	Least important (1), (2), (3), (4), Most important (5), N/A (6)
What best describes your attitude towards brain health research?	N/A	Positive (1), Neutral (2), Negative (3), No opinion (4)
Can you explain why you gave that answer?	N/A	Free text reply #
On a scale of 1–5 how interested would you be in these additional features?	Additional cognitive tests More of the current study tasks available on smartphones and tablets Specific information and resources regarding brain disease More frequent newsletters Summary of your performance on brain tests Other*	Least important (1), (2), (3), (4), Most important (5), N/A (5)
On a scale of 1–5 how much would this encourage you to return to the Brain Health Registry or complete all the study tasks?	Monetary compensation Fewer questionnaires or brain tests A chance to win a prize Better technical support More educational resources Additional opportunities to participate in clinical research More details on how my participation helps research or impacts my community Other*	Not interested (1), (2), (3), (4), Very interested (5), N/A (6)
Over the past 2 months, how often have you used the following websites?	Facebook Twitter Instagram TikTok Snapchat YouTube LinkedIn Pinterest Other*	Not at all (1), Several days (2), More than half the days (3), Nearly every day (4)
Please rate your preference for these ways to receive information on a scale from 1–5.	Phone call Text Email Postcard Radio. What station do you listen to?* Blog. What blogs or bloggers do you follow?* Webinar Social media Which social media channel(s)?* Other*	Do not prefer (1), (2), (3), (4), Prefer the most (5), I do not use this (6)

^*Note. =Includes free text reply option;

^#=questions analyzed in qualitative analysis of “Research Participation;

^{^}=questions analyzed in qualitative analysis of “Barriers to Research Participation”