Lessons Learned from an Online RDoC Positive Valence Assessment Study in Patients with a Severe Mental Illness

Background: Abnormal reward processing has been considered as a core feature of severe mental illness (SMI), such as bipolar disorder and schizophrenia. Deficits in this domain can have severe implications in daily functioning, such as a decreased motivation to engage in social activities or make healthy lifestyle choices. The Online Positive Valence Study aimed to assess reward processing in bipolar disorder and schizophrenia using the NIMH Research Domain Criteria (RDoC) Positive Valence Systems (PVS) framework in an online task-based study. Recruitment and study adherence fell short of expectations. Objective: The current paper critically evaluates the used methodology and shares the lessons learned of conducting an online task-based study of reward processing in a severe mental illness sample. Methods: Participants were recruited mainly via email from two existing cohorts. The research team consisted of a part-time research assistant, a part-time postdoctoral researcher and the principal investigators. The study was built using several software packages and comprised a number of questionnaires and three reward tasks, the monetary incentive delay task (MID), effort expenditure of rewards task (EEfRT) and a social and coin version of the Bandit task. From 2023 onwards, the research team accepted that the initial recruitment goal would not be attained. Results: Participants who were additionally called were over four times more likely to respond “no” and more than twice as likely to respond “yes” versus no response compared to those who received only emails. Personal salutations in invitation mails reduced the likelihood of participation compared to nonpersonal salutations. Reward task performance was largely similar between the in-lab MRI and online groups, though online participants showed longer reaction times on the MID task and lower win-stay rates on both Bandit tasks. Conclusion: It is advised to carefully consider recruiting from existing cohorts, hire full-time dedicated personnel and use personal approaches to recruitment, like phone calls, and adjust recruitment to the target population(s). Furthermore, participation should be technically as simple as possible, using for example browser-based presentation of tasks, after checking their consistency across the most common browsers. Attrition during the course of the study can be limited even more by shortening the duration of participation and/or adding gamification. Keywords: Positive Valence System; reward processing; bipolar disorder; schizophrenia; online study