Mentioning Payment During Recruitment May Actually Reduce Alzheimer's Study Enrollment
A randomized study finds that disclosing financial compensation during recruitment calls lowered consent rates by up to 13 points in Alzheimer's research.
Summary
Researchers at Washington University tested whether mentioning financial compensation during recruitment calls affected enrollment in a longitudinal Alzheimer's study. In a randomized trial of 337 recruitment calls, those who heard about compensation were actually less likely to enroll than those who did not. The consent rate dropped by roughly 10 to 13 percentage points in the compensation-mentioned group. The authors suggest this may be because potential participants perceive payment as conflicting with altruistic motivations for joining research. Importantly, the sample was highly educated, so the findings may not apply to populations with lower socioeconomic status, where compensation could help offset real participation burdens. The results have direct implications for how clinical trial recruiters frame compensation during outreach.
Detailed Summary
Recruiting and retaining participants in Alzheimer's disease research is one of the field's most persistent challenges. Without adequate enrollment, longitudinal studies lose statistical power and generalizability, slowing progress toward treatments and prevention strategies. Understanding what communication strategies help or hinder enrollment is therefore critically important.
This study from Washington University in St. Louis examined a specific and underexplored question: does mentioning financial compensation during a recruitment phone call affect whether someone agrees to enroll in a longitudinal Alzheimer's cohort study? Researchers randomized 337 recruitment calls into two groups — one where compensation was mentioned and one where it was not — then tracked enrollment outcomes.
The results were counterintuitive. Of 320 participants analyzed, 124 enrolled overall (38.75%). However, the group that heard about compensation had a meaningfully lower consent rate. In the per-protocol analysis, the compensation group enrolled at a rate roughly 12.7 percentage points lower than controls, a statistically significant difference. The intention-to-treat analysis showed a similar trend of nearly 10 points, approaching but not reaching conventional significance.
The authors propose that disclosing compensation may trigger a psychological conflict for altruistically motivated volunteers, making participation feel transactional rather than meaningful. This 'crowding out' of intrinsic motivation by extrinsic incentives is a well-documented phenomenon in behavioral economics.
However, important caveats apply. The study sample was highly educated and likely of higher socioeconomic status, a demographic for whom financial incentives may feel unnecessary or even off-putting. For individuals with lower incomes or greater logistical burdens around participation, compensation disclosure could have the opposite effect — increasing enrollment by making participation feasible. Further research across more diverse populations is needed before broad recruitment policy changes are made.
Key Findings
- Mentioning compensation during recruitment calls reduced consent rates by ~13 percentage points in per-protocol analysis.
- Overall enrollment was 38.75% across 320 analyzed participants in this longitudinal Alzheimer's cohort.
- The negative effect of compensation disclosure may reflect 'crowding out' of altruistic motivation.
- Findings may not generalize to lower-income or less-educated populations where compensation offsets real burdens.
- Recruitment communication strategy — not just compensation itself — may significantly shape clinical trial enrollment.
Methodology
This was a randomized controlled trial of 337 recruitment phone calls, split into a compensation-mentioned group (n=170) and a control group (n=167). Enrollment outcomes were assessed using intention-to-treat logistic regression, per-protocol analysis, and complier average causal effect analysis. The study was conducted through the Knight Alzheimer Disease Research Center at Washington University in St. Louis.
Study Limitations
The summary is based on the abstract only, as the full text was not available. The study sample was highly educated and likely not representative of broader socioeconomic diversity, limiting generalizability. The intention-to-treat primary analysis did not reach conventional statistical significance (p=0.074), and the study was conducted at a single academic center.
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