Objectives To assess whether persons with amyotrophic lateral sclerosis (ALS) are at risk of a therapeutic misconception (TM) in which they misconceive research as treatment or overestimate the likelihood of its benefit.

Methods 72 patients with ALS recruited via academic and patient organisations were surveyed using a hypothetical first-in-human intervention study scenario. We elicited their understanding of the purpose of the study (‘purpose-of-research question’) and then asked how they interpreted the question. We then asked for an estimate of the likelihood that their ALS would improve by participating and asked them to explain the meaning of their estimates.

Results Although 10 of 72 (14%) subjects incorrectly said that the intervention study was ‘mostly intending to help [me]’ in response to the purpose-of-research question, 7 of those 10 thought that the question was asking them about their own motivations for participating. Overall, only one of 72 respondents (1.4%) both understood the purpose-of-research question as intended and gave the incorrect response. Subjects’ mean estimate of likelihood of benefit was 31% (SD 26). This was due to 29 of 72 of respondents providing high estimates (50%–54% likelihood), which they said were expressions of hope and need for a positive attitude; among those who said their estimates meant ‘those are the facts’ or ‘there is a lot of uncertainty’, the estimates were much lower (12.6% and 18.5%, respectively).

Conclusions In this group of patients with ALS considering a hypothetical first-in-human intervention study, apparent TM responses have alternative explanations and the risk of true TM appears low.