A qualitative study of the treatment experiences of autistic adults allocated to sertraline or placebo for anxiety in a blinded randomised controlled trial

Antidepressant medications are frequently prescribed to autistic adults, but there are no qualitative accounts of this population’s experiences of taking an antidepressant, or of being blinded and taking a placebo in a randomised controlled trial (RCT). This qualitative study interviewed 62 participants from the STRATA RCT (sertraline vs. placebo for treating anxiety in autistic adults). The study aimed to investigate their experiences of participation, focusing on taking the trial medication for up to 52 weeks (blinded to whether they were taking the active medication or placebo). Interviews were analysed using thematic analysis. Interviewees often discussed improved anxiety regardless of treatment allocation, attributing changes to sertraline, the placebo effect, and positive and negative external factors. Some participants, including those taking placebo experienced side effects, mirroring types, frequency, and severity in non-autistic populations. Many were able to manage these and continue, but some discontinued medication as a result. Factors in trial design and delivery were identified as facilitating retention, including frequent appointments, shared control over their dose, and meaningfully involving autistic people in the trial design. These and other non-pharmacological factors may have enhanced therapeutic benefits and could be considered to improve RCT design and therapeutic alliances with autistic people.