Placebo and nocebo responses in randomized, controlled trials of medications for ADHD: a systematic review and meta-analysis.
Faraone SV, Newcorn JH, Cipriani A, Brandeis D, Kaiser A, Hohmann S, Haege A, Cortese S.
Mol Psychiatry. 2021 May 10.
Commentary* by Dr. Margaret Weiss: It is nice to see the placebo effect framed as the clinician’s friend, rather than as a confound to care.
The nature and magnitude of placebo and nocebo responses to ADHD medications and the extent to which response to active medications and placebo are inter-correlated is unclear. To assess the magnitude of placebo and nocebo responses to ADHD and their association with active treatment response.
We searched literature until June 26, 2019, for published/unpublished double-blind, randomized placebo-controlled trials (RCTs) of ADHD medication. Authors were contacted for additional data. We assessed placebo effects on efficacy and nocebo effects on tolerability using random effects meta-analysis.
We assessed the association of study design and patient features with placebo/nocebo response. We analyzed 128 RCTs (10,578 children/adolescents and 9175 adults) and found significant and heterogenous placebo effects for all efficacy outcomes, with no publication bias.
The placebo effect was greatest for clinician compared with other raters. We found nocebo effects on tolerability outcomes. Efficacy outcomes from most raters showed significant positive correlations between the baseline to endpoint placebo effects and the baseline to endpoint drug effects. Placebo and nocebo effects did not differ among drugs. Baseline severity and type of rating scale influenced the findings. Shared non-specific factors influence response to both placebo and active medication.
Although ADHD medications are superior to placebo, and placebo treatment in clinical practice is not feasible, clinicians should attempt to incorporate factors associated with placebo effects into clinical care. Future studies should explore how such effects influence response to medication treatment. Upon publication, data will be available in Mendeley Data: PROSPERO (CRD42019130292).
* Abstracts are selected for their clinical relevance by Dr. Margaret Weiss, Director of Clinical Research, Child Psychiatry, Cambridge Health Alliance, Harvard University. Her commentary reflects her own opinion. It is not approved or necessarily representative of the CADDRA board.