Blinding and expectancy confounds in psychedelic randomized controlled trials
Abstract
Introduction: There is increasing interest in the potential for psychedelic drugs such as psilocybin, LSD and ketamine to treat several mental health disorders, with a growing number of randomized controlled trials (RCTs) being conducted to investigate the therapeutic effectiveness of psychedelics.Areas covered: We review previous literature on expectancy effects and blinding in the context of psychedelic RCTs – literature which strongly suggest that psychedelic RCTs might be confounded by de-blinding and expectancy. We conduct systematic reviews of psychedelic RCTs using Medline, PsychInfo and EMBASE (Jan 1990 – Nov 2020) and show that currently reported psychedelic RCTs have generally not reported pre-trial expectancy, nor the success of blinding procedures.Expert opinion: While psychedelic RCTs have generally shown promising results, with large effect sizes reported, we argue that treatment effect sizes in psychedelic RCTs are likely over-estimated due to de-blinding of participants and high levels of response expectancy. We suggest that psychedelic RCTs should routinely measure de-blinding and expectancy. Careful attention should be paid to clinical trial design and the instructions given to participants to allow these confounds to be reduced, estimated and removed from effect size estimates. We urge caution in interpreting effect size estimates from extant psychedelic RCTs.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
Systematic unblinding has been raised as a major threat to the validity of extant findings from double-blind psychedelic-assisted therapy trials due to high expectancy, presumably resulting in large placebo and nocebo effects in the experimental and control groups, respectively.
“systematic unblinding has been raised as a major threat to the validity of extant findings from ‘double blind’ PAT trials due to high expectancy, presumably resulting in large placebo and nocebo effects in the experimental group and the control group, respectively [32–34].”
There is a general call for more effective active placebo conditions and systematic reporting of blinding efficacy.
“leading to a general call for more effective active placebo conditions and a systematic reporting of blinding efficacy [32–34].”
The study proposes an active placebo condition aimed at maintaining blinding, while systematically assessing and reporting blinding efficacy in participants and therapists.
“proposing an active placebo condition aimed at maintaining blinding, while systematically assessing and reporting blinding efficacy in participants and therapists.”
Blinding efficacy for participants and therapists and expectancy for participants will be assessed and reported.
“blinding efficacy (participants, therapists) and expectancy (participants) will be assessed and reported, as recommended in the literature [32–34].”
Cites
Estimating causal effects of treatments in randomized and nonrandomized studies
Rubin, D. B. (1974) · Journal of Educational Psychology · doi:10.1037/h0037350 · Cited by 9,436 · see citing works
Moher, D., Hopewell, S., Schulz, K. F., Montori, V., Gotzsche, P. C., Devereaux, P. J., Elbourne, D., Egger, M., & Altman, D. G. (2010) · BMJ · doi:10.1136/bmj.c869 · Cited by 8,883 · see citing works
Statistics and Causal Inference
Holland, P. W. (1986) · Journal of the American Statistical Association · doi:10.1080/01621459.1986.10478354 · Cited by 5,293 · see citing works
Antidepressant effects of ketamine in depressed patients
Berman, R. M., Cappiello, A., Anand, A., Oren, D. A., Heninger, G. R., Charney, D. S., & Krystal, J. H. (2000) · Biological Psychiatry · doi:10.1016/s0006-3223(99)00230-9 · Cited by 3,856 · see citing works
A randomized trial of an N-methyl-D-aspartate antagonist in treatment-resistant major depression.
Zarate, C. A., Singh, J. B., Carlson, P. J., Brutsche, N. E., Ameli, R., Luckenbaugh, D. A., Charney, D. S., & Manji, H. K. (2006) · Archives of General Psychiatry · doi:10.1001/archpsyc.63.8.856 · Cited by 3,766 · see citing works
External validity of randomised controlled trials: “To whom do the results of this trial apply?”
Rothwell, P. M. (2005) · The Lancet · doi:10.1016/s0140-6736(04)17670-8 · Cited by 2,544 · see citing works
Psychometric properties of the credibility/expectancy questionnaire
Devilly, G. J., & Borkovec, T. D. (2000) · Journal of Behavior Therapy and Experimental Psychiatry · doi:10.1016/s0005-7916(00)00012-4 · Cited by 2,295 · see citing works
Griffiths, R. R., Johnson, M. W., Carducci, M. A., Umbricht, A., Richards, W. A., Richards, B. D., Cosimano, M. P., & Klinedinst, M. A. (2016) · Journal of Psychopharmacology · doi:10.1177/0269881116675513 · Cited by 2,201 · see citing works
Misunderstanding analysis of covariance.
Miller, G. A., & Chapman, J. P. (2001) · Journal of Abnormal Psychology · doi:10.1037/0021-843x.110.1.40 · Cited by 2,136 · see citing works
Beecher, H. K. (1955) · JAMA · doi:10.1001/jama.1955.02960340022006 · Cited by 1,850 · see citing works
Understanding and misunderstanding randomized controlled trials
Deaton, A., & Cartwright, N. (2018) · Social Science & Medicine · doi:10.1016/j.socscimed.2017.12.005 · Cited by 1,841 · see citing works
Assessing risk of bias in a randomized trial
Higgins, J. P., Savović, J., Page, M. J., Elbers, R. G., & Sterne, J. A. (2019) · Cochrane Handbook for Systematic Reviews of Interventions · doi:10.1002/9781119536604.ch8 · Cited by 1,765 · see citing works
The alliance in adult psychotherapy: A meta-analytic synthesis
Flückiger, C., Del Re, A. C., Wampold, B. E., & Horvath, A. O. (2018) · Psychotherapy · doi:10.1037/pst0000172 · Cited by 1,763 · see citing works
Ross, S., Bossis, A., Guss, J., Agin-Liebes, G., Malone, T., Cohen, B., Mennenga, S. E., Belser, A., Kalliontzi, K., Babb, J., et al. (2016) · Journal of Psychopharmacology · doi:10.1177/0269881116675512 · Cited by 1,698 · see citing works
Credibility of analogue therapy rationales
Borkovec, T. D., & Nau, S. D. (1972) · Journal of Behavior Therapy and Experimental Psychiatry · doi:10.1016/0005-7916(72)90045-6 · Cited by 1,553 · see citing works
Carhart-Harris, R. L., Bolstridge, M., Rucker, J., Day, C. M. J., Erritzoe, D., Kaelen, M., Bloomfield, M., Rickard, J. A., Forbes, B., Feilding, A., et al. (2016) · The Lancet Psychiatry · doi:10.1016/s2215-0366(16)30065-7 · Cited by 1,540 · see citing works
Hróbjartsson, A., & Gøtzsche, P. C. (2001) · New England Journal of Medicine · doi:10.1056/nejm200105243442106 · Cited by 1,488 · see citing works
Moher, D., Schulz, K. F., Altman, D. G., & for the CONSORT Group* (2001) · Annals of Internal Medicine · doi:10.7326/0003-4819-134-8-200104170-00011 · Cited by 1,426 · see citing works
Pilot Study of Psilocybin Treatment for Anxiety in Patients With Advanced-Stage Cancer
Grob, C. S., Danforth, A. L., Chopra, G. S., Hagerty, M., McKay, C. R., Halberstadt, A. L., & Greer, G. R. (2011) · Archives of General Psychiatry · doi:10.1001/archgenpsychiatry.2010.116 · Cited by 1,206 · see citing works
Murrough, J. W., Iosifescu, D. V., Chang, L. C., Al Jurdi, R. K., Green, C. E., Perez, A. M., Iqbal, S., Pillemer, S., Foulkes, A., Shah, A., et al. (2013) · American Journal of Psychiatry · doi:10.1176/appi.ajp.2013.13030392 · Cited by 1,205 · see citing works
Components of placebo effect: randomised controlled trial in patients with irritable bowel syndrome
Kaptchuk, T. J., Kelley, J. M., Conboy, L. A., Davis, R. B., Kerr, C. E., Jacobson, E. E., Kirsch, I., Schyner, R. N., Nam, B. H., Nguyen, L. T., et al. (2008) · BMJ · doi:10.1136/bmj.39524.439618.25 · Cited by 1,196 · see citing works
Psilocybin-assisted treatment for alcohol dependence: A proof-of-concept study
Bogenschutz, M. P., Forcehimes, A. A., Pommy, J. A., Wilcox, C. E., Barbosa, P., & Strassman, R. J. (2015) · Journal of Psychopharmacology · doi:10.1177/0269881114565144 · Cited by 1,151 · see citing works
Placebo Response in Studies of Major Depression: Variable, Substantial, and Growing
Walsh, B. T., Seidman, S. N., Sysko, R., & Gould, M. (2002) · JAMA · doi:10.1001/jama.287.14.1840 · Cited by 1,109 · see citing works
Psilocybin induces schizophrenia-like psychosis in humans via a serotonin-2 agonist action
Vollenweider, F. X., Vollenweider-Scherpenhuyzen, M. F. I., Bäbler, A., Vogel, H., & Hell, D. (1998) · NeuroReport · doi:10.1097/00001756-199812010-00024 · Cited by 1,018 · see citing works
Diazgranados, N., Ibrahim, L., Brutsche, N. E., Newberg, A., Kronstein, P., Khalife, S., Kammerer, W. A., Quezado, Z., Luckenbaugh, D. A., Salvadore, G., et al. (2010) · Archives of General Psychiatry · doi:10.1001/archgenpsychiatry.2010.90 · Cited by 963 · see citing works
Pilot study of the 5-HT <sub>2A</sub> R agonist psilocybin in the treatment of tobacco addiction
Johnson, M. W., Garcia-Romeu, A., Cosimano, M. P., & Griffiths, R. R. (2014) · Journal of Psychopharmacology · doi:10.1177/0269881114548296 · Cited by 914 · see citing works
Popova, V., Daly, E. J., Trivedi, M., Cooper, K., Lane, R., Lim, P., Mazzucco, C., Hough, D., Thase, M. E., Shelton, R. C., et al. (2019) · American Journal of Psychiatry · doi:10.1176/appi.ajp.2019.19020172 · Cited by 904 · see citing works
The Importance of Placebo Effects in Pain Treatment and Research
Turner, J. A. (1994) · JAMA · doi:10.1001/jama.1994.03510440069036 · Cited by 877 · see citing works
Palhano-Fontes, F., Barreto, D., Onias, H., Andrade, K. C., Novaes, M. M., Pessoa, J. A., Mota-Rolim, S. A., Osório, F. L., Sanches, R., dos Santos, R. G., et al. (2019) · Psychological Medicine · doi:10.1017/s0033291718001356 · Cited by 852 · see citing works
Safety, tolerability, and efficacy of psilocybin in 9 patients with obsessive-compulsive disorder
Moreno, F. A., Wiegand, C. B., Taitano, E. K., & Delgado, P. L. (2006) · The Journal of Clinical Psychiatry · doi:10.4088/jcp.v67n1110 · Cited by 789 · see citing works
Gasser, P., Holstein, D., Michel, Y., Doblin, R., Yazar-Klosinski, B., Passie, T., & Brenneisen, R. (2014) · Journal of Nervous & Mental Disease · doi:10.1097/nmd.0000000000000113 · Cited by 750 · see citing works
The neurobiology of psychedelic drugs: implications for the treatment of mood disorders
Vollenweider, F. X., & Kometer, M. (2010) · Nature Reviews Neuroscience · doi:10.1038/nrn2884 · Cited by 723 · see citing works
Daly, E. J., Singh, J. B., Fedgchin, M., Cooper, K., Lim, P., Shelton, R. C., Thase, M. E., Winokur, A., Van Nueten, L., Manji, H., et al. (2018) · JAMA Psychiatry · doi:10.1001/jamapsychiatry.2017.3739 · Cited by 718 · see citing works
Assessment of blinding in clinical trials
Bang, H., Ni, L., & Davis, C. E. (2004) · Controlled Clinical Trials · doi:10.1016/j.cct.2003.10.016 · Cited by 682 · see citing works
Savović, J., Jones, H., Altman, D., Harris, R., Jűni, P., Pildal, J., Als-Nielsen, B., Balk, E., Gluud, C., Gluud, L., et al. (2012) · Health Technology Assessment · doi:10.3310/hta16350 · Cited by 668 · see citing works
Psychedelics and the essential importance of context
Carhart-Harris, R. L., Roseman, L., Haijen, E., Erritzoe, D., Watts, R., Branchi, I., & Kaelen, M. (2018) · Journal of Psychopharmacology · doi:10.1177/0269881118754710 · Cited by 657 · see citing works
Fedgchin, M., Trivedi, M., Daly, E. J., Melkote, R., Lane, R., Lim, P., Vitagliano, D., Blier, P., Fava, M., Liebowitz, M., et al. (2019) · International Journal of Neuropsychopharmacology · doi:10.1093/ijnp/pyz039 · Cited by 606 · see citing works
The double-blind, randomized, placebo-controlled trial
Kaptchuk, T. J. (2001) · Journal of Clinical Epidemiology · doi:10.1016/s0895-4356(00)00347-4 · Cited by 595 · see citing works
When are randomised trials unnecessary? Picking signal from noise
Glasziou, P., Chalmers, I., Rawlins, M. D., & McCulloch, P. G. (2007) · BMJ · doi:10.1136/bmj.39070.527986.68 · Cited by 585 · see citing works
Lysergic acid diethylamide (LSD) for alcoholism: meta-analysis of randomized controlled trials
Krebs, T. S., & Johansen, P.-Ø. (2012) · Journal of Psychopharmacology · doi:10.1177/0269881112439253 · Cited by 583 · see citing works
Evidence-based policy: a practical guide to doing it better
Cartwright, N. D., & Hardie, J. M. (2013) · Choice Reviews Online · doi:10.5860/choice.50-5831 · Cited by 535 · see citing works
Singh, J. B., Fedgchin, M., Daly, E. J., De Boer, P., Cooper, K., Lim, P., Pinter, C., Murrough, J. W., Sanacora, G., Shelton, R. C., et al. (2016) · American Journal of Psychiatry · doi:10.1176/appi.ajp.2016.16010037 · Cited by 525 · see citing works
Attenuation of Antidepressant Effects of Ketamine by Opioid Receptor Antagonism
Williams, N. R., Heifets, B. D., Blasey, C., Sudheimer, K., Pannu, J., Pankow, H., Hawkins, J., Birnbaum, J., Lyons, D. M., Rodriguez, C. I., et al. (2018) · American Journal of Psychiatry · doi:10.1176/appi.ajp.2018.18020138 · Cited by 519 · see citing works
Osório, F. D. L., Sanches, R. F., Macedo, L. R., dos Santos, R. G., Maia-de-Oliveira, J. P., Wichert-Ana, L., de Araujo, D. B., Riba, J., Crippa, J. A., & Hallak, J. E. (2015) · Revista Brasileira de Psiquiatria · doi:10.1590/1516-4446-2014-1496 · Cited by 488 · see citing works
Hartogsohn, I. (2016) · Journal of Psychopharmacology · doi:10.1177/0269881116677852 · Cited by 483 · see citing works
A Randomized Controlled Trial of Intranasal Ketamine in Major Depressive Disorder
Lapidus, K. A. B., Levitch, C. F., Perez, A. M., Brallier, J. W., Parides, M. K., Soleimani, L., Feder, A., Iosifescu, D. V., Charney, D. S., & Murrough, J. W. (2014) · Biological Psychiatry · doi:10.1016/j.biopsych.2014.03.026 · Cited by 480 · see citing works
Confounding: What it is and how to deal with it
Jager, K. J., Zoccali, C., MacLeod, A. M., & Dekker, F. W. (2007) · Kidney International · doi:10.1038/sj.ki.5002650 · Cited by 480 · see citing works
Sanches, R. F., de Lima Osório, F., dos Santos, R. G., Macedo, L. R. H., Maia-de-Oliveira, J. P., Wichert-Ana, L., de Araujo, D. B., Riba, J., Crippa, J. A. S., & Hallak, J. E. C. (2016) · Journal of Clinical Psychopharmacology · doi:10.1097/jcp.0000000000000436 · Cited by 466 · see citing works
Hróbjartsson, A., Emanuelsson, F., Skou Thomsen, A. S., Hilden, J., & Brorson, S. (2014) · International Journal of Epidemiology · doi:10.1093/ije/dyu115 · Cited by 462 · see citing works
Fava, M., Evins, A. E., Dorer, D. J., & Schoenfeld, D. A. (2003) · Psychotherapy and Psychosomatics · doi:10.1159/000069738 · Cited by 452 · see citing works
The Philosophy of Evidence‐Based Medicine
Howick, J. (2011) · Wiley eBooks · doi:10.1002/9781444342673 · Cited by 434 · see citing works
Fava, M., Freeman, M. P., Flynn, M., Judge, H., Hoeppner, B. B., Cusin, C., Ionescu, D. F., Mathew, S. J., Chang, L. C., Iosifescu, D. V., et al. (2020) · Molecular Psychiatry · doi:10.1038/s41380-018-0256-5 · Cited by 433 · see citing works
Grunebaum, M. F., Galfalvy, H. C., Choo, T.-H., Keilp, J. G., Moitra, V. K., Parris, M. S., Marver, J. E., Burke, A. K., Milak, M. S., Sublette, M. E., et al. (2018) · American Journal of Psychiatry · doi:10.1176/appi.ajp.2017.17060647 · Cited by 431 · see citing works
Anand, A., Charney, D. S., Oren, D. A., Berman, R. M., Hu, X. S., Cappiello, A., & Krystal, J. H. (2000) · Archives of General Psychiatry · doi:10.1001/archpsyc.57.3.270 · Cited by 426 · see citing works
Phillips, J. L., Norris, S., Talbot, J., Birmingham, M., Hatchard, T., Ortiz, A., Owoeye, O., Batten, L. A., & Blier, P. (2019) · American Journal of Psychiatry · doi:10.1176/appi.ajp.2018.18070834 · Cited by 418 · see citing works
Ionescu, D. F., Fu, D.-J., Qiu, X., Lane, R., Lim, P., Kasper, S., Hough, D., Drevets, W. C., Manji, H., & Canuso, C. M. (2021) · International Journal of Neuropsychopharmacology · doi:10.1093/ijnp/pyaa068 · Cited by 418 · see citing works
Bahji, A., Vazquez, G. H., & Zarate, C. A. (2021) · Journal of Affective Disorders · doi:10.1016/j.jad.2020.09.071 · Cited by 408 · see citing works
Papakostas, G. I., & D, M. F. M. (2008) · European Neuropsychopharmacology · doi:10.1016/j.euroneuro.2008.08.009 · Cited by 381 · see citing works
Design and Analysis of Cross-Over Trials
Jones, B. C., & Kenward, M. G. (2014) · Chapman & Hall/CRC eBooks · doi:10.1201/b17537 · Cited by 369 · see citing works
Active placebos versus antidepressants for depression
Moncrieff, J., Wessely, S., & Hardy, R. (2004) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd003012.pub2 · Cited by 342 · see citing works
‘Powerful Placebo: The Dark Side of the Randomised Controlled Trial’
Kaptchuk, T. J. (1998) · The Lancet · doi:10.1016/s0140-6736(97)10111-8 · Cited by 339 · see citing works
Effects of Schedule I drug laws on neuroscience research and treatment innovation
Nutt, D., King, L. A., & Nichols, D. E. (2013) · Nature reviews. Neuroscience · doi:10.1038/nrn3530 · Cited by 338 · see citing works
Ayahuasca-Assisted Therapy for Addiction: Results from a Preliminary Observational Study in Canada
Thomas, G., Lucas, P., Capler, N., Tupper, K., & Martin, G. (2013) · Current Drug Abuse Reviews · doi:10.2174/15733998113099990003 · Cited by 330 · see citing works
Placebo Effects: From the Neurobiological Paradigm to Translational Implications
Benedetti, F. (2014) · Neuron · doi:10.1016/j.neuron.2014.10.023 · Cited by 316 · see citing works
Deakin, J. F. W., Lees, J., McKie, S., Hallak, J. E. C., Williams, S. R., & Dursun, S. M. (2008) · Archives of General Psychiatry · doi:10.1001/archgenpsychiatry.2007.37 · Cited by 311 · see citing works
Approximate Quasi-likelihood Estimation in Models With Surrogate Predictors
Carroll, R. J., & Stefanski, L. A. (1990) · Journal of the American Statistical Association · doi:10.1080/01621459.1990.10474925 · Cited by 299 · see citing works
Ketamine for rapid reduction of suicidal ideation: a randomized controlled trial
Murrough, J. W., Soleimani, L., DeWilde, K. E., Collins, K. A., Lapidus, K. A., Iacoviello, B. M., Lener, M., Kautz, M., Kim, J., Stern, J. B., et al. (2015) · Psychological Medicine · doi:10.1017/s0033291715001506 · Cited by 297 · see citing works
Design and Analysis of Clinical Trials: Concepts and Methodologies
Chow, S., & Liu, J. (2013) · Cited by 272 · see citing works
A Model of Placebo Response in Antidepressant Clinical Trials
Rutherford, B. R., & Roose, S. P. (2013) · American Journal of Psychiatry · doi:10.1176/appi.ajp.2012.12040474 · Cited by 268 · see citing works
Fergusson, D. (2004) · BMJ · doi:10.1136/bmj.37952.631667.ee · Cited by 264 · see citing works
Constantino, M. J., Vîslă, A., Coyne, A. E., & Boswell, J. F. (2018) · Psychotherapy · doi:10.1037/pst0000169 · Cited by 260 · see citing works
Loo, C. K. A., Gálvez, V., O’Keefe, E. J., Mitchell, P. B., Hadzi‐Pavlovic, D., Leyden, J., Harper, S., Somogyi, A. A., Lai, R., Weickert, C. S., et al. (2016) · Acta Psychiatrica Scandinavica · doi:10.1111/acps.12572 · Cited by 258 · see citing works
Ketamine has distinct electrophysiological and behavioral effects in depressed and healthy subjects
Nugent, A. C., Ballard, E. D., Gould, T. D., Park, L. T., Moaddel, R., Brutsche, N. E., & Zarate, C. A. (2019) · Molecular Psychiatry · doi:10.1038/s41380-018-0028-2 · Cited by 250 · see citing works
Ketamine Psychedelic Therapy (KPT): A Review of the Results of Ten Years of Research
Krupitsky, E. M., & Grinenko, A. Y. (1997) · Journal of Psychoactive Drugs · doi:10.1080/02791072.1997.10400185 · Cited by 246 · see citing works
Marley, E. (1962) · Psychopharmacology · doi:10.1007/bf00411372 · Cited by 221 · see citing works
Furukawa, T. A., Cipriani, A., Atkinson, L. Z., Leucht, S., Ogawa, Y., Takeshima, N., Hayasaka, Y., Chaimani, A., & Salanti, G. (2016) · The Lancet Psychiatry · doi:10.1016/s2215-0366(16)30307-8 · Cited by 219 · see citing works
Dore, J., Turnipseed, B., Dwyer, S., Turnipseed, A., Andries, J., Ascani, G., Monnette, C., Huidekoper, A., Strauss, N., & Wolfson, P. (2019) · Journal of Psychoactive Drugs · doi:10.1080/02791072.2019.1587556 · Cited by 217 · see citing works
Younger, J., Gandhi, V., Hubbard, E., & Mackey, S. (2012) · Clinical Trials · doi:10.1177/1740774512465064 · Cited by 212 · see citing works
Hróbjartsson, A., Forfang, E., Haahr, M. T., Als-Nielsen, B. E. T., & Brorson, S. (2007) · International Journal of Epidemiology · doi:10.1093/ije/dym020 · Cited by 206 · see citing works
The Emergence of the Randomized, Controlled Trial
Bothwell, L. E., & Podolsky, S. H. (2016) · New England Journal of Medicine · doi:10.1056/nejmp1604635 · Cited by 201 · see citing works
Rendleman, R. L., & Walkup, J. T. (2012) · Elsevier eBooks · doi:10.1016/b978-1-4377-0435-8.00049-4 · Cited by 197 · see citing works
Ionescu, D. F., Bentley, K. H., Eikermann, M., Taylor, N., Akeju, O., Swee, M. B., Pavone, K. J., Petrie, S. R., Dording, C., Mischoulon, D., et al. (2019) · Journal of Affective Disorders · doi:10.1016/j.jad.2018.09.037 · Cited by 179 · see citing works
Does Study Design Influence Outcome?
Rutherford, B. R., Sneed, J. R., & Roose, S. P. (2009) · Psychotherapy and Psychosomatics · doi:10.1159/000209348 · Cited by 160 · see citing works
Gukasyan, N., & Nayak, S. M. (2021) · Transcultural Psychiatry · doi:10.1177/1363461520983684 · Cited by 153 · see citing works
Li, C., Chen, M., Lin, W., Hong, C., Yang, B., Liu, R., Tu, P., & Su, T. (2016) · Human Brain Mapping · doi:10.1002/hbm.23085 · Cited by 152 · see citing works
Nüesch, E., Reichenbach, S., Trelle, S., Rutjes, A. W., Liewald, K., Sterchi, R., Altman, D. G., & Jüni, P. (2009) · Arthritis Care & Research · doi:10.1002/art.24894 · Cited by 150 · see citing works
Commentary: Measuring the success of blinding in RCTs: don't, must, can't or needn't?
Sackett, D. L. (2007) · International Journal of Epidemiology · doi:10.1093/ije/dym088 · Cited by 150 · see citing works
Do “placebo responders” exist?
Kaptchuk, T. J., Kelley, J. M., Deykin, A., Wayne, P. M., Lasagna, L. C., Epstein, I. O., Kirsch, I., & Wechsler, M. E. (2008) · Contemporary Clinical Trials · doi:10.1016/j.cct.2008.02.002 · Cited by 147 · see citing works
Hu, Y.-D., Xiang, Y.-T., Fang, J.-X., Zu, S., Sha, S., Shi, H., Ungvari, G. S., Correll, C. U., Chiu, H. F. K., Xue, Y., et al. (2016) · Psychological Medicine · doi:10.1017/s0033291715002159 · Cited by 146 · see citing works
Posternak, M., & Zimmerman, M. (2007) · British Journal of Psychiatry · doi:10.1192/bjp.bp.106.028555 · Cited by 146 · see citing works
Positive expectations predict improved mental-health outcomes linked to psychedelic microdosing
Kaertner, L. S., Steinborn, M. B., Kettner, H., Spriggs, M. J., Roseman, L., Buchborn, T., Balaet, M., Timmermann, C., Erritzoe, D., & Carhart-Harris, R. L. (2021) · Scientific Reports · doi:10.1038/s41598-021-81446-7 · Cited by 145 · see citing works
Patient Expectancy as a Mediator of Placebo Effects in Antidepressant Clinical Trials
Rutherford, B. R., Wall, M. M., Brown, P. J., Choo, T.-H., Wager, T. D., Peterson, B. S., Chung, S., Kirsch, I., & Roose, S. P. (2017) · American Journal of Psychiatry · doi:10.1176/appi.ajp.2016.16020225 · Cited by 140 · see citing works
Towards a proposal for assessment of blinding success in clinical trials: up-to-date review
Kolahi, J., Bang, H., & Park, J. (2009) · Community Dentistry and Oral Epidemiology · doi:10.1111/j.1600-0528.2009.00494.x · Cited by 137 · see citing works
Are drug and placebo effects in depression additive?
Kirsch, I. (2000) · Biological Psychiatry · doi:10.1016/s0006-3223(00)00832-5 · Cited by 137 · see citing works
Response Expectancy and the Placebo Effect
Kirsch, I. (2018) · International Review of Neurobiology · doi:10.1016/bs.irn.2018.01.003 · Cited by 134 · see citing works
Active placebos versus antidepressants for depression (Review)
Moncrieff, J., Wessely, S. C., & Hardy, R. (2004) · UCL Discovery (University College London) · Cited by 125 · see citing works
Comparing the actions of lanicemine and ketamine in depression: key role of the anterior cingulate
Downey, D., Dutta, A., McKie, S., Dawson, G. R., Dourish, C. T., Craig, K., Smith, M. A., McCarthy, D. J., Harmer, C. J., Goodwin, G. M., et al. (2016) · European Neuropsychopharmacology · doi:10.1016/j.euroneuro.2016.03.006 · Cited by 116 · see citing works
LSD Increases Primary Process Thinking via Serotonin 2A Receptor Activation
Krähenmann, R., Pokorný, D., Aicher, H., Preller, K. H., Pokorny, T., Bosch, O. G., Seifritz, E., & Vollenweider, F. X. (2017) · Frontiers in Pharmacology · doi:10.3389/fphar.2017.00814 · Cited by 110 · see citing works
Pilot dose–response trial of i.v. ketamine in treatment-resistant depression
Lai, R., Katalinic, N., Glue, P., Somogyi, A. A., Mitchell, P. B., Leyden, J., Harper, S., & Loo, C. K. A. (2014) · The World Journal of Biological Psychiatry · doi:10.3109/15622975.2014.922697 · Cited by 109 · see citing works
The nature and power of the placebo effect
Miller, F. G., & Rosenstein, D. L. (2006) · Journal of Clinical Epidemiology · doi:10.1016/j.jclinepi.2005.12.001 · Cited by 109 · see citing works
Jafarinia, M., Afarideh, M., Tafakhori, A., Arbabi, M., Ghajar, A., Noorbala, A. A., Saravi, M. A., Agah, E., & Akhondzadeh, S. (2016) · Journal of Affective Disorders · doi:10.1016/j.jad.2016.05.076 · Cited by 98 · see citing works
Mathai, D. S., Meyer, M. J., Storch, E. A., & Kosten, T. R. (2020) · Journal of Affective Disorders · doi:10.1016/j.jad.2019.12.023 · Cited by 97 · see citing works
Identifying Ketamine Responses in Treatment-Resistant Depression Using a Wearable Forehead EEG
Cao, Z., Lin, C., Ding, W., Chen, M., Li, C., & Su, T. (2018) · IEEE Transactions on Biomedical Engineering · doi:10.1109/tbme.2018.2877651 · Cited by 93 · see citing works
Arabzadeh, S., Hakkikazazi, E., Shahmansouri, N., Tafakhori, A., Ghajar, A., Jafarinia, M., & Akhondzadeh, S. (2018) · Journal of Affective Disorders · doi:10.1016/j.jad.2018.02.056 · Cited by 89 · see citing works
Turning a blind eye:Why we don't test for blindness at the end of our trials
Sackett, D. L. (2004) · BMJ · doi:10.1136/bmj.328.7448.1136-a · Cited by 88 · see citing works
Domany, Y., Shelton, R. C., & McCullumsmith, C. B. (2020) · Depression and Anxiety · doi:10.1002/da.22975 · Cited by 84 · see citing works
Wilkinson, S. T., Farmer, C., Ballard, E. D., Mathew, S. J., Grunebaum, M. F., Murrough, J. W., Šóš, P., Wang, G., Gueorguieva, R. V., & Zarate, C. A. (2019) · Neuropsychopharmacology · doi:10.1038/s41386-019-0317-8 · Cited by 78 · see citing works
The Double-Blind Variable Placebo Lead-in Period: Results From Two Antidepressant Clinical Trials
Faries, D. E., Heiligenstein, J. H., Tollefson, G. D., & Potter, W. Z. (2001) · Journal of Clinical Psychopharmacology · doi:10.1097/00004714-200112000-00004 · Cited by 76 · see citing works
Xu, Y. Y., Li, Y., Huang, X., Chen, D., She, B.-Z., & Ma, D. (2017) · Archives of Gynecology and Obstetrics · doi:10.1007/s00404-017-4334-8 · Cited by 74 · see citing works
Sumner, R. L., McMillan, R. L., Spriggs, M. J., Campbell, D. A., Malpas, G. A., Maxwell, E., Deng, C., Hay, J., Ponton, R., Kirk, I. J., et al. (2019) · Biological Psychiatry Cognitive Neuroscience and Neuroimaging · doi:10.1016/j.bpsc.2019.07.002 · Cited by 69 · see citing works
Self-citationBurger, J., Capobianco, M., Lovern, R., Boche, B., Ross, E. M., Darracq, M. A., & McLay, R. N. (2016) · Military Medicine · doi:10.7205/milmed-d-15-00431 · Cited by 68 · see citing works
Chen, M.-H., Li, C.-T., Lin, W.-C., Hong, C.-J., Tu, P.-C., Bai, Y.-M., Cheng, C.-M., & Su, T.-P. (2018) · Journal of Affective Disorders · doi:10.1016/j.jad.2017.09.008 · Cited by 63 · see citing works
Κube, T., & Rief, W. (2016) · Drug Discovery Today · doi:10.1016/j.drudis.2016.11.022 · Cited by 57 · see citing works
Ballou, S., Kaptchuk, T. J., Hirsch, W., Nee, J. W., Iturrino, J., Hall, K. T., Kelley, J. M., Cheng, V., Kirsch, I., Jacobson, E., et al. (2017) · Trials · doi:10.1186/s13063-017-1964-x · Cited by 56 · see citing works
Dahan, R., Caulin, C., Figea, L., Kanis, J. A., Caulin, F., & Segrestaa, J. M. (1986) · BMJ · doi:10.1136/bmj.293.6543.363 · Cited by 55 · see citing works
Double blind: Double talk or are there ways to do better research
Ney, P. G., Collins, C. M., & Spensor, C. (1986) · Medical Hypotheses · doi:10.1016/0306-9877(86)90001-0 · Cited by 52 · see citing works
London, A. J. (2017) · JAMA · doi:10.1001/jama.2017.0016 · Cited by 50 · see citing works
Zilcha-Mano, S., Roose, S. P., Brown, P. J., & Rutherford, B. R. (2019) · Frontiers in Behavioral Neuroscience · doi:10.3389/fnbeh.2018.00293 · Cited by 44 · see citing works
A randomized, prospective pilot study of patient expectancy and antidepressant outcome
Rutherford, B., Marcus, S., Wang, P., Sneed, J. R., Pelton, G. H., Devanand, D. P., Duan, N., & Roose, S. P. (2012) · Psychological Medicine · doi:10.1017/s0033291712001882 · Cited by 43 · see citing works
Meta-Analysis of Placebo Response in Adult Antidepressant Trials
Li, F., Nasir, M., Olten, B., & Bloch, M. H. (2019) · CNS Drugs · doi:10.1007/s40263-019-00662-y · Cited by 41 · see citing works
Rees, J. R., Wade, T. J., Levy, D. A., Colford, J. M., & Hilton, J. F. (2005) · Contemporary Clinical Trials · doi:10.1016/j.cct.2004.11.020 · Cited by 36 · see citing works
Clinic Visits in Late-Life Depression Trials: Effects on Signal Detection and Therapeutic Outcome
Rutherford, B. R., Tandler, J. M., Brown, P. J., Sneed, J. R., & Roose, S. P. (2013) · American Journal of Geriatric Psychiatry · doi:10.1016/j.jagp.2013.09.003 · Cited by 27 · see citing works
Peace, K. E., & Chen, D. (2010) · Chapman & Hall/CRC eBooks · doi:10.1201/ebk1584889175 · Cited by 26 · see citing works
Turning a blind eye: Authors have blinkered view of blinding
Senn, S. J. (2004) · BMJ · doi:10.1136/bmj.328.7448.1135-b · Cited by 24 · see citing works
Jamshidian, F., Hubbard, A., & Jewell, N. P. (2011) · Statistical Methods in Medical Research · doi:10.1177/0962280211413449 · Cited by 24 · see citing works
Blinding as a Solution to Bias
(2016) · Elsevier eBooks · doi:10.1016/c2014-0-01237-3 · Cited by 23 · see citing works
Science in flux: Registered reports and beyond at the <i>European Journal of Neuroscience</i>
Chambers, C. D., Forstmann, B., & Pruszynski, J. A. (2019) · European Journal of Neuroscience · doi:10.1111/ejn.14319 · Cited by 8 · see citing works
Flagged first, then by citations
Cited by
Sorted by citations
Aday, J. S., Heifets, B. D., Pratscher, S. D., Bradley, E., Rosen, R., & Woolley, J. D. (2022) · Psychopharmacology · doi:10.1007/s00213-022-06123-7 · Cited by 237 · see citing works
Breeksema, J. J., Kuin, B. W., Kamphuis, J., van den Brink, W., Vermetten, E., & Schoevers, R. A. (2022) · Journal of Psychopharmacology · doi:10.1177/02698811221116926 · Cited by 178 · see citing works
Ketamine for the treatment of major depression: a systematic review and meta-analysis
Nikolin, S., Rodgers, A., Schwaab, A., Bahji, A., Zarate, C. A., Vázquez, G. H., & Loo, C. K. A. (2023) · EClinicalMedicine · doi:10.1016/j.eclinm.2023.102127 · Cited by 173 · see citing works
Psychedelic-Assisted Psychotherapy—A Systematic Review of Associated Psychological Interventions
Cavarra, M., Falzone, A., Ramaekers, J. G., Kuypers, K. P. C., & Mento, C. (2022) · Frontiers in Psychology · doi:10.3389/fpsyg.2022.887255 · Cited by 171 · see citing works
Sloshower, J., Skosnik, P. D., Safi-Aghdam, H., Pathania, S., Syed, S., Pittman, B., & D’Souza, D. C. (2023) · Journal of Psychopharmacology · doi:10.1177/02698811231154852 · Cited by 165 · see citing works
Microdosing with psilocybin mushrooms: a double-blind placebo-controlled study
Cavanna, F., Muller, S. L., de la Fuente, L. A., Zamberlán, F., Palmucci, M., Janeckova, L., Kuchař, M., Pallavicini, C., & Tagliazucchi, E. (2022) · Translational Psychiatry · doi:10.1038/s41398-022-02039-0 · Cited by 148 · see citing works
History repeating: guidelines to address common problems in psychedelic science
van Elk, M., & Fried, E. I. (2023) · Therapeutic Advances in Psychopharmacology · doi:10.1177/20451253231198466 · Cited by 137 · see citing works
Therapeutic effect of psilocybin in addiction: A systematic review
van der Meer, P. B., Fuentes, J. J., Kaptein, A. A., Schoones, J. W., de Waal, M. M., Goudriaan, A. E., Kramers, K., Schellekens, A., Somers, M., Bossong, M. G., et al. (2023) · Frontiers in Psychiatry · doi:10.3389/fpsyt.2023.1134454 · Cited by 127 · see citing works
McCulloch, D. E.-W., Knudsen, G. M., Barrett, F. S., Doss, M. K., Carhart-Harris, R. L., Rosas, F. E., Deco, G., Kringelbach, M. L., Preller, K. H., Ramaekers, J. G., et al. (2022) · Neuroscience & Biobehavioral Reviews · doi:10.1016/j.neubiorev.2022.104689 · Cited by 108 · see citing works
McCulloch, D. E.-W., Grzywacz, M. Z., Madsen, M. K., Jensen, P. S., Ozenne, B., Armand, S., Knudsen, G. M., Fisher, P. M., & Stenbæk, D. S. (2022) · Frontiers in Pharmacology · doi:10.3389/fphar.2022.841648 · Cited by 100 · see citing works
Expectancy in placebo-controlled trials of psychedelics: if so, so what?
Butler, M., Jelen, L., & Rucker, J. (2022) · Psychopharmacology · doi:10.1007/s00213-022-06221-6 · Cited by 100 · see citing works
Randomized trial of ketamine masked by surgical anesthesia in patients with depression
Lii, T. R., Smith, A. E., Flohr, J. R., Okada, R. L., Nyongesa, C. A., Cianfichi, L. J., Hack, L. M., Schatzberg, A. F., & Heifets, B. D. (2023) · Nature Mental Health · doi:10.1038/s44220-023-00140-x · Cited by 118 · see citing works
Bender, D., & Hellerstein, D. J. (2022) · Psychopharmacology · doi:10.1007/s00213-021-06049-6 · Cited by 88 · see citing works
Assessing expectancy and suggestibility in a trial of escitalopram v. psilocybin for depression
Szigeti, B., Weiss, B., Rosas, F. E., Erritzoe, D., Nutt, D., & Carhart-Harris, R. (2024) · Psychological Medicine · doi:10.1017/s0033291723003653 · Cited by 89 · see citing works
Loo, C. K. A., Glozier, N., Barton, D., Baune, B. T., Mills, N. T., Fitzgerald, P. B., Glue, P., Sarma, S., Gálvez, V., Hadži-Pavlović, D., et al. (2023) · The British Journal of Psychiatry · doi:10.1192/bjp.2023.79 · Cited by 82 · see citing works
Psilocybin and MDMA for the treatment of trauma-related psychopathology
Bird, C., Modlin, N. L., & Rucker, J. (2021) · International Review of Psychiatry · doi:10.1080/09540261.2021.1919062 · Cited by 84 · see citing works
Levin, A. W., Lancelotta, R., Sepeda, N. D., Gukasyan, N., Nayak, S., Wagener, T. L., Barrett, F. S., Griffiths, R. R., & Davis, A. K. (2024) · PLoS ONE · doi:10.1371/journal.pone.0300501 · Cited by 82 · see citing works
Expectancy Effects in Psychedelic Trials
Szigeti, B., & Heifets, B. D. (2024) · Biological Psychiatry Cognitive Neuroscience and Neuroimaging · doi:10.1016/j.bpsc.2024.02.004 · Cited by 77 · see citing works
Therapeutic mechanisms of psychedelics and entactogens
Heifets, B. D., & Olson, D. E. (2023) · Neuropsychopharmacology · doi:10.1038/s41386-023-01666-5 · Cited by 67 · see citing works
Wang, S., Deng, C.-M., Zeng, Y., Chen, X., Li, A.-Y., Feng, S., Xu, L., Chen, L., Yuan, H., Hu, H., et al. (2024) · BMJ · doi:10.1136/bmj-2023-078218 · Cited by 69 · see citing works
Right-Wing Psychedelia: Case Studies in Cultural Plasticity and Political Pluripotency
Pace, B. A., & Devenot, N. (2021) · Frontiers in Psychology · doi:10.3389/fpsyg.2021.733185 · Cited by 67 · see citing works
Johnston, J. N., Kadriu, B., Allen, J., Gilbert, J. R., Henter, I. D., & Zarate, C. A. (2023) · Neuropharmacology · doi:10.1016/j.neuropharm.2023.109422 · Cited by 68 · see citing works
Transformative experience and informed consent to psychedelic-assisted psychotherapy
Jacobs, E. (2023) · Frontiers in Psychology · doi:10.3389/fpsyg.2023.1108333 · Cited by 68 · see citing works
Ketamine and psychotherapy for the treatment of psychiatric disorders: Systematic review
Kew, B. M., Porter, R. J., Douglas, K. M., Glue, P., Mentzel, C. L., & Beaglehole, B. (2023) · BJPsych Open · doi:10.1192/bjo.2023.53 · Cited by 69 · see citing works
Murphy, R. J., Sumner, R. L., Evans, W., Ponton, R., Ram, S., Godfrey, K., Forsyth, A., Cavadino, A., Naga, V. K., Smith, T., et al. (2023) · Biological Psychiatry · doi:10.1016/j.biopsych.2023.03.013 · Cited by 67 · see citing works
Self-citationEthical and Practical Considerations for the Use of Psychedelics in Psychiatry
Barber, G., & Dike, C. C. (2023) · Psychiatric Services · doi:10.1176/appi.ps.20220525 · Cited by 66 · see citing works
Rosenblat, J. D., Husain, M. I., Lee, Y. L., McIntyre, R. S., Mansur, R. B., Castle, D. J., Offman, H., Parikh, S. V., Frey, B. N., Schaffer, A., et al. (2022) · The Canadian Journal of Psychiatry · doi:10.1177/07067437221111371 · Cited by 68 · see citing works
Leal, G. C., Souza-Marques, B., Mello, R. P., Bandeira, I. D., Caliman-Fontes, A. T., Carneiro, B. A., Faria-Guimarães, D., Guerreiro-Costa, L. N. F., Jesus-Nunes, A. P., Silva, S. S., et al. (2023) · Journal of Affective Disorders · doi:10.1016/j.jad.2023.02.151 · Cited by 62 · see citing works
Zeifman, R. J., Wagner, A. C., Monson, C. M., & Carhart-Harris, R. L. (2023) · Journal of Affective Disorders · doi:10.1016/j.jad.2023.04.105 · Cited by 65 · see citing works
Maia, L. O., Beaussant, Y., & Garcia, A. C. M. (2022) · Journal of Pain and Symptom Management · doi:10.1016/j.jpainsymman.2022.01.024 · Cited by 61 · see citing works
Sloshower, J., Zeifman, R. J., Guss, J., Krause, R., Safi-Aghdam, H., Pathania, S., Pittman, B., & D’Souza, D. C. (2024) · Scientific Reports · doi:10.1038/s41598-024-58318-x · Cited by 65 · see citing works
“Finally, findings from the present study should be interpreted in light of difficulties with blinding and the likely contribution of expectancy effects (for in depth discussion, see 11,71 ).”
BackgroundNoorani, T. N., Bedi, G., & Muthukumaraswamy, S. D. (2023) · Psychological Medicine · doi:10.1017/s0033291723001289 · Cited by 60 · see citing works
Self-citationHuneke, N. T. M., Veronesi, G. F., Garner, M. J., Baldwin, D. S., & Cortese, S. (2025) · JAMA Psychiatry · doi:10.1001/jamapsychiatry.2025.0085 · Cited by 61 · see citing works
The challenges ahead for psychedelic ‘medicine’
Muthukumaraswamy, S. D., Forsyth, A., & Sumner, R. L. (2022) · Australian & New Zealand Journal of Psychiatry · doi:10.1177/00048674221081763 · Cited by 59 · see citing works
Self-citationKopra, E. I., Ferris, J., WINSTOCK, A. R., Kuypers, K. P. C., Young, A. H., & Rucker, J. (2023) · Journal of Psychopharmacology · doi:10.1177/02698811231158245 · Cited by 61 · see citing works
Mendes, F. R., Costa, C. D. S., Wiltenburg, V. D., Morales-Lima, G., Fernandes, J. A. B., & Filev, R. (2022) · Addiction Neuroscience · doi:10.1016/j.addicn.2022.100025 · Cited by 59 · see citing works
Rootman, J. M., Kiraga, M. K., Kryskow, P., Harvey, K., Stamets, P. E., Santos-Brault, E., Kuypers, K. P. C., & Walsh, Z. (2022) · Scientific Reports · doi:10.1038/s41598-022-14512-3 · Cited by 57 · see citing works
Risk of bias in randomized clinical trials on psychedelic medicine: A systematic review
Hovmand, O. R., Poulsen, E. D., Arnfred, S., & Storebø, O. J. (2023) · Journal of Psychopharmacology · doi:10.1177/02698811231180276 · Cited by 57 · see citing works
Holze, F., Singh, N., Liechti, M., & D'Souza, D. (2024) · Biological Psychiatry: Cognitive Neuroscience and Neuroimaging · doi:10.1016/j.bpsc.2024.01.007 · Cited by 44 · see citing works
Agin-Liebes, G., Zeifman, R., Luoma, J. B., Garland, E. L., Campbell, W. K., & Weiss, B. (2022) · Journal of Psychopharmacology · doi:10.1177/02698811221080165 · Cited by 54 · see citing works
“The contribution of expectancy and placebo effects may not undermine efficacy as some critics suggest (Muthukumaraswamy et al., 2021), as these effects may work synergistically with genuine psychedelic-induced therapeutic mechanisms to potentiate greater change.”
BackgroundMethodLin, Y.-H., Sahker, E., Shinohara, K., Horinouchi, N., Ito, M., Lelliott, M., Cipriani, A., Tomlinson, A., Baethge, C., & Furukawa, T. A. (2022) · EClinicalMedicine · doi:10.1016/j.eclinm.2022.101505 · Cited by 51 · see citing works
Devenot, N., Conner, T., & Doyle, R. (2022) · Anthropology of Consciousness · doi:10.1111/anoc.12154 · Cited by 52 · see citing works
Psychedelic therapies reconsidered: compounds, clinical indications, and cautious optimism
Mitchell, J., & Anderson, B. T. (2023) · Neuropsychopharmacology · doi:10.1038/s41386-023-01656-7 · Cited by 49 · see citing works
An international Delphi consensus for reporting of setting in psychedelic clinical trials
Pronovost-Morgan, C., Greenway, K. T., Roseman, L., Experts, T. R., Aday, J. S., Agin-Liebes, G., Ahmad, K., Aicher, H., Aixalà, M., Amar, S., et al. (2025) · Nature Medicine · doi:10.1038/s41591-025-03685-9 · Cited by 48 · see citing works
Ort, A., Smallridge, J. W., Sarasso, S., Casarotto, S., von Rotz, R., Casanova, A., Seifritz, E., Preller, K. H., Tononi, G., & Vollenweider, F. X. (2023) · iScience · doi:10.1016/j.isci.2023.106589 · Cited by 47 · see citing works
Wells, A., Fernandes, M. T. C. F., & Reynolds, L. (2024) · Journal of Psychedelic Studies · doi:10.1556/2054.2023.00294 · Cited by 44 · see citing works
The need for establishing best practices and gold standards in psychedelic medicine
Feduccia, A. A., Agin-Liebes, G., Price, C. M., Grinsell, N., Paradise, S., & Rabin, D. M. (2023) · Journal of Affective Disorders · doi:10.1016/j.jad.2023.03.083 · Cited by 43 · see citing works
Single Treatment With MM120 (Lysergide) in Generalized Anxiety Disorder
Robison, R. J., Barrow, R., Conant, C., Foster, E., Freedman, J. M., Jacobsen, P. L., Jemison, J., Karas, S. M., Karlin, D. R., Solomon, T. M., et al. (2025) · JAMA · doi:10.1001/jama.2025.13481 · Cited by 44 · see citing works
Schipper, S., Nigam, K. B., Schmid, Y., Piechotta, V., Ljuslin, M., Beaussant, Y., Schwarzer, G., & Boehlke, C. S. (2024) · Cochrane Database of Systematic Reviews · doi:10.1002/14651858.cd015383.pub2 · Cited by 44 · see citing works
Mertens, L. J., Koslowski, M., Betzler, F., Evens, R., Gilles, M., Jungaberle, A., Jungaberle, H., Majić, T., Ströhle, A., Wolff, M., et al. (2022) · Neuroscience Applied · doi:10.1016/j.nsa.2022.100104 · Cited by 41 · see citing works
Psychotherapy with Psilocybin for Depression: Systematic Review
Dawood-Hristova, J. J., & Pérez‐Jover, V. (2023) · Behavioral Sciences · doi:10.3390/bs13040297 · Cited by 41 · see citing works
Personality change in a trial of psilocybin therapy v. escitalopram treatment for depression
Weiss, B., Ginige, I., Shannon, L., Giribaldi, B., Murphy-Beiner, A., Murphy, R., Baker-Jones, M., Martell, J., Nutt, D. J., Carhart-Harris, R. L., et al. (2023) · Psychological Medicine · doi:10.1017/s0033291723001514 · Cited by 43 · see citing works
Schenberg, E. E. (2021) · Expert Review of Clinical Pharmacology · doi:10.1080/17512433.2021.1951473 · Cited by 41 · see citing works
Villiger, D., & Trachsel, M. (2023) · Journal of Medical Ethics · doi:10.1136/jme-2022-108816 · Cited by 41 · see citing works
Side-effects of mdma-assisted psychotherapy: a systematic review and meta-analysis
Colcott, J., Guerin, A. A., Carter, O. L., Meikle, S. E., & Bedi, G. (2024) · Neuropsychopharmacology · doi:10.1038/s41386-024-01865-8 · Cited by 40 · see citing works
Kisely, S. R., Connor, M. A., Somogyi, A. A., & Siskind, D. J. (2022) · Australian & New Zealand Journal of Psychiatry · doi:10.1177/00048674221083868 · Cited by 38 · see citing works
Szigeti, B., Nutt, D., Carhart-Harris, R. L., & Erritzøe, D. (2023) · Scientific Reports · doi:10.1038/s41598-023-34938-7 · Cited by 38 · see citing works
Psychedelics for acquired brain injury: a review of molecular mechanisms and therapeutic potential
Allen, J., Dames, S., Foldi, C. J., & Shultz, S. R. (2024) · Molecular Psychiatry · doi:10.1038/s41380-023-02360-0 · Cited by 38 · see citing works
Gaddis, A., Lidstone, D. E., Nebel, M. B., Griffiths, R. R., Mostofsky, S. H., Mejia, A. F., & Barrett, F. S. (2022) · NeuroImage · doi:10.1016/j.neuroimage.2022.119434 · Cited by 37 · see citing works
Garel, N., Drury, J., Lévesque, J. T., Goyette, N., Lehmann, A., Looper, K. J., Erritzøe, D., Dames, S., Turecki, G., Rej, S., et al. (2023) · Frontiers in Psychiatry · doi:10.3389/fpsyt.2023.1268832 · Cited by 36 · see citing works
Psychedelics for treatment resistant depression: are they game changers?
Kalfas, M., Taylor, R. H., Tsapekos, D., & Young, A. H. (2023) · Expert Opinion on Pharmacotherapy · doi:10.1080/14656566.2023.2281582 · Cited by 37 · see citing works
Aicher, H. D., Mueller, M. J., Dornbierer, D. A., Suay, D., Elsner, C., Wicki, I., Meling, D., Caflisch, L., Hempe, A., Steinhart, C., et al. (2024) · Frontiers in Psychiatry · doi:10.3389/fpsyt.2023.1302559 · Cited by 33 · see citing works
Psilocybin’s effects on cognition and creativity: A scoping review
Bonnieux, J. N., VanderZwaag, B., Premji, Z., Garcia‐Romeu, A., & García-Barrera, M. A. (2023) · Journal of Psychopharmacology · doi:10.1177/02698811231179801 · Cited by 35 · see citing works
Manifest your desires: Psychedelics and the self-help industry.
Plesa, P., & Petranker, R. (2022) · The International journal on drug policy · doi:10.1016/j.drugpo.2022.103704 · Cited by 28 · see citing works
Søndergaard, A., Madsen, M. K., Ozenne, B., Armand, S., Knudsen, G. M., Fisher, P. M., & Stenbæk, D. S. (2022) · Frontiers in Psychology · doi:10.3389/fpsyg.2022.948729 · Cited by 34 · see citing works
Beyond the psychedelic hype: Exploring the persistence of the neoliberal paradigm
Davies, J., Pace, B. A., & Devenot, N. (2023) · Journal of Psychedelic Studies · doi:10.1556/2054.2023.00273 · Cited by 33 · see citing works
Copa, D., Erritzøe, D., Giribaldi, B., Nutt, D. J., Carhart-Harris, R. L., & Tagliazucchi, E. (2024) · Journal of Affective Disorders · doi:10.1016/j.jad.2024.02.089 · Cited by 34 · see citing works
Breathwork-induced psychedelic experiences modulate neural dynamics
Lewis-Healey, E., Tagliazucchi, E., Canales‐Johnson, A., & Bekinschtein, T. A. (2024) · Cerebral Cortex · doi:10.1093/cercor/bhae347 · Cited by 33 · see citing works
Validation of a new instrument for assessing attitudes on psychedelics in the general population
Žuljević, M. F., Buljan, I., Leskur, M., Kaliterna, M., Hren, D., & Duplančić, D. (2022) · Scientific Reports · doi:10.1038/s41598-022-23056-5 · Cited by 33 · see citing works
Harnessing placebo: Lessons from psychedelic science
Pronovost-Morgan, C., Hartogsohn, I., & Ramaekers, J. G. (2023) · Journal of Psychopharmacology · doi:10.1177/02698811231182602 · Cited by 36 · see citing works
Psychedelic Therapy as Form of Life
Langlitz, N., & Gearin, A. K. (2024) · Neuroethics · doi:10.1007/s12152-024-09550-9 · Cited by 31 · see citing works
Erritzøe, D., Barba, T., Spriggs, M. J., Rosas, F. E., Nutt, D., & Carhart-Harris, R. L. (2024) · Journal of Psychopharmacology · doi:10.1177/02698811241237870 · Cited by 33 · see citing works
Mind the Psychedelic Hype: Characterizing the Risks and Benefits of Psychedelics for Depression
Meling, D., Ehrenkranz, R. C., Nayak, S. M., Aicher, H., Funk, X., van Elk, M., Graziosi, M., Bauer, P. R., Scheidegger, M., & Yaden, D. B. (2024) · Psychoactives · doi:10.3390/psychoactives3020014 · Cited by 34 · see citing works
New Frontiers or a Bursting Bubble? Psychedelic Therapy Beyond the Dichotomy
Noorani, T. N., & Martell, J. (2021) · Frontiers in Psychiatry · doi:10.3389/fpsyt.2021.727050 · Cited by 31 · see citing works
Coppola, M., Bevione, F., & Mondola, R. (2021) · Journal of Xenobiotics · doi:10.3390/jox12010004 · Cited by 25 · see citing works
Garel, N., McAnulty, C., Greenway, K. T., Lespérance, P., Miron, J., Rej, S., Richard‐Devantoy, S., & Jutras‐Aswad, D. (2022) · Drug and Alcohol Dependence · doi:10.1016/j.drugalcdep.2022.109606 · Cited by 32 · see citing works
Psychedelic-Assisted Therapy for People with Eating Disorders
Gukasyan, N., Schreyer, C. C., Griffiths, R. R., & Guarda, Á. S. (2022) · Current Psychiatry Reports · doi:10.1007/s11920-022-01394-5 · Cited by 31 · see citing works
Müller, F., Zaczek, H., Becker, A., Ley, L., Borgwardt, S., de Jesus, J. S., Loh, N., Kohut, J., Auernig, M., Boehlke, C. S., et al. (2025) · Med · doi:10.1016/j.medj.2025.100725 · Cited by 30 · see citing works
The therapeutic potential of psychedelics: the European regulatory perspective
Butlen‐Ducuing, F., McCulloch, D. E.-W., Haberkamp, M., Mattila, T. K., Bałkowiec-Iskra, E., Aislaitner, G., Balabanov, P., Lundberg, J., Stenbæk, D. S., Elferink, A. J. A., et al. (2023) · The Lancet · doi:10.1016/s0140-6736(23)00264-7 · Cited by 29 · see citing works
History repeating: A roadmap to address common problems in psychedelic sciencePreprint
van Elk, M., & Fried, E. I. (2023) · doi:10.31234/osf.io/ak6gx · Cited by 30 · see citing works
Smith-Apeldoorn, S. Y., Veraart, J. K. E., Kamphuis, J., Spijker, J., van der Meij, A., van Asselt, A. D. I., Rot, M. A. H., & Schoevers, R. A. (2024) · Molecular Psychiatry · doi:10.1038/s41380-024-02478-9 · Cited by 29 · see citing works
Singleton, S. P., Timmermann, C., Luppi, A. I., Eckernäs, E., Roseman, L., Carhart-Harris, R. L., & Kuceyeski, A. F. (2025) · Communications Biology · doi:10.1038/s42003-025-08078-9 · Cited by 29 · see citing works
Cuijpers, P. J., Harrer, M., & Furukawa, T. A. (2026) · World Psychiatry · doi:10.1002/wps.70002 · Cited by 31 · see citing works
Efficacy and Safety of Psilocybin in Treatment-Resistant Major Depression
Mertens, L. J., Koslowski, M., Betzler, F., Brand, M., Evens, R., Kärtner, L., Jungaberle, A., Jungaberle, H., Majić, T., Schmitz, C. N., et al. (2026) · JAMA Psychiatry · doi:10.1001/jamapsychiatry.2026.0132 · Cited by 28 · see citing works
Kaup, K., Vasser, M., Tulver, K., Munk, M., Pikamäe, J., & Aru, J. (2023) · Frontiers in Psychiatry · doi:10.3389/fpsyt.2023.1088896 · Cited by 26 · see citing works
Bahji, A., Lunsky, I. O., Gutiérrez, G., & Vázquez, G. H. (2023) · Journal of Psychoactive Drugs · doi:10.1080/02791072.2023.2278586 · Cited by 26 · see citing works
Hsu, T., Tsai, C., Kao, Y., Thompson, T., Carvalho, A. F., Yang, F., Tseng, P., Hsu, C.-W., Yu, C., Tu, Y., et al. (2024) · BMJ · doi:10.1136/bmj-2023-078607 · Cited by 25 · see citing works
Addressing blinding in classic psychedelic studies with innovative active placebos
Aday, J. S., Simonsson, O., Schindler, E. A. D., & D’Souza, D. C. (2025) · The International Journal of Neuropsychopharmacology · doi:10.1093/ijnp/pyaf023 · Cited by 26 · see citing works
Randomized Trial of Ketamine Masked by Surgical Anesthesia in Depressed PatientsPreprint
Lii, T. R., Smith, A. E., Flohr, J. R., Okada, R. L., Nyongesa, C. A., Cianfichi, L. J., Hack, L. M., Schatzberg, A. F., & Heifets, B. D. (2023) · medRxiv · doi:10.1101/2023.04.28.23289210 · Cited by 26 · see citing works
Wall, M. B., Demetriou, L., Giribaldi, B., Roseman, L., Ertl, N., Erritzøe, D., Nutt, D. J., & Carhart-Harris, R. L. (2025) · American Journal of Psychiatry · doi:10.1176/appi.ajp.20230751 · Cited by 26 · see citing works
O’Donnell, K. C., Alpert, M., Okano, L., Nicholas, C. R. N., Thomas, C., Poulter, B., Mithoefer, A. T., Mithoefer, M. C., & Marcela Ot’alora, G. (2024) · Frontiers in Psychology · doi:10.3389/fpsyg.2024.1427531 · Cited by 25 · see citing works
Co-design of Guidance for Patient and Public Involvement in Psychedelic Research
Close, J. B., Bornemann, J., Piggin, M., Jayacodi, S., Luan, L., Carhart-Harris, R. L., & Spriggs, M. J. (2021) · Frontiers in Psychiatry · doi:10.3389/fpsyt.2021.727496 · Cited by 23 · see citing works
Averill, L. A., & Abdallah, C. G. (2022) · Expert Opinion on Investigational Drugs · doi:10.1080/13543784.2022.2035358 · Cited by 23 · see citing works
Ahmadi, M., khansary, S., Parsapour, H., Alizamir, A., & Pirdehghan, A. (2022) · Biological Trace Element Research · doi:10.1007/s12011-022-03175-w · Cited by 23 · see citing works
Shafiee, A., Bahri, R. A., Rafiei, M. A., Abianeh, F. E., Razmara, P., Jafarabady, K., & Amini, M. J. (2024) · Journal of Psychopharmacology · doi:10.1177/02698811241234247 · Cited by 23 · see citing works
RetractedSoliman, P., Curley, D. E., Capone, C., Eaton, E. M., & Haass‐Koffler, C. L. (2024) · Psychopharmacology · doi:10.1007/s00213-024-06598-6 · Cited by 24 · see citing works
Tolle, H. M., Farah, J. C., Mallaroni, P., Mason, N. L., Ramaekers, J. G., & Amico, E. (2023) · Network Neuroscience · doi:10.1162/netn_a_00349 · Cited by 22 · see citing works
Beaglehole, B., Glue, P., Neehoff, S., Shadli, S. M., McNaughton, N., Kimber, B., Muirhead, C., de Bie, A., Day-Brown, R., & Medlicott, N. J. (2025) · Journal of Psychopharmacology · doi:10.1177/02698811251344710 · Cited by 22 · see citing works
Williams, Z. J., Barnett, H., & Szigeti, B. (2026) · JAMA Psychiatry · doi:10.1001/jamapsychiatry.2025.4809 · Cited by 22 · see citing works
Dworkin, R. H., Anderson, B. T., Andrews, N., Edwards, R. R., Grob, C. S., Ross, S., Satterthwaite, T. D., & Strain, E. C. (2022) · Journal of Pain · doi:10.1016/j.jpain.2022.05.003 · Cited by 22 · see citing works
- Authors
- Muthukumaraswamy, S. D., Forsyth, A., & Lumley, T.
- Affiliations
- University of Auckland (NZ)
- Corresponding author
- Muthukumaraswamy, Suresh D.
- Venue
- Expert Review of Clinical Pharmacology
- Publisher
- Informa UK Limited
- Published
- 2021-08-26
- Volume
- 14
- Issue
- 9
- Pages
- 1133-1152
- ISSN
- 1751-2433 (ISSN-L)
- 1751-2441
- OpenAlex
- W3164618783
- Cited by
- 324
- References
- 128
- Citations by year
- 2026: 57 · 2025: 75 · 2024: 81 · 2023: 61 · 2022: 42 · 2021: 8
- FWCI
- 6.38
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Expert Review of Clinical Pharmacology (publishedVersion)
- PubMed (publishedVersion)
- Funders
- Health Research Council of New Zealand
- Topics
- Social Sciences › Psychology › Clinical Psychology › Psychedelics and Drug Studies
- Life Sciences › Neuroscience › Cognitive Neuroscience › Pain Management and Placebo Effect
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Keywords
- psychedelics, blinding, response expectancy, confounding, psilocybin, LSD, ketamine, effect size overestimation, trial design, mental illness
- MeSH terms
- Mental Disorders, Hallucinogens, Humans, Ketamine, Lysergic Acid Diethylamide, Psilocybin, Research Design, Confounding Factors, Epidemiologic, Randomized Controlled Trials as Topic
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
