{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T07:06:51Z","timestamp":1784272011463,"version":"3.55.0"},"reference-count":52,"publisher":"Royal College of Psychiatrists","issue":"1","license":[{"start":{"date-parts":[[2026,2,18]],"date-time":"2026-02-18T00:00:00Z","timestamp":1771372800000},"content-version":"unspecified","delay-in-days":48,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Eur. Psychiatr."],"published-print":{"date-parts":[[2026]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec id=\"S0924933826101680_sec1\">\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Psychedelic-assisted psychotherapy has shown potential for psychiatric disorders. However, the magnitude of symptom change in control groups remains poorly understood. We aim to evaluate within-group effects in control groups and compare them to treatment groups in psychedelic trials.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"S0924933826101680_sec2\" sec-type=\"methods\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>A systematic search was conducted up to 1 July 2025. The study protocol was preregistered in PROSPERO (CRD420251111853).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"S0924933826101680_sec3\" sec-type=\"results\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Fourteen randomized controlled trials (n\u00a0=\u00a0643) were included. Direct between-arm meta-analyses showed greater symptom reductions in treatment compared with control across outcomes, including depressive symptoms (number of study arms [k]\u00a0=\u00a013; SMD\u00a0=\u00a0\u22120.82; 95% CI\u00a0=\u00a0\u22121.17, \u22120.47; I\n                      <jats:sup>2<\/jats:sup>\n                      \u00a0=\u00a060.1%), posttraumatic stress disorder (PTSD) symptoms (k\u00a0=\u00a010; SMD\u00a0=\u00a0\u22120.89; 95% CI\u00a0=\u00a0\u22121.14, \u22120.65; I\n                      <jats:sup>2<\/jats:sup>\n                      \u00a0=\u00a00%), and anxiety symptoms (k\u00a0=\u00a05; SMD\u00a0=\u00a0\u22120.66; 95% CI\u00a0=\u00a0\u22120.94, \u22120.38; I\n                      <jats:sup>2<\/jats:sup>\n                      \u00a0=\u00a00%). Subgroup analyses showed limited evidence that effects differed by placebo type for depressive or PTSD symptoms. Descriptive within-group analyses indicated symptom reductions from baseline in both control and treatment groups, with larger within-group improvements observed in treatment groups across outcomes; notably, larger within-group reductions in PTSD symptoms were observed in inactive placebo groups. Sensitivity analyses showed consistent results.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"S0924933826101680_sec4\" sec-type=\"conclusions\">\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Control groups in psychedelic trials demonstrated substantial symptom improvement, which may reflect non-specific trial factors (including expectancy and concurrent psychotherapy). These findings emphasize the importance of robust control conditions in psychedelic research and the need for nuanced interpretation of treatment effects.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1192\/j.eurpsy.2026.10168","type":"journal-article","created":{"date-parts":[[2026,2,18]],"date-time":"2026-02-18T10:46:22Z","timestamp":1771411582000},"source":"Crossref","is-referenced-by-count":0,"title":["Magnitude of response in treatment and control groups within psychedelic trials for psychiatric disorders: A meta-analysis"],"prefix":"10.1192","volume":"69","author":[{"given":"Shakila","family":"Meshkat","sequence":"first","affiliation":[{"name":"Unity Health Toronto"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiaowei","family":"Lin","sequence":"additional","affiliation":[{"name":"Unity Health Toronto"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rachel","family":"Sousa-Ho","sequence":"additional","affiliation":[{"name":"Unity Health Toronto"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7876-4981","authenticated-orcid":false,"given":"Ilya","family":"Demchenko","sequence":"additional","affiliation":[{"name":"Unity Health Toronto"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Richard J.","family":"Zeifman","sequence":"additional","affiliation":[{"name":"NYU Grossman School of Medicine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Howell","family":"Fang","sequence":"additional","affiliation":[{"name":"Unity Health Toronto"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0637-0411","authenticated-orcid":false,"given":"Amy C.","family":"Reichelt","sequence":"additional","affiliation":[{"name":"The University of Adelaide"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2421-157X","authenticated-orcid":false,"given":"Yanbo","family":"Zhang","sequence":"additional","affiliation":[{"name":"University of Alberta"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9591-4355","authenticated-orcid":false,"given":"Lisa","family":"Burback","sequence":"additional","affiliation":[{"name":"University of Alberta"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Olga","family":"Winkler","sequence":"additional","affiliation":[{"name":"University of Alberta"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew","family":"Greenshaw","sequence":"additional","affiliation":[{"name":"University of Alberta"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Candice M.","family":"Monson","sequence":"additional","affiliation":[{"name":"Toronto Metropolitan University"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eric","family":"Vermetten","sequence":"additional","affiliation":[{"name":"Leiden University"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rakesh","family":"Jetly","sequence":"additional","affiliation":[{"name":"University of Ottawa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wendy","family":"Lou","sequence":"additional","affiliation":[{"name":"University of Toronto"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Muhammad Ishrat","family":"Husain","sequence":"additional","affiliation":[{"name":"University of Toronto"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matthew J.","family":"Burke","sequence":"additional","affiliation":[{"name":"University of Toronto"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Venkat","family":"Bhat","sequence":"additional","affiliation":[{"name":"University of Toronto"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"170","published-online":{"date-parts":[[2026,2,18]]},"reference":[{"key":"S0924933826101680_r16","doi-asserted-by":"publisher","DOI":"10.1016\/j.jpsychires.2023.03.031"},{"key":"S0924933826101680_r13","doi-asserted-by":"publisher","DOI":"10.1007\/s00213-020-05719-1"},{"key":"S0924933826101680_r32","unstructured":"[32] Higgins, JPT , Thomas, J , Chandler, J , Cumpston, M , Li, T , Page, MJ , et al. 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