{"id":4556,"date":"2014-12-27T06:30:21","date_gmt":"2014-12-27T05:30:21","guid":{"rendered":"http:\/\/emilkirkegaard.dk\/en\/?p=4556"},"modified":"2015-09-29T02:16:55","modified_gmt":"2015-09-29T01:16:55","slug":"reanalysis-of-josefsson-et-al-2014s-meta-analysis-of-exercise-as-treatment-for-depression","status":"publish","type":"post","link":"https:\/\/emilkirkegaard.dk\/en\/2014\/12\/reanalysis-of-josefsson-et-al-2014s-meta-analysis-of-exercise-as-treatment-for-depression\/","title":{"rendered":"Reanalysis of Josefsson et al (2014)&#8217;s meta-analysis of exercise as treatment for depression"},"content":{"rendered":"<p><a href=\"http:\/\/www.reddit.com\/r\/psychology\/comments\/2qg7p2\/for_some_people_exercise_could_be_an_effective\/\">A link on Reddit<\/a> claimed that exercise could be an effective treatment for depression. I felt it necessary to comment that:<\/p>\n<blockquote><p>Exercise does not have a causal effect on depression or happiness according to twin-control studies (<a class=\"imgScanned\" href=\"https:\/\/www.researchgate.net\/publication\/6735915_The_association_between_exercise_participation_and_well-being_a_co-twin_study\/file\/5046352303d680584d.pdf\">1<\/a>, <a class=\"imgScanned\" href=\"https:\/\/www.researchgate.net\/publication\/23148070_Testing_causality_in_the_association_between_regular_exercise_and_symptoms_of_anxiety_and_depression\/file\/5046352303d67c86c4.pdf\">2<\/a>).<\/p><\/blockquote>\n<p>Another person replied with a meta-analysis which I then took a look at. It showed a large effect, apparently giving inconsistent results with the twin studies.<\/p>\n<ul>\n<li>Josefsson, T., Lindwall, M. and Archer, T. (2014), <a href=\"http:\/\/emilkirkegaard.dk\/en\/wp-content\/uploads\/Physical-exercise-intervention-in-depressive-disorders-Meta-analysis-and-systematic-review.pdf\">Physical exercise intervention in depressive disorders: Meta\u2010analysis and systematic review.<\/a> Scand J Med Sci Sports, 24: 259\u2013272. doi:10.1111\/sms.12050 (<a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pubmed\/23362828\">PUBMED link<\/a>)<\/li>\n<\/ul>\n<p>My reply:<\/p>\n<blockquote>\n<div class=\"usertext-body may-blank-within md-container\">\n<div class=\"md\">\n<p>I skimmed the meta-analysis you found. <a class=\"imgScanned\" href=\"http:\/\/emilkirkegaard.dk\/en\/wp-content\/uploads\/Physical-exercise-intervention-in-depressive-disorders-Meta-analysis-and-systematic-review.pdf\" rel=\"nofollow\">It&#8217;s here for readers without academic access.<\/a><\/p>\n<p>As you can see, it included all kinds of studies, but they were generally small (Table 2+3). There was no analysis of publication bias. Very strange given the ubiquity of this problem. As I reviewer I would not approve a meta-analysis of this sort without an analysis of publication bias.<\/p>\n<p>Luckily, a simply method (<a class=\"imgScanned\" href=\"https:\/\/en.wikipedia.org\/wiki\/Funnel_plot\" rel=\"nofollow\">funnel plot<\/a>) of checking publication bias can be applied to the studies given in Figure 1. <a class=\"imgScanned\" href=\"https:\/\/docs.google.com\/spreadsheets\/d\/1wr71ozujtNaZIsseiKyQi5qIpq85bT9wqpd06Ef9d1w\/edit#gid=0\" rel=\"nofollow\">Here&#8217;s the data and the plot<\/a>.<\/p>\n<p>As you can see, the smaller studies tended to report larger effect sizes in line with publication bias hypothesis. The effect was very strong as you can see, r=-.758.<\/p>\n<p>Perhaps this inconsistency can be solely explained by publication bias.<\/p>\n<\/div>\n<\/div>\n<\/blockquote>\n<p><iframe loading=\"lazy\" src=\"https:\/\/docs.google.com\/spreadsheets\/d\/1wr71ozujtNaZIsseiKyQi5qIpq85bT9wqpd06Ef9d1w\/pubchart?oid=875494184&amp;format=interactive\" width=\"600\" height=\"371\" frameborder=\"0\" scrolling=\"no\" seamless=\"\"><\/iframe><\/p>\n<p><strong>Update 2015-09-28:<\/strong><\/p>\n<p>A new study made the light of the day on Reddit. Since I had already examined this issue, <a href=\"https:\/\/www.reddit.com\/r\/psychology\/comments\/3mnes5\/exercise_for_4_or_more_days_per_week_is\/cvgpvwj\">I wrote a reply<\/a> stating that the evidence indicates that exercise does not work as a treatment for depression. In line with the usual tactics, stating that something doesn&#8217;t work is a sure way to get down-voted.<\/p>\n<p>More strangely, a user tried to counter my post (this one) with the citation of another meta-analysis, which turned out to be older and also doesn&#8217;t have any analysis of publication bias!<\/p>\n<ul>\n<li>Rethorst, C. D., Wipfli, B. M., &amp; Landers, D. M. (2009). <a href=\"http:\/\/emilkirkegaard.dk\/en\/wp-content\/uploads\/The-Antidepressive-Effects-of-Exercise.pdf\">The antidepressive effects of exercise<\/a>. Sports Medicine, 39(6), 491-511. <a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pubmed\/19453207\">PUBMED<\/a>.<\/li>\n<\/ul>\n<p>The two cited twin studies:<\/p>\n<ul>\n<li>Stubbe, J. H., De Moor, M. H. M., Boomsma, D. I., &amp; De Geus, E. J. C. (2007). <a href=\"https:\/\/www.researchgate.net\/publication\/6735915_The_association_between_exercise_participation_and_well-being_A_co-twin_study\">The association between exercise participation and well-being: a co-twin study<\/a>. Preventive medicine, 44(2), 148-152.<\/li>\n<li>De Moor, M. H., Boomsma, D. I., Stubbe, J. H., Willemsen, G., &amp; de Geus, E. J. (2008). <a href=\"https:\/\/www.researchgate.net\/publication\/23148070_Testing_Causality_in_the_Association_Between_Regular_Exercise_and_Symptoms_of_Anxiety_and_Depression\">Testing causality in the association between regular exercise and symptoms of anxiety and depression.<\/a> Archives of General Psychiatry, 65(8), 897-905.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>A link on Reddit claimed that exercise could be an effective treatment for depression. I felt it necessary to comment that: Exercise does not have a causal effect on depression or happiness according to twin-control studies (1, 2). Another person replied with a meta-analysis which I then took a look at. It showed a large [&hellip;]<\/p>\n","protected":false},"author":17,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1727],"tags":[2059,2058,2040],"class_list":["post-4556","post","type-post","status-publish","format-standard","hentry","category-medicine","tag-exercise","tag-funnel-plot","tag-publication-bias","entry"],"_links":{"self":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts\/4556","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/users\/17"}],"replies":[{"embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/comments?post=4556"}],"version-history":[{"count":5,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts\/4556\/revisions"}],"predecessor-version":[{"id":5504,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts\/4556\/revisions\/5504"}],"wp:attachment":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/media?parent=4556"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/categories?post=4556"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/tags?post=4556"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}