Exploring the causal relationships between neighbourhood characteristics and severe mental illness: A systematic review

Exploring the causal relationships between neighbourhood characteristics and severe mental illness: A systematic review | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Systematic Review Exploring the causal relationships between neighbourhood characteristics and severe mental illness: A systematic review Layla Sadek, Anna Tsaligopoulou, Michelle Arellano Spano, Jennifer Dykxhoorn This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8779555/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose Severe mental illness (SMI) is an umbrella term for chronic psychiatric disorders associated with significant functional impairment, including schizophrenia and other psychotic disorders, bipolar disorders, and major depression. Neighbourhood characteristics have emerged as potentially modifiable risk factors for SMI. While associations between neighbourhood-level characteristics and SMI are well-documented, fewer studies have explored their causal relationship. This systematic review synthesises the evidence on the causal relationship between physical and social neighbourhood environments, and SMI. Methods We searched four electronic databases (Medline, EMBASE, PsycINFO, Web of Science) and hand-searched reference lists of included studies. Title/abstract screening, full-text screening, quality assessments, and data extraction were conducted by two independent reviewers. Due to heterogeneity in methodologies, findings were narratively synthesised. Results Thirteen studies were included, encompassing both social and physical characteristics. All studies were rated as high quality. A range of causal methods were employed, including Mendelian randomisation (n = 7), quasi-experiments (n = 4), family-based designs (n = 1), and causal mediation (n = 2). There was some evidence for an association between ethnic density and SMI (n = 1), and weak evidence for a link between social cohesion and SMI (n = 1). Evidence for causal associations between SMI and deprivation (n = 3) or air pollution (n = 7) was mixed, and population density (n = 2) showed weaker, inconclusive associations with SMI. Conclusion Although causal claims remain tentative due to heterogeneity in definitions, methods, and populations, the evidence points towards the neighbourhood context as a contributory factor in the development of SMI, highlighting the need to shift attention towards community-level public health interventions addressing neighbourhood-level determinants. Psychology Severe mental illness Neighbourhood characteristics Physical environment Social environment Causal inference Full Text Additional Declarations The authors declare no competing interests. Supplementary Files causalneighsupplementary.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8779555","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Systematic Review","associatedPublications":[],"authors":[{"id":585264147,"identity":"1ef51f9e-aaab-41e5-98c3-0788488373c1","order_by":0,"name":"Layla Sadek","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABEklEQVRIie2RMUvDQBiG3+MgcTiaNWLFv3ChIIhR/0pDoF0yOHYKB4V2CXZN/0X8BxcO2iXoGuigIujSoWPAIvYsdrugm8M9y3fcdw/3fnyAxfIP6QBEfp+kA2xYCLj7Djcpjn78o5C8OwDoXxTKQvULxa24bJCedZaTPljyGM3GIJsGqmdUWMLLDCqYVwsJv1pFuQI93t2cm4MlXDJIUtRDgSBbRcUu2AmgQqPirXm5RXpTPL0LRJ8PWqEfrYqfcMVAo6J2JCSTWnH0L+Zg/tut6nIVz6tBvxQs7uWKTC4yPjSO73nx/ct6lF7dLRfB65Zdn86mY1U3o8tAmBwc8cMO5L4Q0bIVjfvc1rVYLBYL8AU5ElbIuu1/GAAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0009-0004-0513-1728","institution":"University College London","correspondingAuthor":true,"prefix":"","firstName":"Layla","middleName":"","lastName":"Sadek","suffix":""},{"id":585264148,"identity":"6a9a8625-1ddb-44fe-acb8-66f1007979d3","order_by":1,"name":"Anna Tsaligopoulou","email":"","orcid":"","institution":"University College London","correspondingAuthor":false,"prefix":"","firstName":"Anna","middleName":"","lastName":"Tsaligopoulou","suffix":""},{"id":585264149,"identity":"62a0bfe3-46bf-4a0a-8894-c208591b36bd","order_by":2,"name":"Michelle Arellano Spano","email":"","orcid":"","institution":"University College London","correspondingAuthor":false,"prefix":"","firstName":"Michelle","middleName":"Arellano","lastName":"Spano","suffix":""},{"id":585264150,"identity":"5ca1d15a-d703-4ff9-ba06-b645bfab06bb","order_by":3,"name":"Jennifer Dykxhoorn","email":"","orcid":"","institution":"University College London","correspondingAuthor":false,"prefix":"","firstName":"Jennifer","middleName":"","lastName":"Dykxhoorn","suffix":""}],"badges":[],"createdAt":"2026-02-03 19:47:42","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-8779555/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8779555/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101946661,"identity":"bad58ea1-154a-4dc7-b001-fa41d09fdbd5","added_by":"auto","created_at":"2026-02-05 10:02:03","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":556835,"visible":true,"origin":"","legend":"","description":"","filename":"causalneighv3.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8779555/v1_covered_37e244d4-ffbb-47c8-ba9e-9132454a7e64.pdf"},{"id":101945722,"identity":"cae5ed32-c1ac-4049-91bd-b76ac07fc0b2","added_by":"auto","created_at":"2026-02-05 09:58:19","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":46419,"visible":true,"origin":"","legend":"","description":"","filename":"causalneighsupplementary.docx","url":"https://assets-eu.researchsquare.com/files/rs-8779555/v1/0165702367f79c30b525ff38.docx"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eExploring the causal relationships between neighbourhood characteristics and severe mental illness: A systematic review\u003c/strong\u003e\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"University College London","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Severe mental illness, Neighbourhood characteristics, Physical environment, Social environment, Causal inference","lastPublishedDoi":"10.21203/rs.3.rs-8779555/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8779555/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eSevere mental illness (SMI) is an umbrella term for chronic psychiatric disorders associated with significant functional impairment, including schizophrenia and other psychotic disorders, bipolar disorders, and major depression. Neighbourhood characteristics have emerged as potentially modifiable risk factors for SMI. While associations between neighbourhood-level characteristics and SMI are well-documented, fewer studies have explored their causal relationship. This systematic review synthesises the evidence on the causal relationship between physical and social neighbourhood environments, and SMI.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe searched four electronic databases (Medline, EMBASE, PsycINFO, Web of Science) and hand-searched reference lists of included studies. Title/abstract screening, full-text screening, quality assessments, and data extraction were conducted by two independent reviewers. Due to heterogeneity in methodologies, findings were narratively synthesised.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThirteen studies were included, encompassing both social and physical characteristics. All studies were rated as high quality. A range of causal methods were employed, including Mendelian randomisation (n\u0026thinsp;=\u0026thinsp;7), quasi-experiments (n\u0026thinsp;=\u0026thinsp;4), family-based designs (n\u0026thinsp;=\u0026thinsp;1), and causal mediation (n\u0026thinsp;=\u0026thinsp;2). There was some evidence for an association between ethnic density and SMI (n\u0026thinsp;=\u0026thinsp;1), and weak evidence for a link between social cohesion and SMI (n\u0026thinsp;=\u0026thinsp;1). Evidence for causal associations between SMI and deprivation (n\u0026thinsp;=\u0026thinsp;3) or air pollution (n\u0026thinsp;=\u0026thinsp;7) was mixed, and population density (n\u0026thinsp;=\u0026thinsp;2) showed weaker, inconclusive associations with SMI.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eAlthough causal claims remain tentative due to heterogeneity in definitions, methods, and populations, the evidence points towards the neighbourhood context as a contributory factor in the development of SMI, highlighting the need to shift attention towards community-level public health interventions addressing neighbourhood-level determinants.\u003c/p\u003e","manuscriptTitle":"Exploring the causal relationships between neighbourhood characteristics and severe mental illness: A systematic review","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-05 09:46:54","doi":"10.21203/rs.3.rs-8779555/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b257fe9f-2146-41bc-b98a-d22d46550e1a","owner":[],"postedDate":"February 5th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":62264908,"name":"Psychology"}],"tags":[],"updatedAt":"2026-02-05T09:46:54+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-05 09:46:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8779555","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8779555","identity":"rs-8779555","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}