International Journal of Bipolar Disorders (Jun 2023)
Exploratory study of ultraviolet B (UVB) radiation and age of onset of bipolar disorder
- Michael Bauer,
- Tasha Glenn,
- Eric D. Achtyes,
- Martin Alda,
- Esen Agaoglu,
- Kürsat Altınbaş,
- Ole A. Andreassen,
- Elias Angelopoulos,
- Raffaella Ardau,
- Memduha Aydin,
- Yavuz Ayhan,
- Christopher Baethge,
- Rita Bauer,
- Bernhard T. Baune,
- Ceylan Balaban,
- Claudia Becerra-Palars,
- Aniruddh P. Behere,
- Prakash B. Behere,
- Habte Belete,
- Tilahun Belete,
- Gabriel Okawa Belizario,
- Frank Bellivier,
- Robert H. Belmaker,
- Francesco Benedetti,
- Michael Berk,
- Yuly Bersudsky,
- Şule Bicakci,
- Harriet Birabwa-Oketcho,
- Thomas D. Bjella,
- Conan Brady,
- Jorge Cabrera,
- Marco Cappucciati,
- Angela Marianne Paredes Castro,
- Wei-Ling Chen,
- Eric Y. W. Cheung,
- Silvia Chiesa,
- Marie Crowe,
- Alessandro Cuomo,
- Sara Dallaspezia,
- Maria Del Zompo,
- Pratikkumar Desai,
- Seetal Dodd,
- Bruno Etain,
- Andrea Fagiolini,
- Frederike T. Fellendorf,
- Ewa Ferensztajn-Rochowiak,
- Jess G. Fiedorowicz,
- Kostas N. Fountoulakis,
- Mark A. Frye,
- Pierre A. Geoffroy,
- Michael J. Gitlin,
- Ana Gonzalez-Pinto,
- John F. Gottlieb,
- Paul Grof,
- Bartholomeus C. M. Haarman,
- Hirohiko Harima,
- Mathias Hasse-Sousa,
- Chantal Henry,
- Lone Hoffding,
- Josselin Houenou,
- Massimiliano Imbesi,
- Erkki T. Isometsä,
- Maja Ivkovic,
- Sven Janno,
- Simon Johnsen,
- Flávio Kapczinski,
- Gregory N. Karakatsoulis,
- Mathias Kardell,
- Lars Vedel Kessing,
- Seong Jae Kim,
- Barbara König,
- Timur L. Kot,
- Michael Koval,
- Mauricio Kunz,
- Beny Lafer,
- Mikael Landén,
- Erik R. Larsen,
- Melanie Lenger,
- Rasmus W. Licht,
- Carlos Lopez-Jaramillo,
- Alan MacKenzie,
- Helle Østergaard Madsen,
- Simone Alberte Kongstad A. Madsen,
- Jayant Mahadevan,
- Agustine Mahardika,
- Mirko Manchia,
- Wendy Marsh,
- Monica Martinez-Cengotitabengoa,
- Julia Martini,
- Klaus Martiny,
- Yuki Mashima,
- Declan M. McLoughlin,
- Ybe Meesters,
- Ingrid Melle,
- Fátima Meza-Urzúa,
- Pavol Mikolas,
- Yee Ming Mok,
- Scott Monteith,
- Muthukumaran Moorthy,
- Gunnar Morken,
- Enrica Mosca,
- Anton A. Mozzhegorov,
- Rodrigo Munoz,
- Starlin V. Mythri,
- Fethi Nacef,
- Ravi K. Nadella,
- Takako Nakanotani,
- René Ernst Nielsen,
- Claire O’Donovan,
- Adel Omrani,
- Yamima Osher,
- Uta Ouali,
- Maja Pantovic-Stefanovic,
- Pornjira Pariwatcharakul,
- Joanne Petite,
- Johannes Petzold,
- Andrea Pfennig,
- Yolanda Pica Ruiz,
- Marco Pinna,
- Maurizio Pompili,
- Richard J. Porter,
- Danilo Quiroz,
- Francisco Diego Rabelo-da-Ponte,
- Raj Ramesar,
- Natalie Rasgon,
- Woraphat Ratta-apha,
- Michaela Ratzenhofer,
- Maria Redahan,
- M. S. Reddy,
- Andreas Reif,
- Eva Z. Reininghaus,
- Jenny Gringer Richards,
- Philipp Ritter,
- Janusz K. Rybakowski,
- Leela Sathyaputri,
- Angela M. Scippa,
- Christian Simhandl,
- Daniel Smith,
- José Smith,
- Paul W. Stackhouse,
- Dan J. Stein,
- Kellen Stilwell,
- Sergio Strejilevich,
- Kuan-Pin Su,
- Mythily Subramaniam,
- Ahmad Hatim Sulaiman,
- Kirsi Suominen,
- Andi J. Tanra,
- Yoshitaka Tatebayashi,
- Wen Lin Teh,
- Leonardo Tondo,
- Carla Torrent,
- Daniel Tuinstra,
- Takahito Uchida,
- Arne E. Vaaler,
- Eduard Vieta,
- Biju Viswanath,
- Maria Yoldi-Negrete,
- Oguz Kaan Yalcinkaya,
- Allan H. Young,
- Yosra Zgueb,
- Peter C. Whybrow
Affiliations
- Michael Bauer
- Department of Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus, Faculty of Medicine, Technische Universität Dresden
- Tasha Glenn
- ChronoRecord Association
- Eric D. Achtyes
- Division of Psychiatry and Behavioral Medicine, Michigan State University College of Human Medicine
- Martin Alda
- Department of Psychiatry, Dalhousie University
- Esen Agaoglu
- Department of Psychiatry, Hacettepe University Faculty of Medicine
- Kürsat Altınbaş
- Department of Psychiatry, Selcuk University Faculty of Medicine, Mazhar Osman Mood Center
- Ole A. Andreassen
- NORMENT Centre, Division of Mental Health and Addiction, Oslo University Hospital and Institute of Clinical Medicine, University of Oslo
- Elias Angelopoulos
- Department of Psychiatry, National and Capodistrian University of Athens, Medical School, Eginition Hospital
- Raffaella Ardau
- Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari
- Memduha Aydin
- Department of Psychiatry, Selcuk University Faculty of Medicine
- Yavuz Ayhan
- Department of Psychiatry, Hacettepe University Faculty of Medicine
- Christopher Baethge
- Department of Psychiatry and Psychotherapy, University of Cologne Medical School
- Rita Bauer
- Department of Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus, Faculty of Medicine, Technische Universität Dresden
- Bernhard T. Baune
- Department of Psychiatry, University of Münster
- Ceylan Balaban
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Frankfurt, Johann Wolfgang Goethe-Universität Frankfurt Am Main
- Claudia Becerra-Palars
- National Institute of Psychiatry “Ramón de la Fuente Muñiz”
- Aniruddh P. Behere
- Department of Pediatrics and Human Development, Michigan State University
- Prakash B. Behere
- Department of Psychiatry, Jawaharlal Nehru Medical College, Datta Meghe Institute of Medical Sciences (Deemed University)
- Habte Belete
- Department of Psychiatry, College of Medicine and Health Sciences, Bahir Dar University
- Tilahun Belete
- Department of Psychiatry, College of Medicine and Health Sciences, Bahir Dar University
- Gabriel Okawa Belizario
- Bipolar Disorder Research Program, Department of Psychiatry, University of São Paulo Medical School
- Frank Bellivier
- Département de Psychiatrie et de Médecine Addictologique, Assistance Publique, Hôpitaux de Paris, INSERM UMR-S1144, Université Paris Cité, Fondation FondaMental
- Robert H. Belmaker
- Division of Psychiatry, Ben Gurion University of the Negev
- Francesco Benedetti
- University Vita-Salute San Raffaele
- Michael Berk
- IMPACT, The Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Deakin University
- Yuly Bersudsky
- Department of Psychiatry, Faculty of Health Sciences, Beer Sheva Mental Health Center, Ben Gurion University of the Negev
- Şule Bicakci
- Department of Psychiatry, Hacettepe University Faculty of Medicine
- Harriet Birabwa-Oketcho
- Butabika Hospital
- Thomas D. Bjella
- NORMENT Centre, Division of Mental Health and Addiction, Oslo University Hospital and Institute of Clinical Medicine, University of Oslo
- Conan Brady
- Department of Psychiatry, Trinity College Dublin, St Patrick’s University Hospital
- Jorge Cabrera
- Mood Disorders Clinic, Dr. Jose Horwitz Psychiatric Institute
- Marco Cappucciati
- Department of Mental Health and Substance Abuse
- Angela Marianne Paredes Castro
- IMPACT, The Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Deakin University
- Wei-Ling Chen
- Department of Psychiatry, Chiayi Branch, Taichung Veterans General Hospital
- Eric Y. W. Cheung
- Private Practice, Central
- Silvia Chiesa
- Department of Mental Health and Substance Abuse
- Marie Crowe
- Department of Psychological Medicine, University of Otago
- Alessandro Cuomo
- Department of Molecular Medicine, University of Siena School of Medicine
- Sara Dallaspezia
- Psychiatry and Clinical Psychobiology, Division of Neuroscience, San Raffaele Scientific Institute
- Maria Del Zompo
- Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari
- Pratikkumar Desai
- Division of Psychiatry and Behavioral Medicine, Michigan State University College of Human Medicine
- Seetal Dodd
- IMPACT, The Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Deakin University
- Bruno Etain
- Département de Psychiatrie et de Médecine Addictologique, Assistance Publique, Hôpitaux de Paris, INSERM UMR-S1144, Université Paris Cité, Fondation FondaMental
- Andrea Fagiolini
- Department of Molecular Medicine, University of Siena School of Medicine
- Frederike T. Fellendorf
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University Graz
- Ewa Ferensztajn-Rochowiak
- Department of Adult Psychiatry, Poznan University of Medical Sciences
- Jess G. Fiedorowicz
- Department of Psychiatry, School of Epidemiology and Public Health, University of Ottawa and The Ottawa Hospital
- Kostas N. Fountoulakis
- 3rd Department of Psychiatry, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki
- Mark A. Frye
- Department of Psychiatry and Psychology, Mayo Clinic Depression Center, Mayo Clinic
- Pierre A. Geoffroy
- Département de Psychiatrie et d’addictologie, AP-HP, GHU Paris Nord, DMU Neurosciences, Hopital Bichat, Claude Bernard
- Michael J. Gitlin
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles (UCLA)
- Ana Gonzalez-Pinto
- BIOARABA, Department of Psychiatry, University Hospital of Alava, University of the Basque Country, CIBERSAM
- John F. Gottlieb
- Department of Psychiatry, Feinberg School of Medicine, Northwestern University
- Paul Grof
- Mood Disorders Center of Ottawa and the Department of Psychiatry, University of Toronto
- Bartholomeus C. M. Haarman
- Department of Psychiatry, University Medical Center Groningen, University of Groningen
- Hirohiko Harima
- Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital
- Mathias Hasse-Sousa
- Department of Psychiatry, Universidade Federal do Rio Grande do Sul
- Chantal Henry
- Department of Psychiatry, GHU Paris Psychiatrie and Neurosciences, Université de Paris
- Lone Hoffding
- Department of Clinical Research, University of Southern Denmark
- Josselin Houenou
- Université Paris Est Créteil, INSERM, IMRB, Translational Neuropsychiatry, APHP, Mondor Univ Hospitals, Fondation FondaMental
- Massimiliano Imbesi
- Department of Mental Health and Substance Abuse
- Erkki T. Isometsä
- Department of Psychiatry, University of Helsinki and Helsinki University Hospital
- Maja Ivkovic
- Clinic for Psychiatry, University Clinical Center of Serbia
- Sven Janno
- Department of Psychiatry, University of Tartu
- Simon Johnsen
- Unit for Psychiatric Research, Aalborg University Hospital
- Flávio Kapczinski
- Department of Psychiatry, Universidade Federal do Rio Grande do Sul
- Gregory N. Karakatsoulis
- 3rd Department of Psychiatry, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki
- Mathias Kardell
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg
- Lars Vedel Kessing
- Copenhagen Affective Disorder Research Center (CADIC), Psychiatric Center Copenhagen
- Seong Jae Kim
- Department of Psychiatry, Chosun University School of Medicine
- Barbara König
- BIPOLAR Zentrum Wiener Neustadt
- Timur L. Kot
- Khanty-Mansiysk Clinical Psychoneurological Hospital
- Michael Koval
- Neuroscience Program, Michigan State University
- Mauricio Kunz
- Department of Psychiatry, Universidade Federal do Rio Grande do Sul
- Beny Lafer
- Bipolar Disorder Research Program, Department of Psychiatry, University of São Paulo Medical School
- Mikael Landén
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg
- Erik R. Larsen
- Mental Health Department Odense, University Clinic and Department of Regional Health Research, University of Southern Denmark
- Melanie Lenger
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University Graz
- Rasmus W. Licht
- Psychiatry, Aalborg University Hospital
- Carlos Lopez-Jaramillo
- Mood Disorders Program, Hospital Universitario San Vicente Fundación, Research Group in Psychiatry, Department of Psychiatry, Faculty of Medicine, Universidad de Antioquia
- Alan MacKenzie
- Forensic Psychiatry, University of Glasgow, NHS Greater Glasgow and Clyde
- Helle Østergaard Madsen
- Psychiatric Centre Copenhagen, Copenhagen University Hospitals
- Simone Alberte Kongstad A. Madsen
- Unit for Psychiatric Research, Aalborg University Hospital
- Jayant Mahadevan
- Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (NIMHANS)
- Agustine Mahardika
- Department of Psychiatry, Faculty of Medicine, Mataram University
- Mirko Manchia
- Department of Pharmacology, Dalhousie University
- Wendy Marsh
- Department of Psychiatry, University of Massachusetts Medical School
- Monica Martinez-Cengotitabengoa
- Osakidetza, Basque Health Service, BioAraba Health Research Institute, University of the Basque Country
- Julia Martini
- Department of Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus, Faculty of Medicine, Technische Universität Dresden
- Klaus Martiny
- Psychiatric Centre Copenhagen, Copenhagen University Hospitals
- Yuki Mashima
- Department of Neuropsychiatry, Keio University School of Medicine
- Declan M. McLoughlin
- Department of Psychiatry and Trinity College Institute of Neuroscience, Trinity College Dublin, St Patrick’s University Hospital
- Ybe Meesters
- Department of Psychiatry, University Medical Center Groningen, University of Groningen
- Ingrid Melle
- NORMENT Centre, Division of Mental Health and Addiction, Oslo University Hospital and Institute of Clinical Medicine, University of Oslo
- Fátima Meza-Urzúa
- Department of Child and Adolescent Psychiatry Und Psychotherapy, SHG Klinikum
- Pavol Mikolas
- Department of Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus, Faculty of Medicine, Technische Universität Dresden
- Yee Ming Mok
- Department of Mood and Anxiety Disorders, Institute of Mental Health
- Scott Monteith
- Michigan State University College of Human Medicine, Traverse City Campus
- Muthukumaran Moorthy
- Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (NIMHANS)
- Gunnar Morken
- Department of Mental Health, Norwegian University of Science and Technology, NTNU
- Enrica Mosca
- Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari
- Anton A. Mozzhegorov
- Soviet Psychoneurological Hospital
- Rodrigo Munoz
- Department of Psychiatry, University of California San Diego
- Starlin V. Mythri
- Makunda Christian Leprosy and General Hospital
- Fethi Nacef
- Razi Hospital, Faculty of Medicine, University of Tunis-El Manar
- Ravi K. Nadella
- Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (NIMHANS)
- Takako Nakanotani
- Tokyo Metropolitan Hiroo Hospital
- René Ernst Nielsen
- Psychiatry, Aalborg University Hospital
- Claire O’Donovan
- Department of Psychiatry, Dalhousie University
- Adel Omrani
- Tunisian Bipolar Forum
- Yamima Osher
- Department of Psychiatry, Faculty of Health Sciences, Beer Sheva Mental Health Center, Ben Gurion University of the Negev
- Uta Ouali
- Razi Hospital, Faculty of Medicine, University of Tunis-El Manar
- Maja Pantovic-Stefanovic
- Clinic for Psychiatry, University Clinical Center of Serbia
- Pornjira Pariwatcharakul
- Department of Psychiatry, Faculty of Medicine Siriraj Hospital, Mahidol University
- Joanne Petite
- Department of Psychiatry, Dalhousie University
- Johannes Petzold
- Department of Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus, Faculty of Medicine, Technische Universität Dresden
- Andrea Pfennig
- Department of Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus, Faculty of Medicine, Technische Universität Dresden
- Yolanda Pica Ruiz
- Hospital “Ángeles del Pedregal”
- Marco Pinna
- Section of Psychiatry, Department of Medical Science and Public Health, University of Cagliari
- Maurizio Pompili
- Department of Neurosciences, Mental Health and Sensory Organs, Sant’Andrea Hospital, Sapienza University of Rome
- Richard J. Porter
- Department of Psychological Medicine, University of Otago
- Danilo Quiroz
- Deparment of Psychiatry, Diego Portales University
- Francisco Diego Rabelo-da-Ponte
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire
- Raj Ramesar
- SA MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Diseases and Molecular, Medicine, University of Cape Town
- Natalie Rasgon
- Department of Psychiatry and Behavioral Sciences, Stanford School of Medicine
- Woraphat Ratta-apha
- Department of Psychiatry, Faculty of Medicine Siriraj Hospital, Mahidol University
- Michaela Ratzenhofer
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University Graz
- Maria Redahan
- Department of Psychiatry, Trinity College Dublin, St Patrick’s University Hospital
- M. S. Reddy
- Asha Bipolar Clinic, Asha Hospital
- Andreas Reif
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Frankfurt, Johann Wolfgang Goethe-Universität Frankfurt Am Main
- Eva Z. Reininghaus
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University Graz
- Jenny Gringer Richards
- Departments of Psychiatry, Epidemiology, and Internal Medicine, Iowa Neuroscience Institute, The University of Iowa
- Philipp Ritter
- Department of Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus, Faculty of Medicine, Technische Universität Dresden
- Janusz K. Rybakowski
- Department of Adult Psychiatry, Poznan University of Medical Sciences
- Leela Sathyaputri
- Departments of Psychiatry, Epidemiology, and Internal Medicine, Iowa Neuroscience Institute, The University of Iowa
- Angela M. Scippa
- Department of Neuroscience and Mental Health, Federal University of Bahia
- Christian Simhandl
- Bipolar Zentrum Wiener Neustadt, Sigmund Freud Privat Universität
- Daniel Smith
- Centre for Clinical Brain Sciences, University of Edinburgh
- José Smith
- AREA, Assistance and Research in Affective Disorders
- Paul W. Stackhouse
- Science Directorate/Climate Science Branch, NASA Langley Research Center
- Dan J. Stein
- Department of Psychiatry, MRC Unit on Risk and Resilience in Mental Disorders, University of Cape Town
- Kellen Stilwell
- Division of Psychiatry and Behavioral Medicine, Michigan State University College of Human Medicine
- Sergio Strejilevich
- AREA, Assistance and Research in Affective Disorders
- Kuan-Pin Su
- College of Medicine, China Medical University (CMU)
- Mythily Subramaniam
- Research Division, Institute of Mental Health
- Ahmad Hatim Sulaiman
- Department of Psychological Medicine, Faculty of Medicine, University of Malaya
- Kirsi Suominen
- Department of Social Services and Health Care, Psychiatry, City of Helsinki
- Andi J. Tanra
- Department of Psychiatry, Faculty of Medicine, Hasanuddin University
- Yoshitaka Tatebayashi
- Tokyo Metropolitan Hiroo Hospital
- Wen Lin Teh
- Research Division, Institute of Mental Health
- Leonardo Tondo
- McLean Hospital-Harvard Medical School
- Carla Torrent
- Clinical Institute of Neuroscience, Hospital Clinic, University of Barcelona, IDIBAPS, CIBERSAM
- Daniel Tuinstra
- Division of Psychiatry and Behavioral Medicine, Michigan State University College of Human Medicine
- Takahito Uchida
- Department of Neuropsychiatry, Keio University School of Medicine
- Arne E. Vaaler
- Department of Mental Health, Norwegian University of Science and Technology, NTNU
- Eduard Vieta
- Clinical Institute of Neuroscience, Hospital Clinic, University of Barcelona, IDIBAPS, CIBERSAM
- Biju Viswanath
- Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (NIMHANS)
- Maria Yoldi-Negrete
- Subdirección de Investigaciones Clínicas, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñíz
- Oguz Kaan Yalcinkaya
- Department of Psychiatry, Hacettepe University Faculty of Medicine
- Allan H. Young
- Department of Psychological Medicine, Institute of Psychiatry, Psychology and Neuroscience, King’s College London
- Yosra Zgueb
- Razi Hospital, Faculty of Medicine, University of Tunis-El Manar
- Peter C. Whybrow
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles (UCLA)
- DOI
- https://doi.org/10.1186/s40345-023-00303-w
- Journal volume & issue
-
Vol. 11,
no. 1
pp. 1 – 9
Abstract
Abstract Background Sunlight contains ultraviolet B (UVB) radiation that triggers the production of vitamin D by skin. Vitamin D has widespread effects on brain function in both developing and adult brains. However, many people live at latitudes (about > 40 N or S) that do not receive enough UVB in winter to produce vitamin D. This exploratory study investigated the association between the age of onset of bipolar I disorder and the threshold for UVB sufficient for vitamin D production in a large global sample. Methods Data for 6972 patients with bipolar I disorder were obtained at 75 collection sites in 41 countries in both hemispheres. The best model to assess the relation between the threshold for UVB sufficient for vitamin D production and age of onset included 1 or more months below the threshold, family history of mood disorders, and birth cohort. All coefficients estimated at P ≤ 0.001. Results The 6972 patients had an onset in 582 locations in 70 countries, with a mean age of onset of 25.6 years. Of the onset locations, 34.0% had at least 1 month below the threshold for UVB sufficient for vitamin D production. The age of onset at locations with 1 or more months of less than or equal to the threshold for UVB was 1.66 years younger. Conclusion UVB and vitamin D may have an important influence on the development of bipolar disorder. Study limitations included a lack of data on patient vitamin D levels, lifestyles, or supplement use. More study of the impacts of UVB and vitamin D in bipolar disorder is needed to evaluate this supposition.
