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Influence of birth cohort on age of onset cluster analysis in bipolar I disorder

Published online by Cambridge University Press:  15 April 2020

M. Bauer
Affiliation:
Department of Psychiatry and Psychotherapy, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Germany Fetscherstr, 74, 01307Dresden, Germany
T. Glenn
Affiliation:
ChronoRecord Association, Fullerton, CA, USA
M. Alda
Affiliation:
Department of Psychiatry, Dalhousie University, Halifax, NS, Canada
O.A. Andreassen
Affiliation:
NORMENT - K.G. Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, Oslo University Hospital & Institute of Clinical Medicine, Oslo, Norway
E. Angelopoulos
Affiliation:
Department of Psychiatry, University of Athens Medical School, Eginition Hospital, Athens, Greece
R. Ardau
Affiliation:
Unit of Clinical Pharmacology, University Hospital of Cagliari, Cagliari, Italy
C. Baethge
Affiliation:
Department of Psychiatry and Psychotherapy, University of Cologne Medical School, Cologne, Germany
R. Bauer
Affiliation:
Department of Psychiatry and Psychotherapy, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Germany Fetscherstr, 74, 01307Dresden, Germany
F. Bellivier
Affiliation:
Psychiatrie, GH Saint-Louis – Lariboisière – F.-Widal, AP–HP, INSERM UMR-S1144, Faculté de Médecine, Université D.-Diderot, Paris, France FondaMental Fondation, Créteil, France
R.H. Belmaker
Affiliation:
Department of Psychiatry, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva Mental Health Center, Beer Sheva, Israel
M. Berk
Affiliation:
IMPACT Strategic Research Centre, School of Medicine, Deakin University, Geelong, Victoria3220, Australia Department of Psychiatry, ORYGEN Youth Health Research Centre, Centre for Youth Mental Health and the Florey Institute for Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria3052, Australia
T.D. Bjella
Affiliation:
NORMENT - K.G. Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, Oslo University Hospital & Institute of Clinical Medicine, Oslo, Norway
L. Bossini
Affiliation:
Department of Molecular Medicine and Department of Mental Health (DAI), University of Siena and University of Siena Medical Center (AOUS), Siena, Italy
Y. Bersudsky
Affiliation:
Department of Psychiatry, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva Mental Health Center, Beer Sheva, Israel
E.Y.W. Cheung
Affiliation:
Department of General Adult Psychiatry, Castle Peak Hospital, Hong Kong
J. Conell
Affiliation:
Department of Psychiatry and Psychotherapy, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Germany Fetscherstr, 74, 01307Dresden, Germany
M. Del Zompo
Affiliation:
Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari, Sardinia, Italy
S. Dodd
Affiliation:
IMPACT Strategic Research Centre, School of Medicine, Deakin University, Geelong, Victoria3220, Australia Department of Psychiatry, University of Melbourne, Parkville, Victoria3052, Australia
B. Etain
Affiliation:
AP–HP, Hôpitaux Universitaires Henri-Mondor, INSERM U955 (IMRB), Université Paris Est, and FondaMental Fondation, Créteil, France
A. Fagiolini
Affiliation:
Department of Molecular Medicine and Department of Mental Health (DAI), University of Siena and University of Siena Medical Center (AOUS), Siena, Italy
M.A. Frye
Affiliation:
Department of Psychiatry & Psychology, Mayo Clinic Depression Center, Mayo Clinic, Rochester, MN, USA
K.N. Fountoulakis
Affiliation:
3rd Department of Psychiatry, Division of Neurosciences, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
J. Garneau-Fournier
Affiliation:
Department of Psychiatry and Behavioral Sciences, Stanford School of Medicine, Palo Alto, CA, USA
A. Gonzalez-Pinto
Affiliation:
Department of Psychiatry, University Hospital of Alava, University of the Basque Country, CIBERSAM, Vitoria, Spain
H. Harima
Affiliation:
Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, Setagaya, Tokyo, Japan
S. Hassel
Affiliation:
Department of Psychiatry, Faculty of Medicine, University of Calgary, Calgary, AB, Canada
C. Henry
Affiliation:
AP–HP, Hôpitaux Universitaires Henri-Mondor, INSERM U955 (IMRB), Université Paris Est, and FondaMental Fondation, Créteil, France
A. Iacovides
Affiliation:
3rd Department of Psychiatry, Division of Neurosciences, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
E.T. Isometsä
Affiliation:
Department of Psychiatry, Institute of Clinical Medicine, University of Helsinki, Helsinki, Finland National Institute for Health and Welfare, Helsinki, Finland
F. Kapczinski
Affiliation:
Laboratory of Molecular Psychiatry, Hospital de Clínicas de Porto Alegre, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
S. Kliwicki
Affiliation:
Department of Adult Psychiatry, Poznan University of Medical Sciences, Poznan, Poland
B. König
Affiliation:
BIPOLAR Zentrum Wiener Neustadt, Wiener Neustadt, Austria
R. Krogh
Affiliation:
Department of Affective Disorders, Q, Mood Disorders Research Unit, Aarhus University Hospital, Aarhus, Denmark
M. Kunz
Affiliation:
Laboratory of Molecular Psychiatry, Hospital de Clínicas de Porto Alegre, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
B. Lafer
Affiliation:
Bipolar Disorder Research Program, Department of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil
E.R. Larsen
Affiliation:
Department of Affective Disorders, Q, Mood Disorders Research Unit, Aarhus University Hospital, Aarhus, Denmark
U. Lewitzka
Affiliation:
Department of Psychiatry and Psychotherapy, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Germany Fetscherstr, 74, 01307Dresden, Germany
C. Lopez-Jaramillo
Affiliation:
Mood Disorders Program, Fundacion San Vicente de Paul, Department of Psychiatry, Universidad de Antioquia, Medellín, Colombia
G. MacQueen
Affiliation:
Department of Psychiatry, Faculty of Medicine, University of Calgary, Calgary, AB, Canada
M. Manchia
Affiliation:
Department of Psychiatry, Dalhousie University, Halifax, NS, Canada
W. Marsh
Affiliation:
Department of Psychiatry, University of Massachusetts, Worcester, MA, USA
M. Martinez-Cengotitabengoa
Affiliation:
Department of Psychiatry, University Hospital of Alava, University of the Basque Country, CIBERSAM, Vitoria, Spain
I. Melle
Affiliation:
NORMENT - K.G. Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, Oslo University Hospital & Institute of Clinical Medicine, Oslo, Norway
S. Monteith
Affiliation:
Michigan State University College of Human Medicine, Traverse City Campus, Traverse City, MI, USA
G. Morken
Affiliation:
Department of Neuroscience, NTNU, and St Olavs’ University Hospital, Trondheim, Norway
R. Munoz
Affiliation:
Department of Psychiatry, University of California San Diego, San Diego, CA, USA
F.G. Nery
Affiliation:
Bipolar Disorder Research Program, Department of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil
C. O’Donovan
Affiliation:
Department of Psychiatry, Dalhousie University, Halifax, NS, Canada
Y. Osher
Affiliation:
Department of Psychiatry, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva Mental Health Center, Beer Sheva, Israel
A. Pfennig
Affiliation:
Department of Psychiatry and Psychotherapy, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Germany Fetscherstr, 74, 01307Dresden, Germany
D. Quiroz
Affiliation:
Deparment of Psychiatry, Diego Portales University, Santiago, Chile
R. Ramesar
Affiliation:
UCT/MRC Human Genetics Research Unit, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
N. Rasgon
Affiliation:
Department of Psychiatry and Behavioral Sciences, Stanford School of Medicine, Palo Alto, CA, USA
A. Reif
Affiliation:
Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Frankfurt, Goethe-University Frankfurt am Main, Germany
P. Ritter
Affiliation:
Department of Psychiatry and Psychotherapy, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Germany Fetscherstr, 74, 01307Dresden, Germany
J.K. Rybakowski
Affiliation:
Department of Adult Psychiatry, Poznan University of Medical Sciences, Poznan, Poland
K. Sagduyu
Affiliation:
Department of Psychiatry, University of Missouri Kansas City School of Medicine, Kansas City, MO, USA
A.M. Scippa
Affiliation:
Department of Neuroscience and Mental Health, Federal University of Bahia, Salvador, Brazil
E. Severus
Affiliation:
Department of Psychiatry and Psychotherapy, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Germany Fetscherstr, 74, 01307Dresden, Germany
C. Simhandl
Affiliation:
BIPOLAR Zentrum Wiener Neustadt, Wiener Neustadt, Austria
D.J. Stein
Affiliation:
Department of Psychiatry, University of Cape Town, Cape Town, South Africa
S. Strejilevich
Affiliation:
Bipolar Disorder Program, Neuroscience Institute, Favaloro University, Buenos Aires, Argentina
A. Hatim Sulaiman
Affiliation:
Department of Psychological Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
K. Suominen
Affiliation:
City of Helsinki, Department of Social Services and Health Care, Psychiatry, Helsinki, Finland
H. Tagata
Affiliation:
Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, Setagaya, Tokyo, Japan
Y. Tatebayashi
Affiliation:
Schizophrenia & Affective Disorders Research Project, Tokyo Metropolitan Institute of Medical Science, Seatagaya, Tokyo, Japan
C. Torrent
Affiliation:
Clinical Institute of Neuroscience, Hospital Clinic, University of Barcelona, IDIBAPS, CIBERSAM, Barcelona, Catalonia, Spain
E. Vieta
Affiliation:
Clinical Institute of Neuroscience, Hospital Clinic, University of Barcelona, IDIBAPS, CIBERSAM, Barcelona, Catalonia, Spain
B. Viswanath
Affiliation:
Department of Psychiatry, NIMHANS, Bangalore560029, India
M.J. Wanchoo
Affiliation:
Department of Psychiatry & Psychology, Mayo Clinic Depression Center, Mayo Clinic, Rochester, MN, USA
M. Zetin
Affiliation:
Department of Psychology, Chapman University, Orange, CA, USA
P.C. Whybrow
Affiliation:
Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior University of California Los Angeles (UCLA), Los Angeles, CA, USA
Corresponding
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Abstract

Purpose:

Two common approaches to identify subgroups of patients with bipolar disorder are clustering methodology (mixture analysis) based on the age of onset, and a birth cohort analysis. This study investigates if a birth cohort effect will influence the results of clustering on the age of onset, using a large, international database.

Methods:

The database includes 4037 patients with a diagnosis of bipolar I disorder, previously collected at 36 collection sites in 23 countries. Generalized estimating equations (GEE) were used to adjust the data for country median age, and in some models, birth cohort. Model-based clustering (mixture analysis) was then performed on the age of onset data using the residuals. Clinical variables in subgroups were compared.

Results:

There was a strong birth cohort effect. Without adjusting for the birth cohort, three subgroups were found by clustering. After adjusting for the birth cohort or when considering only those born after 1959, two subgroups were found. With results of either two or three subgroups, the youngest subgroup was more likely to have a family history of mood disorders and a first episode with depressed polarity. However, without adjusting for birth cohort (three subgroups), family history and polarity of the first episode could not be distinguished between the middle and oldest subgroups.

Conclusion:

These results using international data confirm prior findings using single country data, that there are subgroups of bipolar I disorder based on the age of onset, and that there is a birth cohort effect. Including the birth cohort adjustment altered the number and characteristics of subgroups detected when clustering by age of onset. Further investigation is needed to determine if combining both approaches will identify subgroups that are more useful for research.

Type
Original article
Copyright
Copyright © European Psychiatric Association 2020

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References

Akiskal, HS. Validating ‘hard’ and ‘soft’ phenotypes within the bipolar spectrum: continuity or discontinuity?. J Affect Disord 2003;73:15.CrossRefGoogle ScholarPubMed
Azorin, JM, Bellivier, F, Kaladjian, A, Adida, M, Belzeaux, R, Fakra, E, et al.Characteristics and profiles of bipolar I patients according to age at onset: findings from an admixture analysis. J Affect Disord 2013;150:9931000.CrossRefGoogle ScholarPubMed
Baldessarini, RJ, Tondo, L, Vazquez, GH, Undurraga, J, Bolzani, L, Yildiz, A, et al.Age at onset versus family history and clinical outcomes in 1665 international bipolar I disorder patients. World Psychiatry 2012;11:4046.CrossRefGoogle ScholarPubMed
Bauer, M, Glenn, T, Alda, M, Andreassen, OA, Angelopoulos, E, Ardau, R, et al.Relationship between sunlight and the age of onset of bipolar disorder: an international multisite study. J Affect Disord 2014;167:104111.CrossRefGoogle ScholarPubMed
Bauer, M, Glenn, T, Alda, M, Andreassen, OA, Ardau, R, Bellivier, F, et al.Impact of sunlight on the age of onset of bipolar disorder. Bipolar Disord 2012;14:654663.CrossRefGoogle ScholarPubMed
Bauer, M, Priebe, S, Kürten, I, Gräf, KJ, Baumgartner, A. Psychological and endocrine abnormalities in refugees from East Germany: part I. Prolonged stress, psychopathology, and hypothalamic-pituitary-thyroid axis activity. Psychiatry Res 1994;51:6173.CrossRefGoogle ScholarPubMed
Bauer, M, Priebe, S, Gräf, KJ, Kürten, I, Baumgartner, A. Psychological and endocrine abnormalities in refugees from East Germany: part II. Serum levels of cortisol, prolactin, luteinizing hormone, follicle stimulating hormone, and testosterone. Psychiatry Res 1994;51:7585.CrossRefGoogle ScholarPubMed
Bellivier, F, Golmard, JL, Henry, C, Leboyer, M, Schürhoff, F. Admixture analysis of age at onset in bipolar I affective disorder. Arch Gen Psychiatry 2001;58:510512.CrossRefGoogle ScholarPubMed
Bellivier, F, Golmard, JL, Rietschel, M, Schulze, TG, Malafosse, A, Preisig, M, et al.Age at onset in bipolar I affective disorder: further evidence for three subgroups. Am J Psychiatry 2003;160:9991001.CrossRefGoogle ScholarPubMed
Blader, JC, Carlson, GA. Increased rates of bipolar disorder diagnoses among US child, adolescent, and adult inpatients, 1996–2004. Biol Psychiatry 2007;62:107114.CrossRefGoogle Scholar
Brown, AS, van Os, J, Driessens, C, Hoek, HW, Susser, ES. Further evidence of relation between prenatal famine and major affective disorder. Am J Psychiatry 2000;157:190195.CrossRefGoogle ScholarPubMed
Burke, KC, Burke, JD Jr., Rae, DS, Regier, DA. Comparing age at onset of major depression and other psychiatric disorders by birth cohorts in five US community populations. Arch Gen Psychiatry 1991;48:789795.CrossRefGoogle ScholarPubMed
Chen, WJ, Faraone, SV, Orav, EJ, Tsuang, MT. Estimating age at onset distributions: the bias from prevalent cases and its impact on risk estimation. Genet Epidemiol 1993;10:4359.CrossRefGoogle ScholarPubMed
Chengappa, KN, Kupfer, DJ, Frank, E, Houck, PR, Grochocinski, VJ, Cluss, PA, et al.Relationship of birth cohort and early age at onset of illness in a bipolar disorder case registry. Am J Psychiatry 2003;160:16361642.CrossRefGoogle Scholar
da Silva Magalhães, PV, Gomes, FA, Kunz, M, Kapczinski, F. Birth cohort and dual diagnosis effects on age at onset in Brazilian patients with bipolar I disorder. Acta Psychiatr Scand 2009;120:492495.CrossRefGoogle ScholarPubMed
Di Maggio, C, Martinez, M, Ménard, JF, Petit, M, Thibaut, F. Evidence of a cohort effect for age at onset of schizophrenia. Am J Psychiatry 2001;158:489492.CrossRefGoogle ScholarPubMed
Fraley, C, Raftery, AE. How many clusters? Which clustering methods? Answers via model-based cluster analysis. Comput J 1998;41:578588.CrossRefGoogle Scholar
Fraley, C, Raftery, AE. Model-based clustering, discriminant analysis, and density estimation. J Am Stat Assoc 2002;97:611631.CrossRefGoogle Scholar
Fraley, C, Raftery, AE, Scrucca, L MCLUST: normal mixture modeling for model-based clustering, classification, and density estimation. 2013. R package version 4.2; 2013, http://www.stat.washington.edu/mclust/.Google Scholar
Geddes, JR, Miklowitz, DJ. Treatment of bipolar disorder. Lancet 2013;381:16721682.CrossRefGoogle ScholarPubMed
Gershon, ES, Hamovit, JH, Guroff, JJ, Nurnberger, JI. Birth cohort changes in manic and depressive disorders in relatives of bipolar and schizoaffective patients. Arch Gen Psychiatry 1987;44:314319.CrossRefGoogle ScholarPubMed
González Pinto, A, Barbeito, S, José Díaz, F, Vega, P, Mosquera, F, López, P, et al.Age at onset in bipolar I disorder: two may be better than three subgroups. Rev Psiquiatr Salud Ment 2009;2:2934.CrossRefGoogle ScholarPubMed
Grigoroiu-Serbanescu, M, Nothen, M, Propping, P, Poustka, F, Magureanu, S, Vasilescu, R, et al.Clinical evidence for genomic imprinting in bipolar I disorder. Acta Psychiatr Scand 1995;92:365370.CrossRefGoogle ScholarPubMed
Hamshere, ML, Gordon-Smith, K, Forty, L, Jones, L, Caesar, S, Fraser, C, et al.Age at onset in bipolar I disorder: mixture analysis of 1369 cases identifies three distinct clinical subgroups. J Affect Disord 2009;116:2329.CrossRefGoogle Scholar
Hardt, J, Franke, P. Validity, reliability and objectivity of the family history method in psychiatry: a meta-analysis. Eur Psychiatry 2007;22:4958.CrossRefGoogle ScholarPubMed
Healy, D. The latest mania: selling bipolar disorder. PLoS Med 2006;3:e185.CrossRefGoogle ScholarPubMed
Heimbuch, RC, Matthysse, S, Kidd, KK. Estimating age of onset distributions for disorders with variable onset. Am J Hum Genet 1980;32:564574.Google ScholarPubMed
Johnson, RA, Gerstein, DR. Initiation of use of alcohol, cigarettes, marijuana, cocaine, and other substances in US birth cohorts since 1919. Am J Public Health 1998;88:2733.CrossRefGoogle ScholarPubMed
Joyce, PR, Oakley-Browne, MA, Wells, JE, Bushnell, JA, Hornblow, AR. Birth cohort trends in major depression: increasing rates and earlier onset in New Zealand. J Affect Disord 1990;18:8389.CrossRefGoogle ScholarPubMed
Karasz, A. Cultural differences in conceptual models of depression. Soc Sci Med 2005;60:16251635.CrossRefGoogle ScholarPubMed
Kesternich, I, Siflinger, B, Smith, JP, Winter, JK. The effects of world war II on economic and health outcomes across Europe. Rev Econ Stat 2014;96:103118.CrossRefGoogle ScholarPubMed
Klerman, GL, Weissman, MM. Increasing rates of depression. JAMA 1989;261:22292235.CrossRefGoogle ScholarPubMed
Kupfer, DJ, Frank, E, Grochocinski, VJ, Cluss, PA, Houck, PR, Stapf, DA. Demographic and clinical characteristics of individuals in a bipolar disorder case registry. J Clin Psychiatry 2002;63:120125.CrossRefGoogle Scholar
Lasch, K, Weissman, M, Wickramaratne, P, Livingston Bruce, M. Birth cohort changes in the rates of mania. Psychiatry Res 1990;33:3137.CrossRefGoogle ScholarPubMed
Lin, PI, McInnis, MG, Potash, JB, Willour, V, MacKinnon, DF, DePaulo, JR, et al.Clinical correlates and familial aggregation of age at onset in bipolar disorder. Am J Psychiatry 2006;163:240246.CrossRefGoogle ScholarPubMed
Magee, WJ, Eaton, WW, Wittchen, HU, McGonagle, KA, Kessler, RC. Agoraphobia, simple phobia, and social phobia in the National Comorbidity Survey. Arch Gen Psychiatry 1996;53:159168.CrossRefGoogle ScholarPubMed
Manchia, M, Lampus, S, Chillotti, C, Sardu, C, Ardau, R, Severino, G, et al.Age at onset in Sardinian bipolar I patients: evidence for three subgroups. Bipolar Disord 2008;10:443446.CrossRefGoogle ScholarPubMed
Nivoli, AM, Murru, A, Pacchiarotti, I, Valenti, M, Rosa, AR, Hidalgo, D, et al.Bipolar disorder in the elderly: a cohort study comparing older and younger patients. Acta Psychiatr Scand 2014;130:364373.CrossRefGoogle ScholarPubMed
Ortiz, A, Bradler, K, Slaney, C, Garnham, J, Ruzickova, M, O’Donovan, C, et al.An admixture analysis of the age at index episodes in bipolar disorder. Psychiatry Res 2011;188:3439.CrossRefGoogle ScholarPubMed
Perlis, RH, Miyahara, S, Marangell, LB, Wisniewski, SR, Ostacher, M, DelBello, MP, et al.Long-term implications of early onset in bipolar disorder: data from the first 1000 participants in the systematic treatment enhancement program for bipolar disorder (STEP-BD). Biol Psychiatry 2004;55:875881.CrossRefGoogle Scholar
Phelan, JC, Link, BG, Stueve, A, Pescosolido, BAPublic conceptions of mental illness in 1950 and 1996: what is mental illness and is it to be feared?. J Health Soc Behav 2000;188207.CrossRefGoogle Scholar
Schou, M. Lithium treatment at 52. J Affect Disord 2001;67(1–3):2132.CrossRefGoogle ScholarPubMed
Twenge, JM. The age of anxiety? Birth cohort change in anxiety and neuroticism, 1952–1993. J Pers Soc Psychol 2000;79:10071021.CrossRefGoogle ScholarPubMed
Visscher, PM, Yazdi, MH, Jackson, AD, Schalling, M, Lindblad, K, Yuan, QP, et al.Genetic survival analysis of age at onset of bipolar disorder: evidence for anticipation or cohort effect in families. Psychiatr Genet 2001;11:129137.CrossRefGoogle ScholarPubMed
Wadsworth, ME, Kuh, DJ. Childhood influences on adult health: a review of recent work from the British 1946 national birth cohort study, the MRC National Survey of Health and Development. Paediatr Perinat Epidemiol 1997;11:220.CrossRefGoogle ScholarPubMed
Warshaw, MG, Klerman, GL, Lavori, PW. Are secular trends in major depression an artifact of recall?. J Psychiatr Res 1991;25:141151.CrossRefGoogle ScholarPubMed
Willets, RC. The cohort effect: insights and explanations. Br Actuarial J 2004;10:833877.CrossRefGoogle Scholar
Central Intelligence Agency World Factbook 2013–2014. [Accessed 8/30/14] Washington, DC: Central Intelligence Agency; 2013, http://www.cia.gov/library/publications/the-world-factbook/index.html.Google Scholar
Zeger, SL, Liang, KYLongitudinal data analysis for discrete and continuous outcomes. Biometrics 1986;42:121130.CrossRefGoogle ScholarPubMed
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Influence of birth cohort on age of onset cluster analysis in bipolar I disorder
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