Acknowledgements

This work was carried out in conjunction with the Department of Psychiatry and the Department of Public Health Science & General Practice at the University of Oulu. During this study I have had cause to draw upon the knowledge, expertise, and experience of numerous friends and co-workers, acknowledged below, without whom this study would not have been completed so easily.

I wish to express my sincere gratitude to Professor (emerita) Paula Rantakallio and to Professor Marjo-Riitta Järvelin, Department of Public Health Science & General Practice, University of Oulu, for making it possible to use the valuable data, represented by the Northern Finland 1966 Birth Cohort, as a basis for this study.

I am indebted to Professor Matti Isohanni, Department of Psychiatry, University of Oulu, for creating the environment for me to successfully carry out this study, and to Docent Juha Moring, Head of the Department of Psychiatry, Oulu University Hospital, for additional facilities and financial support.

I am most grateful to my supervisor Professor Pirkko Räsänen, for her help and support during all these years I was engaged in this work. She has been the most influential teacher of mine, helping me to learn logical and critical ways of thinking with regard to all aspects of scientific research.

It is my pleasure to thank Professor Juha Kinnunen, Department of Health Policy and Management, University of Kuopio, for introducing me to the interesting world of research and serving as an additional supervisor of this thesis.

I am very grateful to the official referees of the dissertation and thank Professor Jari Tiihonen, Department of Psychiatry, University of Helsinki, and Professor Hasse Karlsson, Department of Psychiatry, University of Helsinki, for their constructive criticism and valuable advice, which helped me to improve the thesis.

I am extremely happy to acknowledge the support I received from my collaborator and statistics expert Helinä Hakko, Ph.D.: her never-failing interest in discussing all the challenges within the context of scientific research and her aptitude for helping out in research-related tasks, no matter how great, were of great support.

I owe my warmest thanks to my co-worker and statistician Jari Jokelainen M.Sc., for his help in the areas of statistics and scientific writing.

It is with deep gratitude that I acknowledge Docent Sylvi Silvennoinen-Kassinen, Department of Medical Microbiology, University of Oulu, for teaching me and sharing with me her experience in the field of immunology.

I am also grateful to Professor Victor Benno Meyer-Rochow, for not only revising the language of the original publications and this thesis, but also for having been a collaborator and co-author in the original papers III and IV.

I am thankful to statistician Jouko Miettunen, M.Sc, for his skilful assistance in the area of statistical knowledge regarding the original publication I and in various of our other projects.

I must not forget to thank my co-authors Anne Herva, M.D., Juha Karvonen, M.D., Outi Peltola (née Koskinen), M.D., Baizhuang Xu, M.D., Ph.D., and Paavo Zitting M.D., for the contributions they have made to some of our joint publications. Furthermore I am grateful to Docent Arto Lahti, who read the original publications III and IV, and provided constructive support during the process related to the submission of these papers.

I am indebted to Ms. Kaisa Viilo, B.Sc., for her skilful and competent graphic design and for checking the layout of my thesis.

The whole staff of the Department of Psychiatry, University of Oulu, is gratefully acknowledged for having created a pleasant and collaborative atmosphere. I am especially thankful to Ms. Pirkko Kaan for assisting to locate pertinent literature, and to Ms. Minna Lakkapää, Mr. Otto Moilanen, Ms. Raija Anttonen, and Ms. Helena Vörlin for their excellent secretarial assistance.

I owe thanks to application designer Markku Koiranen and Ms. Tuula Ylitalo, Department of Public Health Science & General Pracitce, University of Oulu, for their excellent assistance regarding publication procedures of the original paper.

I acknowledge a deep indebtedness to Seppo Voutilainen, M.D., the Director of Health Cervices of City of Oulu, for having allowed me to take leave of absence from my position at the Oulu Health Center during the last year of this project, so that I could finish my thesis.

The following foundations are acknowledged for having provided financial support for this study: Allergiatutkimussäätiö (The Foundation of Allergy Research), the Research Foundation of Orion Corporation, the Finnish Psychiatric Association, the Foundation for Psychiatric Research in Finland, the Oulu University Scholarship Foundation, and the Research Foundation of Oy H. Lundbeck Ab.

All my friends are kindly thanked for their unfailing support towards my research. My special thanks go to psychiatrist and psychotherapist Petri Karttunen, M.D., for inspiring conversations about science, art, spirituality, and about life in general.

My most profound thanks go to my parents, Anna-Liisa and Esko, who have not only constantly encouraged me in the pursuit of my studies, but have also provided invaluable help through child-minding during this project.

My heartfelt thanks go to my wife Merja, who has shared with me the pressures associated with a project like this, and who has supported me throughout the latter and better half of my life. Finally, I am especially grateful to our children Moona and Tatu for having given me a break in my brain work ever so often, so that I had an opportunity to experience aspects of life beyond science. I dedicate this work to you.

Vesala, Ylikiiminki, September 2003 Markku Timonen