The Finnish Adoptive Family Study of Schizophrenia: differences in somatic diseases and conditions between adoptees with high or low genetic risk for schizophrenia spectrum disorders

Abstract

Background and aims

There is some evidence that offspring of patients with schizophrenia have higher somatic morbidity, which is thought to be partially due to genetic links between somatic disorders and schizophrenia. This study explored differences in somatic diseases and conditions of adoptees with high genetic risk (HR) or low genetic risk (LR) for schizophrenia spectrum disorders.

Material and methods

The study is part of the Finnish Adoptive Family Study of Schizophrenia. The adoptive research design used made it possible to examine how the somatic health of adoptees raised in similar adoptive families, is affected by their genetic susceptibility to schizophrenia. The study sample consisted of 373 adoptees, of whom 190 had HR and 183 had LR for schizophrenia spectrum disorders. Data on somatic morbidity were gathered from the hospital records and from the national registers of the Care Register of Health Care and the Social Insurance Institution.

Results

The only statistically significant difference found was in genitourinary diseases, the likelihood being twofold higher in HR adoptees compared to LR adoptees (16.8% vs. 8.2%; adj. OR = 2.13, 95% CI 1.06–4.25, p = .033). Adoptees who were female and aged over 40 had a higher prevalence of genitourinary illnesses than non-adoptees.

Conclusion

The significant prevalence of genitourinary diseases in adoptees at risk for schizophrenia spectrum disorders suggests that some specific somatic diseases and schizophrenia may have a shared hereditary etiology. More research is required for specific somatic diseases in study populations that can differentiate between the effects of genetic and environmental factors.

Keywords:

• Schizophrenia spectrum disorder
• genetic liability
• somatic morbidity
• adoption study
• genitourinary diseases

Acknowledgements

We express our gratitude to all those who have contributed to the Finnish Adoptive Study of Schizophrenia both during the data collection and the analysis stages: the late professor Pekka Tienari, MD, PhD; the late professor Lyman C. Wynne, MD, PhD; Ilpo Lahti, MD, PhD; Mikko Naarala, MD; Anneli Sorri, MD; late Juha Moring, MD, PhD, and late Kristian Läksy, MD, PhD. In particular, we express our upmost gratitude to Kristian Läksy, who provided valuable contributions in the interpretation, collection and content of the somatic data for the adoptees, but who sadly passed away due to serious illness during the final phase of preparing this article.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data supporting these findings contain sensitive personal data and cannot be made publicly available because of restrictions imposed by Finnish data regulations and the EU’s General Data Protection Regulation (GDPR).

Additional information

Funding

This study was supported by a grant from ITLA Children’s Foundation (researcher MN), and Strategic Research Council (SRC) established with in the Academy of Finland, Decision Number 352509 (researchers MN and HH), and by financial support for research from the Department of Psychiatry of Oulu University Hospital, Finland.

Notes on contributors

Emma Karjalainen

Emma Karjalainen, MD, is a licensed General Practitioner working in the Wellbeing Services County of Northern Ostrobothnia, Finland.

Mika Niemelä

Mika Niemelä, PhD, is a Professor of Practice at the University of Oulu, Faculty of Medicine, Research Unit of Population Health, Finland.

Helinä Hakko

Helinä Hakko, PhD, is a Biostatistician working at the Wellbeing Services County of Northern Ostrobothnia, Oulu University Hospital, Department of Psychiatry, Finland, and a Senior Researcher at the University of Oulu, Faculty of Medicine, Research Unit of Population Health, Finland.

Karl-Erik Wahlberg

Karl-Erik Wahlberg, PhD, is Professor (emeritus) in Psychotherapy at the University of Jyväskylä, Finland, and an Adjunct Professor of Medical Psychology and Family Therapy at the University of Oulu, Faculty of Medicine, Research Unit of Clinical Medicine, Finland.

Sami Räsänen

Sami Räsänen, MD, PhD, is currently a Professor in Psychiatry at the University of Oulu, Faculty of Medicine, Research Unit of Clinical Medicine, Finland, and a Chief Physician at the Wellbeing Services County of Northern Ostrobothnia, Oulu University Hospital, Department of Psychiatry, Finland.