Schizophrenia remains a poorly understood mental illness that impacts perception and cognition. It affects approximately one out of 100 individuals and leads to much suffering in the affected individuals and their relatives. Schizophrenia is associated with a substantial disability and has huge economic costs for society.

Access to various Danish registers has allowed researchers to document key risk factors associated with schizophrenia and other mental disorders. The risk factors associated with schizophrenia includes e.g. psychiatric family history, urban birth, paternal age, lifetime risk, infections, socio-economic adversity, and neonatal vitamin D deficiency. Furthermore, researchers at NCRR have studied different outcome measures associated with schizophrenia, such as treatment resistant schizophrenia, suicide, excess mortality, and pharmacological treatment.

Researchers at NCRR are currently involved in projects investigating the genetic background of schizophrenia. Through iPSYCH and together with international colleagues, they have identified some of the genetic variants that may increase the risk of developing schizophrenia. This research has shed new light on biological processes involved in the development of schizophrenia and other mental disorders, which, in time, will have crucial preventative and clinical implications for the future treatment of people with mental illnesses.

Regarding causes of schizophrenia and other severe mental illnesses, novel methods in psychiatric research provides new opportunities to take both environment and genes into consideration. These studies will strongly benefit from the iPSYCH2012 case-cohort sample, that further enhances possibilities to combine genetic, environmental and phenotypic data in aiming at predicting the emergence and development of schizophrenia and other mental illnesses.

  • Currently, NCRR is involved in projects that examine research questions like:
  • Can levels of neonatal vitamin D that are associated with an increased risk of developing schizophrenia also be connected to an increased risk of the development of other mental illnesses?
  • What particular genetic architecture increases the risk of schizophrenia?
  • How is schizophrenia connected to the risk of gaining physical illnesses such as obesity, diabetes and infections?
  • Can we identify genes particularly associated with the risk of developing schizophrenia, and genes particularly predicting a chronic course?
  • What are the genetic similarities between schizophrenia and other mental illnesses such as affective disorders, autism and ADHD? Can we identify a genetic overlap in the various mental disorders?Pedersen CB et al. (2017) The iPSYCH2012 case-cohort sample: new directions for unravelling genetic and environmental architectures of severe mental disorders.

Further reading

Wimberley, T., et al. (2016). "Predictors of treatment resistance in patients with schizophrenia: a population-based cohort study." Lancet Psychiatry:

Agerbo, E. et al. (2015) “Polygenic risk score, parental socioeconomic status, family history of psychiatric disorders, and the risk for schizophrenia: a Danish population-based study and meta-analysis.” JAMA Psychiatry: 10.1001/jamapsychiatry.2015.0346

McGrath, J. J., et al. (2014). "A comprehensive assessment of parental age and psychiatric disorders." JAMA Psychiatry: 10.1001/jamapsychiatry.2013.4081

Petersen, L., et al. (2011). "Paternal age at birth of first child and risk of schizophrenia." Am J Psychiatry:

McGrath, J. J., et al. (2010). "Neonatal vitamin D status and risk of schizophrenia: a population-based case-control study." Arch Gen Psychiatry: 10:1001/archgenpsychiatry.2010.110

Dean, K., et al. (2010). "Full spectrum of psychiatric outcomes among offspring with parental history of mental disorder." Arch Gen Psychiatry: 10.1001/archgenpsychiatry.2010.86

Pedersen, C. B. and P. B. Mortensen (2006). "Why factors rooted in the family may solely explain the urban-rural differences in schizophrenia risk estimates."Epidemiologia E Psichiatria Sociale:

Pedersen, C. B. (2006). "No evidence of time trends in the urban-rural differences in schizophrenia risk among five million people born in Denmark from 1910 to 1986." Psychol Med: 10.1017/S003329170500663X

Mortensen, P. B., et al. (1999). "Effects of family history and place and season of birth on the risk of schizophrenia." New England Journal of Medicine: 10.1056/NEJM199902253400803