Anxiety, schizophrenia, sclerosis, cardiovascular diseases: Why and how do psychological and somatic disorders occur together?

It is well-known that people with mental disorders are at an increased risk of developing further psychological and physical disorders. We also know that it is bad news for the patient's prognosis when several disorders occur at the same time.

The prevalence of several disorders at the same time, referred to as comorbidity, has previously been studied by looking at disorders in pairs – and often focused on either psychological or physical disorders. This does not account for the complex relations that occur when more psychological and physical disorders develop in the same individual.

In a new research project, Associate Professor in psychology Karen-Inge Karstoft will use network analysis of registry data to map precisely this: How multiple psychological and physical disorders in the same individual occur and affect each other over time.

The three main questions that the project will attempt to answer are:

• What disorders typically occur together, and how do they affect each other over time?
• Can psychiatric disorders predict the incidence of specific physical disorders – and vice versa?
• Can the information we find in the network analysis be used to predict future health problems and mortality?

Together with colleagues from the Capital Region of Denmark's Mental Health Services and Leiden University in the Netherlands, Karen-Inge Karstoft will draw on large amounts of data from a number of Danish national health registers – e.g. registration of diagnoses, hospitalisations, prescriptions, and cause of death.

The hope is that the project will contribute important knowledge about comorbidity that can be used in preventive work.

The project ‘Comorbidity networks of mental disorders and general medical conditions’ is supported by a so-called Inge Lehmann grant of DKK 2,776,932 from the Independent Research Fund Denmark (see the box).