A new analysis finds that nearly 50 percent of people who have children with a partner who suffers from schizophrenia or bipolar disorder themselves meet the criteria for a mental disorder.

The results stem from The Danish High-Risk and Resilience Study, a nationwide, representative group consisting of 522 children born to parents with schizophrenia, bipolar disorder or parents from the control group and and 872 parents participated. The parental couples were selected such that one of the parents was registered in the National Patient Register with a diagnosis of schizophrenia or bipolar disorder. Their partner and the parents from the control group were not registered with these disorders. At the time of the study, all of the parents had a seven-year-old child. 

It found a much different result for the control group; 18 percent. 

The results may indicate possible risk factors for children who grow up in families with a parent with schizophrenia or bipolar disorder.

"In the Danish registers we used, each child only had one parent registered with a mental disorder, but the diagnostic interview carried out as part of our study showed that almost half of the partners also fulfilled the criteria for such a disorder. In addition, the partners had a lower functional level compared to the control group," says Psychologist Dr. Aja Neergaard Greve. "The most frequent diagnosis among the partners was depression. We were surprised that six per cent of the partners to people with schizophrenia also met the diagnostic criteria for schizophrenia themselves. In the control group, it was only one percent."

Already at increased risk

Children born to parents with schizophrenia and bipolar disorder have an increased risk of themselves developing mental disorders - in fact, the familial risk is the highest known risk factor for later development of these disorders. If both parents have a mental disorder, the overall risk for the children increases.

"This increased risk is both genetic and environmental. Cognitive functions such as intelligence are e.g. hereditary, but if the parents have cognitive difficulties there will also be an effect on the environment the child grows up in if the parents therefore don't have the opportunity to create good stable routines and predictability or to stimulate the child sufficiently," says Greve. 

The researchers will follow the families from the study up through the child's upbringing and hope to learn more about how the children develop, as well as which factors have greatest importance for the well-being of the families.