Family history can play a vital role in predicting the severity of mental disorder, claim researchers from Duke Institute for Genome Sciences and Policy (IGSP),
They suggest that just 30 minutes or less of question-and-answer about the family history of depression, anxiety, or substance abuse is enough to predict a patient's approximate risks for developing each disorder, and how severe their future illness is likely to be.
"There are lots of kids with behaviour problems who may outgrow them on their own without medication, versus the minority with mental illnesses that need treatment," said Terrie Moffitt, a professor of psychology and neuroscience in the IGSP.
"Family history is the quickest and cheapest way to sort that out," she added.
Co-researcher Avshalom Caspi, professor of psychology and neuroscience, added that researchers searching for genes responsible for mental disorders might also take advantage of the discovery.
During the study, the researchers examined 981 New Zealanders, who were a part of Dunedin Study.
They tested each individual's personal experience with depression, anxiety, alcohol dependence and drug dependence in relation to their family history "scores" - the proportion of their grandparents, parents and siblings over age 10 who were affected.
The analysis shows that family history can predict a more recurrent course of each of the four disorders. It is also indicative of those more likely to suffer a worse impairment and to make greater use of mental health services.
Family history could be used to identify those in need of early intervention or more aggressive treatment.
The findings appear in the Archives of General Psychiatry.