India, Jan. 9 -- A large international group of scientists has helped explain why many people are diagnosed with more than one mental health disorder during their lives, according to a study published in the journal Nature.

The scientists studied genetic data from more than 6 million people, which included genetic information from over 1 million people with a diagnosed mental health disorder and about 5 million people without any diagnosis. By comparing the two groups, researchers identified genetic markers that appear more often in people with certain disorders, helping them understand the biological causes of mental illness.

Using different research methods, the team found 428 genetic changes linked to more than one disorder. They als...