Brain scans are being used to shed light on how a genetic mutation linked to major psychiatric disorders affects the brain's structure and function.
The study, led by researchers at Edinburgh University, is said to be offering clues about how the mutation increases the risk of schizophrenia, bipolar disorder and depression.
Experts said the findings could help in the hunt for new treatments.
The study is published in the Nature partner journal Schizophrenia.
As part of the project, the team scanned the brains of people who have a specific genetic mutation that causes part of one chromosome to swap places with another.
The mutation results in disruption of a gene called DISC1, which is associated with recurrent major depression, schizophrenia and bipolar disorder.
Experts found those with the mutation had changes in the structure of their brains, changes which were ultimately linked with the severity of their symptoms of mental ill-health.
The study also showed carriers of the mutation had lower levels of the chemical glutamate in parts of their brain.
Previous studies have pointed to a strong link between reduced glutamate levels and schizophrenia.
Researchers said their findings confirm that the DISC1 mutation is associated with a "significantly increased risk" of psychiatric illness.
The mutation was first identified in a Scottish family that showed unusually high rates of major psychiatric disorders.
Scientists have been studying generations of the family for four decades but this was the first time they have scanned their brains.
Prof Stephen Lawrie, head Edinburgh University's division of psychiatry, said: "This study confirms and extends the genetics of DISC1 and shows how that and similar genetic effects can increase the risk of major mental illnesses."
The study is funded by the Translational Medicine Research Collaboration.