Four genetic variants appeared to increase the risk of all five disorders studied. Two genes were involved in the balance of calcium in the brain, the BBC reported.
Hundreds of genes and the environment are likely to affect the odds of developing such conditions. However, the rapidly advancing field of psychiatric genetics is trying to describe these disorders on the basis of what is causing them, rather simply by symptoms.
Nick Craddock, a professor of psychiatry at Cardiff University, said it signals the opening of a potential new era for psychiatry.
This is a scientific method that helps understand what is going wrong in the brain, the chemicals that are important in illness, he said.