As we reported recently, scientists have found some common genetic traits shared between mental disorders like autism, schizophrenia, and depression, a massive finding that could help with diagnoses and treatments in the future. But another thing this remarkable study shows is just how incredibly different such disorders are from diseases of the brain like Alzheimer’s, and how huge this could be for people who do not know they have a problem.

In the study, scientists measured the RNA in 700 tissue samples from people with mental disorders ranging from major depression, alcoholism, bipolar disorder, schizophrenia, and autism, to name a few. They then compared those samples with samples from a group of people who did not have such disorders, and found that there seemed to be some common genetic expressions shared between them.

The difference between such mental disorders and diseases of the brain like Parkinson’s and Alzheimer’s is the latter actually causes physical damage to the brain, whereas the former tend to only manifest themselves in the form of behavior that is not so easy to spot. As a result, this finding could help us spot many thousands, or even millions, more people who have such disorders that do not even realize they have it.

“These findings provide a molecular, pathological signature of these disorders, which is a large step forward,” said senior author Daniel Geschwind, a distinguished professor of neurology, psychiatry and human genetics and director of the UCLA Center for Autism Research and Treatment. “The major challenge now is to understand how these changes arose.”