Five seemingly different mental health disorders—major depression, bipolar disorder, schizophrenia, autism, and attention-deficit hyperactivity disorder—may be more alike than we think. A ground-breaking new study has identified four regions of the genetic code that carry same variations in people with these disorders. Two of the affected genes help control the movement of calcium in and out of brain cells. That might not sound like much, but this movement provides a key way that brain cells communicate. Subtle differences in calcium flow could cause problems that, depending on other genes or environmental factors, could eventually lead to a full-blown mental illness. But this work offers tantalizing hints that bipolar disorder, major depression, and schizophrenia—and possibly autism and attention-deficit hyperactivity disorder—may not be so distinct after all, but could be different manifestations of the same underlying disorder. This could change the way we view mental illness and open the door to more effective therapies.