Gene therapy may one day be a viable(実行可能な)treatment for depression. In a recent study, researchers were able to correct a genetic defect in mice that has been linked to depression in humans. It appears that people with depression have lower levels of the p11 gene in an area of the brain known as the nucleus accumbens. When mice with this same deficiency were injected with a virus modified to restore normal p11 levels, their behavior - which had previously been similar to that of depressed humans - became indistinguishable from that of normal mice.