depression and the dying brain

In recent years, scientists have developed a novel theory of what falters in the depressed brain. Instead of seeing the disease as the result of a chemical imbalance, these researchers argue that the brain's cells are shrinking and dying. This theory has gained momentum in the past few months, with the publication of several high profile scientific papers. The effectiveness of Prozac, these scientists say, has little to do with the amount of serotonin in the brain. Rather, the drug works because it helps heal our neurons, allowing them to grow and thrive again.

In this sense, Prozac is simply a bottled version of other activities that have a similar effect, such as physical exercise. They aren't happy pills, but healing pills.

These discoveries are causing scientists to fundamentally reimagine depression. While the mental illness is often defined in terms of its emotional symptoms - this led a generation of researchers to search for the chemicals, like serotonin, that might trigger such distorted moods - researchers are now focusing on more systematic changes in the depressed brain.

more from Boston Globe Ideas here.