Head Lines; April/May 2006; Scientific American Mind; by David Dobbs, Kaspar Mossman, Jonathan Beard, Jamie Talan, JR Minkel, Michael J. Battaglia; 6 Page(s)

In a painstaking experiment that may help revise our view of depression, a team at the Johns Hopkins University School of Medicine found that rats given Prozac did not merely experience a change in their brain chemistry but also grew new nerve fibers in mood-critical areas. This finding, which suggests that depression reflects problems of fine neural structure and not just chemistry (the prevailing model), should bolster the emerging "network hypothesis" of mood.

Over the past quarter of a century, it has become doctrine that depression is primarily a chemical issue. The prevailing model holds that depression occurs largely because shortages of the neurotransmitter serotonin in key synapses dampen mood-regulating neural signaling, opening the door to depression. But the recent results indicate that mood disorders stem at least partly from frail synaptic structures such as weak nerve endings and dead fibers, which cause signaling breakdowns.