According to this Reuters news article, a new study determined the drug Ketamine (also known by the street name "Special K") is effective in treating depression. The mechanism by which it effects a change in mood was also determined via the use of minute-by-minute brain scans of individuals who were administered the drug. Contrary to the expectations of the researchers, Ketamine did not impact the areas of the brain implicated in psychosis (Ketamine is an hallucinogenic drug, as well as a horse tranquilizer), but rather restored a normal level of functioning to the obifrontal cortex. The obifrontal cortex is thought to be responsible for guilt, dread, and apprehension, and in depressed individuals, the obifrontal cortex is considered to be overactive. From the article:
In their study, Deakin and his team gave intravenous ketamine to 33 healthy male volunteers and took minute-by-minute brain scans to see what was happening as the drug took effect. Images from the scans showed that the drug -- also used as a battlefield anesthetic -- worked quickly, Deakin said.
The results were surprising because the researchers had expected that the ketamine would instead affect the part of the brain that controls psychosis, he added. "There was some activity there but more striking was the switching off of the depression centre," Deakin said.
Previous research had shown that ketamine improved symptoms in depressed people after just 24 hours -- far faster than the month it can take for Prozac to kick in -- but until now they did not know exactly how.
While the results of this study sound promising, I hope there isn't any rush to get Ketamine on the market. Given its potency and initiating of psychotic symptoms, taking this slowly would seem to be a no-brainer. However, as the article mentioned, other antidepressants such as SSRIs can take a month or longer to reach a therapeutic level, and the lure of a much-faster acting antidepressant will likely spur a spate of research, with the goal to get Ketamine to market in some form. The good news out of this is that these results may lead to a better understanding of the role of the obifrontal cortex in depression, as well as providing other avenues to effect change in said cortex.