Ketamine, answer to our glutamatergic dreams. In the long November night of the soul, in the ever-dark downpour of depression, it turns out that there might be a better umbrella than Prozac and Zoloft and Paxil and their serotonin-loving ilk.

When it comes to antidepressants, nobody really knows anything, anyway, so why not go with ketamine, a mild hallucinogen known to club freaks as Special K?

Researchers at the National Institute of Mental Health announced a study recently in which 18 chronically depressed patients infused with low dosages of ketamine improved within two hours. Seventy-one percent improved within a day, and nearly 30 percent were depression-free by that time. These were people who had been dealing with depression from three to 47 years. They had failed to respond to just about every drug. Most of them stayed depression-free for up to a week.

Doesn’t it make Prozac and friends look like punks? The subsequent news stories focused on the speed—antidepressants generally take two weeks or longer to work—but the true breakthrough, scientists say, is that ketamine seems to do something entirely new. It focuses on glutamate, a chemical neurotransmitter that is involved in electrical flow among brain cells, which previously had not been targeted.

Think of depression as a leaky water faucet in the kitchen of the mind. Prozac and friends start working on the problem back at the water plant and, in about half of the cases, eventually find the problem. In this trial, glutamate (and the “glutamatergic system’’) was shown to be a wrench-toting plumber who makes house calls. It got right to the problem. “It’s not quite the director of the orchestra, but it’s involved with many other systems in the brain than other antidepressants,’’ said Carlos Zarate, chief of the mood disorders research unit at NIMH, and lead author of the study.

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