The image isn't easily eradicated from memory -- malcontent Randall McMurphy (Jack Nicholson) writhing in agony while undergoing shock treatment in 1975's "One Flew Over the Cuckoo's Nest." Yet shock treatment -- or electroconvulsive therapy (ECT), as its practitioners dub it -- isn't barbaric, as that classic movie moment might have us believe.

The procedure, which involves sending electric currents through a patient's brain to alleviate severe depression, is conducted with considerable safety precautions. Patients are anesthetized and given muscle relaxants to prevent their bodies from thrashing about. Experts say it is an effective way to treat seriously depressed patients and those in acute manic states.

Yet some former ECT patients say the treatments are, in a way, just as horrific as they are portrayed in the Oscar-winning "Cuckoo's Nest." They point to significant memory loss as the price they paid for enduring the therapy.

Even those who favor ECT are left scratching their heads over precisely why it works.

"It's been talked about since it came into being in 1938," says Dr. Frank Moscarillo, a Chevy Chase physician who administers ECT. "It's only a stimulus to a grand mal seizure. Why in the world that should help depression, we don't know."

Doctors first incorrectly believed that instigating seizures in a schizophrenic patient would negate that condition.

Modern ECT involves a series of six to 12 treatments that pass electric currents through the brain via two electrodes placed along the skull.

"It's the single most effective treatment for delusional depression," says Dr. Moscarillo, who also serves as executive director of the Association for Convulsive Therapy, an international group with just under 400 members worldwide that, in part, gives credentials to psychiatrists to use ECT.

Successful ECT sessions yield a break in a patient's depression, a lifting of the dark veil that can induce suicidal thoughts. Side effects can include temporary confusion and short-term memory loss of events around the time of the treatment.

ECT, even at its most effective, only tackles the current depression. It does not necessarily preclude future depressive episodes. Some patients undergo maintenance treatments once every six weeks or so to sustain their depression-free state.

ECT can be conducted through unilateral or bilateral application of electrodes. The former places the electrodes on the right temple and right vertex of the skull and is less likely to affect memory. Bilateral application affixes electrodes on both sides of the skull.

A newer process, what Dr. Moscarillo calls bifrontal, places the electrodes farther down the face, away from the brain. This seems to spare the temporal lobe and is less damaging to short-term memory.

Convincing patients that electroconvulsive therapy can help them isn't always easy, Dr. Moscarillo says. "There is a stigma, no question about it," he says. "They're fearful of it though they don't know about it."

"Sam," a 59-year-old Arlington resident who asked that his name not be revealed, turned to ECT in 1999 when an approaching retirement intensified his lifelong battle with depression.

"My wife had some fear I might commit suicide," says Sam, who eventually came under Dr. Moscarillo's care.

"I remembered my aunt had [ECT] in the early '50s, and the way it sounded was terrible," he says, "but I was in no state to object."

With his wife's consent, Sam underwent about 20 treatments, the last in July 2000.

"Maybe it doesn't work for some people, but these new pills don't work for everybody, either," says Sam, who battled memory problems before the treatments. "Looking back, I'm certain I did the right thing."

Some contend depressed patients have every right to fear ECT.

Dr. Peter Breggin, author of "The Anti-Depressant Fact Book: What Your Doctor Won't Tell You About Prozac, Zoloft, Paxil, Celexa, and Luvox," says the therapy works by "damaging the brain ... rendering the patient unable to feel depressed" or experience "any other subtle human emotion."

The seizures induced are more profound than typical epileptic seizures, Dr. Breggin says. Without the muscle relaxants, a patient could snap his or her bones during the body's thrashing.

"If a woman got an electric shock from her refrigerator, they'd whisk her off to the [Intensive Care Unit]," says the Bethesda doctor, who isn't sure why ECT seizures should require a different response.

Some patients may not speak out against the procedure because they can't, he says. "Closed-head injuries produce an inability to evaluate one's condition.

"It's indicative of the abusive history of my profession," he says, adding that early in the 20th century, "they might give the whole [mental] ward shock treatments. It tends to make people more docile."

Elderly patients often are convinced ECT can be of help, he says.

"It's a moneymaker; it keeps the wards going," he says. "Insurance companies don't question it."

Dr. Lenore Teter, medical director of George Washington Hospital's psychiatric unit, disputes the "cash cow" charge.

"I think that's the most absurd statement. If this person only knew ... how grateful people are when they get better," Dr. Teter says. "It's a very inexpensive treatment, as far as treatments go," she adds, estimating a session's price tag to be about $1,500, including ECT, anesthesia and hospital fees.