BOSTON -- Imagine that you have arrived at the emergency room after a horrific car crash. The doctor in charge offers you two pills. One will relieve the inflammation of whiplash. The other will reduce the psychological trauma, muting the nightmarish flashback to a manageable memory.

Would you take one? Would you take both? Is there any difference?

Imagine that a child came to the hospital after being raped or abused. Should she be given a pill if it would prevent the trauma from literally changing the anatomy of her brain and setting her up for a lifetime of vulnerability?

And finally, what about a soldier just back from battle? Should he be treated with medicine that helps dim the effect of the horrors he has experienced?

These are not idle science fictions. Once we drew a bright line between the pain of the body and the mind, between treatments for physical and mental illness. Now researchers are into the chemistry of emotions, the biology of feelings, the anatomy of psychology.

It appears that memories of shocking events may be like water -- an overwhelming flood or a manageable stream. And scientists may be designing chemical faucets.

Last week, a meeting of traumatic stress specialists heard that a common hypertension drug may help prevent post-traumatic stress disorder (PTSD). If the human trials pan out, it could keep a wrenching experience from being burned too deeply in memory.

There is research, as well, on treatments designed to interrupt the way a painful event can change the brain. And there is also talk of gene therapies that might make vulnerable people react to emotional injuries like resilient people.

What are we to make of this? The goal is simple and uncontroversial. Roger Pitman of Harvard Medical School, who is doing research in this field, says, "I look at it from a medical perspective. We intervene in diseases and disorders to make people more comfortable and to reduce suffering."

Fair enough. A bad memory can be as crippling as a bad back or heart. PTSD is not trivialized by those who live with it or treat it. Dr. Pitman repeats the words of veterans he has treated: "One said to me, 'If Vietnam was only a memory I would be OK. It's more than a memory. It's happening again.'" If we can heal that, we should.

I don't romanticize mental illness. But what will happen if we are able to lighten the load of memory? Would we end up with a drug to make loss "lite," to speed up "closure," to make horror "manageable"? At some point reducing human suffering is editing human experience. For better or for worse.

I remember what happened to Prozac. A drug to alleviate severe depression morphed into what is called a cosmetic pharmacology. It was used to help people feel "better than well," in a phrase made famous by Peter Kramer in Listening to Prozac. The class of drugs not only replaced counseling but was routinely prescribed by internists for patients and even by veterinarians for pets.

It's not that hard to envision PTSD preventive drugs being offered to those who witnessed a Columbine massacre or the collapse of the World Trade Center. Nor is it hard to imagine preventive drugs offered to parents who have just lost a child. Where do we draw the line?

Mr. Kramer sees benefits in helping those who are truly "overwhelmed and haunted." But he too can see abuse. "Imagine," he says, "a totalitarian, militaristic society giving it to soldiers so they will be immune to the horrors of war." And if the horrors of war or of crime are not so "horrible," wouldn't that change our attitude toward war or crime themselves?

Such worries race ahead of the research. Dr. Pitman says succinctly, "We don't want to make people happy automatons. We're not going to eliminate the horrors of war." He says that we won't know where to draw the line -- or the dosage -- until we know what medicine can do.

But it seems to me that we often find ourselves behind the research curve, playing ethical catch-up with cloning or cosmetic pharmacology after they are on the market and in the doctor's office. Now we are at the outset of treatments that could alter mind and memory and our ideas about humanity.

Today, we have to ask the questions first. And so we begin with this one: Isn't human suffering more than a matter of chemistry?

Ellen Goodman is a columnist for The Boston Globe. Her column appears Mondays and Thursdays in The Sun. She can be reached via e-mail at ellengoodman@globe.com.