Researchers predict that one day an emergency treatment will emerge that can halt much of the damage resulting from a traumatic brain injury.

For years scientists assumed that the brain damage resulting from a head injury occurred in a split second, that nerve cells were killed in the initial impact.

But over the past decade researchers have learned that much of the injury to brain cells occurs in slow motion. They now know that the initial injury — whether it’s from a car wreck, a fall or a blow to the head — sets off a sequence of events that takes anywhere from hours to days to complete. In fact, scientists now say traumatic brain injury, or TBI, sets processes in motion that continue throughout a person’s life.

Beyond the bruising that occurs when the brain slams up against the skull, damage is caused by the brain’s own reaction to the trauma:

* Hosts of brain chemicals are released. And while these neurotransmitters are normally present in small amounts in the brain, the flood resulting from a TBI fries brain circuits, says Dr. Douglas H. Smith, director of the Center for Brain Injury and Repair at the University of Pennsylvania.
* Meanwhile, another kind of damage occurs as individual nerve cells stretch and twist. Rips form in the axons — long, slender, cablelike structures that project from the center of the nerve cell and carry information to the cell’s body.
* When an axon rips open, chemicals rush in and cause it to swell. Proteins released in response to the tearing can chew the cell up from the inside out, leading to its eventual destruction.

Recent research shows these processes can lead to long-term brain injury that looks very much like the damage associated with Alzheimer’s disease.

But the damage isn’t inevitable, experts say.

Scientists are working to identify a chemical — or a cocktail of chemicals — to slow or halt these secondary effects of TBI.

So far, nothing’s panned out. While certain medications seemed to help in animal studies, they haven’t worked when tested in humans, says Dr. Douglas I. Katz, medical director of the Traumatic Brain Injury Program at Braintree Rehabilitation Hospital in Braintree, Mass.

Still, Katz says, “I think there will be something in the next five to 10 years.”

It's likely any such therapy would have to be given right away, much like the treatments given to minimize the brain damage suffered by stroke victims.

In the meantime, studies have shown that certain drugs, which are already on the market, can be used to improve the functioning of injured brains, says Katz, also an associate professor of neurology at Boston University School of Medicine.

Stimulants can speed mental processing and a drug used to treat Alzheimer’s disease can sharpen memory and improve attention. And certain medications that have been used to treat depression appear to improve a TBI patient’s ability to reason and make judgments.

As it turns out, these types of medications “appear to enhance brain function in normal people,” Katz explains. “So they may just be tuning the brain up and thus helping compensate for deficits in patients with brain damage.”