There are about 2 million Americans who suffer from Traumatic Brain Injuries (TBI) annually. The severity of the trauma may differ from patient to patient but leads to a wide range of motor, behavioral, cognitive as well as intellectual disabilities in the patients. These disabilities may be long term or short term. TBI is a global health concern and despite the huge number of injuries, the treatment options are limited.
There have been many treatments and studies that suggested excessive burst of new brain cells after TBI helped in the recovery of the patients better. Breaking this common assumption, Dr. Viji Santhakurmar (Associate Professor in the Department of Pharmacology, Physiology and Neuroscience, Rutgers University) and her colleagues proved otherwise with their report. They challenged this assumption and found that an excessive neurogenesis may, in fact, lead to memory decline, seizures.
Neurogenesis aftera a Brain Injury May Lead to Memory Decline, Seizures
It has been proposed that increase in neurogenesis aids in the repair of the injured brain network. However, survivors of a traumatic brain injury often develop life-changing disorders such as a decrease in memory as well as epileptic seizures.
Researchers found there was a considerate increase in the new nerve cell growth (neurogenesis) that was probably to help replace the damaged or destroyed brain cells. However, Santhakumar and her colleagues found evidence contradictory to the popular belief. They found the spike in brain cell growth may, in fact, lead to post-injury seizures and long-term memory decline.
This team from Reuters University examined brain injuries in lab rats and found that brain cells at the injury site play an important role. These cells double in number within 3 days after injury; however, they decrease by more than half after a month as compared to rats with no brain injury. The neural stem cells develop into mature cells too showed a similar increase and decrease pattern. Thus, proving they were responsible for the loss of brain cells.
As quoted by Professor Viji Santhakumar in a press release, "There is an initial increase in birth of new neurons after a brain injury but within weeks, there is a dramatic decrease in the normal rate at which neurons are born, depleting brain cells that under normal circumstances should be there to replace damaged cells and repair the brain's network. The excess new neurons lead to epileptic seizures and could contribute to cognitive decline. It is normal for the birth of new neurons to decline as we age. But what we found in our study was that after a head injury the decline seems to be more rapid."
According to the study, post-injury changes in the development of new cells along with the neural precursor cell proliferation led to a long-term decline in the neurogenic capacity. When the post-injury neurogenesis was reduced early on resulted in dentate excitability and seizure susceptibility.
To achieve this goal of slowing down nerve cell growth after injury, researchers used anti-cancer drugs that are under clinical trials currently. These drugs are known to block the growth and survival of new nerve cells. The drugs were able to stop the rapid proliferation of the nerve cells and prevented the long-term decline in brain cells that lead to memory decline in lab rats. It also showed the rats had reduced risk of seizures after administration of these drugs.
Dr. Santhakumar says that they believe in limiting the process of rapid growth of nerve cells will prove to be helpful in stopping the seizures after a brain injury.
These findings spark hope for those with TBI that one day these methods will definitely help in reducing the short-term and long-term symptoms that alter the life of the patients after a challenging injury to the brain.