For cognitive and functional recovery after a stroke or traumatic brain injury, a longer, even more intense period of rehabilitation might improve the brain’s ability to repair and restructure itself, according to a new animal study that also confirmed the importance of intensive rehab.
Researchers at the University of California, San Diego School of Medicine found rats with cortical injury that did not receive intensive rehab did not rebuild brain structure or recover function — while also learning a longer, even more intense period of rehabilitation might amplify the benefits.
“This has implications for medical practice and medical insurance,” senior study author Mark Tuszynski, MD, PhD, said in a news release. Tuszynski is a professor in the neurosciences department and director of the Center for Neural Repair at UC San Diego School of Medicine and a neurologist with the VA San Diego Healthcare System.
“Typically, insurance supports brief periods of rehab to teach people to get good enough to go home,” he said in the release. “These findings suggest that if insurance would pay for longer and more intensive rehab, patients might actually recover more function.”
Findings were published in the Feb. 22 online early edition of Proceedings of the National Academy of Sciences. In recent years, past studies have documented the surprising plasticity or ability of the adult central nervous system to recover from injury. Researchers continue to explore how to best encourage the repair and regrowth of damaged nerve cells and connections.
To better understand what happens at the molecular and cellular levels and how rehabilitation might be made more effective after brain injury, the team studied rats relearning skills and physical abilities. They found rats that received intensive therapy for an extended period of time showed significant restructuring of the brain around the damage site: Surviving neurons sprouted greater numbers of dendritic spines, which made more connections with other neurons. The result, Tuszynski said in the release, was a dramatic 50% recovery of function.
Animals that did not undergo intensive rehabilitation did not rebuild brain structure or recover function.
The researchers also found a key system in the brain — the basal forebrain cholinergic system — is critical to rehabilitation. Structures in this part of the brain, such as the nucleus basalis, produce acetylcholine, a chemical released by nerve cells to send signals to other cells. Specifically, motor neurons release acetylcholine to activate muscles.
Damage to the cholinergic system, which can occur naturally during aging, completely blocks brain plasticity mediated by rehabilitation and significantly reduces functional recovery. According to Tuszynski, the finding suggests a class of drugs called cholinesterase inhibitors, which boost the levels and persistence of acetylcholine and are used in some treatments for Alzheimer’s disease, might further improve functional outcomes after brain injury.
“We did not try to do this in our study,” Tuszynski said in the release, “but we did suggest future studies could be done to look at this possibility.”
Co-authors include Ling Wang, James M. Conner and Alan H. Nagahara, all of UC San Diego. The study was funded by the National Institutes of Health, the Veterans Administration and the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation.