Although it is known that long-term or chronic stress can affect the brain’s learning and memory region, a new finding discovers short-term stress, lasting as little as a few hours, can also impair brain-cell communication in these critical areas.
“Stress is a constant in our lives and cannot be avoided,” said Dr. Tallie Z. Baram, the Danette Shepard Chair in Neurological Sciences in the UC Irvine School of Medicine and study leader. Stress is a response by the body to a threat in the environment, or some sort of mental or psychological demand that exceeds a person’s ordinary capacity. The stress response is also known as the “fight or flight” response.
“Our findings can play an important role in the current development of drugs that might prevent these undesirable effects and offer insights into why some people are forgetful or have difficulty retaining information during stressful situations.”
In their study, Baram and her UC Irvine colleagues identified a novel process by which stress caused these effects. They found that rather than involving the widely known stress hormone cortisol, which circulates throughout the body, acute stress activated selective molecules called corticotropin releasing hormones, which disrupted the process by which the brain collects and stores memories.
Learning and memory take place at synapses, which are junctions through which brain cells communicate. These synapses reside on specialized branchlike protrusions on neurons called dendritic spines.
In rat and mouse studies, Baram’s group saw that the release of CRH in the hippocampus, the brain’s primary learning and memory center, led to the rapid disintegration of these dendritic spines, which in turn limited the ability of synapses to collect and store memories. It is not entirely clear how the synapses store information.
The researchers discovered that blocking the CRH molecules’ interaction with their receptor molecules eliminated stress damage to dendritic spines in the hippocampal cells involved with learning and memory.
In addition, the authors replicated the effects of stress on dendritic spines by administering low levels of synthetic CRH, and watching how the spines retracted over minutes. “Fortunately, once we removed the CRH, the spines seemed to grow back,” Baram said.
It’s not clear whether the findings from this research will translate to humans, or how the human brains works, which is far more complex and difficult to study.
Baram also noted that there are compounds under development that show the ability to block CRH receptors, and that this study can play a role in the creation of therapies based on these compounds to address stress-related learning and memory loss.
Stress is neither good nor bad. It is simply the body’s response to a situation in which the body is trying to protect you. It can be overwhelming if a person is not equipped to deal with stress, or uses methods which are more harmful than beneficial. Stress can help provide a person motivation to meet challenges in the environment or a person’s life.
The study by University of California, Irvine researchers appeared in the March 2008 edition of the Journal of Neuroscience.
Source: University of California – Irvine