Long-term stress impairs memory, it is often claimed. Now, a new research has revealed that even short-term stress can have the same effect.
Researchers at the University of California have found that short periods of stress lasting as little as a few hours can affect brain cell communication and undermine learning as well as memory, the Journal of Neuroscience reported.
According to lead researcher Dr Tallie Z Baram of the university's School of Medicine, "Stress is a constant in our lives and cannot be avoided.
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 on rodents, the researchers 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 actually junctions via which brain cells communicate.
These synapses reside on specialised branchlike protrusions on neurons called dendritic spines.
In their research, the team found that the release of CRH in the hippocampus -- the brain's primary learning and memory centre -- led to the rapid disintegration of these dendritic spines, which in turn limited the ability of synapses to collect and store memories.
They 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 team 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," Dr Baram said.
The researchers noted in the journal 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".
