Every stressful event we experience could have a major, long-lasting impact on our brains, damaging the structure and altering the function of key regions, new research reveals.
Sustained stress – also known as chronic stress – has long been assumed to carry dire cognitive consequences, leading to a number of mental disorders such as post-traumatic stress disorder. Yet the dangers of acute stress, and the impact of isolated traumatic moments, has remained largely unexplored.
The team therefore decided to observe the brains of mice after being subjected to a 40-minute episode of stress, during which they were repeatedly given an electric shock to the foot. Writing in the journal Molecular Biology, the study authors explain how this caused the release of a stress hormone called corticosterone, which in turn caused a massive increase in levels of a neurotransmitter called glutamate in a part of the brain called the prefrontal cortex (PFC).
Because glutamate is an excitatory molecule, it caused the neurons of the PFC to fire rapidly. By the time that glutamate levels began to return to normal around 24 hours later, many of these neurons had become damaged.
More precisely, the dendrites of these neurons – which are the connecting branches that contain the glutamate receptors – underwent atrophy, or cell death. This is significant because the PFC is heavily involved in higher cognition, and is essential to our ability to think rationally and make decisions.
The fact this damage remained visible for up to two weeks after the experiment suggests that even short episodes of stress can produce lasting destruction to our brains, or as the study authors put it, “the consequences of acute stress are far from being simply acute.”