1. Negative stress: a trigger for illness

“Many violent offenders suffered a traumatic childhood experience,” explained Carmen Sandi, director of the Brain Mind Institute in Lausanne, Switzerland. In some way, “The brain exposed to fear and stress early on develops differently, takes different neural paths.”

According to Roser Nadal, ICREA ACADEMIA professor at the Autonomous University of Barcelona Institut de Neurociències and one of the scientific leaders of this B·Debate, “Negative stress is a proven risk factor that increases a person’s chances of psychosis, anorexia, depression or anxiety. However, it also affects the immune and even cardiovascular systems: the effects are not only mental.”

For example, numerous studies have shown a connection between early trauma and psychosis, as explained Neus Barrantes, ICREA ACADEMIA professor at the Autonomous University of Barcelona. For example, the risk of developing schizophrenia is higher among racial minorities that are more isolated. And psychotic symptoms are seen considerably more in individuals that have suffered from abuse or bullying early on, quite a bit more than a traumatic accident. “It seems to play a secondary role in society, a subordinate position. It could be a unifying mechanism that would explain the environment’s influence on developing psychosis,” said Barrantes.

The great challenge lies in understanding the exact biological mechanisms that increase these risks. In the case of psychosis, there seems to be a dopamine imbalance, among other things, which affects what is known as the hypothalamic–pituitary–adrenal axis. This acts as a bridge for communications, connecting the brain and the adrenal glands, which produce the main stress hormone: cortisol. An early traumatic experience alters this in such a way that it tends to have an exaggerated, disproportionate reaction. This can even have an effect on brain organization.

This is one potential mechanism, but it is extremely complex. Among other players, cell adhesion molecules seem to have a key role. These molecules are important in binding neurons together correctly. “This is a therapeutic pathway that is opening up for the future,” Sandi said.

In fact, understanding these mechanisms would also help explain why the results differ so greatly. For example, in Sandi’s own research, “When we subject a group of lab rats to early stress, we always see that, on the whole, they tend to become more aggressive. But individually, some of them don’t change.” Up to 30% seem to be able to better handle the tension, as they adapt and their corticosterone levels go back to normal. This seems to put a halt to the developmental deviation seen in their companions.

Deeper understanding of all of this –including improvements in research methods, which for many aren’t as robust as they should be- would help fight what Barrantes calls “non-scientific nihilism,” and could limit the social and psychological enrichment and help available to this type of patients. One of these fields of knowledge is the antithesis of what we’ve said so far, the other side of the coin: positive stress.