Psychological consequences How much violence audiences can shape

Violent life has a lasting influence on the brain structure

Fights, shootings and burglaries - even though many are spared in this country, an international research team has found that only the impressions of violence have influences on the brain structure of adolescents. Evidently, indirect experiences of violence can have a negative effect on brain development. The scientists were able to find a lower intelligence quotient and a smaller volume of gray matter in the subjects with frequent indirect violence experiences.

The Max Planck Institute for Human Development and the University of Southern California have conducted a joint study examining the relationship between the effects of stress in the form of violence and the brain structure of adolescents. The focus was on healthy young people between the ages of 14 and 18 who live in high-crime neighborhoods in Los Angeles, gaining many indirect experiences of violence in their neighborhoods. The study results were recently published in the journal "Human Brain Mapping".

According to an international study, passive participation in violence can have a negative effect on brain development. The examined subjects showed deficits in the intelligence test and had demonstrably a below-average proportion of gray matter in the brain. (Image: Jonathan Stutz / fotolia.com)

Violence reduces cognitive performance

"From previous studies, we know that life in conflict-ridden environments is associated with lower cognitive performance and an increased risk of mental illness, including post-traumatic stress disorder (PTSD)," says lead author Oisin Butler from the Max Planck Institute for Human Development Press release on the study. So far, however, there is no study on the extent to which violence experiences have an effect on adolescent brain development.

Passive experiences of violence influence brain development

The study looked at 65 healthy teenagers who grew up in the most criminal areas of Los Angeles. All subjects often experienced violence in the neighborhood without being victim or perpetrator themselves. The researchers found a below-average intelligence quotient and a smaller volume of gray matter in the anterior cingulate cortex and in the lower frontal turn in the adolescents.

Deficits in language ability and emotions

According to the study results, these brain regions are responsible for higher-order cognitive functions. Among them are also particularly important functions for cognitive control, for speech ability and for emotions. "The thinning of the gray matter is part of normal brain maturation," explains Butler. The slower this process goes, the more time remains for the maturation of cognitive functions. In further studies, the researchers want to determine the extent to which stress accelerates the degradation of gray matter, said Butler.

Victim to be without victim or perpetrator

Without having exerted violence or being directly affected by it, all subjects had collected many indirect experiences of violence. All were witnesses of crime, violence or threats in the immediate vicinity. However, the study participants themselves came from intact, if economically weak families. However, they were not direct victims of violence, abuse or neglect at home. "We wanted to make sure that the results are not influenced by other factors, such as mental illness or abuse experiences, which are known to be associated with changes in brain structure," adds author Mary Helen Immordino-Yang of the University of Southern California.

IQ test and MRI

All adolescents completed an intelligence test and their brain structure was analyzed using magnetic resonance imaging (MRI). According to the scientists, the results were similar to those obtained from a study of the effects of military operations on the brain. The study with the soldiers has already established that the duration of military operations in healthy soldiers is associated with decreased gray matter in the same brain region.

Experiences of violence mean chronic stress

"Chronic stress, for example in the form of experiences of violence, can have an impact on the healthy brain," says co-author Simone Kühn, who already led the study on military operations at the Max Planck Institute for Human Development. The affected brain structures would be similar to those of patients with post-traumatic stress disorder, even if no such disorder is present in the examined subjects.

Influence of stress on the brain

Previous studies on this topic only looked at people who have already had clinical symptoms. However, the new study of the Max Planck Institute focuses on the influence of stress on the brain in healthy volunteers. "The majority of the population exposed to violence does not develop any clinical symptoms, such as post-traumatic stress disorder," says Kühn. This would have the researchers drawn a much more sophisticated picture of stress influences on the brain and thus made a contribution to the generalizability of neuroscientific stress research, so Kühn. (Vb)