Violent life has a lasting impact on the structure of the brain
Brawls, shootings and break-ins - even if many in Germany are spared from this, an international team of researchers has found that the impression of violence alone has an impact on the brain structure of adolescents. Apparently, indirect experiences of violence can have a negative impact on brain development. The scientists found a lower intelligence quotient and a smaller volume of the gray matter in the subjects with frequent indirect experiences of violence.
The Max Planck Institute for Human Development and the University of Southern California have conducted a joint study that examines the relationship between stress in the form of violence and the brain structure of adolescents. The focus was on healthy adolescents between the ages of 14 and 18, who live in neighborhoods with high crime rates in Los Angeles and thus gained a lot of indirect violence in their neighborhood. The study results were recently published in the specialist journal "Human Brain Mapping".
Violence reduces cognitive performance
"We know from previous studies that life in conflict-laden environments is associated with lower cognitive performance and an increased risk of mental illnesses, including post-traumatic stress disorder (PTSD)," reports lead author Oisin Butler from the Max Planck Institute for Educational Research in one Press release on the study. So far, however, there has been no study of the extent to which violent experiences affect adolescent brain development.
Passive experiences of violence influence brain development
65 healthy adolescents who grew up in the most criminal areas of Los Angeles were examined. All subjects frequently experienced violence in the neighborhood without being a victim or perpetrator themselves. The researchers found that the adolescents had a below-average intelligence quotient and a smaller volume of gray matter in the anterior cingulate cortex and in the lower forehead.
Deficits in language skills and emotions
According to the study results, these brain regions are responsible for higher-order cognitive functions. These include particularly important functions for cognitive control, for language skills and for emotions. "The thinning out of the gray matter is part of normal brain maturation," explains Butler. The slower this process goes, the more time there is for the maturation of cognitive functions. In further studies, the researchers want to find out to what extent stress accelerates the breakdown of gray matter, says Butler.
Victim without being a victim or a perpetrator
Without having used violence themselves or being directly affected by it, all subjects had gained a lot of indirect violence. All of them witnessed crimes, violence or threats in the immediate vicinity. The study participants themselves came from intact, albeit economically weak families. However, they were not direct victims of violence, abuse or neglect at home. "We wanted to make sure that the results were not influenced by other factors such as mental illness or abuse experiences that are known to be associated with changes in brain structure," added author Mary Helen Immordino-Yang from the University of Southern California.
IQ test and MRI
All adolescents passed an intelligence test and their brain structure was analyzed using magnetic resonance imaging (MRI). According to the scientists, the results were comparable to those obtained from a study of the effects of military operations on the brain. The study with the soldiers has already found that the duration of military operations in healthy soldiers is associated with a reduced gray matter in the same brain region.
Experiences of violence mean chronic stress
"Chronic stress, for example in the form of violent experiences, can have an impact on the healthy brain," says co-author Simone Kühn, who was already leading 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 there was no such disorder in the subjects examined.
Influence of stress on the brain
Previous studies on this subject have only examined people with clinical symptoms that have already appeared. The new study by the Max Planck Institute, however, focuses on the influence of stress on the brain in healthy subjects. "The majority of the population who has been exposed to violence do not develop clinical symptoms such as post-traumatic stress disorder," reports Kühn. With this, the researchers had drawn a much more differentiated picture of stress influences on the brain and thus made a contribution to the generalizability of neuroscientific stress research, said Kühn. (vb)