Violence and Children's Brains

When children are exposed to violence in the family, their brains are visibly changed. That’s the disturbing message of new research published in tomorrow’s issue of Current Biology.

According to the research article, exposure to violence at home can “represent a form of environmental stress that significantly increases [the] risk of later psychopathology, including anxiety.” It’s as if violence tunes the child’s brain to expect more violence.

Earlier studies have shown that physically abused children show “selective hypervigilance to angry cues,” such as pictures of angry faces. Another earlier study used functional magnetic resonance imaging (fMRI) to show increased brain reactivity. When individuals with anxiety disorder where shown angry faces, two brain regions were overly reactive: the anterior insula (AI) and the amygdala. The same response was found in soldiers exposed to combat.

The new research takes this a step further. Children exposed to family violence, including violence between parents, also showed the same increased brain reactivity. The reaction was quite specific in that they responded to pictures of angry faces, not sad faces.

Most important, perhaps, is that this study looked at brain function rather than symptoms of anxiety or depression. In terms of behavior, the children seemed quite normal. Their brains, however, tell a different story, one of being tuned to be anxious.

Some might suggest that given all the violence in the world, the reaction is beneficial. Maybe it’s a good thing that some human beings learn to be especially responsive to potential threats.

But as the researchers note, excessive reactivity “may also constitute a latent neurobiological risk factor increasing vulnerability to psychopathology.” The researchers also found that the degree of the brain reactivity depended on the severity of the violence.

The research “underlines the importance of taking seriously the impact for a child of living in a family characterized by violence. Even if such a child is not showing overt signs of anxiety or depression, these experiences still appear to have a measurable effect at the neural level,” said Eamon McCrory of University College London, lead author, in a press release from the journal.

More than that, this research shows how violence and trauma affect human beings in ways that permanently alter the brain.

The article, “Heightened Neural Reactivity to Threat in Child Victims of Family Violence,” appears in the December 6 issue of Current Biology.

For previous work by some of these same researchers, see “The Impact of Childhood Maltreatment: A Review of Neurobiological and Genetic Factors,” published in July in Frontiers in Psychiatry.

Ancient Humans: Violent? Caring?

A report in the November 21 issue of PNAS opens a sobering window into the lives and deaths of Ice Age humans. The report analyses a skull found in China and dating to 126,000 years ago and showing clear evidence of blunt force trauma.

[See photo, left. This is the right superolateral view of the Maba cranium showing the position (A) and detail (B) of the depressed lesion. Credit: University of the Witwatersrand.]

Was it aggression or an accident, deliberate violence or just an sharp but unlucky bump to the head? No one knows for sure. Based on comparison with similar findings, however, researchers suspect human-to-human violence.

One thing that makes this discovery stand out is its early date. Quite possibly, it is the earliest known evidence of human aggression against another human being.

The injury was not fatal. The trauma to the skull shows clear evidence of healing. For researchers, this healing is proof that the victim lived months and possibly years after the injury, quite possibly because of care offered by fellow Middle Pleistocene humans. If true, then the skull may be evidence of human caring as well as human violence.

According to Prof. Lynne Scheparz, one of the authors of the study, “this wound is very similar to what is observed today when someone is struck forcibly with a heavy blunt object. As such it joins a small sample of Ice Age humans with probable evidence of humanly induced trauma, and could possibly be the oldest example of interhuman aggression and human induced trauma documented.”

At the same time, the skull’s “remodelled, healed condition also indicates the survival of a serious brain injury, a circumstance that is increasingly documented for archaic and modern Homo through the Pleistocene,” according to Schepartz. In other words, this skull is not unusual in suggesting that ancient humans cared for each other after serious brain injury. As Schepartz puts it in a press release from the University of Witwatersrand, this individual “would have needed social support and help in terms of care and feeding to recover from this wound."

According to the report itself, “the lesion…appears most likely to have been the result of a localized, blunt force trauma, sufficiently strong to produce the concentric ridges, the external depression, and the internal bulge. At the same time, the bone was extensively remodeled…Such remodeling minimally takes several months to develop,” possibly longer.

According to the report, it “is probable that it [the injury] was the result of an interpersonal altercation, with blunt-force trauma, given its form, but accidental injury cannot be excluded. It may be the oldest such case known…”

The report provides a sobering picture of the past. A single skull provides what might be the oldest snapshot of human violence and human caring, a scant 14mm in length but a powerfully accurate view of the best and the worst in us.

The report, “New evidence of interhuman aggression and human induced trauma 126,000 years ago, was published in the November 21, 2011 issue of PNAS.