Harsh Family Environment May Adversely Affect Brain's Response to Threat
A harsh early childhood environment may adversely affect how threatening information is processed in the brain, UCLA researchers will report in the journal Biological Psychiatry.
Shelley Taylor, a UCLA social neuroscientist and lead author on the study, has found the first evidence that the regions in the human brain involved in detecting threatening emotional information and regulating our emotional responses to these threats function differently in people from "risky families."
Although scientists have long known that extreme abuse can alter patterns of brain activity, these effects were observed in children raised in "everyday working families," Taylor said.
"These are not children from families where there is physical or sexual abuse, but families in which people don't have a lot of time for one another or opportunities to be caring," emphasized Taylor, a UCLA Distinguished Professor of Psychology, and an expert in the field of stress and health.
Matthew D. Lieberman, assistant professor of psychology at UCLA and co-author of the study, has previously shown in a series of studies that threatening information activates a region or the brain called the amygdala, which serves as an "alarm" to protect the body in times of danger; however, verbally labeling the threat activates a second region of the brain, called the right ventrolateral prefrontal cortex, which generally reduces the amygdala response. In other words, putting negative feelings into words may help to regulate and alleviate those bad feelings by activating the right ventrolateral prefrontal cortex, which in turn, reduces the activity in the amygdala, Lieberman said.
The current study shows that for people from "risky families," the relationship between these two brain regions may not function properly.
The researchers used functional magnetic resonance imaging (fMRI) to examine brain activity, a technique that uses magnetic fields to spot active brain areas by telltale increases in blood oxygen. Lieberman's laboratory conducted this fMRI study at UCLA's Ahmanson-Lovelace Brain Mapping Center.
Most of the time, the two brain regions work like this: Suppose you hear a fire alarm, which sends you frantically running to the door. In that moment, the amygdala, the almond-shaped structure that responds to fear, is activated, Taylor said. A couple of seconds later, you sigh in relief and realize a fire drill was scheduled for today. That, she said, is the right ventrolateral prefrontal cortex in action. Located behind the forehead and eyes, it regulates fear by helping people understand, cope with or control their responses to potentially threatening experiences.
In the study, participants were first shown pictures of angry and fearful faces. Usually, this procedure activates the amygdala, and children from nurturing families showed this pattern of activation. However, the children from "risky" families - that is, a family environment marked by conflict, a cold interaction style or neglect - showed almost no response to these threatening faces.
"This pattern suggests children from risky families may have been tuning out these all-too familiar faces, Taylor said.
When asked to label the angry and fearful faces, a quite different pattern emerged, Taylor said: Young adults who reported being raised in nurturing families showed lower amygdala activation (fear response) as the right ventrolateral prefrontal cortex (emotion regulation) became more active. For those raised in risky families, however, the two brain regions did not work well together. Instead, both the amygdala and ventrolateral prefrontal cortex were simultaneously activated.
"Children from these risky families may be deficient in the ability to regulate their emotional responses," Taylor explained. "They show evidence to suggest that they tune out threatening stimuli that other people react to, but given an opportunity to cope with threatening stimuli, in this case by labeling them, their emotion regulation skills appear to fail them."
This is a cause for concern, she added, because overreacting to stressful situations can compromise health over the long term.
Lieberman said that just as you want your alarm clock turned off once you wake up and get out of bed, you also want your body's alarm - the amygdala - shut off when you get the threat message.
"We think the right ventrolateral prefrontal cortex may be the region of the brain that shuts off the amygdala's alarm system," Lieberman said, "although perhaps not in people from risky families."
Taylor and Lieberman said it is important for the findings to be replicated by other researchers.
This research was supported by funding from the National Institute of Mental Health and UCLA's Center for Psychoneuroimmunology.
The research team included UCLA investigators Naomi I. Eisenberger, Darby Saxbe and Barbara J. Lehman (now at Western Washington University).
In previous research, Taylor and UCLA colleagues, including psychology professor Rena Repetti, reported strong evidence that children who grow up in risky families often suffer lifelong health problems, including cancer, heart disease, hypertension, diabetes, obesity, depression and anxiety disorders, as well as early death (Psychological Bulletin, March 2002, Vol. 128, No. 2, pp. 330-366).
In that study, Repetti, Taylor and UCLA colleague Teresa Seeman reported that some of these diseases do not show up until decades later, while others are evident by adolescence. They described risky families as those in which children grow up in homes marked by conflict, anger and aggression, that are emotionally cold, unsupportive and where children's needs are neglected. The UCLA researchers analyzed more than 500 psychological, medical and biological research studies, and integrated the findings of psychologists, pediatricians, biologists, neuroscientists, social workers and other scientists.
The research studies show that in risky families, a child's genetic predispositions may be exacerbated by the family environment, and this combination can lead to the faster development of health problems, which may be more debilitating than they would be in a more nurturing family.
Children who grow up in risky families are also more likely as teenagers and adults to engage in drug and alcohol abuse, smoking, risky sexual behavior, and aggressive, antisocial behavior, the UCLA analysis showed.