David Wahlberg, Wisconsin State Journal
Abused children tend to develop lifelong emotional and physical problems, and now UW-Madison scientists may have found a biological reason: Maltreatment appears to turn off a gene that regulates stress.
It’s the latest finding from the lab of psychologist Seth Pollak to suggest that abuse, neglect or poverty early in life can alter the brain and make people prone to depression, anxiety, heart disease, cancer and other conditions.
Childhood stress may shrink parts of the brain and cause abnormal hormone responses in girls that could lead to risky sexual behavior, the lab also found.
“The kind of parenting we receive can actually reconfigure our biology in ways that help explain long-term social and behavioral problems,” said Pollak, director of the Waisman Center’s Child Emotion Research Laboratory.
“It’s a whole new world in understanding child development,” Pollak said.
Research in animals suggests that restoring normal caregiving repairs the damage, and it’s possible therapy or medication might also do so, he said.
Pollak studied the stress regulation gene in 56 children referred through the Dane County Department of Human Services. A third of the children had been physically abused.
In those who had been abused, blood samples showed less activation of the glucocorticoid receptor gene, which regulates the hormone cortisol, the primary stress hormone.
A certain amount of cortisol helps people become alert when needed, but too much of it can weaken the immune system and cause people to stay upset and aroused, Pollak said.
If the gene isn’t properly activated, “the system isn’t able to shut down,” he said.
He and colleagues Sarah Romens, Jennifer McDonald and John Svaren reported the finding Thursday in the journal Child Development.
A brain scan study from Pollak’s lab last month found that children around age 12 who experienced abuse, neglect or poverty early in life had smaller amygdalas than children who hadn’t been maltreated.
The amygdala is a part of the brain involved in processing emotions.
Children exposed to abuse or poverty also had smaller hippocampuses, a part the brain involved in memory.
A study in December found that children in families with incomes less than 200 percent of the federal poverty level, or $39,580 for a family of three, had less gray matter, brain tissue critical for processing information and executing actions.
That finding was in children age 4. “Even before they start kindergarten, their brains are significantly smaller,” Pollak said.
Last July, another study showed that girls ages 8 to 11 who had been abused released oxytocin, the “love hormone,” when exposed to stress instead of cortisol, the stress hormone.
The study, in which children gave a speech and did math problems in front of strangers, suggests abused girls might rely on oxytocin to help form new relationships — but perhaps unstable ones.
Abused girls have higher rates of teen pregnancy, for example, which can impact school and job opportunities.
“They’re opening themselves up instead of protecting themselves,” Pollak said. “Maybe this helps explain why these girls often end up in difficult situations later on.”