Growing up poor puts children at a big disadvantage, but why? Is it merely because of inferior health care and missing educational opportunities? No, it’s also because of stress, toxic stress that impairs the immune system, damages DNA, hastens the aging process, causes inflammatory diseases, and even shrinks the brain.
But as bleak as this sounds — for every child who faces toxic stress, regardless of his socioeconomic status — recent research offers a hopeful message.
Even if we can’t make all the stress go away, we can stop much of the damage before it even begins. What’s needed is a warm, emotionally-supportive parenting style.
The latest study, led by Joan Luby of Washington University in St. Louis, tracked the behavioral development of 145 children for 3-6 years. The researchers evaluated parenting, too, and then they scanned the kids’ brains using magnetic resonance imaging.
Did brains differ according by socioeconomic status? The researchers figured they would, and they were right. Kids whose families were poor had smaller brain volumes. They had less white and cortical gray matter, and smaller-sized hippocampi and amygdale—brain structures that play a key role in spatial learning, memory consolidation, stress reactivity, and the processing of emotion.
Previous research has shown that chronic stress reduces growth in the hippocampus and amygdala. It can even shrink these structures. So Luby and her team think stress can explain much of the link between poverty and brain volume. But they also think that parenting — warm, positive, emotionally-supportive parenting — may spare many kids from suffering growth deficits in the hippocampus and amygdala.
How did they reach this conclusion? Midway through the study, when the kids were between the ages of 4 and 7, Luby’s team evaluated parents using a standard laboratory technique. Each child was given a brightly-wrapped gift, along with these instructions: Do not open the present until your parent (who is sitting nearby) has finished filling out a long questionnaire.
The situation was designed to test how parents react under mild stress, and parents were scored as more supportive or more hostile depending on the tactics they used to keep kids in line. For example, praising a child for waiting was counted as emotionally-supportive. Threatening a child with punishment was counted as hostile.
Later on, when researchers analyzed their data, this single measurement of parenting was unrelated to changes in gray or white matter. But it was shown to mediate completely the links between poverty, hippocampus volume, and amygdala volume. In other words, for these brain structures, the negative effects of being poor were wiped out by the positive effects of having a supportive parent.
These results aren’t the last word. The researchers caution that their study included more than the average number of preschoolers suffering from depression, so it’s not clear how applicable their findings might be to the general population. However, the outcome regarding supportive parenting is consistent with other studies showing that sensitive, responsive parents buffer kids from stress-related health problems. The results are also consistent with experiments on rodents. If you expose a mouse pup to toxic, chronic stress, it will nevertheless develop a normal hippocampus – as long as you provide the animal with lots of nurturing parental care.
So it seems that parenting may be crucial for fighting the lasting, harmful consequences of poverty. And if that’s true, we’ve got more evidence that parents can protect kids from the physiological effects of toxic stress. Does it matter if you handle kids with good humor and understanding? Or threats and punishment? When kids have to cope with serious problems, it might matter a great deal for the development of their brains.
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