The Why Files The Why Files --

Branded for life: The long reach of childhood poverty

Poverty, violence, stress and abuse: recipe for trouble

The U.S. unemployment rate is hovering around 10 percent, and more than 17 percent of American children are poor. For too many kids, poverty brings hunger, even homelessness. Fathers who are absent and crime that is present. Stressed-out relationships and burned-out schools. And health care that flits between inadequate and non-existent.

Black and white photo of woman holding baby, child leaning against her, sitting under tent
Dorothea Lange photo, Library of Congress
A migrant farm worker and her family in Nipomo, Calif., shows the face of poverty in March, 1936.

Although it's not news that poverty can be harmful, that poor kids, on average, have an outsize share of problems, researchers are building a detailed, almost mechanistic, picture of how negative conditions associated with poverty can set kids up for physical, emotional and social problems.

"There is growing evidence that adversity early in life has long-term consequences on physical and mental health well into adulthood," says Jack Shonkoff, who organized the "long reach of childhood poverty" session at the February 2010 meeting of the American Association for the Advancement of Science.

To Shonkoff, a professor of pediatrics and child development at Harvard University, the new studies suggest that the long-term impact of childhood deprivation can be seen as a result of "toxic stress," which are demands from the environment that overload the child. New studies suggest that overwhelming stress -- caused by abuse, neglect or violence -- "has an impact on the brain and other organs," Shonkoff says.

Shonkoff hopes the new findings from neuroscience and other branches of science can be the basis for closing the persistent gap between poor kids and the rest of us. "The basic approach now for trying to improve outcomes [for poor kids] ... is to provide rich learning opportunities, Head Start and everything that came after it, to provide rich language stimulation and age appropriate opportunities for learning. When that's done well ... we can shift the trajectory toward better outcomes: more kids graduating high school, fewer kids in jail. But it doesn't completely close the gap. The question is, what else is to be done?"

An enduring pain

Many studies suggest that the effects of childhood troubles -- whether they are caused by poverty or not -- are durable. The Adverse Childhood Experiences project, for example, has studied more than 17,000 California adults, looking at the link between adverse childhood experiences like abuse, witnessing domestic violence, and drug or alcohol abuse in the household, with 18 outcomes, including depression, anxiety, hallucination, difficulty controlling anger and promiscuity.

The project found that every single negative outcome was significantly more common among adults who had suffered adverse experiences as a child (see #1 in the bibliography). The risk of panic reactions, depressed mood, anxiety and hallucinations was more than doubled among adults with at least four adverse types of experience.

After at least four adverse childhood experiences, odds of damaging behavior increase. A study (see "The enduring effects ..." in bibliography) found that the odds for these behaviors increase as follows:
  • Smoking: 1.8
  • Obesity: 1.9
  • Anxiety: 2.4
  • Depression: 3.6
  • Illicit drug use: 4.5
  • Early sexual activity: 6.6
  • Alcoholism: 7.2

Although violence, abuse and neglect can affect any child, "every one of these conditions is more common among people who grew up poor or were abused as children," says Shonkoff. And in a sense, the distinction between poor and non-poor kids does not matter: a better picture of the long-term health effects of a bad environment could lead to a win-win solution for kids who are poor, and for other kids.

How do abuse and neglect change the brain?

Abuse and neglect can overwork the stress response and warp the mind: The stress hormone cortisol normally prepares the body for activity by increasing blood pressure and blood sugar, but problems can arise when stress is overloaded. "Kids who are subject to physical or sexual abuse show either chronically heightened cortisol, or are unable to mount a significant cortisol response to mild stress," says Nathan Fox of the University of Maryland. "Both cases are associated with disregulated behavior, an inability to control emotion or sustain attention."

Abuse and neglect can change the personality: Seth Pollak of the University of Wisconsin-Madison has shown that after significant abuse, children are quicker to detect anger in their environment, and start to see the world as unduly hostile. Pollak recently studied kids after their adoption from orphanages, and found deficits in visual memory and learning, and control of inhibitions, but not in auditory processing, or the ability to plan or follow rules. "These findings suggest that specific aspects of brain behavioral circuitry may be particularly vulnerable" to experience after birth, Pollak wrote with his coauthors (see #2 in the bibliography).

Stress can physically change the brain: A study published in late 2009 showed that the children of mothers who had been highly anxious at 19 weeks of gestation had significantly less gray matter in brain regions devoted to language and thought (see #3 in the bibliography).

Depressed mothers matter: Depression, by sapping energy and interest in life, and by disturbing sleep and concentration, can make a mother less responsive to her child, and detract from the energy and emotional investment necessary for raising a family. Nine months after birth, significant depression affects 25 percent of poor mothers, and 11 percent of non-poor mothers. According to new study from the United Kingdom, "Depression in pregnancy significantly predicted violence in adolescence, even after controlling for the family environment, the child's later exposure to maternal depression, the mother's smoking and drinking during pregnancy, and parents' antisocial behavior" (see #4 in the bibliography).

Poor mothers often have poor children, but timing matters: A program to reduce the trans-generational effects of poverty are most needed when parental poverty is most damaging. A new study has found that the mother's poverty from one year before the child's birth, up to age 5, played the greatest role in economic trouble when the children were in their 20s (see #5 in the bibliography).

 Bar chart showing dramatic increase in maternal depression amongst poor families
Courtesy Working Paper No. 8, Center on the Developing Child.
Depression, a disabling mental disorder that can obstruct mother-child interactions, is much more common among poor mothers.

Explaining what we already know?

As Shonkoff admits, it's no news that being poor causes trouble for children. "People say, 'You're still doing research? We've known that for long time!'" But details on the timing and mechanism of damage are starting to reveal exactly how children are being damaged, and that suggests how to prevent trouble. "What's exciting is that we are learning what it is about poverty that gets under the skin, into the body, and leads to problems with learning and behavior, with physical and mental health," says Shonkoff, who directs Harvard's Center on the Developing Child.

It's not just a matter of abstract research, Shonkoff says. "We can use this information to be smarter in investments to protect children from poverty, and to prevent some consequences. It's not inevitable that kids in poverty should have these problems."

But can you give me some details?

Terry Devitt, editor; Steve Furay, project assistant; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive

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