Genes increase the stress of social disadvantage for some children

Genes amplify the stress of harsh environments for some children, and magnify the advantage of supportive environments for other children, according to a study that’s one of the first to document how genes interacting with social environments affect biomarkers of stress.

"Our findings suggest that an individual’s genetic architecture moderates the magnitude of the response to external stimuli—but it is the environment that determines the direction" says Colter Mitchell, lead author of the paper and a researcher at the University of Michigan Institute for Social Research (ISR).

The study, published today in the Proceedings of the National Academy of Sciences, uses telomere length as a marker of stress. Found at the ends of chromosomes, telomeres generally shorten with age, and when individuals are exposed to disease and chronic stress, including the stress of living in a disadvantaged environment.

For the study, Mitchell and colleagues used telomere samples from a group of 40 nine-year-old boys from two very different environments – one nurturing and the other harsh. Those in the nurturing environment came from stable families, with nurturing parenting, good maternal mental health, and positive socioeconomic conditions, while those in the harsh environment experienced high levels of poverty, harsh parenting, poor maternal mental health, and high family instability.

For those children with heightened sensitivity in the serotonergic and dopaminergic genetic pathways compared to other children, telomere length was shortest in a disadvantaged environment, and longest in a supportive environment.

Nurturing may protect kids from brain changes linked to poverty

Growing up in poverty can have long-lasting, negative consequences for a child. But for poor children raised by parents who lack nurturing skills, the effects may be particularly worrisome, according to a new study at Washington University School of Medicine in St. Louis.

Among children living in poverty, the researchers identified changes in the brain that can lead to lifelong problems like depression, learning difficulties and limitations in the ability to cope with stress. The study showed that the extent of those changes was influenced strongly by whether parents were nurturing.

The good news, according to the researchers, is that a nurturing home life may offset some of the negative changes in brain anatomy among poor children. And the findings suggest that teaching nurturing skills to parents — particularly those living in poverty — may provide a lifetime benefit for their children.

The study is published online Oct. 28 and will appear in the November issue of JAMA Pediatrics.

Using magnetic resonance imaging (MRI), the researchers found that poor children with parents who were not very nurturing were likely to have less gray and white matter in the brain. Gray matter is closely linked to intelligence, while white matter often is linked to the brain’s ability to transmit signals between various cells and structures.

The MRI scans also revealed that two key brain structures were smaller in children who were living in poverty: the amygdala, a key structure in emotional health, and the hippocampus, an area of the brain that is critical to learning and memory.

“We’ve known for many years from behavioral studies that exposure to poverty is one of the most powerful predictors of poor developmental outcomes for children,” said principal investigator Joan L. Luby, MD, a Washington University child psychiatrist at St. Louis Children’s Hospital. “A growing number of neuroscience and brain-imaging studies recently have shown that poverty also has a negative effect on brain development. 

“What’s new is that our research shows the effects of poverty on the developing brain, particularly in the hippocampus, are strongly influenced by parenting and life stresses that the children experience.”

Luby, a professor of psychiatry and director of the university’s Early Emotional Development Program, is in the midst of a long-term study of childhood depression. As part of the Preschool Depression Study, she has been following 305 healthy and depressed kids since they were in preschool. As the children have grown, they also have received MRI scans that track brain development.

“We actually stumbled upon this finding,” she said. “Initially, we thought we would have to control for the effects of poverty, but as we attempted to control for it, we realized that poverty was really driving some of the outcomes of interest, and that caused us to change our focus to poverty, which was not the initial aim of this study.”

In the new study, Luby’s team looked at scans from 145 children enrolled in the depression study. Some were depressed, others healthy, and others had been diagnosed with different psychiatric disorders such as ADHD (attention-deficit hyperactivity disorder). As she studied these children, Luby said it became clear that poverty and stressful life events, which often go hand in hand, were affecting brain development.

The researchers measured poverty using what’s called an income-to-needs ratio, which takes a family’s size and annual income into account. The current federal poverty level is $23,550 for a family of four.

Although the investigators found that poverty had a powerful impact on gray matter, white matter, hippocampal and amygdala volumes, they found that the main driver of changes among poor children in the volume of the hippocampus was not lack of money but the extent to which poor parents nurture their children. The hippocampus is a key brain region of interest in studying the risk for impairments.

Luby’s team rated nurturing using observations made by the researchers — who were unaware of characteristics such as income level or whether a child had a psychiatric diagnosis — when the children came to the clinic for an appointment. And on one of the clinic visits, the researchers rated parental nurturing using a test of the child’s impatience and of a parent’s patience with that child.

While waiting to see a health professional, a child was given a gift-wrapped package, and that child’s parent or caregiver was given paperwork to fill out. The child, meanwhile, was told that s/he could not open the package until the caregiver completed the paperwork, a task that researchers estimated would take about 10 minutes.

Luby’s team found that parents living in poverty appeared more stressed and less able to nurture their children during that exercise. In cases where poor parents were rated as good nurturers, the children were less likely to exhibit the same anatomical changes in the brain as poor children with less nurturing parents.

“Parents can be less emotionally responsive for a whole host of reasons,” Luby said. “They may work two jobs or regularly find themselves trying to scrounge together money for food. Perhaps they live in an unsafe environment. They may be facing many stresses, and some don’t have the capacity to invest in supportive parenting as much as parents who don’t have to live in the midst of those adverse circumstances.”

The researchers also found that poorer children were more likely to experience stressful life events, which can influence brain development. Anything from moving to a new house to changing schools to having parents who fight regularly to the death of a loved one is considered a stressful life event.

Luby believes this study could provide policymakers with at least a partial answer to the question of what it is about poverty that can be so detrimental to a child’s long-term developmental outcome. Because it appears that a nurturing parent or caregiver may prevent some of the changes in brain anatomy that this study identified, Luby said it is vital that society invest in public health prevention programs that target parental nurturing skills. She suggested that a key next step would be to determine if there are sensitive developmental periods when interventions with parents might have the most powerful impact.

“Children who experience positive caregiver support don’t necessarily experience the developmental, cognitive and emotional problems that can affect children who don’t receive as much nurturing, and that is tremendously important,” Luby said. “This study gives us a feasible, tangible target with the suggestion that early interventions that focus on parenting may provide a tremendous payoff.”

Poor concentration: Poverty reduces brainpower needed for navigating other areas of life

Poverty and all its related concerns require so much mental energy that the poor have less remaining brainpower to devote to other areas of life, according to research based at Princeton University. As a result, people of limited means are more likely to make mistakes and bad decisions that may be amplified by — and perpetuate — their financial woes.

Published in the journal Science, the study presents a unique perspective regarding the causes of persistent poverty. The researchers suggest that being poor may keep a person from concentrating on the very avenues that would lead them out of poverty. A person’s cognitive function is diminished by the constant and all-consuming effort of coping with the immediate effects of having little money, such as scrounging to pay bills and cut costs. Thusly, a person is left with fewer “mental resources” to focus on complicated, indirectly related matters such as education, job training and even managing their time.

In a series of experiments, the researchers found that pressing financial concerns had an immediate impact on the ability of low-income individuals to perform on common cognitive and logic tests. On average, a person preoccupied with money problems exhibited a drop in cognitive function similar to a 13-point dip in IQ, or the loss of an entire night’s sleep.

But when their concerns were benign, low-income individuals performed competently, at a similar level to people who were well off, said corresponding author Jiaying Zhao, who conducted the study as a doctoral student in the lab of co-author Eldar Shafir, Princeton’s William Stewart Tod Professor of Psychology and Public Affairs. Zhao and Shafir worked with Anandi Mani, an associate professor of economics at the University of Warwick in Britain, and Sendhil Mullainathan, a Harvard University economics professor.

"These pressures create a salient concern in the mind and draw mental resources to the problem itself. That means we are unable to focus on other things in life that need our attention," said Zhao, who is now an assistant professor of psychology at the University of British Columbia.

"Previous views of poverty have blamed poverty on personal failings, or an environment that is not conducive to success," she said. "We’re arguing that the lack of financial resources itself can lead to impaired cognitive function. The very condition of not having enough can actually be a cause of poverty."

The mental tax that poverty can put on the brain is distinct from stress, Shafir explained. Stress is a person’s response to various outside pressures that — according to studies of arousal and performance — can actually enhance a person’s functioning, he said. In the Science study, Shafir and his colleagues instead describe an immediate rather than chronic preoccupation with limited resources that can be a detriment to unrelated yet still important tasks.

"Stress itself doesn’t predict that people can’t perform well — they may do better up to a point," Shafir said. "A person in poverty might be at the high part of the performance curve when it comes to a specific task and, in fact, we show that they do well on the problem at hand. But they don’t have leftover bandwidth to devote to other tasks. The poor are often highly effective at focusing on and dealing with pressing problems. It’s the other tasks where they perform poorly."

The fallout of neglecting other areas of life may loom larger for a person just scraping by, Shafir said. Late fees tacked on to a forgotten rent payment, a job lost because of poor time-management — these make a tight money situation worse. And as people get poorer, they tend to make difficult and often costly decisions that further perpetuate their hardship, Shafir said. He and Mullainathan were co-authors on a 2012 Science paper that reported a higher likelihood of poor people to engage in behaviors that reinforce the conditions of poverty, such as excessive borrowing.

"They can make the same mistakes, but the outcomes of errors are more dear," Shafir said. "So, if you live in poverty, you’re more error prone and errors cost you more dearly — it’s hard to find a way out."

The first set of experiments took place in a New Jersey mall between 2010 and 2011 with roughly 400 subjects chosen at random. Their median annual income was around $70,000 and the lowest income was around $20,000. The researchers created scenarios wherein subjects had to ponder how they would solve financial problems, for example, whether they would handle a sudden car repair by paying in full, borrowing money or putting the repairs off. Participants were assigned either an “easy” or “hard” scenario in which the cost was low or high — such as $150 or $1,500 for the car repair. While participants pondered these scenarios, they performed common fluid-intelligence and cognition tests.

Subjects were divided into a “poor” group and a “rich” group based on their income. The study showed that when the scenarios were easy — the financial problems not too severe — the poor and rich performed equally well on the cognitive tests. But when they thought about the hard scenarios, people at the lower end of the income scale performed significantly worse on both cognitive tests, while the rich participants were unfazed.

To better gauge the influence of poverty in natural contexts, between 2010 and 2011 the researchers also tested 464 sugarcane farmers in India who rely on the annual harvest for at least 60 percent of their income. Because sugarcane harvests occur once a year, these are farmers who find themselves rich after harvest and poor before it. Each farmer was given the same tests before and after the harvest, and performed better on both tests post-harvest compared to pre-harvest.

The cognitive effect of poverty the researchers found relates to the more general influence of “scarcity” on cognition, which is the larger focus of Shafir’s research group. Scarcity in this case relates to any deficit — be it in money, time, social ties or even calories — that people experience in trying to meet their needs. Scarcity consumes “mental bandwidth” that would otherwise go to other concerns in life, Zhao said.

"These findings fit in with our story of how scarcity captures attention. It consumes your mental bandwidth," Zhao said. "Just asking a poor person to think about hypothetical financial problems reduces mental bandwidth. This is an acute, immediate impact, and has implications for scarcity of resources of any kind."

"We documented similar effects among people who are not otherwise poor, but on whom we imposed scarce resources," Shafir added. "It’s not about being a poor person — it’s about living in poverty."

Many types of scarcity are temporary and often discretionary, said Shafir, who is co-author with Mullainathan of the book, “Scarcity: Why Having Too Little Means So Much,” to be published in September. For instance, a person pressed for time can reschedule appointments, cancel something or even decide to take on less.

"When you’re poor you can’t say, ‘I’ve had enough, I’m not going to be poor anymore.’ Or, ‘Forget it, I just won’t give my kids dinner, or pay rent this month.’ Poverty imposes a much stronger load that’s not optional and in very many cases is long lasting," Shafir said. "It’s not a choice you’re making — you’re just reduced to few options. This is not something you see with many other types of scarcity."

The researchers suggest that services for the poor should accommodate the dominance that poverty has on a person’s time and thinking. Such steps would include simpler aid forms and more guidance in receiving assistance, or training and educational programs structured to be more forgiving of unexpected absences, so that a person who has stumbled can more easily try again.

"You want to design a context that is more scarcity proof," said Shafir, noting that better-off people have access to regular support in their daily lives, be it a computer reminder, a personal assistant, a housecleaner or a babysitter.

"There’s very little you can do with time to get more money, but a lot you can do with money to get more time," Shafir said. "The poor, who our research suggests are bound to make more mistakes and pay more dearly for errors, inhabit contexts often not designed to help."