Children who live in the severely disadvantaged communities have decreased verbal ability later in childhood that continues even after moving out of the neighbourhood, says a study.
The study, led by Robert Sampson, Henry Ford II Professor of the Social Sciences in the Faculty of Arts and Sciences at Harvard University, with Patrick Sharkey of New York University and Stephen Raudenbush of the University of Chicago, found that living in 'concentrated disadvantage' decreases later verbal test scores by about four IQ points, which is roughly equivalent to missing a year of school.
To define a neighbourhood as one of 'concentrated disadvantage', the researchers examined the presence of six social factors in the lives of the children: welfare receipt, poverty, unemployment, female-headed households, segregation, and the number of children per household.
"For children, living in disadvantaged neighbourhoods appears to contribute to a detrimental effect on trajectories of verbal ability. This is important because language skills are a proven indicator of success later in life," Sampson said.
"What is surprising is the durability of the effect, continuing even when the child moves out of the neighbourhood," he added.
In the beginning of the study, over 2,000 children from the lower, middle and upper classes, in the age-group of 6-12 years who lived in Chicago were followed over a seven-year period starting in the mid-1990s as they moved in and out of neighborhoods in Chicago and to other parts of the United States.
At three different periods extensive interviews with the children and their caretakers were conducted and each time the children were also given a vocabulary test and a reading examination.
The researchers focused on the 772 African-Americans in the study because of their unique ecological risk, almost a third of black children were exposed to high concentrated disadvantage compared to virtually no white or Latino children.
After fitting in the propensity of families to live in concentrated disadvantage over time, the results showed that, by the end of the study, black children who lived in a disadvantaged neighbourhood at the mid-point had fallen behind otherwise identical peers that did not live in disadvantage by about four IQ points, the equivalent of missing one year of schooling.
This negative impact on verbal ability persisted even after a child had moved from a disadvantaged to a non-disadvantaged neighbourhood.
"Even beyond their economic situation, children in neighborhoods of concentrated disadvantage are exposed to a myriad of social factors that can deflect developmental trajectories," Sampson said.
"The persistence of the neighbourhood effect on verbal ability indicates the importance of timing in any efforts to intervene. Not only do these circumstances have a lasting impact on a child's language skills, it's not easily remedied by taking the child out of the neighbourhood. This consideration should be included in discussions of educational policy," he added.
The study will appear in the Proceedings of the National Academy of Sciences.