26 August 2009

Exposure to Multiple Risk Factors in Early Childhood Impairs Children’s Brain Development

30 years ago, a group of researchers created a longitudinal study of children called the Rochester Longitudinal Study (RLS) to examine the influence of exposure to multiple known risk factors on children’s cognitive and social/emotional development. The study examined the social/emotional and cognitive development of children at birth, 4 months, 12 months, 30 months and again at 48 months of age. Interestingly, the researchers reexamined the children in the study when they were 13 and 18 years old.

In addition to tests of the children’s social/emotional and cognitive development, the researchers also gathered evidence on the children’s exposure to known risk factors that influence development, including socio-economic status, mother’s physical and mental health status, parent’s education, marital status, family size, stressful life events and occupations. They hypothesized that exposure to multiple risk factors would impair children’s social/emotional and cognitive development in their earliest years and as they grew up. Their formal list of risk factors included:

- Having a mother who sought treatment for mental illness on more than one occasion;

- Having a mother with a high level of anxiety;

- Having a small amount of spontaneous interaction between parent and child;

- Having parents in a semi or unskilled occupation;

- Having parents who lacked a high school education;

- Being a minority;

- Having a parent with rigid beliefs about child development;

- Having a single mother;

- Being exposed to a large number of stressful life events; and

- Being in a family with 4 or more children

Each child in the study was assigned a risk score based on the number of identified risk factors at birth. They also updated the child’s risk score at each visit. As they hypothesized, children with only one or no risk factors did not suffer social/emotional or cognitive delays over the course of their earliest years. Unfortunately, children exposed to two or more risk factors in early childhood did have diminished cognitive and social/emotional development. In fact, the more risk factors a child was exposed to in early life, the larger their developmental deficits. On average, exposure to each additional risk factor in early childhood lowered a child’s IQ at age 4 by 4 points. So a child in the study who was exposed to 5 risk factors during early childhood, on average, had an IQ that was 20 points lower than a child who was exposed to one or no risk factors (Sameroff, 1998).

Disturbingly, the researchers also found that a child’s exposure to risk factors was consistent over the course of their childhoods. Very few children in the study who were at risk, by exposure to multiple risk factors, lost their exposure as they grew up. Additionally, the prolonged exposure to risk factors continued to have a negative effect on cognitive and social/emotional development. At 4 years of age, 22% of the children exposed to 4 or more risk factors had an IQ below 85. By the time the children were re-tested at 13, 46% of them had an IQ below 85 (Sameroff, 1998).

We have no way of knowing if the results of the Rochester Longitudinal Study would hold true for children growing up in Memphis. However, we do know that many children growing up in Memphis are exposed to many of their identified risk factors on a daily basis. While poverty is often identified as a serious risk factor for cognitive and social/emotional delays, we often do not examine what it means to live in poverty.

Fundamentally, poverty is an umbrella term, describing the multiplicity of psychosocial
and bio-ecological risks children growing up in poverty are likely to encounter, such as
family turmoil or instability, less responsive parenting, less access to educational
stimulation at home or in school, increased exposure to dangerous neighborhoods, and
environmental pollution
(Evans, 2004).

In other words, children growing up in poverty are regularly exposed to multiple risk factors which work together to undermine their foundational cognitive, social/emotional and physical development. Beyond being troubling, the RLS’s findings have important implications for the way that we seek to improve children’s developmental and long term outcomes. Most importantly, they imply that it is not enough to meet one identified need here and there. Our approach must be holistic and seek to provide protective factors which insulate children from the range of risk factors that interact to undermine their development.


Evans, G. (2004). The environment of childhood poverty. American Psychologist, 59, 77–92.

National Scientific Council on the Developing Child, Young Children Develop in an Environment of Relationships. (2004). Working Paper No. 1. Retrieved [August 21, 2009] from www.developingchild.net/pubs/wp/environment_of_relationships.pdf

Sameroff, Arnold J. (1998). Environmental Risk Factors in Infancy. Pediatrics, 102, 1287-1292. Accessed August 20, 2009 <http://www.pediatrics.org/cgi/content/full/102/5/SE1/1287>

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