Early experiences and environments

Population health and developmental psychology findings converge: developmental trajectories are set early in life (Brownell, Roos, Fransoo, et al., 2006; Hertzman & Power, 2004; Keating & Hertzman, 1999; McCain, Mustard, & Shanker, 2007). The experiences and environments of early childhood have a long reach into lifelong learning, behaviour and health.

Illnesses and disabilities that emerge in adult life, along with their accompanying behaviours and lifestyles, have their roots in early childhood and prenatal development (Hertzman & Power, 2004). Academic achievement, literacy skills, emotional maturity, social competence and overall abilities to cope with challenges in middle childhood, adolescence and adulthood track back to early periods of development (McCain et al., 2007; Tremblay, 2006). Measures of physical growth, cognition and behaviour in early childhood predict health status in adult life (Hertzman & Power, 2004).

Studies in developmental psychology and population health point to the persistent influence of SES on child development. Developmental psychology findings consistently report the association of lower socioeconomic status (SES) environments with poorer outcomes. Epidemiological and demographic studies find that SES in early life influences health status in middle and late adulthood. Wadsworth and colleagues in a detailed study of the 1946 British birth cohort show that conditions in early life can set risks for both physical and mental health problems in adult life (Wadsworth, 1991). Power, Manor, and Fox (1991), in their studies of the 1958 British birth cohort conclude that circumstances prevailing at each stage of child and adolescent development are relevant to the health differences among adults. Scientists came to the same conclusion in a study of the 1970 New Zealand birth cohort (Poulton et al., 2002). Poor socioeconomic circumstances for early child development have long lasting negative influences on adult health. Findings from several longitudinal studies indicate that socioeconomic position in early life influences health several decades later and for some outcomes, early circumstances override those of adult life.

Because the link between SES and children’s development health is a gradient, low SES and poverty is not the only factor that makes some children more likely to be in poor health and have developmental delays. SES gradients are present across a range of developmental health measures in early childhood.

Poverty is not the only factor that makes some children more likely to be in poor health or have developmental delays.

No socioeconomic threshold exists below which all children have problems and above which all children do well. While children in the lowest-income families are more likely to experience problems with health and development, a high proportion of children in middle income and higher-income families also have problems. Programs that target only low-income children and youth will miss the majority of vulnerable young people. Also the greatest numbers of children having difficulties are actually living in moderate income, two-parent families. Gradients in early development reflect daily experiences and environments that are shaped by family, neighbourhood and societal factors. SES is a powerful factor but other elements of nurturant or non-nurturant environments and experiences influence the course of development.

The relationship between SES and developmental outcomes can be illustrated by considering measures of children’s social, emotional, physical and cognitive readiness for school learning. Investigators often measure child development at the time of school entry to examine the relationship between a child’s school readiness and performance in the school system. They conclude that assessments of readiness for school learning in kindergarten can predict 60% or more of the variance in grade three tests (Rock & Stenner, 2005). About one quarter of all children in Canada appear to be vulnerable (that is, one quarter of children have a developmental difficulty or problem that is likely to interfere with learning or behaviour or health) when they enter Grade One (McCain et al, 2007). They may have problems getting along with other children, meeting challenges, regulating their emotions, attending to tasks or learning new concepts and skills. When children’s developmental outcomes at age five are considered in context of SES the gradient pattern emerges. The overall average of vulnerability may be 25% but in some regions of the country as many as 75% of the children may be vulnerable but only 10% may be vulnerable in other communities. The differences are often related to SES but other factors are also involved. In the lowest SES communities, some children do very well and in the most affluent communities some children are having difficulties.

What is less clear is how the SES experiences become incorporated into the actual biology of individuals. A strong suspect, based on a plethora of research findings in developmental psychology over the past three decades,  is the limbic hypothalamus-pituitary-adrenal (HPA) pathway that is set early in life and its role in the secretion of cortisol (Boyce & Keating, 2004; Hertzman & Frank, 2006; Li, Power, Kelly, Kirschbaum, & Hertzman, 2007; Power & Kuh, 2006). Less affluent circumstances with reduced resources are often associated with fewer opportunities to support development and increased challenges that increase the activity of the HPA pathways. Access to nurturant experiences and developmental opportunities, regardless of SES, also seems to influence the development of the architecture of the brain and neural pathways such as the HPA pathway.

Early learning, behaviour and health are markers for brain development. SES gradients in early childhood can be interpreted as evidence of differences in access to developmental opportunities that provide adequate nurturance, nutrition and stimulation (Hertzman & Power, 2004; McCain et al., 2007).

References

Boyce, W.T., & Keating, D.P. (2004). Should we intervene to improve childhood circumstances? In D.L. Kuh, & Y. Ben-Shlomo (Eds.). A life course approach to chronic disease epidemiology (2nd ed., pp. 415-445). New York: Oxford University Press.

Brownell, M., Roos, N., Fransoo, R., et al. (2006, October). Is the class half empty? A population-based perspective on socioeconomic status and educational outcomes. Choices, 12(5).

Hertzman, C., & Frank, J. (2006). Biological pathways linking the social environment, development, and health. In J. Heymann, C. Hertzman, M. L. Barer, & R. G. Evans (Eds.), Healthier societies: From analysis to action (pp. 35-57). New York: Oxford University Press.

Hertzman, C., & Power, C. (2004, October). Child development as a determinant of health across the life course. Current Paediatrics, 14(5), 438-443.

Keating, D. P., & Hertzman, C. (Eds.). (1999). Developmental health and the wealth of nations. New York: The Guildford Press.

Li, L., Power, C., Kelly, S., Kirschbaum, C., & Hertzman, C. (2007). Life-time socio-economic position and cortisol patterns in mid-life. Psychoneuroendocrinology, Vol 32(7), 824-833.

McCain, M., Mustard, J. F., & Shanker, S. (2007). The early years study 2: Putting science into action. Toronto, ON: Council for Early Child Development.

Poulton, R., Caspi, A., Milne, B. J., Thomson, W.M., Taylor, A., Sears, M.R., &               Moffitt, T.E. (2002, November). Association between children’s experience of socioeconomic disadvantage and adult health: A life-course study. The Lancet, 360(9346), 1640-1645.

Power, C., & Kuh, D. (2006). Life course development of unequal health. In J. Siegrist & M. Marmot (Eds.). Social inequalities in health: new evidence and policy implications (pp. 27-53). Oxford, UK: Oxford University Press.

Power, C., Manor, O., & Fox, J. (1991). Health and class: The early years. London: Chapman & Hall.

Rock, D. A., & Stenner, A. J. (2005, Spring). Assessment issues in the testing of children at school entry. The Future of Children, 15(1), 15-34.

Tremblay, R. (2006, April 27). Is 18 months too early for an Early Development Instrument? Presentation presented at the colloquia Measuring Early Child Development, Vaudreuil, Canada.

Wadsworth, M. E. J. (1991). The imprint of time: Childhood, history and adult life. New York: Oxford University Press.