2.2 The gradient effect
To fully understand trajectories and social determinants of health we need to be aware of socioeconomic gradients. The relationship between socioeconomic status (SES) and a variety of developmental health outcomes can be represented as a socioeconomic gradient.
The gradient effect means that there are differences at every point along a line. There are many reasons for different outcomes but in general, the gradients show clearly that the health and well-being of populations are linked to different social settings and how resources are distributed within the population. For example, the poorest mothers have the least literate children and the wealthiest mothers have the most literate children. It is also notable that for every step in between the two extremes, the relationship between maternal poverty and literacy is there. Mothers who are slightly less poor have children with a slightly higher rate of literacy and so on up the scale so that every improvement in SES has an effect on the developmental outcome.
We need to pay attention to these childhood gradients because they tend to set the path of the life course trajectory. In other words, they continue into adulthood.
In the next clip, Dr. Clyde Hertzman continues his talk, “Equity from the Start”, (the first part is on Page DH 1.1) and explains the social gradient in early child development.
Dr. Martin Guhn is an assistant professor in the School of Population and Public Health at the University of British Columbia. In the next video, he elaborates on socio-economic gradients and discusses using the information to make policy changes to improve outcomes for individuals.
In the next video, Dr. Marni Brownell explains a population study that looked at the correlations between SES and outcomes on a standardized high school language arts test in Manitoba. Being able to use population-level linked data sets allowed for deeper analysis with very interesting results.
Dr. Daniel Keating (personal communication), from the University of Michigan, makes these points about the gradient effect:
- Different outcomes, same patterns: For every aspect of developmental health there is a gradient showing a correlation between outcomes and SES. In other words, children growing up in poverty have poorer physical and mental health later in life than those growing up in middle class homes who, in turn, have poorer outcomes than those growing up in wealthy homes. This is true for every society.
- Development varies across populations: However (and this is a big however), in a society where there is less of a gap between rich and poor, not only is there less difference in developmental health outcomes but, interestingly, the overall developmental health outcomes are higher. In other words, flatter gradients are higher.
- Early development influences later development: Development later in life is strongly influenced by peoples’ SES status very early in life. For example, nutritional deficits or malnutrition in the early years impact children’s brain development, physical, cognitive, social & emotional development as well as their ability to resist illness. This can have lifelong impacts on their health and wellness.
Try the following activity to help you review your understanding of the gradient effect. This activity depicts the relationship between language scores and parental level of education (a common SES measure) for some Latin American countries.
Though Cuba is considered a resource-poor country, children’s language scores are much higher than other Latin American countries, no matter what their background. Cuba has invested in mothers through intensive pre and post-natal programs and services as well as through early child development programs.
On the next page you will see more about how early investments can impact individual and population health.
