It might seem like this could be explained by the fact that the wealthier kids simply got better jobs and became wealthier, healthier adults, but that’s not quite the full picture. The participants’ level of education and jobs throughout their adulthood partly, but not entirely, ameliorated the effect of a poor upbringing on their cognitive skills in old age. The authors conclude that there seem to be three ways childhood poverty might be affecting the brain in adulthood, and they’re not mutually exclusive.
First, there’s the latency model, or the idea that more cognitive stimulation in childhood leads to more advanced brain development later on. Kids in wealthy families might be sent to computer camp, for example, while those in poorer families do less enriching things, such as watch TV. And wealthy families might be more likely to have time to do things such as ask their kids questions or read them books.
“The brain architecture is much more complex if you are stimulated,” says Marja Aartsen, a professor at the Oslo Metropolitan University in Norway and the lead author of the study. “If the architecture is more complex, there are more connections between all the neurons.” Those extra connections come in handy when some of them begin to die off.
Then there’s the pathway model, or the idea that people who grow up wealthier end up going to better colleges, getting better jobs, and generally living less stressful, more enriching lives that protect brain health. In essence, being a rich kid puts you on a pathway to cultivating a healthier brain.
Finally, there’s the cumulative model, which suggests that all the difficult things that happen to poor kids—the so-called adverse childhood experiences, such as neglect or substance abuse—compound one another and lead to worse academic performance, and eventually to cognitive decline.
In the new study’s results, all these factors might be working together. “I found it interesting that they had data that could support all the models,” says Susan A. Everson-Rose, a professor of medicine at the University of Minnesota who has also studied the topic but was not involved with the PNAS study. “It makes a lot of conceptual sense to me.”
Past studies found that socioeconomic conditions in childhood can influence the level of verbal skills and executive functioning that people have when they enter old age. A person’s economic status in adulthood can affect brain health and cognitive functioning in old age as well. The idea that’s now emerging about memory loss is that a problem often thought of as purely related to old age is actually a lifelong process that begins in childhood.
“Epidemiological research in cognitive aging highlights an intuitive yet oftentimes overlooked aspect of brain aging: It is lifelong,” said Emily Greenfield Cohen, an associate professor of social work at Rutgers, in an email.