Dr. Frederick Zimmerman is professor of health policy and management in the Fielding School of Public Health and co-director of the UCLA Center for Health Advancement at the University of California, Los Angeles. He is an economist with a background in institutional and behavioral economics. His research illuminates the intersection of economics and the determinants of health. Dr. Zimmerman has a particular interest in how economic structure — including poverty and inequality — influence population health.

Q: Around the LENA office, we know your name from frequently citing the 2009 study you published in Pediatrics exploring how conversational turns help children develop language. That study looked specifically at the home language environment, but these days you’re researching more broadly how social, political, and economic environments influence health. How did you make that transition?

A: What we found earlier — and I should stress that although I was the lead author it was very much a team effort — was that the language environment really matters to child language development and therefore to school readiness. So the obvious next questions to me were, “What affects the language environment? What social, political, and economic factors contribute to parents’ capacity to engage with their children? Who has the time and who doesn’t, and why?”

Q: Your recent research focuses on how the environment influences the health of populations. Could you start off by explaining what determinants of health are?

A: I teach a class on the determinants of health, and I’ve noticed that most students come into class assuming that health is determined by medical care. But actually, only about 10 to 15 percent of health is determined by medical care. The rest is determined by the social, political, and physical environment.

An example of how the physical environment affects health is when there’s lead in the environment. Lead is an incredible neurotoxin, and it has a really adverse effect on children’s health and development. Some of those are direct outcomes, but some are indirect and not immediately obvious.

The United States banned lead paint in 1976, so blood lead levels in kids declined through the 80s and 90s. Crime rates also began to decline, with a lag of about 20 years, because that’s how long it takes to grow a criminal. Crime rates peaked in the early 1990s then began to fall. Now, violent crime has decreased by about 75 percent in the United States, mostly because we got lead out of the environment.

So that’s an example of the great importance of the environment to population health, whether you’re exposed directly [because you suffer from the lead] or indirectly [because you suffer from crime — or from the stigma and harsh policing of neighborhoods affected by crime]. Those are the kinds of issues that I’ve become very interested in. Lead is an interesting example of how population health is produced and has very little to do with healthcare.

You certainly want people to have access to medical care after they get shot, but I’m interested in learning how to prevent people from getting shot in the first place. I want to identify the next thing that causes huge parts of the population to have poor health.

Q: So what’s the next issue that will have the same population-level health effects as lead?

A: One of those next things is high housing costs. If you’re dealing with high housing costs, you’ll do one of three things. The first reaction is to live farther away from your job and drive longer to get there. The second reaction, that’s increasingly common, is crowding. Families will move into smaller apartments or put two families in a space that previously held one. Kids don’t move out; they live with their parents longer. And the third response is to take money away from other needs like food and medicine.

Q: How are you studying the effects of high housing costs?  

A: Together with Eryn Block, a terrific PhD student here at UCLA, I published a recent paper in the American Journal of Public Health about the effect of high housing costs on child development.

We had data on the commute time of the parents in the study and on residential crowding. To measure children’s development, we used the Early Development Instrument, which is an assessment tool that tracks the five domains of school readiness — physical health and wellbeing, emotional maturity, language and cognitive development, and communication skills.

We found that in many of those domains, residential crowding inhibited school readiness — if there was more crowding, children were less likely to be ready for school. We saw that crowding was particularly impactful on the language and communication domains, but we didn’t see any effect on emotional maturity or social competence in our general sample. What we think is happening is that when there’s more crowding, there’s less opportunity for kids to have the kind of natural interactions they would otherwise be having.

Q: So it sounds like some of those factors associated with high housing cost could be affecting the home language environment of the children?

A: I think it could be affecting the home language environment. We can only infer in this analysis, because we didn’t collect any high-quality language environment data using LENA, but what we did notice is that within the high-poverty sample, children whose parents had longer commutes scored lower for social competence and emotional maturity. So they’re likely getting language stimulation from their babysitters and other caregivers, but they miss their parents, and this may be causing their social competence to decrease. It could be about the long commute, or it could be about the variability. It could be that longer commute times take away from the average amount of time that parents have for their kids, but it could also be that the commute makes parents’ arrival unpredictable, which is hard for kids.

There’s an enormous amount more to know about this issue. In the context of other literature, it does feel as if we’re on to something — all the studies (like Newman, 2014, Pollack, 2010, and Mason, 2013) are telling a consistent story — but we’re not exactly sure what that story is yet.

Q: What are the takeaways from this research?

A: For me, the really big takeaway is not at the individual level, but at the community level. Some research says that urban density is associated with better health. Urban density [many people per acre] is not the same thing as residential crowding [many people per room], and densifying our communities can actually make us all better off.

For example, when developers add new housing, they’re also adding a new cafe, a new grocery store — and when they add all that, people might be able to walk or bike there instead of driving, and maybe they’ll have better opportunities to interact with friends and neighbors on the way there, all of which have cascading positive effects. People tend to be worried about the wrong things when they think about urbanization.

Q: What’s next for you?

A: We are very interested in health equity and how some of these issues break down differently by racial-ethnic groups. We’re also interested in arts education in schools, looking at the impact of access to music and other performing and visual arts programs that may have an impact on wellbeing and health.

Read Dr. Zimmerman’s new study examining trends in health equity.