Poverty and trauma take more than mental tolls on children. Childhood adversity affects kids’ physical development too, and new research suggests it leaves its mark in an unexpected place: teeth.

In a study published this month, University of Pennsylvania scientists found that kids who are exposed to significant stressors often see their first molars emerge earlier than less-stressed youngsters. Molar growth could be accelerated by months in some Black or Hispanic kids or those from lower-income families. While the reasons are still unclear, the study confirms years of research showing that adversity and inequity affect the body — and it starts early.

Though the research began before the pandemic, it has taken on added resonance.

“We all just went through a massive stressor,” said Allyson Mackey, assistant professor of psychology at the University of Pennsylvania. “We need new ways to understand how stress is impacting our kids.”

Previous studies show that kids facing adversity can go through puberty earlier. When scientists look at these kids’ cells, they can even see signs of aging in their DNA, which is sprinkled with molecules that are usually accumulated over years, and buffer regions called telomeres that protect the ends of the DNA already start fraying.

But Mackey suspected that kids who entered puberty early may have signs of premature aging even younger.

“If we know that a kid is growing up too fast when they’re 9 or 10, there’s a shorter window to do something about it,” Mackey said. “We were looking for a measure of accelerated development that we can see early and easily.”

That’s where she thought teeth could help. Growing and losing teeth are milestones of aging, and changes in teeth are easier and cheaper to detect than DNA changes.

Working with a group of 117 Philadelphia-area children ages 4 to 7, Mackey’s team used a form of magnetic resonance imaging (MRI) to snap pictures of the teeth before they broke through the gums’ surface. They scored each kid’s stage of molar development and recorded potential stressors like low family income and 10 adverse childhood experiences, or ACEs, including abuse, neglect, substance abuse, and incarceration of an adult in the household.

Mackey was surprised to see just how strongly the stressors correlated with molar growth. Children in the study from lower-income families or with more ACEs tended to grow first molars earlier, a trend that also showed up in a nationwide survey. Mackey noted that these differences were small — only a four-month gap between kids in the lowest- and highest-income families — and reflect broader population patterns more than any individual child’s trajectory.

There were also racial disparities in timing of molar growth; Black and Hispanic children in the study tended to grow molars earlier. “We think that this pattern is very consistent with elevated risk for stress in communities of color due to structural racism,” Mackey said.

For Daniel Taylor, an associate professor at Drexel University College of Medicine and director of community pediatrics and child advocacy at St. Christopher’s Hospital for Children, this study confirms what he has long known as a pediatrician for low-income patients and families of color in North Philadelphia.

“This research is validation to me that poverty and racism affect health,” Taylor said. “It doesn’t tell me that I should get X-rays to identify early molars … we have to focus on the huge systemic issues.”

The 2013 Philadelphia Urban ACE Survey found that 37% of Philadelphia adults reported having experienced at least four ACEs. In Mackey’s study, over half the participants had at least one ACE, which previous studies have linked to chronic illnesses such as heart disease and depression. The trauma that ACEs cause can also increase the levels of stress hormones such as cortisol that can have long-term effects on brain development.

Taylor said it’s important for pediatricians to be aware of all aspects of their patients’ early development.

“If you don’t know about premature aging, and you don’t know the factors that go into it like poverty and racism, then you won’t be asking those questions as a pediatric provider,” Taylor said.

He emphasized the importance of trauma-informed care and evidence-based interventions that can be offered to families during a pediatrician visit or through community outreach, such as screening mothers for depression and legal struggles such as with landlords and employers, and connecting them with services such as lawyers and social workers. Even helping parents file for tax credits can have a big impact: Alleviating financial insecurity can decrease stress and minimize negative developmental effects on the children, Taylor said.

Mackey hopes that her study can justify the importance of policies that address poverty and children’s well-being, such as unconditional cash transfers and home visit programs.

“I think we know a lot about what can work for helping kids experience less stress and thrive despite some of these environmental risks,” Mackey said. Her study, she said, can “provide greater support for these kinds of policies.”

The original data were collected before COVID-19, but the kids and their parents have now also filled out surveys about stressors related to the death, illness, and isolation they may have faced during the pandemic. She’ll follow the kids in this study as they grow older to see whether early molars are an indicator of any longer-term outcomes or if later traumas or interventions can modify the speed of aging.

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The Philadelphia Inquirer is one of more than 20 news organizations producing Broke in Philly, a collaborative reporting project on solutions to poverty and the city’s push toward economic justice. See all of our reporting at brokeinphilly.org.