Ryan Keen

When we think of homelessness, we often picture an older person bundled in every piece of clothing they own sleeping rough in a storefront or on a park bench. The truth is that homelessness—the most severe form of housing insecurity—is often more complicated and less obvious. It’s the 20-something single mother who must sleep in a shelter because she has exhausted her options while trying to provide for her children. It’s the middle-aged woman who sleeps in her car because she can’t make rent in town, where the jobs are. It’s the 30-something man couch-surfing from friend to friend, not knowing where he’ll next find a place to rest his head. And, most often, it’s children who don’t have a safe or stable place to live.

“Several million children experience outright homelessness or severe housing insecurity on any given night in the United States,” says Ryan Keen, a PhD student in population health sciences at GSAS. “There are children who are separated from their parents involuntarily and don't know where they're going to end up; children constantly moved between foster homes; children who lose everything suddenly when their family is evicted without much notice.”

There are costs to all that insecurity—ones that show up in the wellbeing of the young people who experience it. In his 2023 Harvard Horizons project, “Housing Insecurity and Homelessness,” Keen looks at children who experience housing insecurity and finds profound impacts on their mental and physical health and development. Children who experience episodic, chronic, or even transient periods of homelessness, for instance, often don’t make the close friendships and stable relationships critical for healthy social development, Keen says, leaving them feeling lonely and isolated. Then there’s the social stigma they encounter.

“Most of us dress in an old pair of sweatpants and baggy hoodie one day, and it’s just what we decided to throw on,” he says. “We’re not experiencing housing insecurity. A friend or a relative might look at us and say, ‘Oh, you're dressing like a homeless person today.’ They think it’s a harmless comment, but for someone who’s dealing with the actual circumstance of being homeless, it’s disparaging and creates an added stress.”

In his research, Keen examines a longitudinal cohort study of children from the western Appalachian region of North Carolina, not far from where he grew up. Prospective cohorts enrolled at ages 9, 11, and 13 were repeatedly assessed by developmental and psychiatric epidemiologists at Duke University for 25 years. Using this extraordinary data set, Keen tries to clarify cause-and-effect relationships between childhood housing insecurity and a number of different health outcomes. In a recent paper he authored, for instance, Keen found significant increases in symptoms of anxiety and depression among children who experienced housing insecurity compared to those who didn’t.

But were the outcomes Keen measured the result of housing insecurity or simply of poverty? To find out, Keen separated the two in his study. “The data were of such high quality that I could include a distinct indicator for housing insecurity that was separate from the one for poverty in my models,” he says. “When I coded those separately, I saw that even when poverty didn't have a significant impact on mental health, housing insecurity did.”

Keen says housing insecurity manifests in the physical health of children as well. During each assessment, researchers measured the level of C-reactive protein (CRP)—a biological indicator of inflammation—in the blood of the subjects in Keen’s data. Research indicates that chronically elevated levels of CRP are a marker for a range of adverse health outcomes—particularly cardiovascular disease. With that in mind, Keen analyzed his data to see what happened to children in the study.

“What we see in our preliminary results is that kids who experience housing insecurity are likely to have chronically elevated levels of CRP,” he says. “Now we’re looking to see if that particular increase is also associated with increased risk of cardiovascular disease once the children became young adults.”

Keen says he hopes his work will help policymakers think about housing insecurity and homelessness not simply as adverse social conditions, but also as chronic illnesses—ones that can have a lifelong impact if untreated. He imagines a day when, just as children receive antibiotics to combat a case of strep throat, they might be prescribed housing as part of an integrated care model that seeks to prevent adverse health outcomes, from depression to heart disease.

“The research that I'm doing considers housing insecurity as a pediatric illness,” he says. “If the evidence base becomes strong enough to link social adversity to biological consequences, maybe we stand a better chance at convincing policymakers to fund more innovative evidence-based interventions for children and families. That would be a new standard of care.”