For the past few weeks, the young man’s heart has been racing. His hands are sweaty. During the day, he has flashbacks of the world he fled in El Salvador: gang members chasing him, threatening murder. Nightmares of the same scenes disturb his sleep. He’s not a patient in my psychiatric practice. Just another young guy studying for his high school equivalency diploma at the Latin American Youth Center in Washington. Like the 4,000 other kids taking classes there, he’s been worrying as he watches what the center’s chief executive, Lori Kaplan, calls “the big reality show . . . on cable news — and the tweets.”

In St. Paul, Minn., Sharif Mohamed’s children are also “paying attention” to the TV news, he says. Mohamed is an imam, a spiritual leader of the Somali community there and a U.S. citizen; he came as a refu­gee 20 years ago. Every day, Muslim women and children tell him about being verbally abused on the street and in schools. The nearly 100,000 other east Africans in Minnesota are painfully aware of the president’s recent temporary ban on refugees and visa-holders from their homeland and other predominantly Muslim countries, and of the administration’s public statements: Michael Flynn, President Trump’s national security adviser, has called Islam “a cancer.”

Sharif says his fellow Somali immigrants “love [our] country and can accept the incredible burdens” of rising out of poverty. He is proud of his community’s “working people, soldiers, police officers, politicians, business leaders, doctors and teachers.” But now his children worry that they will never again be able to visit overseas relatives. They worry, even more, that they may not be able to stay in this country, the only home they’ve ever known.

These and other fears are now the daily bread of large numbers of the 42 million immigrants in this country — including the children who, years ago, immigrated and became citizens. Physicians, therapists and community leaders such as Mohamed have for years been using my Center for Mind-Body Medicine’s model of self-care and group support to help this population deal with their stress. They tell me now that fears and powerlessness and uncertainty are causing many to be increasingly anxious and angry, depressed and withdrawn. Over time, such chronic stress, unaddressed, will make them far more vulnerable to heart disease, asthma, diabetes and post-traumatic stress disorder.

We’re learning that disrespect, discrimination and detention can have long-term physical and psychological consequences — on those who observe as well as those who experience them. Over the past few years, surveys and qualitative research have begun to reveal the extent of the physical and emotional effects. And a study published last month in the International Journal of Epidemiology by University of Michigan researchers provides hard biological evidence that these changes can be transmitted to the next generation.

The study found that Latino babies born in the 37 weeks following a federal immigration raid in Postville, Iowa, in 2008 had a 24 percent greater risk of low birth weight than the babies who were born to Latina women in the same period a year earlier. (Previous years, too, showed normal rather than depressed birth rates.) Low birth weight is associated with long-term risks to physical health and mental health, cognition and academic performance. What is most troubling, as well as surprising, about the study is the extent of the effect. Low birth weight and its risks were, perhaps predictably, high among undocumented immigrants, but they were just as high among Latinas across the state who were legally in the United States. In spite of their apparent safety, their bodies were reacting as if they, too, could soon be deported. Years before the latest presidential threats and actions upped the immigration ante, fear was overriding immigrants’ faith in the dependability of their legal status.

Undocumented immigrants, who have long lived in fear of deportation, are probably the most profoundly affected. Among them are the 800,000 “dreamers ,” the young people who came to the United States as undocumented children and are now all but indistinguishable from U.S. citizens in high schools and colleges, as they serve in the military and work and marry and raise their own children. In 2012, when President Barack Obama created the Deferred Action for Childhood Arrivals program, he granted them a measure of relief, allowing them to apply every two years for continuing permission to stay in the United States. These dreamers know that the platform Trump ran on contains a different kind of promise: to “immediately terminate” their status.

The green-card holders and immigrants who became citizens are worried, too. Over the years, they’ve watched roundups and deportations of people who share their history, speak their language and work in their communities. In recent months, Trump’s threats and promises have reawakened fears and physical symptoms that patients of mine, long-ago refugees from tyrannical regimes, thought they’d left behind. Like the Salvadoran youth studying for his GED, memories of the danger and dictatorships they fled are intruding on their thoughts and agitating their bodies. During the past week, many of my and my colleagues’ patients have been panicked by stories of people with green cards prevented from returning to the United States.

The damage to the next generation may be compounded by other, less obvious assaults on their biology and psychology. Research by Rachel Yehuda and her colleagues at Mount Sinai Hospital in New York has demonstrated that the consequences of Holocaust survivors’ extreme trauma can be passed down to their children and grandchildren, making them exquisitely sensitive to the ordinary stresses of relatively safe lives. Yehuda and other researchers believe that these are “epigenetic” effects, modifications in the ways genes express themselves, which transmit vulnerabilities to stress from one generation to the next. Though the mechanisms are not completely understood, animal studies as well as those on human adults who were abused as children demonstrate similar changes.

“There is no short-term fix for this kind of damage,” Lori Kaplan commented sadly, thinking about the young people and their families who are anxiously calling her and her colleagues, reporting physical and emotional distress, looking for answers. “We’ve been dealing with the trauma of the immigrant experience for so long,” the flight from violence, the loneliness, the poverty, the struggle to survive in a strange land and the longing for home. “Obama was deporting people, sure, and there was anxiety, but he also gave us hope. And now the roof’s been blown off.”

As Trump orders more border guards and detention centers , and as the wall looms large, the fears of young people and their parents at the Latin American Youth Center grow. Perhaps they’ll be denied housing; fired from their jobs; maybe their health care will disappear. Latino immigrant parents in the Washington area are desperate for their kids to get an education, explains Angelica Garcia-Ditta, a counselor at the center, and they’re still sending their children to school. But, she says, they worry that “immigration authorities will seize them.”

Still, amid a national clamor that diminishes and isolates them, immigrants are organizing. Spiritual leaders, lay counselors, kids, families and friends are joining circles of support, they tell me. They are sharing sadness and fears, using self-care techniques to lower stress, and finding connections to others who have similar concerns. The children of Latino immigrants, Kaplan tells me, now understand that Black Lives Matter is about them, too.

“Our anxiety is very high,” says Sharif Mohamed. “We come together as families in our mosques. We are praying together” and using self-care techniques, hoping to relieve stress and forestall long-term psychological and biological damage. “It gives us the capacity to address our anxiety, our hopelessness and our anger in a profoundly healing way. I and every other Muslim parent is guiding our children to hold close to our faith, to God’s love, to kindness, to a deep belief that we are all here on earth to love and respect.”