It was like any other day. An early-morning panel of pediatric patients. A mother asking me why her 6-month-old is always crying no matter what she does to calm him. A 3-year-old asthmatic child jumping back slightly as I approach to listen to his lungs. A 12-year-old in for a suture removal after getting hurt in a fight at school, his third this year.

As a pediatrician working at St. Christopher's Hospital for Children in North Philadelphia, I see these scenarios play out daily. Our hospital is smack in Philly's epicenter of childhood poverty, hunger, violence, and unemployment - factors that contribute to individual, family, and community stress. Factors that can make babies more twitchy, toddlers more hyper-vigilant, school-aged children more prone to headaches, and children more overweight and likelier to be asthmatic. These factors can also cause tweens to be more apt to fight and teens to self-medicate and engage in more violent acts. As I read The Inquirer's seven-part series on school violence, "Assault on Learning," that exposed the brutal attacks on both children and teachers and the complexities of balancing school safety and learning, I saw a common thread in this tragedy: stress.

When a soldier comes home after witnessing the horrors of war, or a woman is raped, they may be diagnosed with post-traumatic stress disorder. Many studies in adults have shown the devastating costs of trauma and the difficulty of treating PTSD. What about the consequences of trauma in the developing brains of our children? What if there is no post in their trauma? What if it's continuous traumatic stress disorder.

This term was introduced in 1986 by South African writer Frank Chikane as he chronicled the effects of continuous trauma on children living through apartheid.

Research has confirmed the detrimental effects of pesticides, childhood lead poisoning, and secondhand smoke. More recent work has pointed to substances made internally to ward off actual or perceived danger: hormones involved in the fight-or-flight mechanism for human survival. Substances that, if chronically bathing a child's developing brain, will alter its architecture along with the child's response to environmental stimulus.

The culprits have names such as beta endorphins, epinephrine, and the major offender, the "stress" hormone cortisol. These chemicals help us jump out of the way of an oncoming car, fight off infections, and do better on a math test. If they are secreted in short bursts, we are safer, faster, and stronger. If there is prolonged activation of these chemicals, they become toxic and increase a child's allostatic load, a term coined by two psychologists, McEwen and Stellar, at Yale in 1993.

Allostatic load is defined as the effects of chronic exposure to changing or elevated chemical responses stemming from repeated or chronic stress. This concept has been demonstrated in several large studies in children and adults, including the Adverse Childhood Experience Study (ACE Study) in California, which has shown that the more adverse experiences children have - such as child abuse or domestic violence - the less likely they are to work or have a high school diploma and the more likely they are to be unhealthy, take risks, and die at a young age.

More recent studies show that children exposed to chronic domestic violence, housing instability, and hunger had more asthma diagnoses, obesity, and developmental delays.

Continuous stress is especially toxic to infants and younger children who are starting to make connections in their developing brains.

Armed with this knowledge, doctors and child advocates fight against continuous traumatic stress. Domestic-violence screening and trauma-informed therapy can help the healing process. Connecting families to resources, such as those on www.cap4kids.org/philadelphia, also can help.

Knowing the negative effects of stress on a child should guide public policy and get us to rethink cuts to efforts that nourish children, such as Medicaid, Head Start, and WIC.

The morning session is over and the afternoon panel awaits.

My first patient, a 7-year-old boy, is struggling in second grade and has a history of living in a household with documented domestic violence. He looks me in the eye, pensive and distrustful. Broken.

I empathetically discuss school testing with his mother for possible learning disabilities, suggest an after-school program that offers free homework help and mentoring, and discuss resources for families affected by household violence. These are small interventions, but with two other charts waiting in adjacent doors, it is all I can offer.

As I leave, his look reminds me that we must heal the hurt to stop the cycle of violence.

More than 100 years ago Frederick Douglass wrote, "It's easier to build strong children than repair broken men." It's time to build.

Dan Taylor's e-mail address