Each year, child protection agencies receive more than 3.6 million referrals involving more than 6.6 million children who may be experiencing abuse, according to the advocacy group Childhelp. In some cases, that abuse turns deadly: On average, between four and seven American children die each day because of abuse and neglect. Most of them — approximately 70% — were two years old or younger. But even when children survive abuse, the psychological and cognitive effects of growing up with trauma can last a lifetime.

Adam Brown, PsyD, a child psychologist at the NYU Child Study Center, told Teen Vogue that child abuse can take many forms, ranging from neglect to physical and sexual abuse. In cases of neglect, a child's development may be stunted as a result, Brown said. In order to understand how abuse affects the brain, Brown said, it's helpful to understand what kinds of environments children need to thrive.

"The structures of the brain continue to grow throughout childhood, with a lot of growth happening in the first year," Brown said. "Neurons in the brain grow in result to experience, so that's why it's so important to have nurturing, stimulating, and safe experiences in the first year of life. In the absence of that, kids are not going to grow in an optimal way."

One of the biggest issues in cases of neglect, according to Brown, is that children won't learn to "regulate their emotions," since they may learn to do so from their caregivers.

Dr. Kim Schrier, a pediatrician who's running for Congress in Washington state's eighth district, explained how parents should teach children to regulate their emotions. "When you put a child in stress, they don't know how to self-calm," Schrier told Teen Vogue. "That's why when you see babies cry, parents hug, we sing lullabies, we do deep breathing, we blow bubbles. These are all things we do to help kids control and adapt to stress."

But, as Brown and Schrier explained, the absence of these stress-management lessons can have an adverse effect on young brains. "If kids don't have the ability to develop these adaptations [to stress], then it becomes what we call toxic stress," Schrier said. "You're flooding the developing brain with cortisol and adrenaline.

Nearly 15% of respondents to a questionnaire for a joint study on adverse childhood experiences by the Centers for Disease Control and Prevention and the health organization Kaiser Permanente mentioned emotional neglect during their first 18 years of life, while an additional 10% mentioned physical neglect. Even more spoke to physical abuse (28.3%), sexual abuse (20.7%), or emotional abuse (10.6%), all of which Brown says are experiences that can lead to increased aggression and psychological issues in children.

"Neglect can have such a negative impact," Brown said, "but then imagine if the people who are supposed to keep you safe are actually harming you." Much like in cases of neglect, physical, sexual, and emotional abuse can "trigger the stress response system in the brain," leading to that "flight/fight/freeze" response in children, Brown said.

Everyone has the flight or flight response — it's why your heart races when you're scared, why some people are able to fend off attackers, or why sometimes you freeze up in times of danger. But when this response is being constantly triggered in a child's brain, the effects can be seriously detrimental, according to Brown.

"If a child is experiencing danger in a chronic way, like when they're being abused, then their stress response system is on high alert all the time," Brown said.

Being forcibly removed from one's parents at a young age could trigger that stress response.

"You certainly could imagine a very young child being suddenly and forcibly removed from their parents, and being made to live somewhere where they don't know anyone, is going to have a very serious stress response," Brown said.

"We know that adults who have a history of child abuse or other negative effects in childhood are at a much higher likelihood for psychiatric problems, for medical problems, to be unemployed, and to have problems with the juvenile or adult justice systems," Brown continued.

Some issues can be addressed through psychological treatment and counseling — and, most importantly, by removing the child from an abusive situation — but child abuse can also lead to medical issues down the line. According to the CDC/Kaiser study, "adverse childhood experiences" like abuse and neglect can increase risk of heart disease, liver disease, and chronic obstructive pulmonary disease, as well as conditions like depression.

"You take these children who don't know how to adapt and put them in these toxic stressors, and you're basically setting them up for academic struggles, for emotional struggles, not knowing how to bond, for not knowing how to seek help," Schrier said. "These are lifelong impacts."

Related: How Family Separation at the Border Impacts Children

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