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How Does Parental Separation Affect a Child’s Brain?

  • Published22 Jun 2018
  • Reviewed22 Jun 2018
  • Source BrainFacts/SfN
Hands separated reach out toward each other for help.

In June 2018, medical and scientific associations including the Society for Neuroscience, the American Psychological Association, the American Academy of Pediatrics, the American College of Physicians, the American Psychiatric Association, among others, urged the U.S. government to halt the practice of separating immigrant children from their parents at the U.S. border. In doing so, these medical and scientific experts focused not on an abstract concept such as cruelty, but on the long-lasting damage that separation can do to a child’s developing brain. The U.S. government rescinded the practice on June 21, 2018.

The incident, however, raised questions about how stress and trauma affect the developing brain. To understand more, spoke with Charles A. Nelson, a professor of pediatrics and neuroscience at Harvard Medical School. Nelson, with his colleagues Charley Zeanah and Nathan Fox, studied children from Romania who had been abandoned by their parents and put in state-run institutions. Nelson and his colleagues randomly assigned half of the children to a foster care situation and then followed the children for almost 18 years. They have found changes in the brains of abandoned children that can be permanent. 

What do we know about how parental separation affects a child’s brain? 

In institutionalized children, we pretty quickly see a dramatic reduction in brain electrical activity. If a child is removed from the institution and put in foster care before age two, it looks as though a lot of this recovers, but if they’re older than two, we observe far less recovery. 

When we take magnetic resonance images of the children’s brains when they are older, we see a dramatic reduction in the gray and white matter. We also find that the integrity of various white matter tracts has been compromised. White matter is made up of insulated bundles of nerve fibers that allow various regions of the brain to communicate. We can’t tell whether the reduction in gray matter, the part of the brain that gives us our computing power, represents a change in neuronal cell bodies or synapses, but it’s very concerning.

Some of these effects are permanent. Kids we placed in foster care show a bump in white matter compared to those who remained in an orphanage, but they don’t ever show the white matter volume of never-institutionalized kids. Some white matter tracts recover after placement into a family, some do not. We see no recovery of grey matter. 

How does this happen?  Do we know what mediates these changes in the brain?

My intuition is that the reduction in grey and white matter is due to a lack of input during critical periods. As our brains develop, we overproduce neurons and synapses, and then we prune them back. But with a lack of input, there may be an overpruning – too many neurons and synapses are deleted. And once they are gone, that’s it—you don’t make up for this. 

Some of it is also probably mediated by stress. Chronic, unremitting stress that’s unbuffered by a supportive relationship is toxic stress, and it has both a physiological toll and a psychological toll. When babies are placed in institutions right after they are born, it’s the only world they’ve known. But if a child is old enough at the time of separation, separation itself becomes a stressor. Then there’s the social deprivation inherent in these sorts of care conditions, which we know has deleterious effects on the brain. 

Who is most vulnerable to this type of stress and trauma?

Kids with a history of trauma or adversity are going to be more vulnerable. If, for example, they leave a town that’s rife with violence and make an arduous journey and then they’re separated from their parents at the border, the separation is going to be superimposed on an already bad development history. All of those things conspire to make things much worse. 

Core Concepts
Trauma and stress can pose long-term effects on the brain.

The way in which the separation occurs, and the conditions the child experiences also matter. If separated children are kept under conditions that lead to sleep deprivation, this can have a negative effect on brain development. If they are in a crowded situation, where there are few caretakers taking care of a lot of kids, that is also bad, because they’ll have no comfort or nurture — much like we see in Romanian orphanages.

Another factor is age. Older children will be more aware of their circumstances than very young children. In animal studies, we’ve observed that the effects of separation are very different for very young babies and those separated when they are older. If they’ve had the opportunity to form an attachment before you separate them, then they have deep psychological distress. In children, attachments start to come online around six or seven months. Babies younger than this may get through this if they are taken care of by someone who is invested in the child.

What is the potential for a parental separation to cause lasting effects?

For babies, if the separation is limited to weeks and they are then put into a very good nurturing home, it may not have long-term effects. For older kids, how long the psychological effects last may be determined by who’s taking care of the kids. If the separation is limited to a few weeks and they are provided mental health services, hopefully this will be in the rear-view mirror in a number of years. But even if families are reunited, if the parents continue to be profoundly stressed, that will carry through to the child. That is probably the pathway to long-term effects.


This Ask an Expert was answered by Charles A. Nelson as told to Jennifer Michalowski for


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