Is Attention Deficit Hyperactivity Disorder (ADHD) more commonly diagnosed in adopted children? One study published in the Journal of Abnormal Psychology found that of 808 adopted children, ages 4-18 years, 21 percent had enough behavioral symptoms to qualify for a diagnosis of ADHD. This is twice the rate in the general child population. (This study was based on extensive parent questionnaires.)
An analysis of risk factors showed that those with behavioral symptoms usually had pre-adoptive risk factors such as history of abuse or neglect, later age at adoption, prenatal drug exposure and/or multiple foster placements.
Still, experts advise being cautious about assumptions. Adoption and ADHD may be associated, but adopted children’s experiences vary so widely it is hard to separate out an explanation. Many studies fail to differentiate between children adopted at birth and those who spent time in institutions or experienced multiple moves.
If adoption is linked with a higher risk for ADHD, why? Some point to a genetic link and theorize that people with impulse control problems are more likely than others to experience or to cause an unplanned pregnancy, therefore children placed for adoption may be more likely to have a birthparent with ADHD. Other theories involve low birthweight, prenatal environment and drug or alcohol exposure.
Still others believe the idea of a relationship between ADHD and adoption becomes a self-perpetuating idea—that doctors, teachers and adoptive parents are more likely to perceive a problem because they believe these children are vulnerable. (The flip side, of course, is that adoptive parents may be more vigilant and willing to seek help when there truly is a problem, resulting in higher diagnosis rates.)
Many experts believe that a poor environment triggers problems of many kinds in people who are genetically susceptible. However, a couple of studies suggest that early environment may have a profound biological effect regardless of genes.
A study at the University of Minnesota is following children adopted from overseas orphanages. One finding of this study involves the body’s stress response. A system of glands called the Hypothalamic-Pituitary-Adrenal Axis (HPA) is forming during the first months of life and is set by the end of the first year. The study found that children who have formed secure attachments with caregivers by age one do not seem to produce increases in the hormone cortisol when they are upset, whereas children who do not have a secure attachment in the first year do produce extra cortisol when upset. It appears this effect of the first year of life may continue indefinitely.
A National Institute of Child Health and Human Development study found that monkeys who had been separated from their mothers at birth or soon after show more aggressive play, leap dangerously from branch to branch, are ostracized by their peers and drink more alcohol when given the chance. A study found low levels of a marker for the brain chemical serotonin in these monkeys.
The relationship between adoption and ADHD has not been definitively studied and more needs to be known. But it appears that some of our children could be contending with biological impacts of their prior environment, in addition to psychological impacts.
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