It has been shown that ADHD is more prevalent among adoptive children than it is in the general population. Simmel, Brooks, Barth and Hinshaw (2001) conducted a study examining 808 adopted children aged between 4 and 18 years old. Of these, 21% of the children had ADHD compared to 3 – 5% in the general population. But what is the reason for this?
Approximately 40% of children with ADHD have one parent with the same condition, demonstrating that there is a strong biological factor involved in developing ADHD behaviours. It is suggested that a mother with ADHD may be more likely to act impulsively and therefore has a higher chance of having an unplanned pregnancy. During pregnancy, an ADHD mother is more likely to have an unstable prenatal environment and be involved in impulsive behaviours such as smoking and drug use, which will further increase the chances of the child having ADHD as these are further risk factors. As a result of impulsive behaviour, the mother may be unable to care for the child and consequently is put up for adoption. One possible reason for ADHD rates being higher among adopted children is that this population of individuals are more likely to be exposed to more prenatal risk factors in ADHD mothers and inherit impulsive behaviour.
A further reason is due to the nature of adoptive parents. Evidence shows that adoptive parents tend to be wealthier, more financially stable, well educated, middle class families. As a result, adoptive parents are likely to be aware of potential child difficulties and would investigate this further through evaluation and treatment. This may be why it is not just ADHD that is more prevalent in adopted individuals but also other neurodevelopmental conditions. Behavioural disorders, particularly Oppositional Defiant Disorder, has been found to be twice as likely among adopted teenagers compared to those who are not adopted.
