ADHD and heredity: the role of genetics in this neurodevelopmental disorder
ADHD is one of the most strongly heritable neurodevelopmental disorders. If a parent or a sibling has this disorder, the risk for other family members is significantly higher. Here is what genetic research says about ADHD.
Is ADHD hereditary?
Yes, ADHD is largely hereditary. Studies of identical twins show a high concordance: if one identical twin has ADHD, the other has a 70 to 80% probability of presenting the same disorder. Family studies confirm that ADHD is much more common in families where other members have this disorder. The estimated heritability of 70 to 80% makes it one of the most genetically determined neurodevelopmental disorders.
The genes involved: discoveries in progress
Genome-wide association studies have identified many genetic variants associated with ADHD. The most studied genes are those involved in the dopaminergic system, notably DRD4 and DRD5, which encode dopamine receptors, and SLC6A3, which encodes the dopamine transporter. Genes involved in norepinephrine, ADRA2A, have also been identified. These genes do not explain ADHD on their own, but they contribute to a neurobiological vulnerability to the disorder.
Complex polygenic transmission
As with most neurodevelopmental disorders, ADHD does not follow a simple genetic transmission. It results from the interaction of many genes, each with a small individual effect, and environmental factors. Parents with ADHD may have children without the disorder, and children with ADHD may be born into families with no identifiable history. This complexity explains the great variability in the clinical presentations observed.
Environmental factors and genetics: a complex interaction
Genetics is not everything. Perinatal environmental factors such as prematurity, prenatal exposure to tobacco or alcohol, and certain birth complications increase the risk of ADHD independently of genetic vulnerability. Furthermore, the postnatal environment, notably the quality of the attachment bond and parenting strategies, modulates the expression and severity of the disorder.
What this means for families
If you or your partner have ADHD, increased vigilance regarding your children’s attentional development is warranted. Observe early signs attentively from nursery school onwards, and do not hesitate to consult a professional if difficulties persist. For information on ADHD and DYS disorders, lesdys.fr offers comprehensive resources that are regularly updated.
