Genetics and ADHD: What You Need to Know ‣ ADHD Lounge

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by a persistent pattern of inattention, impulsivity, and hyperactivity that significantly impairs social, academic, and occupational functioning. ADHD affects about 5-10% of school-aged children and 2.5% of adults worldwide. While the exact causes of ADHD are not fully understood, a growing body of research suggests that genetics play a significant role in its development.

Is ADHD Genetic?

Yes, ADHD is believed to have a strong genetic component. Studies have shown that ADHD tends to run in families, and that there is a higher risk of developing ADHD if one or both parents have the disorder. In fact, the heritability of ADHD is estimated to be around 70-80%, which means that genetics account for a significant portion of the variance in ADHD risk.

What genes are involved in ADHD?

ADHD is a complex disorder, and there is no single gene that has been identified as the cause of the disorder. Instead, ADHD is believed to be a polygenic disorder, meaning that it is caused by multiple genes, each of which contributes a small effect to the overall risk of developing the disorder.

Many genes have been implicated in ADHD, but some of the most promising candidates include genes that are involved in dopamine regulation, a neurotransmitter that plays a critical role in attention, motivation, and reward processing. Dopamine is thought to be dysregulated in people with ADHD, leading to problems with attention, impulsivity, and hyperactivity.

Dopamine Transporter Gene (DAT1)

One of the most studied genes in ADHD is the dopamine transporter gene (DAT1), which codes for a protein that regulates dopamine reuptake in the brain. Variants of the DAT1 gene have been associated with an increased risk of ADHD in several studies. Other genes involved in dopamine regulation that have been implicated in ADHD include the dopamine receptor D4 gene (DRD4) and the dopamine receptor D5 gene (DRD5).

The Problem Genes

Another group of genes that has been linked to ADHD is the catechol-O-methyltransferase gene (COMT) and the monoamine oxidase A gene (MAOA). These genes are involved in the breakdown of dopamine and other neurotransmitters, and variants of these genes have been associated with an increased risk of ADHD.

Second, genetic variants can interact with environmental factors to increase the risk of ADHD. For example, a variant of the COMT gene has been shown to interact with prenatal exposure to tobacco smoke to increase the risk of ADHD. Similarly, a variant of the DRD4 gene has been shown to interact with early childhood stress to increase the risk of ADHD.

The Other Genes

Other genes that have been implicated in ADHD include genes involved in the development and functioning of the prefrontal cortex, a brain region that is important for executive functions such as planning, working memory, and self-regulation. Variants of genes such as the brain-derived neurotrophic factor (BDNF) gene and the synaptosomal-associated protein 25 (SNAP-25) gene have been associated with an increased risk of ADHD.

How do Genetics Affect ADHD?

Genetics can affect ADHD in several ways. First, genetic variants can affect the development and functioning of brain regions and neural circuits that are important for attention, impulse control, and hyperactivity. For example, variants of the DAT1 gene have been associated with reduced dopamine transporters in the brain, leading to dysregulated dopamine signaling that can contribute to ADHD symptoms.