There are many things that our parents pass on to us, such as our belief system, eye color, and personality traits. Our genetics also play a significant role in overall health and wellness, which is why it’s often a factor in many diagnoses.
ADHD is a common neurodevelopmental disorder that affects up to 6.7% of adults around the world and 7.2% of youth. In the U.S. alone, it has a higher prevalence rate than the global average for adolescents, affecting around 8.7% of youth in the country. With such a high prevalence rate, one of the main questions that’s asked when a child is diagnosed with ADHD is, “How?”
A person can either be born with ADHD or it develops during their early childhood. When it comes to health conditions like ADHD, learning about how it developed can help individuals come to terms with their diagnosis. When a child is diagnosed, the medical professional will often be asked, “Is ADHD genetic?” The answer is: yes, but not always on its own.
If that sounds like a complicated answer, that’s because ADHD itself is complicated. No singular cause of ADHD has been identified by research; even so, genetics can play a large factor. We’ll talk about how genetics impacts the likelihood of ADHD, how it compares to environmental factors, and how ADHD affects the brain.
Free resource: ADHD Success Kit
Research shows that ADHD often runs in the family, with a 74% heritability rate. While an inheritance pattern hasn’t been determined, the risk of developing ADHD is nine times higher for immediate family, such as children or siblings.
The heritability of ADHD from one generation to the next isn’t due to one gene variation, but actually thousands of minor gene variations that can lead to the disorder. On their own, gene variations are quite common and have little effect on a person. However, when one person has many of the variations, it increases the likelihood of having ADHD. It’s important to note that genetic changes associated with ADHD mean that the risk of developing the disorder has been passed on, not the disorder itself.
Severe or rare gene variants often lead to conditions that have symptoms less mild than ADHD, such as an autism spectrum disorder or intellectual disability, though ADHD may still be a feature.
While genetics can increase the likelihood of a person developing ADHD, environmental factors may also be at play. While environmental factors are never the only reason for ADHD, they often combine with genetics to lead to the disorder or influence how it's presented. Research hasn’t determined a direct connection between environmental and genetic factors that result in a risk of ADHD. Environmental factors tend to have a short-term impact on ADHD.
There are several environmental factors that can increase the risk of a child developing ADHD, particularly before they are born. The factors often come from prenatal aspects and the mother’s lifestyle while pregnant, such as:
The factors can also come from the birth circumstances or complications, including:
There are several environmental factors that may influence the risk of ADHD as a child starts to grow, including:
Now we know that ADHD is a result of a combination of genetics and environmental factors, but what do those actually do to the brain?
Let’s take a look at the genetic component. The gene variations associated with ADHD produce proteins that impact brain development and function. The proteins can influence how nerve cells are produced, grown or organized. They also play a role in neuron communication. This impact on the brain can lead to Executive Function challenges associated with ADHD, such as time blindness and lack of focus.
Differences in particular genetically defined receptors, such as dopamine, can impact the likelihood of ADHD. People with ADHD have a low level of dopamine, a neurotransmitter that plays a role in emotional regulation and feelings of reward or pleasure. When a person has a low level of dopamine, it can lead to common ADHD symptoms, such as mood instability, lack of focus, and motivation challenges.
While genetics is often the main contributor to brain differences leading to ADHD, environmental factors may have an impact on the brain as well. When we look at the role of environmental factors on the brain in relation to ADHD, it often comes down to how those particular factors impact the development process of the brain.
For example, birth complications can impact the blood and oxygen flow to the baby, leading to long-term effects, such as ADHD, as well as speech delays, and autism spectrum disorder. Birth asphyxia means that a baby hasn’t received enough oxygen at some point during childbirth, and it’s associated with a 26% risk of developing ADHD.
Most studies of the brain in relation to ADHD focus on the prefrontal cortex sometimes referred to as the “personality center.” Research shows that the prefrontal cortex circuits have less function and weaker structure in people with ADHD. These circuits play a vital role in regulating emotion, attention, and behavior. The right hemisphere of the prefrontal cortex seems to be impacted the most, which is responsible for behavioral inhibition.
There are a lot of aspects of the brain that can indicate the likelihood of ADHD. For example, the physical structure of the brain can differentiate those with and without ADHD. People with ADHD tend to have:
ADHD impacts a child’s Executive Function skills, which are life management skills that we all need in order to be effective in planning, initiating, and achieving goals at home, in school, and in the workplace. These skills include time management, organization, and emotional regulation.
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