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Written by:Bisma Anwar, MA, MSc, LMHC

Published On: July 14, 2022

Medically reviewed by: Elizabeth Keohan, LCSW-C, MSW

Reviewed On: July 14, 2022

Updated On: June 13, 2023


Researchers have identified several factors that can increase the likelihood of someone developing Attention-Deficit Hyperactivity Disorder (ADHD), and in many cases, it’s a combination of factors that’s the cause.

What are the causes of ADHD exactly? Despite years of research, we still don’t know definitively what causes ADHD. However, research and studies have identified potential ADHD causes that are important for us to look at. These might include environmental, biological, and genetic components. Keep reading to learn more about what science says about the causes of ADHD.

What Research Says

Here’s what we do know: ADHD is a neurodevelopmental disorder that can affect communication between different parts of the brain. Brain scans show that ADHD increases activity in some brain regions, while decreasing it in others. This can lead to some of the main symptoms of ADHD, like hyperactivity and issues with executive function.

The majority of people with ADHD report an onset of symptoms before age 12, but symptoms really can appear earlier or later in life. This is why though ADHD is often diagnosed during childhood, an ADHD diagnosis can be given to adults as well. While we once believed that most children would outgrow ADHD symptoms as time went on, recent research suggests that it’s common for people to continue experiencing symptoms well into and through adulthood. The most common ADHD symptoms include inattention, hyperactivity, and impulsivity.

In the past, it had been suggested that ADHD symptoms might be caused by sugar consumption or food additives, but these claims have never truly been backed by evidence. What the research does tell us is that there are many things that could contribute to the causes of ADHD.

“ADHD is caused by a combination of factors such as genetics, premature birth, and brain function. Individuals diagnosed with ADHD can be treated through a combination of therapy and medication. If you notice your child might be struggling with some symptoms, such as difficulty focusing and concentrating, then they might need to get an evaluation by a medical doctor and be referred to a specialist.”

Licensed Mental Health Counselor (LMHC), MA, MSc Bisma Anwar

6 Possible Causes of ADHD

Despite experts not knowing exactly what causes ADHD, there are multiple things that likely play a role. As current research suggests that ADHD can be caused by a combination of factors, we’ve identified a number of potential causes.

Brain structure and function

One thing we’ve understood for quite a while is that ADHD impacts brain function, but newer research has given us a better look at exactly how. Evidence suggests that people with ADHD may have structural differences in their brains. One study used MRIs to identify a difference in brain volume between children with ADHD and those without.

In the same study, researchers also realized that neural pathways can vary in the brains of people with ADHD. These differences in brain structure could be the cause of many ADHD symptoms.

Genetic factors

Approximately 44% of children with childhood ADHD have parents who also exhibit symptoms of the condition. We know that parents with ADHD are much more likely to have children with ADHD — in fact, some research estimates the chance of passing ADHD on to children is somewhere between 75 and 91%.

Still, even though evidence strongly suggests a genetic component to ADHD, we have limited research explaining exactly how the condition might be inherited. It’s possible that other factors may contribute to ADHD’s heritability. For example, it may be easier for adults with ADHD to recognize ADHD symptoms in their children.

Prenatal exposure

Research shows us that children who are exposed to nicotine in the womb are more likely to develop ADHD. Prenatal alcohol use is strongly correlated with ADHD as well. One study found that the children of mothers who drink during pregnancy are 5 times more likely to develop ADHD.

It’s possible that exposure to certain substances increases the risk of brain abnormalities which might lead to ADHD in children. However, it’s also a possibility that mothers with ADHD are less likely to abstain from cigarettes and alcohol while pregnant. More research is needed to confirm which may be true.

Severe head trauma

Serious head injuries have been linked to many mental health conditions, including ADHD. Some research suggests that 1 in every 5 children who sustains a traumatic brain injury (TMI) will develop ADHD. Symptoms usually start within a few years post-injury, but some research suggests it might take as long as 10 years for them to appear.

Interestingly, and worthy of more study, researchers have also discovered that people who develop ADHD after a brain injury don’t have a higher genetic risk factor. This further suggests that there could be a direct link between ADHD and brain trauma. Some experts even believe that TBI-related ADHD may be a distinct condition.

Prematurity or low birth weight

Babies who are born prematurely are more likely to develop ADHD, according to some studies. This seems to be true of babies born with low birth weight as well. Being born early can impact brain development, but that doesn’t mean that all pre-term babies will eventually be diagnosed with ADHD. Even though there’s an apparent correlation between ADHD and premature birth, most babies who are born early won’t develop attention problems.

It’s worth noting, though, that certain factors that have been linked to ADHD — for example, smoking during pregnancy — also increase the risk of low birth weight and premature delivery. This makes it difficult to identify which of these factors, if any, actually might contribute to an ADHD diagnosis.

Environmental toxins

Exposure to chemicals and other environmental toxins can interfere with brain development. In particular, lead poisoning can be very harmful to children. It might, according to some research, be associated with ADHD. Studies suggest that even low levels of lead exposure could potentially contribute to the development of ADHD.

Other environmental toxins, such as perfluorinated compounds, have also been linked to ADHD in some research. The risk of exposure begins during pregnancy and continues throughout childhood. Potentially harmful chemicals can be found in many household items, making it difficult for parents to limit exposure. Findings thus far warrant the need for more research.

Understanding More About ADHD

It’s common for parents to ask questions like: What are the causes of ADHD? While we do have an abundance of information about potential ADHD causes, the evidence isn’t inclusive. We need to continue focusing on better-understanding ADHD.

Whether you’re the parent of a young child with ADHD or an adult with adult ADHD symptoms, understanding more about the condition — including how it affects the brain — and how it can be treated is essential. ADHD behaviors are often misinterpreted, and many people aren’t aware of how ADHD can affect someone’s thoughts, emotions, behaviors, and day-to-day life.

“Attention deficit hyperactivity disorder (ADHD) is a neurobiological condition that can develop in children. It has become one of the most common conditions of childhood. Therapy and medication can help manage the symptoms of ADHD.”

Licensed Mental Health Counselor (LMHC), MA, MSc Bisma Anwar

When someone has any one of the types of ADHD, they can have great difficulty concentrating or focusing. People with ADHD often abandon tasks before they’re completed. They might seem distracted, thoughtless, careless, or ambivalent. ADHD can also cause impulsive behavior and emotional outbursts, and it can make it difficult for some people to fall or stay asleep.

When you have a better understanding of ADHD, it can be easier to develop strategies and coping mechanisms to effectively manage symptoms. People with untreated ADHD will almost always benefit immensely from professional help. Although we aren’t sure exactly what causes ADHD, we have identified many effective ADHD treatment options that can improve symptoms and quality of life.

If you’re wondering how to treat ADHD, therapy and ADHD medication can be game-changers. Talkspace therapists are skilled and experienced in treating all types of ADHD. They have expert knowledge in helping people understand their condition and learn to cope. Talkspace isn’t your average therapy platform. We make getting therapy for ADHD simple and convenient, so you can manage ADHD, or any other mental health condition, in the best way possible.

You don’t have to live with the struggles ADHD can cause in life. Reach out to Talkspace today to learn more about our online therapy options.

See References

Bisma Anwar, MA, MSc, LMHC

Bisma Anwar is the Team Lead for the Talkspace Council of Mental Health Experts. A major focus in her work has been anxiety management and helping her clients develop healthy coping skills, reduce stress and prevent burnout. She serves on the board of a non-profit organization based in NYC called The Heal Collective which promotes advocacy and awareness of mental health issues in BIPOC communities.

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