What is the Root Cause of ADHD?

What is the Root Cause of ADHD?

Attention-deficit/hyperactivity disorder (ADHD) is a common mental health condition observed in children but also found in adults. It’s estimated that 8.4% of children and 2.5% of adults struggle with the disorder. ¹ Due to its prevalence, many ask what is the root cause of ADHD?

Unfortunately, there isn’t always a singular answer. ADHD is a complicated illness that can be caused by a number of factors.

Throughout this article, we’re going to look at the different causes of ADHD and how you or your child may be affected by them. At the end, we invite you to ask further questions.

What is ADHD?

There are three sets of symptoms in attention-deficit/hyperactivity disorder (ADHD): ²

  • Inattention – Inability to concentrate
  • Hyperactivity – Excessive energy and movements
  • Impulsivity – Acting on behaviors without second thought

While some may experience both sets of symptoms, others will have either mostly inattentive or hyperactive-impulsive ones. Furthermore, mild ADHD symptoms are common among the general population. However, they become concerning when they interfere with daily responsibilities, like school and work.

ADHD treatment usually involves stimulating medication to produce attention and focus alongside a variety of different psychotherapies. ³

What is the Root Cause of ADHD?

Scientists have yet to pinpoint a singular root cause of ADHD. Most people with the condition usually develop it from a number of sources. However, researchers aren’t even 100% sure of these sources.

It’s unclear whether or not ADHD can be avoided. Some of the factors discussed here will give a clear indication that it can’t (i.e. genetics). Still, there are other factors that can be avoided (i.e. toxins in the environment).

We invite you to follow along as we take a look at the different causes of ADHD.

Brain Anatomy and Function

Researchers have pinpointed that various areas of the brain can lead to ADHD symptoms throughout child and adulthood. More particularly, these areas tend to not only be smaller but also have more difficulty in development. ⁴

These areas of the brain include:

  • Amygdala – Involved in emotional control and prioritizing action. ⁵
  • Caudate Nucleus – Responsible for decision-making and purposeful behavior. ⁶
  • Cerebral Cortex – Responsible for self-management. Research has observed that children with ADHD take longer to develop this area. ⁷
  • Hippocampus – Involved in long-term and working memory. ⁵
  • Nucleus Accumbens – Responsible for mood, motivation, and experiencing pleasure. ⁸

Since these abnormalities work themselves out by adulthood, some believe that ADHD goes away. However, research has found ADHD is able to present itself in other ways – making it a lifelong condition.

ADHD causes in the brain


Most scientists agree that genetics plays a crucial role in the development of ADHD. In other words, if a close family member struggles with ADHD (i.e. a parent or sibling), there’s a much higher chance of a child developing it. ⁹

However, there is no ADHD gene. How ADHD passes itself through genetic lines remains in question.

Head Injuries

Since children who’ve experienced significant head injuries have developed ADHD, some scientists believe there is a link. But as to how this link works remains unclear.

For example, some research suggests it can take well over a decade after a head injury for ADHD to develop. ¹⁰

Traumatic brain injury (TBI) may play some role in the development of ADHD or secondary ADHD. However, since research hasn’t made a clear connection, TBI doesn’t automatically result in ADHD symptoms.


In babies born prematurely, ADHD symptoms were more likely to develop during pre-school years. ¹¹ As reported by MedPage Today in a sibling-comparison study:

“We found that the observed association between being born premature and ADHD symptoms in childhood was not explained by genetic or environmental factors shared between siblings. In other words, the association appears to be of a causal nature.”

In such cases, children have developed more inattentive symptoms rather than hyperactive-impulsive ones. Being a mental health professional may not immediately see these symptoms, not all premature babies will find themselves with an ADHD diagnosis. ¹²

Toxins in the Environment

Since ADHD has been on the rise in recent decades, some believe it has to do with changes to the environment. More particularly, everyday toxins such as those in foods, flooring and carpeting, lawn and cleaning products, and personal-care products. ¹³

Infants and young children are most vulnerable to these toxins since their biological system is still developing. Furthermore, research suggests that exposure to even small amounts of toxins during the fetal stages can have a significant impact. ¹⁴

Toxins in environment cause ADHD

What Doesn’t Cause ADHD?

When it comes to the causes of ADHD, there have been some myths circulating that parents have taken seriously. We want to be clear that there’s NO evidence to suggest the following causes ADHD:

  • Allergies
  • Excessive sugar
  • Food additives
  • Immunizations

Why Are More Children Developing ADHD?

As mentioned, ADHD statistics clearly show the condition is on the rise. However, whether or not this is from a specific cause isn’t clear.

While causes like toxins in the environment or head injuries may be furthering this condition, it’s likely there’s simply more awareness. Within the past few decades, our understanding of ADHD has improved alongside our diagnosis criteria.

Since more information is now available concerning this condition, more children and adults are receiving help who would’ve previously been unattended to.

Final Word

Being as there is no specific cause of ADHD, you may never know where you or your child developed it from. However, such information isn’t necessarily important. If you know you or your child has ADHD, then you want to work on overcoming symptoms.

Your Questions

Still have questions about what is the root cause of ADHD?

We invite you to ask them in the comments section below. If you have any further knowledge to share – whether personal or professional – we’d also love to hear from you.

Reference Sources

¹ Journal of Clinical Child & Adult Psychology: Prevalence of Parent-Reported ADHD Diagnosis and Associated Treatment Among U.S. Children and Adolescents, 2016

² National Institute of Mental Health (NIMH): Attention-Deficit/Hyperactivity Disorder

³ Centers for Disease Control and Prevention (CDC): Treatment of ADHD

⁴ PLOS ONE: The brain anatomy of attention-deficit/hyperactivity disorder in young adults – a magnetic resonance imaging study

⁵ HHS Public Access: Hippocampus and Amygdala Morphology in Attention-Deficit/Hyperactivity Disorder

⁶ Journal of Child Neurology: Caudate nucleus volume asymmetry predicts attention-deficit hyperactivity disorder (ADHD) symptomatology in children

⁷ Human Brain Mapping: Abnormal cerebral cortex structure in children with ADHD

⁸ Molecular Psychiatry: Motivation deficit in ADHD is associated with dysfunction of the dopamine reward pathway

⁹ Europe PMC Funders Group: An Overview on the Genetics of ADHD

¹⁰ JAMA Pediatrics: Secondary Attention-Deficit/Hyperactivity Disorder in Children and Adolescents 5 to 10 Years After Traumatic Brain Injury

¹¹ Journal of Attention Disorders: Prematurity and ADHD in Childhood: An Observational Register-Based Study in Catalonia

¹² PLOS ONE: ADHD symptoms and their neurodevelopmental correlates in children born very preterm

¹³ Environmental Health Perspectives: Exposures to Environmental Toxicants and Attention Deficit Hyperactivity Disorder in U.S. Children

¹⁴ Annual Reviews: The Impact of Toxins on the Developing Brain

Leave a Reply