Attention-deficit/hyperactivity disorder (ADHD) is a mental health condition that’s defined by a difficulty in focusing along with an overabundance of energy. While ADHD typically effects children, it can also impact adults. Children who are left untreated can develop more severe symptoms that worsen in adulthood. ¹
In order to prevent the condition from developing, psychologists have been trying to figure out what causes ADHD in the brain. Unfortunately, like with most mental disorders, we only have a vague sense of the underlying issues that develop into ADHD.
Throughout this article, we’re going to review the causes of ADHD and how it chemically changes the brain. At the end, we invite you to ask further questions.
Since there are no accurate tests to determine whether or not an individual struggles with ADHD, most mental health professionals will look at the symptoms.
ADHD symptoms vary from person-to-person. Not to mention, children with ADHD are likely to display different symptoms from adults with ADHD. Furthermore, there are different types of ADHD – each of which produces their own set of symptoms.
The following are the most common symptoms associated with ADHD:
- Difficulty getting along with others
- Difficulty resisting temptation
- Difficulty taking turns
- Forget or lose things a lot
- Frequent daydreaming
- Making careless mistakes
- Squirming or fidgeting
- Taking unnecessary risks
- Talking too much
Some of these symptoms overlap other mental health conditions, such as anxiety and depression. For this reason, it might be difficult for a mental health professional to come to an immediate diagnosis.
What Causes ADHD?
As mentioned, scientists still don’t have a clear understanding as to what causes ADHD. However, research has shown that there are a number of risk factors for individuals. These include:
- Alcohol and tobacco use during pregnancy
- Brain injury
- Exposure to environmental (i.e. lead) during pregnancy or at a young age
- Low birth rate
- Premature delivery
Some may assume that ADHD is the result of unhealthy activities, such as eating too much sugar or watching too much television. Current research does not support these claims. However, research does show that these types of behaviors can worsen symptoms in those who already have the condition. ²
Rather than behavioral habits, it’s believed there’s a lot more going on in terms of brain chemistry when it comes to the development of ADHD.
The Neuroscience of ADHD
In order to understand what causes ADHD in the brain, we first must have some basic knowledge about the brain itself.
Through millions of cells (or neurons) compacted into different regions, the brain is able to perform a number of different functions. From interpreting vision to helping us figure out complicated problems to regulating other organs within the body. ³
All of these regions are connected through myriad pathways (or neural circuits) which passes along information. In order for each of them to perform properly, their connections must be stimulated and maintained properly.
Research has found that those who struggle with common mental health conditions usually have a deficiency in certain neurotransmitters. This makes it difficult for information to properly transmit from one region of the brain to the next. ⁴
In the case of ADHD, the neurotransmitter known as norepinephrine tends to be lacking. This neurotransmitter is a key building block within our brains – starting off as dopa and then being converted to dopamine which is then converted into norepinephrine. ⁵
While it has a number of responsibilities, norepinephrine is most responsible for:
- Breaking down fat
- Increasing attention and focus when performing tasks
- Increasing blood pressure
- Increasing blood sugar levels
- Increasing heart rate (and blood pumping from the heart)
- Memory storage
- Regulating emotions
- Sleep-wake cycle
Lacking norepinephrine has been connected to a number of mental health conditions. However, as you can see from the neurotransmitter’s responsibility, it can play a substantial role in the development of ADHD symptoms.
ADHD Impairment in the Brain
Along with norepinephrine, ADHD will impair other neurotransmitter activity within four different regions in the brain. These include:
- Basal Ganglia – All information that’s processed within the brain is initially sent to the basal ganglia and then relayed to its final destination. ADHD causes a deficiency in basal ganglia which can cause inattention and/or impulsivity. ⁶
- Frontal Cortex – With a lack of norepinephrine, this area of the brain will begin to have trouble with attention, organization, and/or executive functioning. ⁷
- Limbic System – Found deeper within the brain, this region is primarily responsible for our emotions. When not maintained properly, it can lead to inattention, restlessness, and/or emotional discomfort. ⁸
- Reticular Activating System (RAS) – This area of the brain is primarily well-known for playing a major role in relaying transmitters among other pathways within the brain. When one has a RAS deficiency, there’s a chance they’ll struggle with inattention, impulsivity, and/or hyperactivity. ⁹
Since each of these regions interacts with one another, there needs to be stability in all four. A deficiency in one can lead to problems in another. It’s believed that ADHD causes difficulties in at least one of these regions. Unfortunately, we still don’t know which exact region is the primary cause of ADHD symptoms.
While it still remains a mystery what causes ADHD in the brain, we do know those with the condition have a positive reaction to certain medications. These medications can do wonders in replacing the deficient neurotransmitters and, when combined with therapy, people can go on to live fulfilling lives.
The only difficulty is ADHD medication is addicted and can cause further complications in some individuals. With that said, we highly suggest you strictly follow your mental health professionals suggested dosage.
As mentioned, outside factors can play a role in worsening ADHD symptoms. If you struggle with this condition and are looking to further recovery, we highly suggest researching activities and diet plans that can help ease symptoms.
Still have questions about what causes ADHD in the brain?
We invite you to ask them in the comments section below. If you have any further knowledge on the topic to offer – whether personal or professional – we’d also love to hear from you.
¹ Centers for Disease Control and Prevention (CDC): What is ADHD?
² Nutrition Research and Practice: Correlation between attention deficit hyperactivity disorder and sugar consumption, quality of diet, and dietary behavior in school children
³ National Institute of Neurological Disorders and Stroke (NINDS): Brain Basics: Know Your Brain
⁴ Clinical Psychopharmacology and Neuroscience: Serotonin and Mental Disorders: A Concise Review on Molecular Neuroimaging Evidence
⁵ JAMA psychiatry (Europe PMC Funders): The Norepinephrine Transporter in Attention-Deficit/Hyperactivity Disorder Investigated With Positron Emission Tomography
⁶ National Library of Medicine: Basal ganglia volume and shape in children with attention deficit hyperactivity disorder
⁷ Current Topics in Behavioral Neurosciences (HHS Public Access): Neurodevelopmental Abnormalities in ADHD
⁸ Archives of general psychiatry (HHS Public Access): Hippocampus and Amygdala Morphology in Attention-Deficit/Hyperactivity Disorder
⁹ Neuropsychopharmacology (Nature Publishing Group): Attention-Deficit/Hyperactivity Disorder and Attention Networks