The ADHD Brain

Attention Deficit Hyperactivity Disorder (ADHD) is a complex and inconsistent condition. It can be overwhelming for people who deal with it on a daily basis. Many people are unsure whether or not they even have the condition because of the vague and seemingly outdated diagnostic criteria that have been in use for the past 40 years. Doctors must filter through and check off a long list of symptoms. There are 18 criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM), while some symptom lists mention up to 100 traits.

But what is it that makes ADHD brains so different and hard to diagnose?

One factor that largely contributes to the difficulties diagnosing ADHD is that it frequently occurs with at least 1 comorbidity such as depression, anxiety, or dyslexia. This is sometimes referred to as Complex ADHD.

ADHD is linked to unusually low levels of dopamine and norepinephrine, neurotransmitters that transfer between the prefrontal cortex and the basal ganglia. Dopamine interacts with other powerful neurotransmitters to regulate mood and is tightly linked to reward areas in the brain. As a result of the low dopamine levels, the person seeks the reward feeling in other ways.

These differences in the ADHD brain can cause a number of neurodevelopmental symptoms.

These include:


These symptoms help to form the criteria used in the Diagnostic and Statistical Manual of Mental Disorders (DSM - 5) to Diagnose ADHD. Not all of these symptoms are used in the criteria however. Some of the symptoms such as Emotional Dysregulation have been difficult for scientists to quantify and therefore we haven't been able to get accurate studies done for them.

You can read about the DSM criteria for an ADHD Diagnosis here.

Criteria not listed in the DSM-5 that can be a key indicator of ADHD are:

  • Emotional Dysregulation: Often unable to regulate emotion. This can cause disproportionate emotional responses to events or stimuli such as becoming overly happy and excited over something you see or hear. Another example could be becoming easily frustrated or even explosively angry at someone because they said something with the wrong tone in their voice.

  • Hyper-focus: This one isn't directly in the DSM-5 but one of the criteria IS often caused by hyper-focus "Often does not seem to listen when spoken to directly." Hyper-focus happens when an ADHD brain hones in on something that is interesting or exciting. When this happens the brain will focus on this one singular thing so heavily that the rest of the world will seem to melt away and not exist. Think of being "in the zone" times 100. It can be so intensely focused that it may seem like the person is not listening when spoken to.

  • Sensory Sensitivity: Although sensory overload can impact anyone, it is most common in those with ADHD or other sensory or neurodevelopmental disorders, particularly children. Sensory overload occurs when something, usually an environmental factor, overstimulates one or more of the five senses.