Extensive studies of brain function have been performed in people with ADHD. Here are some of the most important findings that have been made in recent studies on brain dysfunction in people with ADHD.

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What is ADHD?

ADHD is characterized by marked deviations in relation to concentration, impulsivity and hyperactivity. ADHD is associated with difficulties in the brain's executive functions (control functions) such as (1):

 

  1. Ability to inhibit impulses (e.g. disallowing yourself to be distracted by irrelevant impressions; avoid being led by sudden impulses)
  2. Ability to stay focused (e.g. being able to stay focused despite working on a tedious task; keeping the thread in a conversation)
  3. Working memory (e.g. to hold and use information in the short-term memory, such as remembering a series of numbers; remembering a message at the same time as you receive a new one; ability to understand the main contents of a longer message)

The prevalence of ADHD varies from study to study, but one has calculated it worldwide to be somewhere around 5%.

 

People with ADHD have a different functioning in the brain

In the following section we look at some review studies that summarize research on brain function in people with ADHD.

 

Frontal areas

Brain scan studies that have used fMRI (a methodology for obtaining images of the brain and where in the brain there is activity) have found that ADHD is associated with abnormal functioning in frontal areas of the brain (inferior frontal cortex and dorsolateral prefrontal cortex (1), and medial prefrontal cortex (2)). Dysfunction has been demonstrated in frontal areas of the brain (cortical and subcortical areas) in both children and adults with ADHD (3).

These findings suggest that the "commander in chief" function in the brain is put out of play when you have ADHD. That is: the organizer of the brain ain't there; the conductor of the orchestra is not working; or similar metafores. 

 

Striatal areas (basal ganglia)

Dysfunction has also been detected in another part of the brain - in the area we call the basal ganglia (strital areas) (1). A recent meta-analysis has shown that there is less gray mass in the brain in these areas around the basal ganglia, ie there is talk of structural differences between the ADHD brain and a normally developed brain (3).

 

Other areas of the brain that may be affected

Studies have also shown that there may be other abnormalities in the brain in people with ADHD, including in the cerebellum, the cerebral bridge (corpus callosum), and in the total brain volume of the right hemisphere (4).

Overall, this gives a clear picture that people with ADHD have a different brain function than normally developed people, and that there is a close connection between dysfunction in the brain and the core symptoms of ADHD.

 

Stimulant medications counteract brain dysfunction in people with ADHD

There are several approaches to treating ADHD, where treatment with stimulant medications is often recommended (5). The medication can improve the child's behavior, make your child less restless, less impulsive and better able to concentrate. Not enough research has been done to say which of these two drugs works best.

Methylphenidate (best known as Ritalin) and dexamphetamine are highlighted as stimulants that have been shown to have a good effect in reducing the symptoms for many with ADHD. According to a review study, 70% of people with ADHD have a good effect of such medication (1).

These stimulant medications affect the neurotransmitters in the areas of the brain that have been shown to be dysfunctional in people with ADHD. For example, methylphenidate contributes to dopamine uptake in the striatal areas (basal ganglia), as well as dopamine and norepinephrine uptake in frontal areas of the brain (1).

A review study suggested that the abnormalities around the basal ganglia (striatal areas) in children with ADHD improve with increasing age, and in connection with the use of stimulant medications (3). There are findings that indicate a greater normalization of striatal areas in children with ADHD who have received stimulant medication compared with those who have not received such treatment (6).

 

Differential Diagnosis: ADHD or Traumatic Reactions?

A good article has been written on how to think about ADHD versus trauma reactions (7).

Where the ADHD brain struggles to deal with normal impressions, the traumatized brain struggles to deal with the trauma-related material.
- Ellen B. Nitman

In short: Both ADHD and experiencing early trauma lead to difficulties in the brain's control functions / executive functions, but where the ADHD brain struggles to deal with normal impressions, the traumatized brain struggles to deal with the trauma-related material.

The symptoms may look the same, but they are about different things, and differential diagnosis may sometimes be be difficult in clinical practice.

The case is also complicated by the fact that children with ADHD have a behavior that in various ways can increase the probability of experiencing traumatic events, among other things by the person with ADHD seeking riskier situations to a greater extent than others. Traumatized children with ADHD also appear to have a deteriorating function compared with both ADHD children without trauma, and with traumatized children without ADHD.

In practice, this means that it is important to recognize the ADHD diagnosis as very real, to make good differential diagnostic assessments (either-or-assessments) against trauma, to check whether the child with ADHD has additional problems related to trauma (both-and- assessments), and to meet children with ADHD with a lot of understanding, support and coherent treatment.

 

Sources:

  1. Effect of stimulants on brain functioning in Attention-Deficit / Hyperactivity Disorder: A systematic review and meta-analysis. Biological Psychiatry, 2014.
  2. The attenuation of dysfunctional emotional processing with stimulant medication: An fMRI study of adolescents with ADHD. Psychiatry Res, 193 (2011)
  3. Gray matter volume abnormalities in ADHD and the effects of stimulant medication: Voxel-based meta-analysis. Am J Psychiatry, 168 (2011)
  4. Meta-analysis of structural imaging findings in attention-deficit / hyperactivity disorder. Biol Psychiatry, 61 (2007)
  5. ADHD: What treatment works? The Health Library.
  6. Dopamine transporter alterations in ADHD: Pathophysiology or adaptation to psychostimulants? A meta-analysis. Am J Psychiatry, 169 (2012)
  7. Toward an understanding of the ADHD-trauma connection. Ellen B. Nitman, 2009. 

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Written by

ove heradstveit

Ove Heradstveit

Psychologist, specialist in clinical community psychology. PhD.
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