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ADHD, MRI Research, and Complications in the Dual Pathway Model

My oldest son, Sam, with his grandpa. Sam has been diagnosed with ADHD and is doing well without medication.  Sam performs better when we put our attention into exploring alternative methods of organization and yoga.
My oldest son, Sam, with his grandpa. Sam has been diagnosed with ADHD and is doing well without medication. Sam performs better when we put our attention into exploring alternative methods of organization and yoga. | Source

My Son, Sam

Sam is now ten years old and has been struggling with ADHD ever since his diagnosis four years ago. My family decided against medication, and we work on ways to teach him organization skills and impulse management skills. We work hand in hand with Sam's educators and school administrators in order to tackle some of the hardest struggles.

In this article, I will discuss research indicating that ADHD is more complicated than previously thought. For some time, researchers believed that symptoms arose from dysfunction in the frontal lobe of the brain. New MRI research has shown that complications in dual pathways within the brain lead to ADHD symptoms and behavior.

Dual Pathway or Multiple Pathways?

Students with Attention-Deficit/Hyperactivity Disorder (ADHD) have problems with poor academic performance, conduct disorders, and higher risk taking behaviors (Durston, 2003). Research has shown that a reason for ADHD could be the slightest dysfunction within an organized system of the brain, or the dual pathway model. ADHD has been viewed as a “frontal lobe disorder,” but through the use of Magnetic Resonance Imaging (MRI), it has been shown that multiple pathways are involved with each symptom (Zeeuw, Weusten, Dijk, Belle, and Durston, 2012). Changes in the frontal-striatal-thalamic circuitry effect the ability to concentrate and finish tasks (Spencer, 2008), reduction in the mass of the cerebellum inhibits dopamine regulation (Durston, 2003), and a marked decrease in blood flow within the frontal-striatal-thalamic circuitry also inhibits dopamine regulation (Furukawa, Bado, Tripp, Wickens, Bramati, Alsop, Ferreira, Tovar-Moll, Sergeant, and Moll, 2014). Hopefully following the footsteps of the research using MRI scientists can begin to fill in the details of this disorder and find acceptable treatments.

A Change in View...

ADHD is associated with problems in organization, flexibility, working memory, and impulse control (Durston, 2003). Although the frontal lobe has been suspect due to comparisons made between individuals with ADHD and those with frontal lobe disorders, there is no single area of the brain shown to be the culprit (Spencer, 2008). Recent research has shown that the true villain could be the slightest dysfunction within an organized system of the brain (Spencer, 2008). Historically ADHD has been viewed as a “frontal lobe disorder,” but through the use of Magnetic Resonance Imaging (MRI), it has been determined that multiple neurological pathways are involved with each symptom (Zeeuw, Weusten, Dijk, Belle, and Durston, 2012). Changes in the frontal-striatal-thalamic circuitry have been found to effect the ability to concentrate and finish tasks (Durston, 2003). Reduction in the mass of the cerebellum inhibits dopamine regulation and has been known to affect all behaviors linked to dopamine neurotransmission (Durston, 2003). There has also been seen a marked decrease in blood flow within the frontal-striatal-thalamic circuitry which directly effects metabolism and also dopamine levels (Furukawa, Bado, Tripp, Wickens, Bramati, Alsop, Ferreira, Tovar-Moll, Sergeant, and Moll, 2014). The discovery of where the disruptions in the brain may occur is the first step in the discovery of appropriate treatments for the disorder.

Questions So Far

What part of the brain was considered the main cause of ADHD prior to this research?

See results

How MRI Research Has Helped

Scientists first discovered that regions of the brain that seemed not to be in use actually had recognizable patterns not noticed without MRI. Soon research began to use MRI as the major tool in the mapping and synchronizing of these new patterns (Nigg, 2012). This influx of MRI studies and their results brought to light that multiple neurological pathways could be the reason for the symptoms of ADHD (Spencer, 2008). Changes in the frontal-striatal-thalamic circuitry have been found to affect the ability to concentrate and finish tasks (Spencer, 2008). This theory has been titled the dual-pathway model and has three active regions (Spencer, 2008). The first is the dorsalfrontostriatal region that consists of the dorsolateral caudate and the thalamus and is known to control the execution of tasks. The second is the cerebellum that controls the timing and organization of the task. The third region is the parietal region that helps in inhibition and emotional regulation (Spencer, 2008). Before this extensive look at this pathway scientists seemed to hover over the frontal lobe for answers. Now research seems to be branching out into other areas of the brain involved and beginning to understand the complexity of ADHD.

Sometimes Sam's thoughts are so jumbled he cannot even produce a rational thought.
Sometimes Sam's thoughts are so jumbled he cannot even produce a rational thought. | Source

Possibility of Better Medications

For many years Amphetamine has been used as the primary medication for ADHD. Amphetamine works directly with dopamine regulation in the brain. Reduction in the mass of the cerebellum in individuals with ADHD inhibits dopamine regulation (Durston, 2003). The volume of the cerebellar vermis is decreased in the posterior and inferior lobules. This region is dense in dopaminergic neurotransmission. Another area also reduced in mass is the parts of the brain included in the frontal-striatal-thalamic circuitry, also dense in dopaminergic neurotransmission (Durston, 2003). Since these areas of dopaminergic neurotransmission are lacking Amphetamine takes over to theoretically fill in the gap. The dual pathway model now involves more than just low dopamine levels due to lower volumes in dopaminergic neurotransmission. The model has shown that the functioning of the dorsalfrontostraital regions working along with the cerebellum and the parietal regions may have as much to do with ADHD then the low areas of Dopamine production. So not only have areas included in the dual-pathway model been spotted at work, now the workers have been identified working improperly. When we are closer to a having a better understanding of this process within this system we may find more effective and less invasive medications for ADHD.

Are There Alternative Treatments?

Along with mapping pathways of neural activity researchers have been able to use MRI to map circulation within the pathway (Furukawa, Bado, Tripp, Wickens, Bramati, Alsop, Ferreira, Tovar-Moll, Sergeant, and Moll, 2014). This ability to follow blood circulation has led to research supporting the dual pathway model. There is noted decline in blood flow within the models circuitry during response to stimuli of individuals with ADHD. Blood-oxygen-level-dependent (BOLD) responses are lower in the areas of the brain within the pathway in individuals with ADHD (Furukawa, Bado, Tripp, Wickens, Bramati, Alsop, Ferreira, Tovar-Moll, Sergeant, and Moll, 2014). A decline in blood flow would mean that the tissue is not receiving enough oxygen to fulfill metabolic requirements. Also, the area receiving the low blood flow, would be receiving markedly lower levels of neurotransmitters, like dopamine. This decline in dopamine levels and the subsequent decline in dopamine uptake would directly affect the individual with ADHD. Each area affected would have an assigned symptom according to the region within the pathway. The next question to be asked would be how to control the blood flow in these regions to help control proper neurotransmission and the subsequent symptoms.

Brain Area Affected
Change in Physiology
Resultant Behavior
dorsalfrontostraital
Reduction in mass/blood
execution of tasks
Cerebellum
Reduction in mass
timing and execution of tasks
Parietal
Reduction in Bloodflow
inhibition and emotional regulation
The affected brain areas and the resultant change in physiology and behavior work hand in hand in the dual pathway model. To provide effective treatment, the whole pathway should be considered.

Conclusion

Students with ADHD have problems with poor academic performance, conduct disorders, and higher risk-taking behaviors (Durston, 2003). Research has shown that a reason for ADHD could be the slightest dysfunction within an organized system of the brain, or the dual-pathway model. ADHD has been viewed as a “frontal lobe disorder,” but through the use of Magnetic Resonance Imaging (MRI) has been shown that multiple pathways are involved with each symptom (Zeeuw, Weusten, Dijk, Belle, and Durston, 2012). Changes in the frontal-striatal-thalamic circuitry effect the ability to concentrate and finish tasks (Spencer, 2008), reduction in the mass of the cerebellum inhibits dopamine regulation (Durston, 2003), and a marked decrease in blood flow within the frontal-striatal-thalamic circuitry also inhibits dopamine regulation (Furukawa, Bado, Tripp, Wickens, Bramati, Alsop, Ferreira, Tovar-Moll, Sergeant, and Moll, 2014). Hopefully following the footsteps of the research using MRI scientists can begin to fill in the details of this disorder and find better acceptable treatments.

Keeping our son active is extremely important to keeping him in control of his ADHD.
Keeping our son active is extremely important to keeping him in control of his ADHD. | Source

References

  • Durston, S. (2003) “A Review of the Biological Bases of ADHD: What Have We Learned From Imaging Studies?” Mental Retardation and Developmental Disabilities Research Reviews. 9: 184-195.
  • Furukawa, E., Bado, P., Tripp, G., Mattos, P., Wickens, J.R., Bramati, I.E., Alsop, B., Ferreira, F.M., Lima, D., Tovar-Moll, F., Sergeant J.A., Moll, J. (2014) “Abnormal Striatal BOLD Response to Reward Anticipation and Reward Delivery in ADHD.” PLOS ONE. 1-8.
  • Nigg, J.T. (2012) “Future Directions in ADHD Etiology Research.” Journal of Clinical Child & Adolescent Psychology. 524-533.
  • Spencer, T.J. (2008) “Neurobiology and Genetics of ADHD in Adults.” Primary Psychiatry 15:9 (Suppl 5).
  • Zeeuw, P., Weusten J., Dijk, S., Belle J., Durston S. (2012) “Deficits in Cognitive Control, Timing and Reward Sensitivity Appear to be Dissociable in ADHD.” PLOS ONE. 1-10.


8 comments

Jodah profile image

Jodah 5 weeks ago from Queensland Australia

A very thorough and informative hub on the newest research in regard to ADHD. I am glad Sam is doing well with alternative methods other than medication. Our youngest son, Trent was diagnosed with ADHD. If he became too stressed at school he would often hide under the desk and refuse to come out. We never resorted to drugs, but managed to control it through diet and getting him involved in lots of sport. Anything with red colouring or high sugar content could set him off so we restricted those. Now he is the most successful of all our children. Is co-owner of a gym, a personal trainer, Mua Thai fighter and employed in juvenile corrections.


jhamann profile image

jhamann 5 weeks ago from Reno NV Author

Thank you John. Hey I needed to get my Adsense up and working. How long does it take for them to reply?


whonunuwho profile image

whonunuwho 5 weeks ago from United States

As a former teacher of children with this problem, I appreciate this researched report. Thank you for showing that the ADHD problem is more complex than just Frontal Lobe disruption. Over the years many of my students struggled mightily with this ans proud to say there were some who overcame and now live a happy and productive life. Blessings. whonu


Jodah profile image

Jodah 5 weeks ago from Queensland Australia

Jamie, I think it varies from country to country. If I remember rightly it took me about a week to be approved.


suzettenaples profile image

suzettenaples 5 weeks ago from Taos, NM

You have certainly done your research and this was interesting to read. Being a retired teacher I have experienced students with ADHD. I see you have not gone the medication route and I commend you for that. I have notice that my students with ADHD did seem get better as they grew up. I can't say they "grew out of it" but their confusion and organization improved with time. Many of children with this are very intelligent. I wish the best for you and your son as you tackle this condition.


jhamann profile image

jhamann 5 weeks ago from Reno NV Author

Thank you whonunuwho and suzettenaples it is good to hear from you. Jamie


teaches12345 profile image

teaches12345 4 weeks ago

The photo of letters over tangled lines very much describes it in a nutshell. This new finding is going to help find better ways to deal with ADHD. It is something for parents to hold onto.


jhamann profile image

jhamann 4 weeks ago from Reno NV Author

Thank you teaches12345. Jamie

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