Neurology of Attention Deficit Hyperactivity Disorder from the "ADD ADHD Information Library"

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The Neurology of Attention Deficit Hyperactivity Disorder

What is Happening in the Attention Deficit Disorder Brain?

The most recent models describing what is happening in the brains of people with Attention Deficit Disorder - ADD ADHD - suggest that several areas of the brain may be affected by the disorder.

They include:

• the frontal lobes,
• the inhibitory mechanisms of the cortex,
• the limbic system, and
• the reticular activating system.

Each of these areas of the brain is associated with various functions. 

The frontal lobes help us to pay attention to tasks, focus concentration, make good decisions, plan ahead, learn and remember what we have learned, and behave appropriately for a given situation.  The inhibitory mechanisms of the cortex keep us from being hyperactive, from saying things out of turn, and from getting mad at inappropriate times, for examples. They help us to "inhibit" our behaviors.

It has been said that 70% of the brain is there to inhibit the other 30% of the brain.

When the inhibitory mechanisms of the brain aren't working as hard as they ought to, then we can see results of what are sometimes called "dis-inhibition disorders" such as impulsive behaviors, quick temper, poor decision making, hyperactivity, and so on.  The limbic system is the base of our emotions and our highly vigilant look-out tower.

If over-activated, a person might have wide mood swings, or quick temper outbursts. He might also be "over-aroused," quick to startle, touching everything around him, hyper-vigilant. A normally functioning limbic system would provide for normal emotional changes, normal levels of energy, normal sleep routines, and normal levels of coping with stress. A dysfunctional limbic system results in problems with those areas. 

The Attention Deficit Disorder might affect one, two, or all three of these areas, resulting in several different "styles" or "profiles" of children (and adults) with Attention Deficit Disorder.   Here are sample Q-EEGs of two Attention Deficit Disorder children compared to two non- ADD ADHD children.

The Attention Deficit Disorder children show excessive slow brainwave activity (theta and alpha ranges) compared to non- ADD ADHD activity. The slow brainwave activity indicates a lack of control in the cortex of the brain.

Lack of control... pretty descriptive of Attention Deficit Disorder kids. Medications, EEG Biofeedback training, Attend Nutraceuticals, and some other interventions, seem to change this and normalize, at least temporarily.

Attention Deficit Disorder and the Reticular Activating System

• What causes these various systems of the brain to get out of balance with Attention Deficit Hyperactivity Disorder individuals?
• Why would these systems become under aroused or over aroused?
• Is there one central system that controls or regulates these other systems? 

The answer may be found with the Reticular Activating System.

The Reticular Activating System is the attention center in the brain. It is the key to "turning on your brain," and seems to be the center of motivation.

The Reticular Activating System is connected at its base to the spinal cord where it receives information projected directly from the ascending sensory tracts. The brainstem reticular formation runs all the way up to the mid-brain. As a result, the Reticular Activating System is a very complex collection of neurons that serve as a point of convergence for signals from the external world and from interior environment.

In other words, it is the part of your brain where the world outside of you, and your thoughts and feelings from "inside" of you, meet. 

This Reticular Activating System is very capable of generating dynamic effects on the activity of the cortex, including the frontal lobes, and the motor activity centers of the brain. It plays a significant role in determining whether a person can learn and remember things well or not, on whether or not a person is impulsive or self-controlled, on whether or not a person has high or low motor activity levels, and on whether or not a person is highly motivated or bored easily.

The Reticular Activating System is the center of balance for the other systems involved in learning, self-control or inhibition, and motivation. When functioning normally, it provides the neural connections that are needed for the processing and learning of information, and the ability to pay attention to the correct task.  If the Reticular Activating System doesn't excite the neurons of the cortex as much as it ought to, then we see the results of an under-aroused cortex, such as difficulty learning, poor memory, little self-control, and so on. In fact, if the Reticular Activating System failed to activate the cortex at all one would see a lack of consciousness or even coma. 

What would happen if the Reticular Activating System was too excited, and aroused the cortex or other systems of the brain too much?

Then we would see individuals with excessive startle responses, hyper-vigilance, touching everything, talking too much, restless, and hyperactive. So the Reticular Activating System must be activated to normal levels for the rest of the brain to function as it should. 

What factors could cause the Reticular Activating System to be either over-activated or under-activated? 

According to Harvard Medical School, current research strongly suggests that Attention Deficit Disorder - ADD ADHD is caused in part by a deficiency of Norepinephrine in the ascending reticular activating system, and it is thought that the stimulant medications, such as Ritalin, increase the levels of Norepinephrine in that part of the brain, as well as probably increasing dopamine levels in the frontal lobes. This treatment strategy works well for the inattentive under-aroused ADD kids, and somewhat well for the over-aroused impulsive-hyperactive ADHD kids.

However, for the kids who have an over-aroused Reticular Activating System to begin with, the use of stimulants will often exacerbate the problems with temper, sleep, and hyper-vigilance or anxiety. For these individuals their physicians will often prescribe a Norepinepherine antagonist such as Clonadine, or an antidepressant such as Prozac, which works to enhance the Serotonin driven inhibitory mechanisms of the brain.  

See our discussion on the Different Types of ADHD.

However, it is not just activation levels of the Reticular Activating System that are a problem with Attention Deficit Disordered individuals.

It seems that the same problems that cause the Reticular Activating System to be under or over aroused also restricts the development of neural connections and the required neural density needed to process incoming information.

In other words, these are issues with the number of brain cells, the size of the brain cells, and the number of connections between brain cells. It is not uncommon for one brain cell to have as many as 5,000 connections with other brain cells.

Picture the incoming information to be processed and learned as the volume of water coming out of your shower head. And picture the brain's ability to process this information as the drain and the drain pipe in the shower floor. If the pipe is clogged up, your shower will have problems draining. If the contractor originally installed a drain pipe that is too small, again your shower will have problems draining. In either case, you will either have to reduce the amount of water coming out of the shower head, or you will have to let the shower back up and wait a while for the water to finally drain out.

Here's the connection. If the brain does not have enough neural connections, or lacks the neural density, to process the incoming information, then it will be like a pipe that is too small to handle a large volume of water. It will take in some, but the rest will be stopped and won't go down the pipe rapidly. Learning will take place, but the time that it takes to process the information will be slowed significantly. 

The impact of this with an Attention Deficit Hyperactivity Disorder child is best seen when the child is given a timed test, even with material that the child understands pretty well.

The "timed" aspect of the test requires that the child have a "larger drain pipe," as it were, to quickly process the problems on the test and recall the answer. However, with Attention Deficit Disorder - ADD ADHD - the "pipe" is often too small, and the results of the timed test will probably be very poor. However, take away the timed element on the same test, and "allow the water to drain a the slower rate," and the child will probably do well on the test.

So the Attention Deficit Disorder - ADD ADHD child, or adult, needs a greater degree of neural density, and a larger number of neural connections to process information faster and more efficiently. 

Now, please do not think that this information to be processed is only what takes place in the classroom. The information to be processed includes information from the outside world, including the touch of the clothes on his skin, the buzz of the lights overhead, the sound of the kids playing outside, and the new information that the teacher is lecturing on at the front of the classroom. It also includes the information from inside the head, the thoughts and feelings of the ADHD person. All of that must be sorted out and filtered, so that only the important information is paid attention to, and the unimportant information is ignored.

Without proper filtering by the Reticular Activating System, the individual will be distracted by "noise," both from outside of him as well as from inside of him.   

Other Issues Currently Being Researched

We have listed 45 research articles, out of perhaps hundreds, on the physiological differences between of Attention Deficit Disorder individuals and those without ADD ADHD that are available for you to read on the internet.

These studies include both functional differences and structural differences in the brain. They also include research on Essential Fatty Acid deficiencies, performance differences on psychological tests measuring Executive Functions, Genetic factors, and much more.

ATTEND
Powerful Alternative to Stimulants

The Functional Differences include studies with EEGs, Q-EEGs, CPTs, psychological testing, and "functional" MRIs (fMRI). They showed differences in activation levels of various areas of the brain, differences in brainwave patterns, and differences in glucose metabolism (as measure of brain work load). They also showed the ADD ADHD groups to have poorer performance on timed tasks, slower reaction time, slower processing times, lower problem solving abilities, less fine motor control, less gross motor control, differences in evoked potentials, and problems with inhibition, as compared to the controls.

The Structural Differences include studies with MRIs, PET scans, and SPECT scans. They show subtle structural differences in the prefrontal cortex (smaller right anterior frontal cortex, and less white matter in the right frontal lobes which cause problems with sustained or focused attention), caudate nucleus (asymmetries which cause problems with self-control), and globus pallidus. They also show that the right hemisphere of the ADD ADHD brain is, on average, 5% smaller than the control groups. They also show differences in blood flow in certain parts of the brain, as well as chemical abnormalities in Attention Deficit Disorder - ADD ADHD subjects.

The studies on Essential Fatty Acid levels in Attention Deficit Disorder - ADD ADHD subjects vs. non-ADD ADHD subjects are interesting. The ADD ADHD groups had significantly lower concentrations of key essential fatty acids than did the control groups, and about 40% of the ADD ADHD group showed signs of EFA deficiency (increased thirst, frequent urination, dry skin, and dry hair). Low levels of Omega 6 EFAs contributed to higher incidents of illness (colds, flu, etc.), and deficits in Omega 3 EFAs contributed to problems with learning, behavior, sleep, and temper. These studies support the case for EFA supplementation as a part of the overall treatment approach to Attention Deficit Disorder - ADD ADHD.

See the discussion on EFAs and Nutraceutical treatment of Attention Deficit Disorder - ADD ADHD

Genetic Studies on Attention Deficit Disorder - ADD ADHD show gene alterations that may contribute to ADD ADHD in some children. They are especially looking at the DRD4 dopamine receptor gene. Familial Genetic Studies show that Attention Deficit Disorder - ADD ADHD runs in families. For example, a child with an older sibling with ADD ADHD is 300% to 500% more likely to himself have Attention Deficit Disorder than is a child without ADD ADHD siblings. Twin studies and Adoption studies are also included.

Other studies on Treatment, Behavior, and Diagnostic Issues are also included.

Proper Diagnosis of Attention Deficit Disorder - ADD ADHD

 

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