Autoimmune Thyroid Disease

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Archive for November 2008

GABA and ADHD

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I think I am on the right track.

In the last post I speculated that ADHD and ADD were related in some way to GABA deficiency. I believe attention deficit disorder may be characterised by low glutamate levels with low dopamine levels, and attention deficit hyperactivity disorder may be characterised by high glutamate levels with low dopamine levels. I believe all types are characterised by low GABA levels, the same root cause that produces bipolar disorder and some types of autism in other individuals.

So here’s some research to back me up.

Dec. 4, 2003 — Children with attention deficit hyperactivity disorder (ADHD) may actually have different levels of certain chemicals in the brain than other children, a new study shows.

Using new imaging techniques, researchers found that children with the hyperactive form of ADHD had 2 1-2 times more of a brain chemical known as glutamate, which acts like a stimulant in the brain. In addition, the brains of children with this subtype of ADHD also had lower than normal levels of GABA, a chemical that has inhibitory properties in the brain.

Both of these chemicals are neurotransmitters that carry signals to and from nerve cells in the brain. Researchers say these differences may explain the behavior of children with poor impulse control.

“Glutamate is an excitatory amino acid that leads to easier stimulation and excited neuronal pathways,” says researcher Helen Courvoisie, MD, assistant professor of child and adolescent psychiatry at Johns Hopkins Medical Institutions in Baltimore. “GABA is an inhibitory neurotransmitter and inhibits those pathways in the brain.”

In addition to revealing differences in brain chemistry, the study also showed that these gaps correlated to the children’s scores on tests of language, memory, sensory, and learning skills. Brain Scans Reveal ADHD Differences

The study was small and limited, and is a few years old now. I do not know whether it has been followed up with any further studies.

Dr. Courvoisie spoke today at an American Medical Association media briefing on advances in neurology in New York.

“Children with adhd have problems that are associated with the part of the brain called the frontal lobes,” said Dr. courvoisie. “The frontal lobes are like the ‘boss of the brain,’ responsible for what we call executive functioning telling the brain and body what to do.” This area regulates impulse control, attention, movement and elaborating on thoughts.

[…]

“There are three types of adhd: attention-deficit, hyperactive and combined type,” explained Dr. courvoisie. “We focused on the hyperactive type to try to get the clearest picture of what was going awry with their executive function.”

“There is a partial malfunctioning of this ‘boss of the brain’ in adhd,” said Dr. courvoisie. “I describe it as having a poor manager, like the pointy-headed boss in the Dilbert cartoons he doesn’t know what he’s doing, he can”t run a good company and everyone becomes frustrated.”

adhd is characterized by difficulty concentrating and paying attention, and a high degree of restless and impulsive behavior. Although the problems may be less pronounced in adulthood, it is often a lifelong condition.

[…]

“The great increase in the diagnosis of adhd has created some controversy,” said Dr. courvoisie. “It is important to understand and identify the underlying neurology of adhd so that children with adhd can be appropriately treated. There are real deficients these are not just fidgety kids.” Imaging children with ADHD

Here is a link to the pubmed abstract, and another to the free full text of the study online. Something interesting of note is that glutamine as well as glutamate were elevated in both frontal areas of the brain in these children, while increased N-acetyl aspartate and choline were found in the right frontal area of the group.

Eggs contain high amounts of choline. I wonder if this is why some people react badly to eggs? My ADHD sister was sensitive to eggs when she was a child. I am ADD without the hyperactivity, unless I really push up my glutamate levels with B12/folate. I am not sensitive to eggs. The other difference between us is that she is left handed and I am right handed. Could brain laterality affect outcome?

Unfortunately the pubmed abstract does not contain the word ‘GABA’ which makes it difficult to find in searches. Courvisie has also done a similar study on children with bipolar disorder (full text here) and found that glutamate and glutamine were both elevated in the frontal lobes and basal ganglia. They also had elevated lipid levels in the frontal lobes but not the temporal lobes, while while N-acetyl aspartate and choline levels were normal.

If the main problem in ADHD is glutamate/gaba imbalance, one would expect to find that ADHD children are helped by epilepsy medications that enhance GABA signalling, like sodium valproate. So, whilst perusing pubmed, I also found the following mini-study:

We treated three boys with attention deficit/hyperactivity disorder (ADHD) associated with giant somatosensory evoked potentials (SEP). All responded well to extended-release valproate (EVA), a gamma-aminobutyric acid (GABA) enhancer. Improvement particularly involved hyperactivity and impulsivity. When methylphenidate previously was administered to two patients, symptoms worsened. EVA therefore may be preferable for ADHD with giant SEP. Favorable response of ADHD with giant SEP to extended-release valproate

It looks like a ketogenic diet all round then!

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Written by alienrobotgirl

10 November, 2008 at 12:59 pm

Posted in Neurotransmitters

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