Many in the autism community, especially those interested in biomedical solutions are familiar with the concept of leaky gut or intestinal hyper permeability. Many however, are not familiar with the concept of a leaky brain. I was asked the other day by the mom of a child with ADHD if she should give her child GABA, gama amino butyric acid, to help. The thought being if we could get him to calm down then we could get more out of the hemispheric integration therapy sessions he was participating in. In order to get the most benefit from hemispheric integration therapy the patient must be able to participate in the treatment program. That is, the more he can do, the more we can do for him and the better it works. In this particular case, the child’s attention span is so short that it is difficult to get him to perform a particular therapeutic exercise long enough for it to be of benefit to him. This led me to discuss GABA, the GABA challenge and a leaky brain.
GABA is an inhibitory neurotransmitter in the central nervous system. Inhibitory meaning that it encourages nerve cells not to fire, as opposed to excitatory which encourages neurons to fire. Thus, GABA supplements have the reputation of acting as a calming agent. This was the rationale behind the mom’s suggestion to give him GABA before his treatments in order to calm him down and thus we could get more work done during the time of his treatment sessions.
The problem with this theory is that our brains are considered very precious and therefore have a special barrier to protect them from substances circulating in the blood and the rest of the body. This is called the blood brain barrier. The blood brain barrier is semipermeable meaning that it allows some substances to get through while prevents other substances from crossing over to the environment of the brain. Therefore, the blood brain functions to protect the brain from foreign substances circulating in the blood that could be harmful to the brain. This semipermeable function is similar to the way the intestinal barrier that acts as a screening portal of entry from the outside world to the body. For example, the blood brain barrier is very effective in protecting the brain from bacterial agents in the blood and body. These bacterial agents are screened out by the blood brain barrier and not allowed to cross into the environment of the brain making infections of the brain very rare.There is an issue when the semi-perm permeable blood brain barrier becomes too permeable and allows substances that should not pass through to the brain, into the brain and its environment. This is obviously of significant importance when dealing with patients on the autism spectrum.
In the case of testing for a leaky gut barrier we give the patient two sugars in a solution to drink. One sugar should be absorbed and one sugar should not.We then collect the patient’s urine. If the sugar that should not have been absorbed appears in the urine then the gut barrier was not doing its job and is leaky. To test for a leaky brain or hyper permeable blood brain barrier we use a similar concept. This is called the GABA challenge. GABA taken orally should not be able to cross the blood brain barrier assuming that the barrier is intact. That is, when the doorman of the brain(the barrier) is at the door deciding who gets to go in and who should be kept out, GABA should be kept out. A healthy blood brain barrier should not allow GABA to cross into the environment of the brain. It is impractical to measure cerebral spinal fluid before and after administering GABA to see if there has been a significant change. However we do know the effects of GABA and we can observe for those. That is to say, if GABA did cross the blood brain barrier we would expect to see a calming effect on the individual who took the GABA. This is the basis for the GABA challenge. A GABA supplement is given to the patient and if within a two-hour period the patient becomes more relaxed, then we make the assumption that the GABA crossed the blood brain barrier and had its inhibitory/calming effect. This suggests a leaky blood brain barrier.
So the leaky brain may answer the question as to why some people take GABA and it has a calming effect, while the same GABA does not have any effect on others. Therefore, in this case, if mom gives her son some GABA in order to calm him down so that we may have more effective hemispheric integration therapy sessions with the child and this is effective, then we have unearthed another problem. Although this may help us have more effective sessions, we will have discovered the issue of a leaky blood brain barrier. A leaky brain is a serious problem which needs to be dealt with particularly in relation to autism spectrum disorders. We do not want a weak blood brain barrier leaving the brain susceptible potential bacteria, toxins and inflammatory reactions.
As always, these illustrations are simplified examples with many other factors that need to be taken into consideration and performing tests such as a GABA challenge should only be done with appropriate physician supervision.