There is no doubt that autism affects boys more than it does girls with most authorities putting that ratio at 4:1. Scientists have been unsure about the reasons for this uneven distribution for a long time. Now, research conducted at the University of California, Los Angeles, in the US, has uncovered a possible explanation. The research also sheds light on underlying mechanisms of autism spectrum disorders and other developmental disorders.

The researchers looked at the protective coating around the delicate axons which extend from nerve cells in the brain. This insulating jacket around the axons, known as myelin, is made predominantly from fatty substances, including cholesterol, and is essential for ensuring proper communication between cells, and therefore brain function as a whole.

After reviewing information from brain scans and autopsies, the researchers say that they can now explain the role of myelin in developmental disorders including autism and attention deficit hyperactivity disorder (ADHD). Many researchers have looked at what is going on inside the nerve cells, and at neurotransmitters, the chemical messengers in the brain, but this is the first time that myelin has been directly studied in these disorders.

The research team that carried out the myelin investigations at UCLA was led by Dr. George Bartzokis, professor of neurology at the David Geffen School of Medicine and director of the UCLA Memory Disorders and Alzheimer's Disease Clinic and the Clinical Core of the UCLA Alzheimer's Disease Research Center.

Dr. Bartzokis was quoted as saying in an interview "The thicker and heavier the cells' coat, the faster and more effective their communication," he went on "Myelination, a process uniquely elaborated in humans, arguably is the most important and most vulnerable process of brain development as we mature and age."

This latest research suggests that the protective myelin coat on every nerve cell in the brain is the major weak spot in the neural system, and is vulnerable to a host of environmental assaults. Dr. Bartzokis commented that "The effect of all toxins should be examined in this context. At present, this is rarely done."

Dr. Bartzokis is considered a neuroscience pioneer, as this latest study demonstrates, being the first to look at the myelin sheath in this context. In previous studies he has discovered that myelin is produced continually throughout the first four decades of life before peaking and rapidly decreasing around age 45.

The researchers carried out a series of experiments that showed a thinning and breakdown in the myelin sheath can expose the nerve beneath and open the gates to an array of neurological and behavioral problems. Dr. Bartzokis says that from this it can be concluded that without adequate insulation, cells won't connect properly. This knowledge could have implications for numerous neurological and degenerative conditions, as well as for autism and ADHD.

The link to autism and ADHD comes from Dr. Bartzokis's theory that humans "myelinate" different brain circuits at various points in life, which could explain the sizeable differences between neurological disorders seen in children, adults, and the elderly.

He says that, an early disruption of the process of myelin production, for instance, may have serious consequences for the development of the basic brain circuits that govern language and social communication, two major areas of dysfunction in autism. Additionally, a problem with the protective myelin coat during the early school years could interfere with a child's ability to process information efficiently and effectively, leading to problems with attention that characterize ADHD.

Dr. Bartzokis has said that these same abnormalities of myelination in later life may result in symptoms characteristic of Alzheimer's disease and other degenerative neurological conditions.

The reason this research is a possible explanation for more boys than girls being autistic becomes apparent when you look at myelin differences between the sexes. The research carried out at UCLA found that female brains make thicker myelin than male brains, therefore providing better protection and ensuring efficient brain function. It's precisely this type of definitive difference between the sexes that scientists would look for to explain why boys are 4 times more likely to become autistic. Further research that replicates these findings would mean another mystery in the autism story would have been unraveled. Of course, it is possible that this is just one of many differences between the sexes that contribute to boys being more likely to be autistic.

The discovery of this gender difference in myelin production may result in a much greater understanding of how male-female differences are generated in the brain in a general sense too. This understanding may in turn provide insights into why disorders such as autism and ADHD, but also depression and multiple sclerosis, are so unevenly distributed between the sexes.

Dr. Bartzokis' research also opens up another avenue of investigation for researchers concerned with investigating the role of environmental toxins in autism. It's now widely accepted that autism is the result of an interaction between genetic and environmental factors. Dr. Bartzokis' assertion that the effect of all toxins should be examined in the context of his findings with regard to myelin may be an indicator of future research direction in the field of autism and environmental toxins. Differences in the level of protection afforded by myelin at different ages may be associated with different tolerances for environmental toxins. Many parents and physicians will be keen to see how this ties in with the mercury toxicity that has been associated with autistic spectrum disorders. Further research may lead to more accurate guidelines on safe levels of various chemicals in children and hopefully a corresponding reduction in the current high rate of autism cases.

The growing body of scientific research that is showing harmful effects from very low doses of chemicals that were previously thought to be safe, may also contribute to advances in this area.

Research studies such as these are opening new doorways for future autism research and shedding light on the role of environmental toxins in the conditions development.

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written by Stephanie Seneff, MIT PhD, July 28, 2008

I am thrilled to see researchers catching on to the idea that autism and ADHD are likely related to the development of the myelin sheath. This has long been my belief -- I remember reading that autistic brains often display a profusion of overgrowth of short myelin fibers that don't manage to connect up. My own opinion is that a major contributor to the enormous increase observed in the last two decades in autism and Asperger's syndrome is the combined influence of a misguided low-fat diet and over-protection from the sun in both the pregnant mother and the child after they're born (certainly from the impoverished milk supply, as well as the mother's misguided attempt to provide their child with a "healthy" diet throughout their childhood). Vitamin D plays a critical role in many areas, one of which is as a factor influencing the development of the baby's brain. The developing brain is awash in both cholesterol and Vitamin D, which makes sense since a large supply of fat is needed to coat and thus insulate the nerve fibers. To further compound the problem, Vitamin D itself is manufactured from cholesterol, so the Vitamin D shortage comes BOTH from inadequate exposure to the sun AND inadequate fat in the diet. I am surprised and disappointed to see that this article mentions only toxins rather than the direct supply of raw materials to build the myelin sheath.

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written by Maff, July 28, 2008

Very good points Stephanie! It seems to be a common theme that the supply of raw materials for vital components of our anatomy and biochemistry are ignored as a cause of disease. The points you have made about autism are also true for other conditions such as mood disorders. Again, a lack of essential fatty acids (primarily omega-3 EPA and DHA) has been shown to be a major contributor, neurotransmitter imbalances can result from a lack of amino acid building blocks such as tryptophan and phenylalanine, and again, a lack of cholesterol interferes with the production of important mood regulating hormones such as cortisol, DHEA and thyroid hormones. There is all too often a focus on trying to directly alter things that have gone wrong in the body rather than looking at why they may have gone wrong in the first place e.g. deficient supply and/or assimilation of essential nutrients.

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written by jera, September 02, 2009

i thought the article was a great start to nudge other researchers to zone in on this possible cause of Autism. Now I am just pondering the idea that... omega-3 fatty acids that aid in myelination are most prevalent in fish, yet pregnant women are directed to cut down on thier intake of fish (although if the FDA suggests to cut down - you should probably avoid altogether) to avoid mercury poisening and brain damage. Why do we just turn our heads and allow a entire food supply to be poisened then wonder why our children have brain damage and serious mental diasabilities? Not to mention that women seem to want to feed thier babies formula instead of cholesterol heavy breast milk...

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written by Maff, September 03, 2009

The mercury-contamination of fish is greatest with the larger fish such as tuna, king mackeral, marlin, swordfish, and shark as methylmercury accumulates the higher up the food chain you go. If you stick to smaller fish with high omega-3 content such as sardines or even anchovies then you get the benfits with greatly reduced risk. I'm not saying there is no risk however, as you rightly say, a whole food chain has been poisoned by human activities. The trend towards formula feeding babies is certainly also very worrying as it is occurring just as science is showing definite connections between breast feeding, a healthy gut flora, and general health throughout the lifespan.

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