Sunday, August 31, 2014

Evidence of Brain Overgrowth in the First Year of Life in Autism

"Courchesne et al. present data linking autism to an unusual pattern of brain growth shortly after birth. Infants who later develop autism have a slightly reduced head circumference at birth, compared to normal infants, but undergo a rapid spurt in growth during the first two years of life. This growth spurt is so strong that by the age of 3-4, when behavioral signs of autism are just beginning to show, autistic children's brains are larger than normal.

"The authors conclude that the causes of autism must therefore lie in factors that lead first to reduced head circumference in birth and the subsequent the rapid spurt in brain growth, rather than factors that are not experienced until behavioral signs of autism are evident, such as exposure to mercury in vaccines.

"(...) The abnormally high rates of brain growth they observed were seen in only 6% of nonautistic cases but in 59% of autistic cases.

"One variation on their interpretation would be that the high rates of brain growth from birth to 2 years of age are necessary antecedants of autism, but that an additional trigger is essential to inducing the actual expression of autism. Thus children that did not undergo the brain growth spurt would not be vulnerable to exposure to the trigger, whereas those that had would develop autism, once exposed to the trigger. Hence a possible role for exposures during childhood cannot be ruled out on the basis of these observations.

"(...) Several contaminants that affect the pace and pattern of brain development in animals, or interfere with mechanisms controlling brain development, have become increasingly widespread in humans over the past two decades, over the same period that autism has become more common:

· Perchlorate disrupts the action of thyroid in directing brain development. This contaminant is now in the drinking water of over 20 million people in the US.

· Polybrominated flame retardants have been found to alter the brain growth spurt in mice; PBDE levels have increased exponential in Americans over the past 20 years.

· Bisphenol A activates genes involved in regulating brain growth. Exposure to bisphenol A has become ubiquitous as a result of its use to make polycarbonate plastic.

"With these clear results from Courchesne et al. showing that brain growth patterns in the womb and postnatally differ in autistic children, work on possible contributions by contaminants interfering with brain development is now warranted." Continue reading: Evidence of Brain Overgrowth in the First Year of Life in Autism - Courchesne, E, R Carper and N akshoomoff. 2003. JAMA 290: 337-344. Ourstolenfuture.org