Autism Linked With Too Many Brain Cells, Study Finds

 A model showing human brain-cell action is lighted by fiber optics; photo by John Schneeberger and Larry Kinney

         

by Amanda Chan  
USA Today, November 11, 2011

Autism is linked with having too many neurons in the part of the brain responsible for communication, cognitive development and social skills, according to a new study. Researchers said the finding suggests autism may begin when the baby is still in the womb.

Researchers from the Autism Center of Excellence at the University of California, San Diego found that boys with autism had 67 percent more neurons -- called cortical cells, which are made before a baby is born -- than boys without autism. Their work was published in the Journal of the American Medical Association.

"An excess of brain cells was found in each child with autism that we studied," study researcher Eric Courchesne, Ph.D. said in a statement. "While we think that ultimately not every child with an autism disorder will show this, our study does suggest that an abnormal excess of cells may be quite common among children with autism. This is an exciting finding because, if future research can pinpoint why an excessive number of brain cells are there in the first place, it will have a large impact on understanding autism, and perhaps developing new treatments."

Because these extra cells are only made before the child has been born, the findings suggest that something had to have happened prenatally.

Researchers examined the postmortem tissue of the prefrontal cortexes of 13 boys -- seven of them had autism, six did not. They found that the children with autism had more cortical cells in this brain region, and also had heavier brains than the children without autism.

Lizabeth Romanski, an associate professor of neurobiology and anatomy at the University of Rochester Medical Center who was not involved with the study, told USA Today that typically in the second trimester of pregnancy, a healthy baby's neurons are supposed to be "pruned" and die off in order for the brain to properly develop.

It needs to be determined if an autistic baby's brain isn't properly "pruning" these neurons, or, if the brain just develops too many of the neurons, Romanski told USA Today.

Previously in 2003, researchers from UCSD found that being born with a small head circumference, followed by a rapid increase in head circumference before age 1, is linked with autism. That research was also published in the Journal of the American Medical Association in 2003.

Signs of autism can occur early in life -- even in infancy -- for some children, while for others, it's something that occurs suddenly after the child has been developing without any problems for months or years, the Mayo Clinic reported.

And from the National Geographic website:

Being called a brainiac may be a compliment but when it comes to gray matter, a person can have too much of a good thing.  Scientists at University College London recently conducted a study that links high levels of distractibility with an increased volume of grey matter in the brain’s left superior parietal lobe.

The reasons for this are not yet fully understood, but it might have something to do with the way the brain pares away excess neurons as it matures in order to more effectively carry out certain tasks.  The brains of adults who suffer from attention deficit disorder may have failed to complete this process, and the connection may also help explain why children tend to be more easily distracted.

The results of the study appear in this week’s issue of The Journal of Neuroscience.