The Critical Role of Tissue Donation in Finding Answers to Autism
H. Ronald Zielke, Ph.D.
Date first published: December 3, 2012
NICHD Brain and Tissue Bank
While many approaches are needed to unlock the secrets of autism spectrum disorders (ASD), researchers are learning much by studying brain tissue. To understand the basic underlying causes of autism, scientists have to look into the brain with an eye for detail that is at least 1,000 times more sensitive than can be obtained by Magnetic Resonance Imaging (MRI) pictures. The only way this can be achieved is by identifying changes in the brain using the most sophisticated tools available in research laboratories. Once the underlying causes of autism are identified, new approaches can be undertaken to treat autism.
The Eunice Kennedy Shriver National Institute of Child Health and Human Development Brain and Tissue Bank for Developmental Disorders (NICHD BTB) has been at the forefront in collecting, storing and distributing brain tissue to more than 90 autism researchers worldwide. After donation, brain tissue is evaluated and stored for later distribution to carefully screened researchers. Maintaining these facilities requires constant attention along with monitoring systems that assure that these samples are available for decades.
Scientists already have identified distinct physical and neurochemical differences in the autistic brain. However, their work is hindered by the limited availability of brain tissue.
Some researchers turned away
Every week, researchers approach the Brain and Tissue Bank (BTB) with new ideas to explore with the hope of finding treatments for autism. Unfortunately, some of these researchers are turned away due to the limited availability of brain tissue to study. Other researchers receive fewer samples than is ideally needed to produce statistically significant results. Because there are many subtypes of autism, a large number of samples is needed to make meaningful discoveries about the causes of and potential treatments for autism. In addition, it is very helpful to have brain tissue from individuals who do not have autism (such as unaffected family members) in order to compare the two types of brains.
Some of the donated brains have been studied by more than 50 investigators, thereby building a detailed information base of the changes in molecular biology and neurochemistry that influence brain function and that prevent normal brain function.
Donations support research on possible causes of autism
Brain tissue donated to the BTB supports research on multiple possible causes of autism. For example, several researchers are looking at how certain neurotransmitters are formed in the brain of someone with autism, as well as at changes in activity of the receptor proteins with which those neurotransmitters interact.
There have been suggestions of abnormal energy metabolism in some people with autism. Some studies with post-mortem brain tissue indicate alterations in mitochondria, the power source of cells.
Microscopic studies have found abnormalities of glial cells in the brains of people with autism. These cells are critical to the recycling of the major neurotransmitter glutamate. A second type of glial cell is directly involved in immune mechanisms in the brain. The complex biology of glial cells can only be studied in postmortem tissue.
Brain remodels itself
During the early years of life, the brain is constantly remodeling itself. New neurons are formed and others are pruned out. One of the processes that contributes to the pruning is called apoptosis. Several investigators are looking at different aspects of apoptosis in autism.
Another aspect of brain research may have implications for the study of how environmental factors may affect genes. There are several mechanisms that modify individual molecules called nucleotides within genes, and affect how these genes are expressed. The primary process is the addition of methyl groups to nucleotides. Several researchers are looking at the patterns of methylation on DNA between people with ASD and control subjects without autism. Others are taking this question further by comparing the methylation pattern in different brain regions.
The cells in the brain are highly organized. For instance, organizational structures called minicolumns interconnect the cell layers of the brain. These minicolumns have been reported to be smaller in the brain of a person with autism. These changes in organization can only be studied in post-mortem tissue. There are also questions about changes in the number and size of brain cells in specific brain regions. These changes cannot be detected by MRI or any other means in a living individual.
Registering with the Brain and Tissue Bank
The reality is that only a small percentage of the brains from people with autism who die are donated for research. The reasons for this are many. Some families are too grief-stricken to consider donation. Some are not aware that donation is an option, and others do not know whom to contact for information.
Just as many people fill out organ donor cards, people may register themselves or their children with the NICHD Brain and Tissue Bank. Information is available at 1-800-847-1539 or www.btbankfamily.org. Individuals with and without autism are welcome to register with the NICHD BTB. A person who has registered in advance is free to change his or her mind at any time.
The decision to donate tissue for research, just like the decision to donate tissue or cornea for medical purposes, is a personal decision. No one has the right to judge the decision of any family. However, if a family decides to donate tissue, several organizations, including the NICHD BTB, are ready to support its goal of improving the understanding of autism.
National Public Radio report, "Shortage Of Brain Tissue Hinders Autism Research"
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