Autism Speaks Official Blog

Scientists used several different brain imaging methods to better understand the structure and function of the brain.  Structural magnetic resonance imaging (also, simply referred to as “MRI”) and functional MRI (fMRI) have been mainstays in autism research for the past two decades. MRI provides detailed information about the anatomy of the brain, whereas fMRI allows scientists to understand what parts of the brain are active when people are engaged in different tasks or other activities.  This is done by measuring the distribution of blood flow in the brain. Researchers have sought—and found—some differences in brain structure and function in individuals  with autism.  These experiments can measure differences in size or activity of brain structures and the connections between different areas.  However, these methods can not assess the chemicals within brain cells that support brain function.  For this, scientists rely on a method called “Magnetic Resonance Spectroscopy” or “MRS.”

MRS uses some of the same technology as MRI, but with a unique twist.  It allows scientists to measure several chemicals that exist within the neurons themselves.  These chemicals offer clues to the integrity of the neurons. Different brain chemicals, or metabolites, have signature spectra that can be measured in the magnet.    Some metabolites, such as N-acetylaspartate have spectral signatures that can indicate relative health of the neurons.  Other metabolites can offer information about cellular energy reserves, lipid and fat metabolism, and the integrity of neural glial cells.  Recent advances have permitted the imaging of glutamate, glutamine and GABA, all of which are neurotransmitters that have been suggested to have some role in ASD.

Autism Speaks has supported two research investigations using MRS.  The first was an award to Evdokia Anagostou, M.D., Ph.D.,  an Assistant Professor at Bloorview Research Institute and the University of Toronto, to investigate brain levels of glutamate and glutamine in young children with ASD.  Dr. Anagostou and others have hypothesized that finding ways to reduce the overabundance of glutamate found in some individuals with autism might yield improvements in behavior.  A preliminary study using similar methods in older children was published in March in Brain Research.  In this study, they examined brain areas associated with attention and orienting functions, such as the anterior cingulate cortex (ACC).  The teens with ASD showed reduced glutamate and glutamine in the ACC, indicating that this important region may be functioning differently in individuals with autism. Dr. Anagostou has also recently reviewed MRS findings in autism as well as other neuroimaging results and we look forward to the results from her study in younger children.

Beatrice Golomb, M.D., Ph.D., an Associate Professor of Medicine at UCSD, has also used MRS in an Autism Speaks-supported study that was part of a larger investigation of mitochondria and autism.  Dr. Golomb designed a unique study to probe the effects of mitochondrial “fatigue” on brain function.  MRS assessments in children with and without ASD were made before and immediately after cycling exercise.  This particular study was designed as a small pilot, and though not discriminating in and of themselves, the results showed greater differences in mitochondria-related metabolites after cycling for some of the children with autism. The results encouraged the team to pursue further investigations of mitochondrial dysfunction in autism.

As magnetic imaging technology improves, so too will our ability to use MRS in new ways to non-invasively observe the working brain’s chemistry.  Not surprisingly, this technology will be valuable in our search for the pieces of the autism puzzle.  Steven Dager, M.D., Professor of Radiology at the University of Washington and a member of the Scientific Advisory Board for Autism Speaks, has expertise in many varieties of imaging techniques and especially their use in neurodevelopmental disorders. Dr. Dager says “Although MRI has identified intriguing alterations of brain structure in ASD, an important advance has been applications of MRS to reveal neurochemical, bioenergetic and cellular level structural alterations that underlie these anatomical changes and symptom expression in ASD.  This is important because a better understanding of these biological mechanisms can better inform the development of new treatments by targeting biological mechanisms that may not respond to behavioral intervention.”