Two Autism Studies Open the Door to More Questions
By daisymayfattypants on December 09, 2010
BlogHer Original Post
Two recent autism-focused studies have generated both discussion and hope: one on early autism diagnosis using magnetic resonance imaging (MRI) tests, and the other on mitochondrial function in people with autism. The first study used imaging to detect differences in the brains of autistic males compared to non-autistic males, while the second identified differences in mitochondrial function between autistic and non-autistic children. Both open doors to more research and to intriguing possibilities for diagnosis and therapies, but neither resolves the question of whether these differences exist because of autism, or whether autism exists because of these differences.
You may have seen news reports sensationalizing an “autism test” that leads to early and definitive autism diagnosis: the Lange-Lainhart test, which uses MRI techniques to image brain areas and detect changes associated with autism.
The study focused on six brain areas linked with language, social, and emotional functioning, all of which are associated with deficits among people with autism. In the brains of non-autistic participants, researchers saw connective pathways organized in a typical way, indicating interaction among the brain regions. In the participants diagnosed with high-functioning autism, the images indicated disorganized patterns, with less connectivity and interaction and thus less exchange of information in the network. The researchers repeated the test on another, smaller set of participants and produced similar results.
These findings imply that autistic brains may operate like perfectly functional computer hardware components that cannot communicate very well with each other: think of a camera that captures visual images accurately, or a microphone that captures a voice clearly, integrated into a non- or imperfectly networked system.
News reports are trumpeting the MRI study as an imaging breakthrough that could lead to earlier diagnosis of autism, something that most experts believe is key to effective autism treatment and support. But experts also urge the standard cautious optimism -- and rightfully so.
For one thing, the participants in this study were ages 8 to 26 -- outside the time frame for early diagnosis of autism -- and all participants were male. The study findings also can’t tell us if the participants’ brains have different connectivity pathways because they developed in a person with autism, or if the participants have autism because their brains were already built that way. Before we can talk of “early diagnosis,” we need studies showing these differences in much younger children. And, given the frequent findings of differences between males and females on the spectrum, we need studies involving autistic girls and women.
Mitochondrial Dysfunction and Autism
Mitochondria are the powerhouses of the cell, as biology teachers will tell you. They have their own DNA, their own proteins, and their own protein-making machinery. They also have the potential to undergo genetic mutations that affect the sequence of the proteins their genes encode. Because most of the proteins in mitochondria are mission-critical and must function exactly right, the persistence of such mutations is relatively rare. But they do happen and can cause disease. Might such changes underlie at least a portion of the cases of autism?
This was certainly the question in the high-profile case of Hannah Poling, whose mitochondrial disorder appeared to be linked to her autism symptoms. Her disorder may have interacted with a bolus of vaccine doses she received, as the series of shots during one office visit was reportedly followed by a high fever. Fevers can tax our cellular powerhouses, and if mitochondrial function is already compromised, the high temperatures and extra burden may result in chronic negative outcomes.
Poling’s case brought media attention to the question of whether or not people with autism might have mitochondrial dysfunction at greater rates. A recent study in the Journal of the American Medical Association (which keeps its full-text articles behind a paywall) has sought to address that question by measuring markers of mitochondrial dysfunction in 10 children with autism and comparing these endpoints with outcomes in 10 children without autism.
The authors report that while only one child among the group who had autism fulfilled the definitive criteria for a mitochondrial respiratory chain disorder, the children with autism were more likely to have statistically significant indicators of mitochondrial dysfunction.
Do these findings mean that all or most people with autism have mitochondrial dysfunction? No. The authors note that a small study like theirs does not allow anyone to draw conclusions about a cause-and-effect association between autism and mitochondria, and they urge caution in generalizing their findings to a larger population.
If there is an association, it leads to the same type of questions as the MRI study: Does mitochondrial dysfunction underlie autism, producing autistic-like symptoms, as some argued in the Hannah Poling case? Or, do autistic manifestations such as anxiety or high stress or some other autism-related factor influence the mitochondria?
Right now, these chicken-and-egg questions may not matter as much as the findings do for helping to identify autism more specifically and addressing some of its negative aspects. Regardless of your stance on neurodiversity or acceptance or cure or the in-betweens where most of us fall, it would be difficult to argue that a mitochondrial dysfunction shouldn’t be identified and ameliorated, or that an awareness of brain structure differences won’t lead to useful information about what drives autism behaviors.
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