MRI, brain differences, and autism

MRI: Sagittal view of the brain. Photo courtesy of Wikipedia commons.

You may have read the news reports blaring the finding of an “autism test” that could lead to early and definitive diagnosis of autism. The new evaluation, which has proved worthy of its own name, the Lange-Lainhart test, uses magnetic resonance imaging (MRI) techniques to image brain areas to detect changes associated with autism.

I’ve been unable to find the complete paper, reported to have been published in Autism Research on Nov. 29; the journal has only papers through October available on its Website as of this writing. According to reports, however, the authors state that the new test was 94% accurate in identifying who was autistic and who wasn’t among 60 males tested. The participants in the study were ages  8 to 26; 30 were diagnosed with what the researchers call “high-functioning autism,” and 30 were typically developing.

The imaging technique the authors used involves tracing water diffusion along axons, the long connectors that link neurons to other neurons or tissues. This diffusion tensor imaging process yields an image that can highlight variations in the patterns of these connective pathways in different areas of the brain. This study focused on six brain areas associated with language, social, and emotional functioning, all of which are traditionally considered to be problematic among people with autism.

In the brains of non-autistic participants, the flow patterns were organized in a typical way that indicated connectivity among the brain regions. In the participants diagnosed with high-functioning autism, the flow was disorganized in a pattern common to the autistic group, indicating less connectivity and interaction and thus less exchange of information in the network. The researchers repeated the test on another, smaller set of participants, 12 with autism and 7 without, and produced similar results.

These findings imply that autistic brains may operate like a set of computer hardware components that cannot communicate very well with each other while still functioning perfectly well separately. There may be camera that captures a visual image without trouble or a microphone that captures a voice clearly, but the system lacks the network necessary to integrate the two inputs into a unified perception.

The news reports I’ve read on the study make a big deal out the prospect that this imaging breakthrough could lead to earlier diagnosis of autism, something that most experts believe is key to ameliorating some of its negative manifestations. But experts also urge the standard cautious optimism, and rightfully so.

For one thing, the participants in this study were ages 8 to 26, not within the time frame for early diagnosis of autism, and all of them were male. The study findings can’t tell us whether their brains present with these differences as a result of developing with autism, or whether they have autism because their brains are built this way. Before there can be talk of “early diagnosis” and linking these changes to manifestations of autism, we’d need studies showing these differences in much younger children. Further, given the frequent findings of differences between males and females on the spectrum, investigations involving autistic girls and women are necessary.

This study is not the first to use imaging to identify distinctions between autistic and non-autistic people. Other studies have also done so, finding pattern variations in the neuronal tracts of children with autism compared to children without it, in critical areas relevant to the clinical symptoms of autism.

While I find these results intriguing, I note one thing that no one seems to have commented on. In the reports I’ve read about this study, the researchers observe that currently, the only way to diagnose autism is based on a symptom checklist, questionnaires, screenings, and so on—any autism parents reading this will know that drill—and the ultimate call relies on the expertise of the medical professional conducting the evaluations. The implication of these comments is that we need some better, more unequivocal, less-subjective methods of identifying autistic people.

Yet, presumably the autistic boys and men they used for this study were diagnosed using just such subjective evaluation, and their autism diagnoses appear to have been confirmed in 94% of cases by similarities of MRI findings. In my mind, this outcome suggests that the process of subjective evaluation seems to be working pretty well. Of course, we’re a visual species and like our decisions to be given literally in black and white. Such MRI results may fulfill a need that has less to do with correct outcomes than it does with a dose of visual confirmation–and satisfaction.

Update: Belgian "coma man's" "communication" actually facilitated

Man in vegetative state not really communicating

In a follow-up to the post below about communicating in a vegetative state, a new report indicates that the Belgian man whose alleged communications first opened the window to such studies may not have been saying what was attributed to him.  Rom Houben made headlines around the world when researchers reported that in spite of his having been in a vegetative state for many years following a car accident, he appeared to be functioning at a level high enough to perceive and respond mentally to the world around him. In spite of the optimistic headlines, however, some observers expressed skepticism that Houben was doing the communicating.

Facilitated communication a bit too facilitated

As just reported in Der Spiegel, follow-up testing to address lingering questions about the report seems to indicate that Houben likely was not formulating those responses himself. Instead, the speech therapist appears to have been doing the responding. While the physician conducting the original study said that he had already tested for this possibility, further, more stringent tests demonstrated that Houben lacked even the muscle strength to have typed the responses attributed to him. It is not uncommon in facilitated communication for the person doing the facilitating to unconsciously begin communication their own thoughts or perception of the patient’s thoughts.

Not ruling out consciousness

In spite of these findings, because of the results from imaging of activity of Houben’s brain, there is little doubt that he lives in some kind of consciousness. The imaging suggests a level of activity near that of a healthy brain.  Also of interest is the fact that even though Houben didn’t pass the more stringent set of tests, another patient with a comparable diagnosis did. Thus, the quest to determine the magnitude of consciousness, perception, and response in patients diagnosed as “vegetative” continues.

Vegetative state or consciousness?

The brain is a funny thing

Brains are funny things, and neuroscientists are learning more and more every day about the unpredictability of the human brain. While a decade ago, experts might have insisted, based on their standard bedside tests, that a person in a persistent vegetative state could not understand anything being said around them, two recent reports have signaled a shift in the dogmatic wind. The first was the celebrated discovery that a Belgian man, who’d been considered PVS for 23 years after a car accident, emerged from his state and reported having been conscious the entire time. The second, just released, indicates that a small percentage of patients in a persistent vegetative state may not only be conscious but also be able to process questions and answer them accurately. In this latter study (available in full text here), investigators used a technique called functional MRI, which provides an image of the blood flow that occurs to areas of the brain that have become active.

A question of ethics?

These findings raise a number of ethical questions. Some issues of concern center on whether or not these patients might be able to express a wish to live or die, and if so, what the response should be. On a more potentially positive note, doctors suggest that they might be able to ask some presumed PVS patients if they’re experiencing pain and take steps to alleviate it if the answer is yes. Some people may remember the Terry Schiavo case, which raised a number of ethical questions about such conditions and end-of-life issues. In her case, her condition arose from oxygen deprivation. Researchers in the most recent study report that only patients who had experienced traumatic brain injury–rather than oxygen deprivation or blood deprivation–were in the group of patients who seemed able to respond to questions.

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