FMRI and Normal

Recently I was researching functional magnetic resonance imaging, both for a post on this blog and an article that I am writing for The Best Schools blog. I wanted to look at where fMRI has been used in the clinical setting, and was looking through Functional MRI: Basic Principles and Clinical Applications (2006), which was a very helpful book on the subject. Chapter eight was on “Applications of fMRI to Psychiatry.” In several places the chapter kept referring to testing a person with a particular mental disorder compared to a “normal” patient, but the chapter provided neither a quantitatively nor qualitatively definition of normal. I am not sure if I am missing a technical definition here, or if the definition is assumed.

Brain scanning technologies, such as fMRI, are qualitative measurements. This means your readings are meaningless unless you compare them to something else, preferably a baseline from the same patient. For example, the chapter on “FMRI and Clinical Pain” mentions that fMRI is a good tool for measuring acute pain, but is not as helpful for measuring chronic pain. With acute pain, one can take a baseline reading of the patient while not feeling pain. Then by inducing pain, usually through touching the site of acute pain and an image of the brain can be taken showing what parts of the brain became more active when the pain occurred. In this way, doctors might be able to classify the pain or develop a treatment to reduce the pain. Chronic pain is different because doctors cannot take an adequate baseline (no pain) to then study the neurological response to inducing the pain.

The chapter on psychiatry, however, compares patients with autism spectrum disorder, or attention deficit disorder, or schizophrenia, or manic depression or obsessive compulsive disorder with brain scans of normal patients. Since this technique relies on a baseline for meaningful information, the lack of clarity on what is meant by “normal” makes it difficult to interpret.

Now, I am not saying that the author of this chapter is a eugenicist, nor am I saying that the field of psychiatry is bunk. Furthermore, I am not saying these issues do not having a neurological component to them.  I, actually, am concerned with scientific method here: Are researchers able to obtain meaningful data from these scans when the baseline is 1) a different person from the patient (similar to chronic pain), and 2) is seemingly subjective?

To the authors’ credit, they do point out that as of now “the clinical utility of fMRI to patients has thus far been limited, as no findings have been shown to be diagnostically specific for any psychiatric illness or treatment. Although many hospitals and research facilities complete MRI on psychiatric patients, this information cannot, as yet, be used reliably to generate a psychiatric diagnosis; however scans often are used to rule out the presence of a neurological illness” (185). They seem to be careful not to overstate their case. This is careful science, which is good, but the issue is what is meant by the comparison to normal.

(By the way, neuroscience is an active field. If new research has come out about diagnosing psychiatric disorders, please let us know in the comments section.)

I do not want to make the mistake of quote hunting especially because the chapter is very thorough, but I did want to give a sampling of what I mean by comparing to a “normal” subject. Some of the findings are reasonable, but with others, it seems like the only conclusion that can be drawn is this person’s brain is responding differently from this other person.

Autism spectrum disorder (ASD):

Functional MRI research on autism, although limited, has illustrated that individuals diagnosed with autistic disorder demonstrate an alternate method of facial processing when compared to normal healthy control subjects… In contrast to control subjects, when autistic individuals were asked to respond with a button press to determine the emotion of a facial photograph, they again showed no activation in the left amygdalahippocampal region and left cerebellum. (186)

The patients were people who were diagnosed with ASD and are compared with “normal healthy control subjects” that I am assuming are normal and healthy because they not diagnosed with ASD or any other disorder that would qualify as a mental disorder. This was not stated, specifically, though.

Schizophrenia

Because of the severity of schizophrenia, much fMRI research has been devoted to it. One study that did seem helpful was looking at a patient with schizophrenia before medication treatments, and then after a course of treatment. In this case, the baseline is the patient, himself, so a comparison can be made. Even so, the drug was assumed to be working because the patient’s fMRI looked more similar to the control subjects.

“Mood Disorders”

Depression and bipolar disorder studies are limited because of difficulties with diagnosis. However, studies that have been done have been conducted compared to “nonpsychiatric populations.” This apparently means people that do not meet the criteria for depression, bipolar disorder, or any other psychological disorder.

Certainly there are people who are affected by any of these psychological disorders, and surely many of these disorders have a neurological component. However, I am uncertain how helpful an analytical technique that relies on comparative studies, particularly comparisons to an accepted, yet undefined “normal,” really is for understanding a disorder.

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Thomas
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Thomas

Is autism a psychological disorder?

Danielle
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Nice post which then by inducing pain, usually through touching the site of acute pain and an image of the brain can be taken showing what parts of the brain became more active when the pain occurred. In this way, doctors might be able to classify the pain or develop a treatment to reduce the pain. Chronic pain is different because doctors cannot take an adequate baseline to then study the neurological response to inducing the pain. Thanks a lot for posting.

Rick
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No, Thomas Autism is not a psychological disorder.